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Sample records for jri tamm kutsub

  1. Tamm-Langmuir surface waves

    NASA Astrophysics Data System (ADS)

    Golenitskii, K. Â. Yu.; Koshelev, K. Â. L.; Bogdanov, A. Â. A.

    2016-10-01

    In this work we develop a theory of surface electromagnetic waves localized at the interface of periodic metal-dielectric structures. We have shown that the anisotropy of plasma frequency in metal layers lifts the degeneracy of plasma oscillations and opens a series of photonic band gaps. This results in appearance of surface waves with singular density of states—we refer to them as Tamm-Langmuir waves. Such naming is natural since we have found that their properties are very similar to the properties of both bulk Langmuir and surface Tamm waves. Depending on the anisotropy parameters, Tamm-Langmuir waves can be either forward or backward waves. Singular density of states and high sensitivity of the dispersion to the anisotropy of the structure makes Tamm-Langmuir waves very promising for potential applications in nanophotonics and biosensing.

  2. Tamm states in electron plasma

    NASA Astrophysics Data System (ADS)

    2013-11-01

    Researchers have fabricated a voltage-tunable plasmonic crystal in a two-dimensional electron gas that operates at terahertz frequencies. Nature Photonics spoke to Eric Shaner, Greg Dyer and Greg Aizin about the observation of Tamm states at the crystal's edge.

  3. Tamm plasmon polaritons in multilayered cylindrical structures

    NASA Astrophysics Data System (ADS)

    Little, C. E.; Anufriev, R.; Iorsh, I.; Kaliteevski, M. A.; Abram, R. A.; Brand, S.

    2012-12-01

    It is shown that cylindrical Bragg reflector structures with either a metal core, a metal cladding, or both can support Tamm plasmon polaritons (TPPs) that can propagate axially along the interface between the metallic layer and the adjacent dielectric. A transfer matrix formalism for cylindrical multilayered structures is used in association with cavity phase matching considerations to design structures that support Tamm plasmon polaritons at specified frequencies, and to explore the field distributions and the dispersion relations of the excitations. The cylindrical TPPs can exist in both the TE and TM polarizations for the special cases of modes with either azimuthal isotropy or zero axial propagation constant and also as hybrid cylindrical modes when neither of those conditions applies. In the cases considered the TPPs have low effective masses and low group velocities. Also, when there is both metallic core and cladding, near degenerate modes localized at each metallic interface can couple to produce symmetric and antisymmetric combinations whose frequency difference is in the terahertz regime.

  4. Fluorescence of semiconductor nanocrystals coupled to optical Tamm cavities

    NASA Astrophysics Data System (ADS)

    Feng, Fu; Pascale Senellart Team; Benoit Dubertret Team; Agnes Maitre Team

    We describe here the photoluminescence properties of a layer of colloidal CdSe/CdS fluorescent nanocrystals embedded in such a Tamm cavity. Spectral and angular analysis of fluorescence shows that the nanocrystals emission is into the Tamm states ; the emission dispersion relation for disks of various diameters shows the effect of the Tamm states lateral confinement. We also combined spatial and angular emission analysis and showed that the direction of emission is not the same for different points on a disk: emission from the left (resp. right) portion of the cavity is directed mostly in the left (resp. right) direction, in agreement with our numerical simulations. Our measurement scheme constitutes a probe of the Tamm state electric field phase gradient inside the cavity. Spatial and K space resolved spectroscopy.

  5. Deeply subwavelength electromagnetic Tamm states in graphene metamaterials

    NASA Astrophysics Data System (ADS)

    Smirnova, Daria; Buslaev, Pavel; Iorsh, Ivan; Shadrivov, Ilya V.; Belov, Pavel A.; Kivshar, Yuri S.

    2014-06-01

    We study localized modes at a surface of a multilayer structure made of graphene layers separated by dielectric layers. We demonstrate the existence of deeply subwavelength surface modes that can be associated with the electromagnetic Tamm states, with the frequencies in the THz frequency range the negative group velocities. We suggest that the dispersion properties of these Tamm surface modes can be tuned by varying the thickness of a dielectric cap layer.

  6. Emission of Tamm plasmon/exciton polaritons

    NASA Astrophysics Data System (ADS)

    Symonds, C.; Lemaître, A.; Homeyer, E.; Plenet, J. C.; Bellessa, J.

    2009-10-01

    We report on the observation of the strong coupling regime occurring between a Tamm plasmon (TP) mode and an exciton from inorganic quantum wells (QWs). The sample is formed by a silver thin film deposited onto an AlAs/GaAlAs Bragg reflector containing InGaAs QWs located in the high refractive index layers. Angular resolved reflectometry experiments evidence a clear anticrossing in the dispersion relations, a signature of the strong coupling regime. The Rabi splitting energy is 11.5 meV. The experimental data are in very good agreement with simple transfer matrix calculations. The emission from low and high energy TP/exciton polaritons is also demonstrated.

  7. Tamm plasmon-polaritons: First experimental observation

    NASA Astrophysics Data System (ADS)

    Sasin, M. E.; Seisyan, R. P.; Kaliteevski, M. A.; Brand, S.; Abram, R. A.; Chamberlain, J. M.; Iorsh, I. V.; Shelykh, I. A.; Egorov, A. Yu.; Vasil'ev, A. P.; Mikhrin, V. S.; Kavokin, A. V.

    2010-01-01

    We report on the first experimental observation of Tamm plasmon-polaritons (TPP) formed at the interface between a metal and a dielectric Bragg reflector (DBR). Contrary to conventional surface plasmons, TPPs have an in-plane wave vector less than the wave vector of light in vacuum, which allows for their direct optical excitation, and can be formed in both the TE and TM polarizations. The angular resolved reflectivity and transmission spectra of a GaAs/AlAs DBR covered by Au films of various thicknesses show the resonances associated with the TPP at low temperatures and at room temperature. The in-plane dispersion of TTPs is parabolic with an effective mass 4×10-5 of the free electron mass.

  8. Strong coupling between Tamm plasmon and QW exciton

    NASA Astrophysics Data System (ADS)

    Homeyer, Estelle; Symonds, Clémentine; Lemaître, Aristide; Plenet, Jean-Claude; Bellessa, Joel

    2011-03-01

    We report on the strong coupling between a Tamm plasmon mode and excitons from inorganic quantum wells. The sample is formed by an AlAs/GaAlAs Bragg reflector containing InGaAs QWs in its high refractive index layers, on top of which a thin silver film is deposited. Angle resolved reflectometry experiments at low temperature (77 K) show a clear anticrossing in the dispersion relations, evidencing the strong coupling regime. The Rabi splitting amounts to 11.5 meV. Emission from low and high energy Tamm plasmon/exciton polaritons is also demonstrated. Experimental data are in very good agreement with transfer matrix simulations.

  9. Tamm-Horsfall glycoprotein and calcium nephrolithiasis.

    PubMed

    Hess, B

    1994-01-01

    Available data on the effects of Tamm-Horsfall glycoprotein (THP) on calcium oxalate crystallization processes are apparently conflicting. With the main emphasis on calcium oxalate crystal aggregation, this review demonstrates that THP has a dual role as a modifier of crystal aggregation: in solutions with high pH, low ionic strength (IS) and low concentrations of calcium and THP itself, the glycoprotein acts as a powerful inhibitor of calcium oxalate crystal aggregation. Conversely, low pH, high IS and high concentrations of calcium and THP all favor self-aggregation of THP molecules which lowers their inhibitory activity against calcium oxalate crystal aggregation. Some patients with severely recurrent Ca stone disease excrete abnormal THPs which self-aggregate at levels of pH, IS and concentrations of Ca and THP at which normal THPs remain in monomeric form. With high Ca concentrations, such abnormal THPs become strong promoters of crystal aggregation, since conformational changes in crystal-bound THP molecules induce strong viscous binding forces which overcome repulsive electrostatic surface charges. By chelating free Ca ions, citrate reduces self-aggregation of THP molecules and turns promoting THPs into inhibitors of calcium oxalate crystal aggregation.

  10. Tamm State-Coupled Emission: Effect of Probe Location and Emission Wavelength

    PubMed Central

    2015-01-01

    We report the effect of the probe location and wavelength on the emission spatial distribution and spectral properties of fluorophores located on structures which display Tamm states. Our structure consists of a one-dimensional photonic crystal (1DPC)—that is, a multilayer structure of alternate high and low refractive index dielectrics—and a thin top silver film. Simulations show the presence of Tamm and surface plasmon modes in the structure. The electric field intensities for the Tamm modes are located mostly in the dielectric layer below the metal film. The corresponding field intensities for the surface plamon modes are located above the metal film in the distal side. Tamm states can be in resonance with the incident light normal or near normal to the surface, within the light line, and can be accessed without the use of a coupling prism or gratings. We investigated the emission spectra and angular distribution of the emission for probes located above and below the metal film to explore the interaction of fluorophores with Tamm plasmons and surface plasmons modes. Three probes were chosen with different overlap of the emission spectra with the Tamm modes. The fluorophores below the metal film coupled predominantly with the Tamm state and displayed more intense and only Tamm state-coupled emission (TSCE). Probes above the metal film display both surface plasmon-coupled emission (SPCE) and Tamm state-coupled emission. In contrast to SPCE, which shows only KR, P-polarized emission, the Tamm states can display both S- and P-polarized emission and can be populated using both RK and KR illuminations. The TSCE angle is highly sensitive to wavelength, which suggests the use of Tamm structures to provide both directional emission and wavelength dispersion. The combination of plasmonic and photonic structures with directional emission close to surface normal offers the opportunities for new design formats for clinical testing, portable devices, and other

  11. Hybrid states of Tamm plasmons and exciton-polaritons

    NASA Astrophysics Data System (ADS)

    Kaliteevski, M.; Brand, S.; Abram, R. A.; Iorsh, I.; Kavokin, A. V.; Liew, T. C. H.; Shelykh, I. A.

    2011-03-01

    We have demonstrated theoretically that it is possible to use the resonant coupling of exciton-polaritons in a planar microcavity and Tamm plasmons at a metal film on the surface of the structure to provide lateral spatial control of the exciton-polaritons within the cavity. The resonant coupling of the Tamm plasmons to cavity exciton-polaritons results in a triplet of hybrid plasmon-exciton-polariton modes with the lowest at a significantly lower energy than that of the unperturbed exciton-polaritons. Further, a patterned metal film on the structure surface can provide a sufficiently large lateral modulation of the excitation energy that localization of the exciton-polaritons within chosen regions of the cavity is possible. We show how the approach opens the way to a practical demonstration of polariton channels, traps, and devices, including logic gates.

  12. Projected BCS-Tamm-Dancoff approximation with blocking effect

    NASA Astrophysics Data System (ADS)

    Dias, H.; Krmpotić, F.

    1982-05-01

    The blocking effect is introduced through a canonical transformation in the projected BCS-Tamm-Dancoff approximation. It is suggested that the blocking effect may play an important role in the description of the low-lying states in odd-mass nuclei. Present address: Departamento de Física, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 1900 La Plata, Argentina. Member of Carrera de Investigador Científico, CONICET, Argentina. Sponsored by Financiadora de Estudos e Projetos (FINEP), Brasil.

  13. Hybrid states of Tamm plasmons and exciton polaritons

    NASA Astrophysics Data System (ADS)

    Kaliteevski, M.; Brand, S.; Abram, R. A.; Iorsh, I.; Kavokin, A. V.; Shelykh, I. A.

    2009-12-01

    Channeling of exciton polaritons in the plane of semiconductor microcavities can be achieved by the deposition of metallic mesas on the top of the semiconductor structure. We show theoretically that the regime of strong coupling between cavity polaritons and Tamm surface plasmons is possible in such structures. The effect is favorable for the spatial confinement of polaritons and the formation of hybrid one-dimensional plasmon-polariton modes.

  14. Hybrid states of Tamm plasmons and exciton polaritons

    SciTech Connect

    Kaliteevski, M.; Brand, S.; Abram, R. A.; Iorsh, I.; Kavokin, A. V.; Shelykh, I. A.

    2009-12-21

    Channeling of exciton polaritons in the plane of semiconductor microcavities can be achieved by the deposition of metallic mesas on the top of the semiconductor structure. We show theoretically that the regime of strong coupling between cavity polaritons and Tamm surface plasmons is possible in such structures. The effect is favorable for the spatial confinement of polaritons and the formation of hybrid one-dimensional plasmon-polariton modes.

  15. Femtosecond dynamics of Tamm plasmon-polaritons (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Afinogenov, Boris I.; Popkova, Anna A.; Bessonov, Vladimir O.; Fedyanin, Andrey A.

    2016-09-01

    Tamm plasmon-polaritons (TPPs) have attracted many interest due to the peculiarities of their optical properties. TPPs are optical surface states, which can be excited at the boundary of distributed Bragg reflector and metal film. Like in case of surface plasmon-polaritons or surface electromagnetic waves excitation, the emergence of the TPP leads to the localization of the electromagnetic field near the DBR/metal interface. Experimentally, TPP can be detected by a narrow resonance in reflectance or transmittance spectrum of the DBR/metal structure. Tamm plasmon-polaritons were proposed to be used in several types of novel optical elements, such as sensors and lasers. It was also shown that TPPs can be effectively coupled with other localized states like surface plasmons and microcavity modes. In this contribution the direct measurements of the Tamm plasmon-polariton relaxation dynamics are presented. The lifetime of the TPP in one-dimensional photonic crystal is estimated experimentally and compared to the results of numerical calculations. The dependence of the lifetime on the angle of incidence and duration of the incident pulse is supported by numerical studies performed with the finite difference time-domain technique.

  16. Observation of a hybrid state of Tamm plasmons and microcavity exciton polaritons.

    PubMed

    Rahman, Sk Shaid-Ur; Klein, Thorsten; Klembt, Sebastian; Gutowski, Jürgen; Hommel, Detlef; Sebald, Kathrin

    2016-10-04

    We present evidence for the existence of a hybrid state of Tamm plasmons and microcavity exciton polaritons in a II-VI material based microcavity sample covered with an Ag metal layer. The bare cavity mode shows a characteristic anticrossing with the Tamm-plasmon mode, when microreflectivity measurements are performed for different detunings between the Tamm plasmon and the cavity mode. When the Tamm-plasmon mode is in resonance with the cavity polariton four hybrid eigenstates are observed due to the coupling of the cavity-photon mode, the Tamm-plasmon mode, and the heavy- and light-hole excitons. If the bare Tamm-plasmon mode is tuned, these resonances will exhibit three anticrossings. Experimental results are in good agreement with calculations based on the transfer matrix method as well as on the coupled-oscillators model. The lowest hybrid eigenstate is observed to be red shifted by about 13 meV with respect to the lower cavity polariton state when the Tamm plasmon is resonantly coupled with the cavity polariton. This spectral shift which is caused by the metal layer can be used to create a trapping potential channel for the polaritons. Such channels can guide the polariton propagation similar to one-dimensional polariton wires.

  17. Observation of a hybrid state of Tamm plasmons and microcavity exciton polaritons

    PubMed Central

    Rahman, SK. Shaid-Ur; Klein, Thorsten; Klembt, Sebastian; Gutowski, Jürgen; Hommel, Detlef; Sebald, Kathrin

    2016-01-01

    We present evidence for the existence of a hybrid state of Tamm plasmons and microcavity exciton polaritons in a II-VI material based microcavity sample covered with an Ag metal layer. The bare cavity mode shows a characteristic anticrossing with the Tamm-plasmon mode, when microreflectivity measurements are performed for different detunings between the Tamm plasmon and the cavity mode. When the Tamm-plasmon mode is in resonance with the cavity polariton four hybrid eigenstates are observed due to the coupling of the cavity-photon mode, the Tamm-plasmon mode, and the heavy- and light-hole excitons. If the bare Tamm-plasmon mode is tuned, these resonances will exhibit three anticrossings. Experimental results are in good agreement with calculations based on the transfer matrix method as well as on the coupled-oscillators model. The lowest hybrid eigenstate is observed to be red shifted by about 13 meV with respect to the lower cavity polariton state when the Tamm plasmon is resonantly coupled with the cavity polariton. This spectral shift which is caused by the metal layer can be used to create a trapping potential channel for the polaritons. Such channels can guide the polariton propagation similar to one-dimensional polariton wires. PMID:27698359

  18. Observation of a hybrid state of Tamm plasmons and microcavity exciton polaritons

    NASA Astrophysics Data System (ADS)

    Rahman, Sk. Shaid-Ur; Klein, Thorsten; Klembt, Sebastian; Gutowski, Jürgen; Hommel, Detlef; Sebald, Kathrin

    2016-10-01

    We present evidence for the existence of a hybrid state of Tamm plasmons and microcavity exciton polaritons in a II-VI material based microcavity sample covered with an Ag metal layer. The bare cavity mode shows a characteristic anticrossing with the Tamm-plasmon mode, when microreflectivity measurements are performed for different detunings between the Tamm plasmon and the cavity mode. When the Tamm-plasmon mode is in resonance with the cavity polariton four hybrid eigenstates are observed due to the coupling of the cavity-photon mode, the Tamm-plasmon mode, and the heavy- and light-hole excitons. If the bare Tamm-plasmon mode is tuned, these resonances will exhibit three anticrossings. Experimental results are in good agreement with calculations based on the transfer matrix method as well as on the coupled-oscillators model. The lowest hybrid eigenstate is observed to be red shifted by about 13 meV with respect to the lower cavity polariton state when the Tamm plasmon is resonantly coupled with the cavity polariton. This spectral shift which is caused by the metal layer can be used to create a trapping potential channel for the polaritons. Such channels can guide the polariton propagation similar to one-dimensional polariton wires.

  19. Tamm-Hubbard surface states in the continuum.

    PubMed

    Longhi, S; Della Valle, G

    2013-06-12

    In the framework of the Bose-Hubbard model, we show that two-particle surface bound states embedded in the continuum (BIC) can be sustained at the edge of a semi-infinite one-dimensional tight-binding lattice for any infinitesimally-small impurity potential V at the lattice boundary. Such thresholdless surface states, which can be referred to as Tamm-Hubbard BIC states, exist provided that the impurity potential V is attractive (repulsive) and the particle-particle Hubbard interaction U is repulsive (attractive), i.e. for UV < 0.

  20. Tamm plasmon polaritons: Slow and spatially compact light

    NASA Astrophysics Data System (ADS)

    Sasin, M. E.; Seisyan, R. P.; Kalitteevski, M. A.; Brand, S.; Abram, R. A.; Chamberlain, J. M.; Egorov, A. Yu.; Vasil'ev, A. P.; Mikhrin, V. S.; Kavokin, A. V.

    2008-06-01

    We report on the first experimental observation of Tamm plasmon polaritons (TPPs) formed at the interface between a metal and a dielectric Bragg reflector (DBR). In contrast to conventional surface plasmons, TPPs have an in-plane wavevector less than the wavevector of light in vacuum, which allows for their direct optical excitation. The angular resolved reflectivity and transmission spectra of a GaAs /AlAs DBR covered by Au films of various thicknesses show the resonances associated with the TPP at low temperatures and room temperature. The in-plane dispersion of TTPs is parabolic with an effective mass of 4×10-5 of the free electron mass.

  1. Electro optical tuning of Tamm-plasmon exciton-polaritons

    NASA Astrophysics Data System (ADS)

    Gessler, J.; Baumann, V.; Emmerling, M.; Amthor, M.; Winkler, K.; Höfling, S.; Schneider, C.; Kamp, M.

    2014-11-01

    We report on electro optical tuning of the emission from GaAs quantum wells resonantly coupled to a Tamm-plasmon mode in a hybrid metal/dielectric structure. The structures were studied via momentum resolved photoluminescence and photoreflectance spectroscopy, and the surface metal layer was used as a top gate, which allowed for a precise tuning of the quantum well emission via the quantum confined Stark effect. By tuning the resonance, we were able to observe the characteristic anticrossing behavior of a polaritonic emission in the strong light-matter coupling regime, yielding a Rabi splitting of (9.2 ± 0.2) meV.

  2. Measurements of the femtosecond relaxation dynamics of Tamm plasmon-polaritons

    NASA Astrophysics Data System (ADS)

    Afinogenov, B. I.; Popkova, A. A.; Bessonov, V. O.; Fedyanin, A. A.

    2016-10-01

    This paper reports on measurements of the lifetime of Tamm plasmon-polaritons (TPPs) excited in a 1D photonic-crystal/thin-metal-film structure. A femtosecond pulse reflected from a structure of this kind is found to be significantly distorted if its spectrum overlaps with the Tamm plasmon resonance. It is shown that the TPP lifetime possesses strong polarization and angular dependence. It varies from 20 fs for p-polarized light to 40 fs for s-polarized light at a 45° angle of incidence. The reported lifetime of Tamm plasmons is several times smaller than the previously reported lifetime of surface plasmons.

  3. Transforming Fabry-Pérot resonances into a Tamm mode

    NASA Astrophysics Data System (ADS)

    Durach, Maxim; Rusina, Anastasia

    2012-12-01

    We propose an optical structure composed of two metal nanolayers enclosing a distributed Bragg reflector (DBR) mirror. The structure is an open photonic system whose bound modes are coupled to external radiation. We apply the special theoretical treatment based on inversion symmetry of the structure to classify its resonances. We show that the structure supports resonances transitional between Fabry-Pérot modes and Tamm plasmons. When the dielectric contrast of the DBR is removed these modes are a pair of conventional Fabry-Pérot resonances. They spectrally merge into a Tamm mode at high contrast. The optical properties of the structure in the frequency range of the DBR stop band, including highly beneficial 50% transmittivity through thick structures with sub-skin-depth metal films, are determined by the hybrid quasinormal modes of the open nonconservative structure under consideration. The results can find a broad range of applications in photonics and optoelectronics, including the possibility of coherent control over optical fields in the class of structures similar to the one proposed here.

  4. Shift happens: optical sensing with Dyakonov-Tamm waves

    NASA Astrophysics Data System (ADS)

    Lakhtakia, Akhlesh; Faryad, Muhammad

    2014-08-01

    An optical modality to sense a fluid by exploiting Dyakonov-Tamm (DT) waves was devised. In the modality, the fluid is present on both sides of the guiding interface. Theory showed that the angular location of reflectance dip in a practically implementable configuration will shift if the refractive index of the fluid changes. Furthermore, the detection sensitivity will decrease as the refractive index of the fluid increases over a wide range, and should be comparable to that for sensing modalities that exploit surface-plasmon-polariton (SPP) waves. Higher sensitivities are available with DT waves than with SPP waves, and the DT-wave-based sensor should be simpler to fabricate than the SPP-wave-based sensor. Multiple DT waves are excitable at the same frequency, leading to multiple channels for more reliable sensing as well as for sensing multiple analytes simultaneously.

  5. Theory of optical sensing with Dyakonov-Tamm waves

    NASA Astrophysics Data System (ADS)

    Lakhtakia, Akhlesh; Faryad, Muhammad

    2014-01-01

    An optical modality to sense a fluid by exploiting Dyakonov-Tamm (DT) waves was devised. In the modality, the fluid is present on both sides of the guiding interface. Theoretical analysis indicated that the angular location of the reflectance dip in a practically implementable configuration will shift if the refractive index of the fluid changes. Furthermore, the detection sensitivity will decrease as the refractive index of the fluid increases over a wide range, and should be comparable to that for sensing modalities that exploit surface-plasmon-polariton (SPP) waves. Higher sensitivities are available with DT waves than with SPP waves, and the DT-wave-based sensor should be simpler to fabricate than the SPP-wave-based sensor. Multiple DT waves are excitable at the same frequency, leading to multiple channels for more reliable sensing as well as for sensing multiple analytes simultaneously.

  6. Direct excitation of the Tamm plasmon-polaritons on a dielectric Bragg reflector coated with a metal film

    NASA Astrophysics Data System (ADS)

    Zhu, Y.-G.; Hu, W.-L.; Fang, Y.-T.

    2013-09-01

    Tamm plasmon-polariton is a surface state or surface wave formed at the boundary between a metal and a dielectric Bragg reflector. In order to directly excite the Tamm plasmon-polaritons with unit transmission, we design a structure of Bragg reflector coated with a metal film. Through the Bloch theorem of periodic structures and transfer matrix method, we deduce the existence conditions of the Tamm plasmon-polaritons. For a a finite structure, the Tamm plasmon-polaritons can be excited, which is dependent on the thickness of metal, the period number of the Bragg reflector, the incident direction and frequency. On proper conditions, a perfect transmission for the Tamm plasmon-polariton mode can be achieved without the use of attenuated total reflection prism coupling or diffraction grating.

  7. Efficient out-coupling and beaming of Tamm optical states via surface plasmon polariton excitation

    SciTech Connect

    Lopez-Garcia, M.; Ho, Y.-L. D.; Taverne, M. P. C.; Chen, L.-F.; Rarity, J. G.; Oulton, R.; Murshidy, M. M.; Edwards, A. P.; Adawi, A. M.; Serry, M. Y.

    2014-06-09

    We present evidence of optical Tamm states to surface plasmon polariton (SPP) coupling. We experimentally demonstrate that for a Bragg stack with a thin metal layer on the surface, hybrid Tamm-SPP modes may be excited when a grating on the air-metal interface is introduced. Out-coupling via the grating to free space propagation is shown to enhance the transmission as well as the directionality and polarization selection for the transmitted beam. We suggest that this system will be useful on those devices, where a metallic electrical contact as well as beaming and polarization control is needed.

  8. Efficient out-coupling and beaming of Tamm optical states via surface plasmon polariton excitation

    NASA Astrophysics Data System (ADS)

    Lopez-Garcia, M.; Ho, Y.-L. D.; Taverne, M. P. C.; Chen, L.-F.; Murshidy, M. M.; Edwards, A. P.; Serry, M. Y.; Adawi, A. M.; Rarity, J. G.; Oulton, R.

    2014-06-01

    We present evidence of optical Tamm states to surface plasmon polariton (SPP) coupling. We experimentally demonstrate that for a Bragg stack with a thin metal layer on the surface, hybrid Tamm-SPP modes may be excited when a grating on the air-metal interface is introduced. Out-coupling via the grating to free space propagation is shown to enhance the transmission as well as the directionality and polarization selection for the transmitted beam. We suggest that this system will be useful on those devices, where a metallic electrical contact as well as beaming and polarization control is needed.

  9. Unconventional optical Tamm defect states in metal-terminated opal photonic crystals

    NASA Astrophysics Data System (ADS)

    Korovin, Alexander V.; Romanov, Sergei G.

    2016-04-01

    Optical Tamm surface states are formed in 3-dimensional photonic crystals coated by thin metal films. These states appear in registry with diffraction resonances and localize the electromagnetic energy in resonators formed by diffraction mirrors of lattice planes and metal semishells. Tamm defect states provide the bypass for light in the spectral range of photonic stop-bands and thus reduce the efficiency of the Bragg diffraction resonances. In spite of hidden nature of this effect, its magnitude is comparable to the extraordinary transmission associated with tunneling of surface plasmon polaritons, which are simultaneously excited at surfaces of corrugated metal film coating.

  10. Unconventional optical Tamm states in metal-terminated three-dimensional photonic crystals

    NASA Astrophysics Data System (ADS)

    Korovin, Alexander V.; Romanov, Sergei G.

    2016-03-01

    Unconventional optical Tamm surface states have been demonstrated in transmission and reflectance spectra of three-dimensional opal photonic crystals coated by thin metal films. These states appear in registry with diffraction resonances and localize the electromagnetic energy in asymmetric resonators formed by stacks of lattice planes and metal semishells. Tamm defect states provide the bypass for light at the edges of the Bragg diffraction resonances and thus reduce the diffraction efficiency. Despite the hidden nature of this effect, its magnitude is comparable to the extraordinary transmission associated with the surface-plasmon polaritons that are simultaneously excited at the surfaces of the corrugated metal films.

  11. Second-harmonic generation enhancement in the presence of Tamm plasmon-polaritons.

    PubMed

    Afinogenov, B I; Bessonov, V O; Fedyanin, A A

    2014-12-15

    Resonant enhancement of second-harmonic generation (SHG) intensity from a thin metal film is demonstrated in a Tamm plasmon-polariton mode excited at a metal/photonic crystal interface using nonlinear spectroscopy. Nonlinear effects enhancement in proposed structures exhibit strong polarization dependence (1:200 for the orthogonal fundamental polarizations). SHG enhancement factor evinces considerable angular dependence, rising from 50 for the 45° angle of incidence to 170 for the 10° angle of incidence. The results are analyzed numerically using a nonlinear transfer matrix technique. The findings elucidate the potential of Tamm plasmon-polaritons in the nonlinear optical applications.

  12. Planar Hot-Electron Photodetection with Tamm Plasmons.

    PubMed

    Zhang, Cheng; Wu, Kai; Giannini, Vincenzo; Li, Xiaofeng

    2017-02-28

    There is an increasing interest in harvesting photoejected hot-electrons for sensitive photodetectors, which have highly tunable detection wavelengths controlled by structural engineering rather than the classic doped semiconductors. However, the widely employed metallic nanostructures that excite surface plasmons (SPs) to enhance the photoemission of hot-electrons are usually complex with a high fabrication challenge. Here, we present a purely planar hot-electron photodetector based on Tamm plasmons (TPs) by introducing a distributed Bragg reflector integrated with hot-electron collection layers in metal/semiconductor/metal configuration. Results show that the light incidence can be strongly confined in the localized region between the top metal and the adjacent dielectric layer due to the excitation of TP resonance so that more than 87% of the light incidence can be absorbed by the top metal layer. This enables a strong and unidirectional photocurrent and a photoresponsivity that can even be higher than that of the conventional nanostructured system. Moreover, the planar TP system shows a narrow-band resonance with high tunability, good resistance against the change of the incident angle, and the possibility for extended functionalities. The proposed TP-based planar configuration significantly simplifies the conventional SP-based systems and opens the pathway for high-performance, low-cost, hot-electron photodetection.

  13. Dyakonov-Tamm waves guided by the interface between two structurally chiral materials that differ only in handedness

    SciTech Connect

    Gao Jun; Lakhtakia, Akhlesh; Lei Mingkai

    2010-01-15

    The boundary-value problem of the propagation of Dyakonov-Tamm waves guided by the planar interface between two structurally chiral materials that are identical except for structural handedness was formulated and numerically solved. Detailed analysis showed that either two or three different Dyakonov-Tamm waves can propagate. These waves have different phase speeds and degrees of localization to the interface with a sudden handedness change. The most localized Dyakonov-Tamm waves are essentially confined to within a small number of structural periods of the interface on either side.

  14. Tunable coupled states of a pair of Tamm plasmon polaritons and a microcavity mode

    NASA Astrophysics Data System (ADS)

    Fang, Yun-tuan; Yang, Li-xia; Kong, Wa; Zhu, Na

    2013-12-01

    The coupled states of a pair of Tamm plasmon polaritons and a microcavity mode are studied through the transfer matrix method in a metal-Bragg reflectors-cavity-Bragg reflectors-metal configuration. The properties of coupled states can be adjusted through the cavity thickness, but there is one coupled state for which the frequency remains the same as for the uncoupled Tamm plasmon polariton and independent of the cavity thickness. When the frequency of the uncoupled cavity mode is equal to that of the bare Tamm plasmon polariton, an anticrossing behavior with the most intense coupling occurs. There are three coupled modes with antisymmetry coupling and symmetry coupling in the anticrossing region. As cavity thickness increases, two coupled modes are degenerated into one state with frequency equal to that of the bare Tamm plasmon polariton. The third lower coupled mode and the uncoupled cavity mode are merged into one frequency by steps, but a huge amplification of field occurs in the cavity with the coupled mode. An analytical description is in good agreement with the numerical results.

  15. Radiative Decay Engineering 7: Tamm State-Coupled Emission Using a Hybrid Plasmonic-Photonic Structure

    PubMed Central

    Badugu, Ramachandram; Descrovi, Emiliano; Lakowicz, Joseph R.

    2014-01-01

    There is a continuing need to increase the brightness and photostability of fluorophores for use in biotechnology, medical diagnostics and cell imaging. One approach developed during the past decade is to use metallic surfaces and nanostructures. It is now known that excited state fluorophores display interactions with surface plasmons, which can increase the radiative decay rates, modify the spatial distribution of emission and result in directional emission. One important example is Surface Plasmon-Coupled Emission (SPCE). In this phenomenon the fluorophores at close distances from a thin metal film, typically silver, display emission over a small range of angles into the substrate. A disadvantage of SPCE is that the emission occur at large angles relative to the surface normal, and at angles which are larger than the critical angle for the glass substrate. The large angles make it difficult to collect all the coupled emission and have prevented use of SPCE with high-throughput and/or array applications. In the present report we describe a simple multi-layer metal-dielectric structure which allows excitation with light that is perpendicular (normal) to the plane and provides emission within a narrow angular distribution that is normal to the plane. This structure consist of a thin silver film on top of a multi-layer dielectric Bragg grating, with no nanoscale features except for the metal or dielectric layer thicknesses. Our structure is designed to support optical Tamm states, which are trapped electromagnetic modes between the metal film and the underlying Bragg grating. We used simulations with the transfer matrix method to understand the optical properties of Tamm states and localization of the modes or electric fields in the structure. Tamm states can exist with zero in-plane wavevector components and can be created without the use of a coupling prism. We show that fluorophores on top of the metal film can interact with the Tamm state under the metal film

  16. Observation of hybrid state of Tamm and surface plasmon-polaritons in one-dimensional photonic crystals

    NASA Astrophysics Data System (ADS)

    Afinogenov, B. I.; Bessonov, V. O.; Nikulin, A. A.; Fedyanin, A. A.

    2013-08-01

    Experimental observation of hybrid mode of Tamm plasmon-polariton and surface plasmon-polariton is reported. The hybrid state is excited in one-dimensional photonic crystal terminated by semitransparent metal film under conditions of total internal reflection for transverse-magnetic-polarized light. Coupling between Tamm and surface plasmon-polaritons leads to repulsion of their dispersion curves controlled by metal film thickness.

  17. Glycoprotein biosynthesis in calf kidney. Glycoprotein sialyltransferase activities towards serum glycoproteins and calf Tamm-Horsfall glycoprotein.

    PubMed

    van Dijk, W; Lasthuis, A M; van den Eijnden, D H

    1979-04-18

    CMP-AcNeu:glycoprotein sialyltransltransltransltransltransferase of calf kidney cortex was characterized using serum glycoproteins and Tamm-Horsfall glycoprotein, obtained from calf urine, as acceptors. Native calf Tamm-Horsfall glycoprotein showed the best acceptor properties, followed by desialylated calf fetuin and desialylated human alpha 1-acid glycoprotein exhibiting V values of, respectively, 114, 63 and 41 nmol/h per g wet wt. of kidney cortex and Km values of 0.12, 0.16 and 0.26 mM glycoprotein acceptor. Desialylated ovine submaxillary mucine appeared to be a very poor acceptor. Tamm-Horsfall glycoprotein sialyltransferase could be distinguished from serum glycoprotein sialyltransferase by competition studies. In addition the two glycoprotein sialyltransferase activities showed different distributions over the three regions of the calf kidney: the ratios of the Tamm-Horsfall to serum glycoprotein sialyltransferase activities decreased from 3.3 in the cortex to 0.8 and 0.4 in the medulla and the papilla, respectively. It was concluded that in calf kidney at least two different sialyltransferases exist. The high cortical Tamm-Horsfall glycoprotein sialyltransferases activity corresponds markedly to the origin of the urinary Tamm-Horsfall glycoprotein, namely the distal part of the kidney tubule. Inactivation of glycoprotein sialyltransferase activity by preincubation at various temperatures and during storage at 0 degree C, could be reduced by the addition of CMP-AcNeu. The possible relevance towards the in vivo sialylation of this finding is discussed.

  18. One-way Tamm plasmon polaritons at the interface between magnetophotonic crystals and conducting metal oxides

    NASA Astrophysics Data System (ADS)

    Dong, Hui Yuan; Wang, Jin; Cui, Tie Jun

    2013-01-01

    We demonstrate theoretically the existence of one-way Tamm plasmon polaritons on the interface between magnetophotonic crystals and conducting metal oxides. In contrast to conventional surface plasmon-polaritons (SPPs), Tamm plasmon polaritons (TPPs) occur at frequencies above the bulk plasma frequency of the conducting materials, provided that the dispersion curves of such surface modes lie outside the light cone for the conducting oxides and simultaneously fall into the photonic band gap of the magnetophotonic crystal. The nonreciprocal properties of TPPs are caused by violation of the periodicity and time-reversal symmetry in the structure. Calculations on the field distribution and transmission spectra through the structure are employed to confirm the theoretical results, which could potentially impact on a broad range of SPP-related phenomena in applications.

  19. The optical Tamm states at the interface between a photonic crystal and nanoporous silver

    NASA Astrophysics Data System (ADS)

    Bikbaev, R. G.; Vetrov, S. Ya; Timofeev, I. V.

    2017-01-01

    The optical Tamm states (OTSs) localized at the edges of a photonic crystal bounded by a nanoporous silver (NPS) film are investigated. NPS involves spherical vacuum nanopores dispersed in the metal matrix and is characterized by the effective resonance permittivity. The transmission, reflection, and absorption spectra of the structures under study at the normal incidence of light are calculated. It is shown that each Tamm state has its own frequency range where the real part of effective permittivity is negative. The light field localization at the high- and low-frequency OTSs is investigated. The specific features of spectral manifestation of the OTSs are studied in dependence on the nanopore concentration in the metal matrix and on the NPS film thickness.

  20. The Tamm-Dancoff Approximation as the Contraction Limit of the Richardson-Gaudin Equations

    NASA Astrophysics Data System (ADS)

    de Baerdemacker, S.

    2013-03-01

    A connection is made between the exact eigenstates of the level-independent Bardeen-Cooper-Schrieffer (BCS) Hamiltonian and its Tamm-Dancoff Approximation (TDA). This is done by means of a deformation of the quasi-spin algebra, which connects the Bethe Ansatz states with a unique multi-phonon mode of the TDA. The procedure is illustrated with a model describing neutron superluidity in 56Fe.

  1. Long-range Tamm surface plasmons supported by graphene-dielectric metamaterials

    NASA Astrophysics Data System (ADS)

    Hajian, Hodjat; Caglayan, Humeyra; Ozbay, Ekmel

    2017-01-01

    Considering the Ohmic losses of graphene in the calculations and by obtaining exact dispersion relations of the modes, we theoretically study propagation and localization characteristics of Tamm surface plasmons supported by terminated graphene metamaterials. The metamaterials are composed of alternating layers of graphene and dielectric with subwavelength periods. We also examine the Tamm modes within the framework of long-wavelength approximation. It is shown that, in case the Ohmic losses of the graphene layers are taken into account, surface plasmons are not supported in a long-wavelength region, in which the graphene-dielectric multilayer structure behaves as a hyperbolic metamaterial. We prove that, when the metamaterial is truncated with air, by choosing sufficiently thick but still subwavelength dielectric layers, i.e., d = 300 nm, these surface waves will have a moderate propagation (localization) length that is comparable with those of a single layer of graphene. On the other hand, in case a miniaturized graphene metamaterial (10 < d(nm) < 100) is truncated by a thick cap layer (dcap = 5d) with ɛcap > ɛdielectric, it is possible to considerably improve the propagation and localization characteristics of the Tamm modes supported by the system within the 5.5-50 THz range of frequency, as compared to a single layer of graphene.

  2. Evolution of surface-plasmon-polariton and Dyakonov-Tamm waves with the ambichirality of a partnering dielectric material

    NASA Astrophysics Data System (ADS)

    Faryad, Muhammad; Lakhtakia, Akhlesh

    2014-01-01

    The planar interface of an isotropic homogeneous metal and an ambichiral dielectric material can guide surface-plasmon-polariton (SPP) waves. The planar interface of an isotropic, homogeneous dielectric material and an ambichiral dielectric material can guide Dyakonov-Tamm waves. In either instance, we found that, as the ambichiral partnering material evolves into a finely chiral material, the solutions of the dispersion equation for surface-wave propagation evince convergence. The convergence is faster for Dyakonov-Tamm waves than for SPP waves.

  3. Tamm plasmon-polaritons: Possible electromagnetic states at the interface of a metal and a dielectric Bragg mirror

    NASA Astrophysics Data System (ADS)

    Kaliteevski, M.; Iorsh, I.; Brand, S.; Abram, R. A.; Chamberlain, J. M.; Kavokin, A. V.; Shelykh, I. A.

    2007-10-01

    Conventional surface plasmons have a wave vector exceeding that of light in vacuum, and therefore cannot be directly excited by light that is simply incident on the surface. However, we propose that a plasmon-polariton state can be formed at the boundary between a metal and a dielectric Bragg mirror that can have a zero in-plane wave vector and therefore can be produced by direct optical excitation. In analogy with the electronic states at a crystal surface proposed by Tamm, we call these excitations Tamm plasmons, and predict that they may exist in both the TE and TM polarizations and are characterized by parabolic dispersion relations.

  4. Tuneable polaritonics at room temperature with strongly coupled Tamm plasmon polaritons in metal/air-gap microcavities

    NASA Astrophysics Data System (ADS)

    Grossmann, C.; Coulson, C.; Christmann, G.; Farrer, I.; Beere, H. E.; Ritchie, D. A.; Baumberg, J. J.

    2011-06-01

    We report strong coupling between Tamm plasmons and excitons in III-V quantum wells at room temperature in ultracompact sample designs. A high refractive index contrast air-gap mirror together with optical Tamm states at a metal/semiconductor interface tightly confines the intracavity field leading to substantial local field enhancements. Angular-resolved reflectivity spectra give clear evidence for anticrossing in the dispersion relation. Room temperature Rabi splittings of 10 meV are found in excellent agreement with simulations. Electrical control of the polariton modes is realized without need for doped mirror layers. Such air-gap microcavities open innovative possibilites for electrically tunable microcavities and polaritonic microelectromechanics.

  5. Comparing resonant photon tunneling via cavity modes and Tamm plasmon polariton modes in metal-coated Bragg mirrors.

    PubMed

    Leosson, K; Shayestehaminzadeh, S; Tryggvason, T K; Kossoy, A; Agnarsson, B; Magnus, F; Olafsson, S; Gudmundsson, J T; Magnusson, E B; Shelykh, I A

    2012-10-01

    Resonant photon tunneling was investigated experimentally in multilayer structures containing a high-contrast (TiO(2)/SiO(2)) Bragg mirror capped with a semitransparent gold film. Transmission via a fundamental cavity resonance was compared with transmission via the Tamm plasmon polariton resonance that appears at the interface between a metal film and a one-dimensional photonic bandgap structure. The Tamm-plasmon-mediated transmission exhibits a smaller dependence on the angle and polarization of the incident light for similar values of peak transmission, resonance wavelength, and finesse. Implications for transparent electrical contacts based on resonant tunneling structures are discussed.

  6. Nanofocusing of the free-space optical energy with plasmonic Tamm states

    PubMed Central

    Niu, Linyu; Xiang, Yinxiao; Luo, Weiwei; Cai, Wei; Qi, Jiwei; Zhang, Xinzheng; Xu, Jingjun

    2016-01-01

    To achieve extreme electromagnetic enhancement, we propose a plasmonic Tamm states (PTSs) configuration based on the metal-insulator-metal Bragg reflector, which is realized by periodically modulating the width of the insulator. Both the thick (2D) and thin (3D) structures are discussed. Through optimization performed by the impedance-based transfer matrix method and the finite difference time domain method, we find that both the electric field and magnetic field intensities can be increased by three orders of magnitude. The field-enhancement inside the PTSs configuration is not limited to extremely sharp waveguide terminal, which can greatly reduce processing difficulties. PMID:27995956

  7. Optical Tamm state and giant asymmetry of light transmission through an array of nanoholes

    NASA Astrophysics Data System (ADS)

    Klimov, Vasily V.; Treshin, Ilya V.; Shalin, Alexander S.; Melentiev, Pavel N.; Kuzin, Artur A.; Afanasiev, Anton E.; Balykin, Victor I.

    2015-12-01

    We have predicted theoretically and verified experimentally the occurrence of a giant asymmetry of the transmission of arbitrarily polarized light propagating through a linear nonmagnetic optical system that consists of a metal film with a two-dimensional array of nanoholes in it and that is deposited on the surface of a planar dielectric photonic crystal. The asymmetry of the light transmission is caused by two factors: (i) the excitation of an optical Tamm state in the system, and (ii) the existence of many secondary lobes in the diffraction pattern. Our results are of interest for the development of efficient planar optical diodelike systems and related nanophotonic devices.

  8. Generalized q-deformed Tamm-Dancoff oscillator algebra and associated coherent states

    SciTech Connect

    Chung, Won Sang; Hounkonnou, Mahouton Norbert Arjika, Sama

    2014-08-15

    In this paper, we propose a full characterization of a generalized q-deformed Tamm-Dancoff oscillator algebra and investigate its main mathematical and physical properties. Specifically, we study its various representations and find the condition satisfied by the deformed q-number to define the algebra structure function. Particular Fock spaces involving finite and infinite dimensions are examined. A deformed calculus is performed as well as a coordinate realization for this algebra. A relevant example is exhibited. Associated coherent states are constructed. Finally, some thermodynamics aspects are computed and discussed.

  9. Tamm plasmon polaritons in composite structures composed of the metal film and truncated photonic crystals

    NASA Astrophysics Data System (ADS)

    Du, Guiqiang; Cui, Liyong; Zhang, Liwei; Jiang, Haitao

    2012-12-01

    Tamm plasmon polaritons (TPPs) are studied theoretically and experimentally in heterostructures and sandwiched structures with the metallic film and truncated photonic crystals. Different from conventional surface plasmon polaritons, TPPs can be realized in both the transverse electric (TE) and transverse magnetic (TM) polarizations, and they can be excited from a free space. Because of nonreciprocal electromagnetic field distributions of TPPs, the structures possess strongly nonreciprocal absorption and reflection. Moreover, two tunneling peaks or a narrow transmission band can be realized in sandwiched structures for both polarizations due to the coupling effect between two TPPs.

  10. Optical isolator based on nonreciprocal coupling of two Tamm plasmon polaritons

    NASA Astrophysics Data System (ADS)

    Fang, Yun-Tuan; Zheng, Jing

    2014-12-01

    In this paper, we have studied the one-dimensional photonic crystal (PC) including a magneto-optical metal defect using the developed transfer matrix method for magnetic materials. Around the two interfaces between metal and one-dimensional PC, two nonsymmetric Tamm magneto-plasmon polaritons may be excited and coupled. The coupled states take on a clear nonreciprocal behavior and result in nonreciprocal transmission. The results are demonstrated through electromagnetic field distribution simulations based on finite element software. It provides a useful reference to realize optical isolator design.

  11. Lasing of Tamm states in highly efficient organic devices based on small-molecule organic semiconductors.

    PubMed

    Brückner, R; Lyssenko, V G; Hofmann, S; Leo, K

    2014-01-01

    We discuss approaches to increase the light outcoupling efficiency in organic microcavity (MC) lasers and organic light-emitting diodes (OLEDs). We find that the introduction of metals into the cavities leads to additional Tamm-plasmon polariton modes, while the corrugation of metal contacts, such as perforated μ-size holes or a periodic array of metal stripes, leads to 2D confinement of the cavity modes, which in turn reduces the lasing threshold in MCs. Furthermore, we elucidate light loss mechanisms in OLEDs and reveal how external dielectric layers and periodic gratings can be used to enhance outcoupling from the OLED cavity.

  12. Spectral engineering by flexible tunings of optical Tamm states and Fabry-Perot cavity resonance.

    PubMed

    Zhang, Xu-Lin; Song, Jun-Feng; Feng, Jing; Sun, Hong-Bo

    2013-11-01

    We present a design for spectral engineering in a metal dual distributed Bragg reflector (DBR)-based structure. Optical Tamm states and Fabry-Perot cavity mode, dual windows for light-matter interaction enhancement, can be excited simultaneously and tuned flexibly, including their respective bandwidth and resonant wavelength, due to the variable reflection phase from the outer DBR's internal surface. The design can find applications in solar cells for light trappings. Via calculations of overall absorptivity, the proposed simpler dual-states-based scheme is demonstrated to be almost as effective as the coherent-light-trapping scheme, owing to the dual-states-induced broader-band absorption enhancement.

  13. Meta-Optics with Nanowire Grid Arrays: Hyperbolic Fabry-Perot Modes and Hyperbolic Tamm Plasmons

    NASA Astrophysics Data System (ADS)

    Durach, Maxim; Keene, David; Lepain, Matthew

    2015-03-01

    In this talk we introduce a new class of structures - cavities formed by metal-dielectric metasurfaces. These cavities support a zoo of various resonances, including hyperbolic Tamm plasmons and hyperbolic Fabry-Perot modes, which feature anisotropic clover-leaf dispersion parallel to the metasurface and strong coupling between TM and TE polarizations in the modes. The properties and spectrum of the modes are highly tunable by the dimensional and material parameters of the structure and can be used for directional emission, modification of radiation produced by electric dipole emitters into magnetic dipole radiation as well as 90 degree polarization rotators and polarization rotation mirrors.

  14. Tamm plasmon-polariton with negative group velocity induced by a negative index meta-material capping layer at metal-Bragg reflector interface.

    PubMed

    Liu, Cunding; Kong, Mingdong; Li, Bincheng

    2014-05-05

    Influence of a negative refractive index meta-material (NIM) capping layer on properties of Tamm plasmon-polariton at the interface of metal-Bragg reflector structure is investigated. Conditions for excitation of the plasmon-polariton is determined from reflectivity mapping calculation and analyzed with cavity mode theory. For specific thicknesses of capping layers, Tamm plasmon-polariton with negative group velocity is revealed in a wide region of frequency. Different from backward optical propagation induced by negative effective-group-refractive-index in dispersive media, negative group velocity of Tamm plasmon-polariton results from opposite signs of cross-section-integrated field energy and Poynting vector.

  15. Strong coupling between Tamm plasmon polariton and two dimensional semiconductor excitons

    NASA Astrophysics Data System (ADS)

    Hu, Tao; Wang, Yafeng; Wu, Lin; Zhang, Long; Shan, Yuwei; Lu, Jian; Wang, Jun; Luo, Song; Zhang, Zhe; Liao, Liming; Wu, Shiwei; Shen, Xuechu; Chen, Zhanghai

    2017-01-01

    Two dimensional (2D) semiconductor materials of transition-metal dichalcogenides (TMDCs) manifest many peculiar physical phenomena in the light-matter interaction. Due to their ultrathin property, strong interaction with light and the robust excitons at room temperature, they provide a perfect platform for studying the physics of strong coupling in low dimension and at room temperature. Here we report the strong coupling between 2D semiconductor excitons and Tamm plasmon polaritons (TPPs). We observe a Rabi splitting of about 54 meV at room temperature by measuring the angle resolved differential reflectivity spectra and simulate the theoretical results by using the transfer matrix method. Our results will promote the realization of the TPP based ultrathin polariton devices at room temperature.

  16. Two-component hybrid time-dependent density functional theory within the Tamm-Dancoff approximation

    SciTech Connect

    Kühn, Michael; Weigend, Florian

    2015-01-21

    We report the implementation of a two-component variant of time-dependent density functional theory (TDDFT) for hybrid functionals that accounts for spin-orbit effects within the Tamm-Dancoff approximation (TDA) for closed-shell systems. The influence of the admixture of Hartree-Fock exchange on excitation energies is investigated for several atoms and diatomic molecules by comparison to numbers for pure density functionals obtained previously [M. Kühn and F. Weigend, J. Chem. Theory Comput. 9, 5341 (2013)]. It is further related to changes upon switching to the local density approximation or using the full TDDFT formalism instead of TDA. Efficiency is demonstrated for a comparably large system, Ir(ppy){sub 3} (61 atoms, 1501 basis functions, lowest 10 excited states), which is a prototype molecule for organic light-emitting diodes, due to its “spin-forbidden” triplet-singlet transition.

  17. Two-component hybrid time-dependent density functional theory within the Tamm-Dancoff approximation

    NASA Astrophysics Data System (ADS)

    Kühn, Michael; Weigend, Florian

    2015-01-01

    We report the implementation of a two-component variant of time-dependent density functional theory (TDDFT) for hybrid functionals that accounts for spin-orbit effects within the Tamm-Dancoff approximation (TDA) for closed-shell systems. The influence of the admixture of Hartree-Fock exchange on excitation energies is investigated for several atoms and diatomic molecules by comparison to numbers for pure density functionals obtained previously [M. Kühn and F. Weigend, J. Chem. Theory Comput. 9, 5341 (2013)]. It is further related to changes upon switching to the local density approximation or using the full TDDFT formalism instead of TDA. Efficiency is demonstrated for a comparably large system, Ir(ppy)3 (61 atoms, 1501 basis functions, lowest 10 excited states), which is a prototype molecule for organic light-emitting diodes, due to its "spin-forbidden" triplet-singlet transition.

  18. Wide-angle Spectrally Selective Perfect Absorber by Utilizing Dispersionless Tamm Plasmon Polaritons

    PubMed Central

    Xue, Chun-hua; Wu, Feng; Jiang, Hai-tao; Li, Yunhui; Zhang, Ye-wen; Chen, Hong

    2016-01-01

    We theoretically investigate wide-angle spectrally selective absorber by utilizing dispersionless Tamm plasmon polaritons (TPPs) under TM polarization. TPPs are resonant tunneling effects occurring on the interface between one-dimensional photonic crystals (1DPCs) and metal slab, and their dispersion properties are essentially determined by that of 1DPCs. Our investigations show that dispersionless TPPs can be excited in 1DPCs containing hyperbolic metamaterials (HMMs) on metal substrate. Based on dispersionless TPPs, electromagnetic waves penetrate into metal substrate and are absorbed entirely by lossy metal, exhibiting a narrow-band and wide-angle perfect absorption for TM polarization. Our results exhibit nearly perfect absorption with a value over 98% in the angle of incidence region of 0–80 degree. PMID:27991565

  19. Two-component hybrid time-dependent density functional theory within the Tamm-Dancoff approximation.

    PubMed

    Kühn, Michael; Weigend, Florian

    2015-01-21

    We report the implementation of a two-component variant of time-dependent density functional theory (TDDFT) for hybrid functionals that accounts for spin-orbit effects within the Tamm-Dancoff approximation (TDA) for closed-shell systems. The influence of the admixture of Hartree-Fock exchange on excitation energies is investigated for several atoms and diatomic molecules by comparison to numbers for pure density functionals obtained previously [M. Kühn and F. Weigend, J. Chem. Theory Comput. 9, 5341 (2013)]. It is further related to changes upon switching to the local density approximation or using the full TDDFT formalism instead of TDA. Efficiency is demonstrated for a comparably large system, Ir(ppy)3 (61 atoms, 1501 basis functions, lowest 10 excited states), which is a prototype molecule for organic light-emitting diodes, due to its "spin-forbidden" triplet-singlet transition.

  20. Derivative couplings between TDDFT excited states obtained by direct differentiation in the Tamm-Dancoff approximation

    SciTech Connect

    Ou, Qi; Fatehi, Shervin; Alguire, Ethan; Subotnik, Joseph E.; Shao, Yihan

    2014-07-14

    Working within the Tamm-Dancoff approximation, we calculate the derivative couplings between time-dependent density-functional theory excited states by assuming that the Kohn-Sham superposition of singly excited determinants represents a true electronic wavefunction. All Pulay terms are included in our derivative coupling expression. The reasonability of our approach can be established by noting that, for closely separated electronic states in the infinite basis limit, our final expression agrees exactly with the Chernyak-Mukamel expression (with transition densities from response theory). Finally, we also validate our approach empirically by analyzing the behavior of the derivative couplings around the T{sub 1}/T{sub 2} conical intersection of benzaldehyde.

  1. Wide-angle Spectrally Selective Perfect Absorber by Utilizing Dispersionless Tamm Plasmon Polaritons

    NASA Astrophysics Data System (ADS)

    Xue, Chun-Hua; Wu, Feng; Jiang, Hai-Tao; Li, Yunhui; Zhang, Ye-Wen; Chen, Hong

    2016-12-01

    We theoretically investigate wide-angle spectrally selective absorber by utilizing dispersionless Tamm plasmon polaritons (TPPs) under TM polarization. TPPs are resonant tunneling effects occurring on the interface between one-dimensional photonic crystals (1DPCs) and metal slab, and their dispersion properties are essentially determined by that of 1DPCs. Our investigations show that dispersionless TPPs can be excited in 1DPCs containing hyperbolic metamaterials (HMMs) on metal substrate. Based on dispersionless TPPs, electromagnetic waves penetrate into metal substrate and are absorbed entirely by lossy metal, exhibiting a narrow-band and wide-angle perfect absorption for TM polarization. Our results exhibit nearly perfect absorption with a value over 98% in the angle of incidence region of 0-80 degree.

  2. Optical harmonics generation in metal/dielectric heterostructures in the presence of Tamm plasmon-polaritons

    NASA Astrophysics Data System (ADS)

    Afinogenov, B. I.; Popkova, A. A.; Bessonov, V. O.; Fedyanin, A. A.

    2016-03-01

    We have studied an influence of Tamm plasmon-polaritons (TPPs) excitation on the nonlinear-optical response of one-dimensional photonic crystal/metal structures. It was shown that in case when the fundamental radiation is in resonance with the TPP, second-harmonic generation in the sample is enhanced over two times of magnitude in comparison with a bare metal film. Using methods of nonlinear transfer matrices it was demonstrated that the third-order nonlinear response of a metal/dielectric heterostructure, when both fundamental and third-harmonic radiation are in resonance with the first- and third-order TPPs respectively, can be enhanced via two mechanisms: fundamental field localization and optical harmonic resonant tunneling. The overall enhancement of the third harmonic generation in that case can exceed three orders of magnitude in comparison with the non-resonant case.

  3. The optical Tamm states at the interface between a photonic crystal and a nanocomposite containing core-shell particles

    NASA Astrophysics Data System (ADS)

    Vetrov, S. Ya; Pankin, P. S.; Timofeev, I. V.

    2016-06-01

    We investigate the optical Tamm states (OTSs) localized at the interface between a photonic crystal (PC) and a nanocomposite consisting of spherical nanoparticles with a dielectric core and a metallic shell, which are dispersed in a transparent matrix, and is characterized by the resonance permittivity. Spectra of transmission, reflection, and absorption of normally incident light waves by the investigated structure are calculated. The spectral manifestation of the Tamm states caused by negative values of the real part of the effective permittivity in the visible spectral range is studied. It is demonstrated that, along with the significantly extended band gap of the PC, the transmission spectrum contains an additional stopband caused by nanocomposite absorption near the resonance frequency. It is shown that the OTSs can be implemented in two band gaps of the PCs, each corresponding to a certain plasmon resonance frequency of the nanocomposite. It is established that the characteristics of the Tamm state localized at the edge of the PCs significantly depend on the ratio between the particle core volume and the total particle volume.

  4. The role of Tamm-Horsfall protein in the pathogenesis of reflux nephropathy and chronic pyelonephritis.

    PubMed Central

    Andriole, V. T.

    1985-01-01

    Recurrent bacterial infection of the kidney was previously thought to be responsible for the renal scarring typical of chronic pyelonephritis until recent studies suggested that recurrent bacteriuria rarely produces chronic pyelonephritis in the absence of obstructive uropathy. In contrast, the association between vesicoureteral reflux (VUR) and chronic pyelonephritis has been observed frequently in the absence of urinary infection. Although the mechanism by which VUR injures the kidney has not been defined, recent observations have suggested that some component of urine might serve as an antigenic determinant involved in the immunopathogenesis of renal scarring in VUR. Therefore, the present studies investigated the immunopathogenic role of Tamm-Horsfall protein (THP) in (1) a rabbit model of tubulointerstitial nephritis; (2) a swine model of reflux nephropathy; and (3) patients with recurrent nephrolithiasis. The antigenic similarities between THP and uropathic bacteria were also studied. Our observations indicate that autoimmune responses to THP may occur after exposure to THP by intravenous challenge in rabbits, by urinary reflux in pigs, and in recurrent nephrolithiasis in man. Also, extracts of uropathic coliforms competitively inhibit the binding of human THP to its antibody. These studies suggest that autoimmune responses to THP may be the pathogenetic mechanism by which these factors, including bacteriuria, contribute to "chronic pyelonephritis." PMID:2412354

  5. Performance of Tamm-Dancoff approximation on nonadiabatic couplings by time-dependent density functional theory

    NASA Astrophysics Data System (ADS)

    Hu, Chunping; Sugino, Osamu; Watanabe, Kazuyuki

    2014-02-01

    The Tamm-Dancoff approximation (TDA), widely used in physics to decouple excitations and de-excitations, is well known to be good for the calculation of excitation energies but not for oscillator strengths. In particular, the sum rule is violated in the latter case. The same concern arises within the TDA in the calculation of nonadiabatic couplings (NACs) by time-dependent density functional theory (TDDFT), due to the similarities in the TDDFT formulations of NACs and oscillator strengths [C. Hu, H. Hirai, and O. Sugino, J. Chem. Phys. 127, 064103 (2007)]. In this study, we present a systematic evaluation of the performance of TDDFT/TDA for the calculation of NACs. In the cases we considered, including a variety of systems possessing Jahn-Teller and Renner-Teller intersections, as well as an example with accidental conical intersections, it is found that the TDDFT/TDA performs better than the full TDDFT, contrary to the conjecture that the TDA might cause the NAC results to deteriorate and violate the sum rule. The surprisingly good performance of the TDA for NACs is probably because the TDA can partially compensate for the local-density-approximation error and give better excitation energies in the vicinity of intersections of potential energy surfaces. Our study also shows that it is important to use the TDA based on the rigorous full-TDDFT formulation of NACs, instead of using it based on an alternative approximate formulation.

  6. Performance of Tamm-Dancoff approximation on nonadiabatic couplings by time-dependent density functional theory.

    PubMed

    Hu, Chunping; Sugino, Osamu; Watanabe, Kazuyuki

    2014-02-07

    The Tamm-Dancoff approximation (TDA), widely used in physics to decouple excitations and de-excitations, is well known to be good for the calculation of excitation energies but not for oscillator strengths. In particular, the sum rule is violated in the latter case. The same concern arises within the TDA in the calculation of nonadiabatic couplings (NACs) by time-dependent density functional theory (TDDFT), due to the similarities in the TDDFT formulations of NACs and oscillator strengths [C. Hu, H. Hirai, and O. Sugino, J. Chem. Phys. 127, 064103 (2007)]. In this study, we present a systematic evaluation of the performance of TDDFT/TDA for the calculation of NACs. In the cases we considered, including a variety of systems possessing Jahn-Teller and Renner-Teller intersections, as well as an example with accidental conical intersections, it is found that the TDDFT/TDA performs better than the full TDDFT, contrary to the conjecture that the TDA might cause the NAC results to deteriorate and violate the sum rule. The surprisingly good performance of the TDA for NACs is probably because the TDA can partially compensate for the local-density-approximation error and give better excitation energies in the vicinity of intersections of potential energy surfaces. Our study also shows that it is important to use the TDA based on the rigorous full-TDDFT formulation of NACs, instead of using it based on an alternative approximate formulation.

  7. Restricted second random phase approximations and Tamm-Dancoff approximations for electronic excitation energy calculations

    NASA Astrophysics Data System (ADS)

    Peng, Degao; Yang, Yang; Zhang, Peng; Yang, Weitao

    2014-12-01

    In this article, we develop systematically second random phase approximations (RPA) and Tamm-Dancoff approximations (TDA) of particle-hole and particle-particle channels for calculating molecular excitation energies. The second particle-hole RPA/TDA can capture double excitations missed by the particle-hole RPA/TDA and time-dependent density-functional theory (TDDFT), while the second particle-particle RPA/TDA recovers non-highest-occupied-molecular-orbital excitations missed by the particle-particle RPA/TDA. With proper orbital restrictions, these restricted second RPAs and TDAs have a formal scaling of only O(N4). The restricted versions of second RPAs and TDAs are tested with various small molecules to show some positive results. Data suggest that the restricted second particle-hole TDA (r2ph-TDA) has the best overall performance with a correlation coefficient similar to TDDFT, but with a larger negative bias. The negative bias of the r2ph-TDA may be induced by the unaccounted ground state correlation energy to be investigated further. Overall, the r2ph-TDA is recommended to study systems with both single and some low-lying double excitations with a moderate accuracy. Some expressions on excited state property evaluations, such as < hat{S}2rangle are also developed and tested.

  8. Molecular properties in the Tamm-Dancoff approximation: indirect nuclear spin-spin coupling constants

    NASA Astrophysics Data System (ADS)

    Cheng, Chi Y.; Ryley, Matthew S.; Peach, Michael J. G.; Tozer, David J.; Helgaker, Trygve; Teale, Andrew M.

    2015-07-01

    The Tamm-Dancoff approximation (TDA) can be applied to the computation of excitation energies using time-dependent Hartree-Fock (TD-HF) and time-dependent density-functional theory (TD-DFT). In addition to simplifying the resulting response equations, the TDA has been shown to significantly improve the calculation of triplet excitation energies in these theories, largely overcoming issues associated with triplet instabilities of the underlying reference wave functions. Here, we examine the application of the TDA to the calculation of another response property involving triplet perturbations, namely the indirect nuclear spin-spin coupling constant. Particular attention is paid to the accuracy of the triplet spin-dipole and Fermi-contact components. The application of the TDA in HF calculations leads to vastly improved results. For DFT calculations, the TDA delivers improved stability with respect to geometrical variations but does not deliver higher accuracy close to equilibrium geometries. These observations are rationalised in terms of the ground- and excited-state potential energy surfaces and, in particular, the severity of the triplet instabilities associated with each method. A notable feature of the DFT results within the TDA is their similarity across a wide range of different functionals. The uniformity of the TDA results suggests that some conventional evaluations may exploit error cancellations between approximations in the functional forms and those arising from triplet instabilities. The importance of an accurate treatment of correlation for evaluating spin-spin coupling constants is highlighted by this comparison.

  9. Restricted second random phase approximations and Tamm-Dancoff approximations for electronic excitation energy calculations

    SciTech Connect

    Peng, Degao; Yang, Yang; Zhang, Peng; Yang, Weitao

    2014-12-07

    In this article, we develop systematically second random phase approximations (RPA) and Tamm-Dancoff approximations (TDA) of particle-hole and particle-particle channels for calculating molecular excitation energies. The second particle-hole RPA/TDA can capture double excitations missed by the particle-hole RPA/TDA and time-dependent density-functional theory (TDDFT), while the second particle-particle RPA/TDA recovers non-highest-occupied-molecular-orbital excitations missed by the particle-particle RPA/TDA. With proper orbital restrictions, these restricted second RPAs and TDAs have a formal scaling of only O(N{sup 4}). The restricted versions of second RPAs and TDAs are tested with various small molecules to show some positive results. Data suggest that the restricted second particle-hole TDA (r2ph-TDA) has the best overall performance with a correlation coefficient similar to TDDFT, but with a larger negative bias. The negative bias of the r2ph-TDA may be induced by the unaccounted ground state correlation energy to be investigated further. Overall, the r2ph-TDA is recommended to study systems with both single and some low-lying double excitations with a moderate accuracy. Some expressions on excited state property evaluations, such as 〈S{sup ^2}〉 are also developed and tested.

  10. Restricted second random phase approximations and Tamm-Dancoff approximations for electronic excitation energy calculations.

    PubMed

    Peng, Degao; Yang, Yang; Zhang, Peng; Yang, Weitao

    2014-12-07

    In this article, we develop systematically second random phase approximations (RPA) and Tamm-Dancoff approximations (TDA) of particle-hole and particle-particle channels for calculating molecular excitation energies. The second particle-hole RPA/TDA can capture double excitations missed by the particle-hole RPA/TDA and time-dependent density-functional theory (TDDFT), while the second particle-particle RPA/TDA recovers non-highest-occupied-molecular-orbital excitations missed by the particle-particle RPA/TDA. With proper orbital restrictions, these restricted second RPAs and TDAs have a formal scaling of only O(N(4)). The restricted versions of second RPAs and TDAs are tested with various small molecules to show some positive results. Data suggest that the restricted second particle-hole TDA (r2ph-TDA) has the best overall performance with a correlation coefficient similar to TDDFT, but with a larger negative bias. The negative bias of the r2ph-TDA may be induced by the unaccounted ground state correlation energy to be investigated further. Overall, the r2ph-TDA is recommended to study systems with both single and some low-lying double excitations with a moderate accuracy. Some expressions on excited state property evaluations, such as ⟨Ŝ(2)⟩ are also developed and tested.

  11. Photon echoes from (In,Ga)As quantum dots embedded in a Tamm-plasmon microcavity

    NASA Astrophysics Data System (ADS)

    Salewski, M.; Poltavtsev, S. V.; Kapitonov, Yu. V.; Vondran, J.; Yakovlev, D. R.; Schneider, C.; Kamp, M.; Höfling, S.; Oulton, R.; Akimov, I. A.; Kavokin, A. V.; Bayer, M.

    2017-01-01

    We report on the coherent optical response from an ensemble of (In,Ga)As quantum dots (QDs) embedded in a planar Tamm-plasmon microcavity with a quality factor of approximately 100. Significant enhancement of the light-matter interaction is demonstrated under selective laser excitation of those quantum dots which are in resonance with the cavity mode. The enhancement is manifested through Rabi oscillations of the photon echo, demonstrating coherent control of excitons with picosecond pulses at intensity levels more than an order of magnitude smaller as compared with bare quantum dots. The decay of the photon echo transients is weakly changed by the resonator, indicating a small decrease of the coherence time T2 which we attribute to the interaction with the electron plasma in the metal layer located close (40 nm) to the QD layer. Simultaneously we see a reduction of the population lifetime T1, inferred from the stimulated photon echo, due to an enhancement of the spontaneous emission by a factor of 2, which is attributed to the Purcell effect, while nonradiative processes are negligible, as confirmed from time-resolved photoluminescence.

  12. Distributional and regularized radiation fields of non-uniformly moving straight dislocations, and elastodynamic Tamm problem

    NASA Astrophysics Data System (ADS)

    Lazar, Markus; Pellegrini, Yves-Patrick

    2016-11-01

    This work introduces original explicit solutions for the elastic fields radiated by non-uniformly moving, straight, screw or edge dislocations in an isotropic medium, in the form of time-integral representations in which acceleration-dependent contributions are explicitly separated out. These solutions are obtained by applying an isotropic regularization procedure to distributional expressions of the elastodynamic fields built on the Green tensor of the Navier equation. The obtained regularized field expressions are singularity-free, and depend on the dislocation density rather than on the plastic eigenstrain. They cover non-uniform motion at arbitrary speeds, including faster-than-wave ones. A numerical method of computation is discussed, that rests on discretizing motion along an arbitrary path in the plane transverse to the dislocation, into a succession of time intervals of constant velocity vector over which time-integrated contributions can be obtained in closed form. As a simple illustration, it is applied to the elastodynamic equivalent of the Tamm problem, where fields induced by a dislocation accelerated from rest beyond the longitudinal wave speed, and thereafter put to rest again, are computed. As expected, the proposed expressions produce Mach cones, the dynamic build-up and decay of which is illustrated by means of full-field calculations.

  13. Tamm plasmon- and surface plasmon-coupled emission from hybrid plasmonic–photonic structures

    PubMed Central

    Chen, Yikai; Zhang, Douguo; Zhu, Liangfu; Wang, Ruxue; Wang, Pei; Ming, Hai; Badugu, Ramachandram; Lakowicz, Joseph R.

    2015-01-01

    Photonic and plasmon-coupled emissions present new opportunities for control on light emission from fluorophores, and have many applications in the physical and biological sciences. The mechanism of and the influencing factors for the coupling between the fluorescent molecules and plasmon and/or photonic modes are active areas of research. In this paper, we describe a hybrid photonic–plasmonic structure that simultaneously contains two plasmon modes: surface plasmons (SPs) and Tamm plasmons (TPs), both of which can modulate fluorescence emission. Experimental results show that both SP-coupled emission (SPCE) and TP-coupled emission (TPCE) can be observed simultaneously with this hybrid structure. Due to the different resonant angles of the TP and SP modes, the TPCE and SPCE can be beamed in different directions and can be separated easily. Back focal plane images of the fluorescence emission show that the relative intensities of the SPCE and TPCE can be changed if the probes are at different locations inside the hybrid structure, which reveals the probe location-dependent different coupling strengths of the fluorescent molecules with SPs and TPs. The different coupling strengths are ascribed to the electric field distribution of the two modes in the structure. Here, we present an understanding of these factors influencing mode coupling with probes, which is vital for structure design for suitable applications in sensing and diagnostics. PMID:26526929

  14. Beyond the Tamm-Dancoff approximation for extended systems using exact diagonalization

    NASA Astrophysics Data System (ADS)

    Sander, Tobias; Maggio, Emanuele; Kresse, Georg

    2015-07-01

    Linear optical properties can be accurately calculated using the Bethe-Salpeter equation. After introducing a suitable product basis for the electron-hole pairs, the Bethe-Salpeter equation is usually recast into a complex non-Hermitian eigenvalue problem that is difficult to solve using standard eigenvalue solvers. In solid-state physics, it is therefore common practice to neglect the problematic coupling between the positive- and negative-frequency branches, reducing the problem to a Hermitian eigenvalue problem [Tamm-Dancoff approximation (TDA)]. We use time-inversion symmetry to recast the full problem into a quadratic Hermitian eigenvalue problem, which can be solved routinely using standard eigenvalue solvers even at a finite wave vector q . This allows us to access the importance of the coupling between the positive- and negative-frequency branch for prototypical solids. As a starting point for the Bethe-Salpeter calculations, we use self-consistent Green's-function methods (GW ), making the present scheme entirely ab initio. We calculate the optical spectra of carbon (C), silicon (Si), lithium fluoride (LiF), and the cyclic dimer Li2F2 and discuss why the differences between the TDA and the full solution are tiny. However, at finite momentum transfer q , significant differences between the TDA and our exact treatment are found. The origin of these differences is explained.

  15. Dyakonov-Tamm waves-based optical sensing using sculptured nematic thin film

    NASA Astrophysics Data System (ADS)

    Abbas, Farhat; Naqvi, Qaisar A.; Faryad, Muhammad

    2015-06-01

    Dyakonov-Tamm (DT) waves are highly sensitive to the constitutive properties of the partnering materials near the interface. DT waves are excited at the interface of two dielectric materials of which at least one is anisotropic and periodically nonhomogeneous normal to their interface. Sculptured nematic thin film (SNTF) is a good candidate for the periodically nonhomogeneous dielectric partner for optical sensing of a fluid due to its porosity. The nanoscale parameters of an uninfiltrated SNTF obtained from the inverse Bruggeman homogenization formalism were used in the forward Bruggeman homogenization formalism to determine the constitutive parameters for the infiltrated SNTF. The sensitivity of DT waves to the refractive index was analyzed for two possible sensing modalities and it was found that the sensitivity was comparable to that of the chiral sculptured thin films (STFs) made of the same material as of the SNTF. This implies that the sensing with DT waves is robust, is independent of the morphology of the partnering nonhomogeneous dielectric material and could make the sensing easier since SNTFs are easier to fabricate than the chiral STFs.

  16. Room-temperature Tamm-plasmon exciton-polaritons with a WSe2 monolayer

    PubMed Central

    Lundt, Nils; Klembt, Sebastian; Cherotchenko, Evgeniia; Betzold, Simon; Iff, Oliver; Nalitov, Anton V.; Klaas, Martin; Dietrich, Christof P.; Kavokin, Alexey V.; Höfling, Sven; Schneider, Christian

    2016-01-01

    Solid-state cavity quantum electrodynamics is a rapidly advancing field, which explores the frontiers of light–matter coupling. Metal-based approaches are of particular interest in this field, as they carry the potential to squeeze optical modes to spaces significantly below the diffraction limit. Transition metal dichalcogenides are ideally suited as the active material in cavity quantum electrodynamics, as they interact strongly with light at the ultimate monolayer limit. Here, we implement a Tamm-plasmon-polariton structure and study the coupling to a monolayer of WSe2, hosting highly stable excitons. Exciton-polariton formation at room temperature is manifested in the characteristic energy–momentum dispersion relation studied in photoluminescence, featuring an anti-crossing between the exciton and photon modes with a Rabi-splitting of 23.5 meV. Creating polaritonic quasiparticles in monolithic, compact architectures with atomic monolayers under ambient conditions is a crucial step towards the exploration of nonlinearities, macroscopic coherence and advanced spinor physics with novel, low-mass bosons. PMID:27796288

  17. Room-temperature Tamm-plasmon exciton-polaritons with a WSe2 monolayer

    NASA Astrophysics Data System (ADS)

    Lundt, Nils; Klembt, Sebastian; Cherotchenko, Evgeniia; Betzold, Simon; Iff, Oliver; Nalitov, Anton V.; Klaas, Martin; Dietrich, Christof P.; Kavokin, Alexey V.; Höfling, Sven; Schneider, Christian

    2016-10-01

    Solid-state cavity quantum electrodynamics is a rapidly advancing field, which explores the frontiers of light-matter coupling. Metal-based approaches are of particular interest in this field, as they carry the potential to squeeze optical modes to spaces significantly below the diffraction limit. Transition metal dichalcogenides are ideally suited as the active material in cavity quantum electrodynamics, as they interact strongly with light at the ultimate monolayer limit. Here, we implement a Tamm-plasmon-polariton structure and study the coupling to a monolayer of WSe2, hosting highly stable excitons. Exciton-polariton formation at room temperature is manifested in the characteristic energy-momentum dispersion relation studied in photoluminescence, featuring an anti-crossing between the exciton and photon modes with a Rabi-splitting of 23.5 meV. Creating polaritonic quasiparticles in monolithic, compact architectures with atomic monolayers under ambient conditions is a crucial step towards the exploration of nonlinearities, macroscopic coherence and advanced spinor physics with novel, low-mass bosons.

  18. Optical Tamm states above the bulk plasma frequency at a Bragg stack/metal interface

    NASA Astrophysics Data System (ADS)

    Brand, S.; Kaliteevski, M. A.; Abram, R. A.

    2009-02-01

    We demonstrate theoretically that surface-plasmon polaritons, a form of optical Tamm state, can occur at the interface between a metal and a Bragg reflector at frequencies above the bulk plasma frequency of the metal. The frequencies of the excitations are within the photonic band gap of the Bragg reflector which provides the required evanescent decay on that side of the interface. At finite in-plane wave vector, the low value of the permittivity of the metal above its plasma frequency can lead to an imaginary normal wave vector component in the metal, which provides the localization on the other side of the interface. It is proposed that the necessary conditions can be realized using a GaAs/AlAs Bragg stack coated with a suitable conducting metal oxide having a bulk plasma frequency of 1 eV, but the concept is valid for other systems given an appropriate plasma frequency and photonic band-gap structure. The dispersion relations of the plasmon polaritons in the structures considered are calculated for both possible polarizations, and it is shown how the excitations result in distinct features in the predicted reflectivity spectra.

  19. Plasmons in the presence of Tamm-Shockley states with Rashba splitting at noble metal surfaces

    NASA Astrophysics Data System (ADS)

    Farid, A. M.; Mishchenko, E. G.

    2008-11-01

    Au(111) or similar noble metal surfaces feature Tamm-Shockley surface states that are known to possess considerable spin-orbit splitting of the Rashba type of order Δ=0.1eV . When interacting with an electromagnetic field such states are expected to have resonances when the frequency of the field is near the energy of the spin-orbit splitting Δ . They originate from the intersubband transitions between spin-split subbands and can be observed in the frequency dependence of the surface impedance. Plasmons in thin metal films are gapless and can be strongly affected by these spin resonances, acquiring significant modification of the spectrum when it intersects the ω=Δ line. Finally, an interesting demonstration of the intersubband resonances can be achieved when metal films are coated with ionic dielectrics that have a frequency of longitudinal or transverse optical phonons above or below Δ . The dielectric function between the two optical phonon frequencies is negative which forbids propagation of conventional plasmon polaritons. However, the presence of spin-orbit-split surface states allows plasmon polaritons to exist in this otherwise forbidden range of frequencies.

  20. Tamm-plasmon and surface-plasmon hybrid-mode based refractometry in photonic bandgap structures.

    PubMed

    Das, Ritwick; Srivastava, Triranjita; Jha, Rajan

    2014-02-15

    The transverse magnetic (TM) polarized hybrid modes formed as a consequence of coupling between Tamm plasmon polariton (TM-TPP) mode and surface plasmon polariton (SPP) mode exhibit interesting dispersive features for realizing a highly sensitive and accurate surface plasmon resonance (SPR) sensor. We found that the TM-TPP modes, formed at the interface of distributed Bragg reflector and metal, are strongly dispersive as compared to SPP modes at optical frequencies. This causes an appreciably narrow interaction bandwidth between TM-TPP and SPP modes, which leads to highly accurate sensing. In addition, appropriate tailoring of dispersion characteristics of TM-TPP as well as SPP modes could ensure high sensitivity of a novel SPR platform. By suitably designing the Au/TiO₂/SiO₂-based geometry, we propose a TM-TPP/SPP hybrid-mode sensor and achieve a sensitivity ≥900  nm/RIU with high detection accuracy (≥30  μm⁻¹) for analyte refractive indices varying between 1.330 and 1.345 in 600-700 nm wavelength range. The possibility to achieve desired dispersive behavior in any spectral band makes the sensing configuration an extremely attractive candidate to design sensors depending on the availability of optical sources.

  1. Room-temperature Tamm-plasmon exciton-polaritons with a WSe2 monolayer.

    PubMed

    Lundt, Nils; Klembt, Sebastian; Cherotchenko, Evgeniia; Betzold, Simon; Iff, Oliver; Nalitov, Anton V; Klaas, Martin; Dietrich, Christof P; Kavokin, Alexey V; Höfling, Sven; Schneider, Christian

    2016-10-31

    Solid-state cavity quantum electrodynamics is a rapidly advancing field, which explores the frontiers of light-matter coupling. Metal-based approaches are of particular interest in this field, as they carry the potential to squeeze optical modes to spaces significantly below the diffraction limit. Transition metal dichalcogenides are ideally suited as the active material in cavity quantum electrodynamics, as they interact strongly with light at the ultimate monolayer limit. Here, we implement a Tamm-plasmon-polariton structure and study the coupling to a monolayer of WSe2, hosting highly stable excitons. Exciton-polariton formation at room temperature is manifested in the characteristic energy-momentum dispersion relation studied in photoluminescence, featuring an anti-crossing between the exciton and photon modes with a Rabi-splitting of 23.5 meV. Creating polaritonic quasiparticles in monolithic, compact architectures with atomic monolayers under ambient conditions is a crucial step towards the exploration of nonlinearities, macroscopic coherence and advanced spinor physics with novel, low-mass bosons.

  2. Plasmons in the presence of Tamm-Shockley states with Rashba splitting at noble metal surfaces

    NASA Astrophysics Data System (ADS)

    Farid, Abdel-Khalek; Mishchenko, Eugene

    2009-03-01

    Au(111) or similar noble metal surfaces feature Tamm-Shockley surface states that are known to possess considerable spin-orbit splitting of the Rashba type of order δ=0.1 eV. When interacting with an electromagnetic field such states are expected to have resonances when the frequency of the field is near the energy of the spin-orbit splitting δ. They originate from the intersubband transitions between spin-split subbands and can be observed in the frequency dependence of the surface impedance. Plasmons in thin metal films are gapless and can be strongly affected by these spin resonances, acquiring significant modification of the spectrum when it intersects the φ=δ line. Finally, an interesting demonstration of the intersubband resonances can be achieved when metal films are coated with ionic dielectrics that have a frequency of longitudinal/transverse optical phonons above/below δ. The dielectric function between the two optical phonon frequencies is negative which forbids propagation of conventional plasmon-polaritons. However, the presence of spin-orbit-split surface states allows plasmon-polaritons to exist in this otherwise forbidden range of frequencies.

  3. Isoelectric focusing of Tamm-Horsfall glycoproteins: a simple tool for recognizing recurrent calcium oxalate renal stone formers.

    PubMed

    Schnierle, P; Hering, F; Seiler, H

    1996-01-01

    Tamm-Horsfall glycoproteins (THPs) from healthy probands and a majority of recurrent calcium oxalate renal stone formers reveal different physicochemical properties when analyzed using isoelectric focusing (IEF). The pI values of THPs from healthy probands are approximately 3.5 while THPs from recurrent renal stone formers have pI values of between 4.5 and 6. The two groups of THPs exhibit completely different protein patterns. The differences in IEF analysis allow differentiation between THPs from healthy probands and recurrent calcium oxalate stone formers and may possibly be used as a simple diagnostic method for the recognition of recurrent calcium oxalate renal stone formers.

  4. Tamm states at the interface between a conventional material and a one dimensional photonic crystal with metamaterials

    NASA Astrophysics Data System (ADS)

    Becerra O, G.; Granada E, J. C.

    2014-12-01

    Using the Green's function formalism, Tamm states of localized modes are investigated at the interface separating auniform conventional material and a one-dimensional semi-infinite photonic crystal consisting of a series of alternating conventional materials and metamaterials. We investigate how the presence of such metamaterials influences the band structure of collective modes that appear in the photonic crystal, with special attention to the power spectrum of collective excitations and the dispersion relations. It is shown that there is one localized backward TE mode with frequencies below the resonance frequency of the metamaterial magnetic permeability and above such frequency there are one forward TM, and two backward TM and TE localized modes.

  5. All-optical diode actions through a coupled system of Tamm plasmon-polariton and nonlinear cavity mode

    NASA Astrophysics Data System (ADS)

    Fang, Yun-Tuan; Zheng, Jing; Yang, Li-Xia; Zhou, Xiang

    2013-08-01

    Light propagation in a coupled system of Tamm plasmon-polariton and nonlinear cavity mode is theoretically investigated through the nonlinear transfer matrix method. It is found that the asymmetric layered structure exhibits both pronounced unidirectionality and high transmission. This leads to all-optical diode actions. Compared with other similar studies, the designed structure is much simple only with seven periods. The unique feature is that the direction of on-off can be reversed depending on the working frequencies. The effect of metal loss is also considered in this study.

  6. Tunneling time in attosecond experiments, intrinsic-type of time. Keldysh, and Mandelstam-Tamm time

    NASA Astrophysics Data System (ADS)

    Kullie, Ossama

    2016-05-01

    Tunneling time in attosecond and strong-field experiments is one of the most controversial issues in current research, because of its importance to the theory of time, the time operator and the time-energy uncertainty relation in quantum mechanics. In Kullie (2015 Phys. Rev. A 92 052118) we derived an estimation of the (real) tunneling time, which shows an excellent agreement with the time measured in attosecond experiments, our derivation is found by utilizing the time-energy uncertainty relation, and it represents a quantum clock. In this work, we show different aspects of the tunneling time in attosecond experiments, we discuss and compare the different views and approaches, which are used to calculate the tunneling time, i.e. Keldysh time (as a real or imaginary quantity), Mandelstam-Tamm time, the classical view of the time measurement and our tunneling time relation(s). We draw some conclusions concerning the validity and the relation between the different types of the tunneling time with the hope that they will help to answer the question put forward by Orlando et al (2014 J. Phys. B 47 204002, 2014 Phys. Rev. A 89 014102): tunneling time, what does it mean? However, as we will see, the important question is a more general one: how to understand the time and the measurement of the time of a quantum system? In respect to our result, the time in quantum mechanics can be, in more general fashion, classified in two types, intrinsic dynamically connected, and external dynamically not connected to the system, and consequently (perhaps only) classical Newtonian time remains as a parametric type of time.

  7. Numerical investigation of optical Tamm states in two-dimensional hybrid plasmonic-photonic crystal nanobeams

    SciTech Connect

    Meng, Zi-Ming E-mail: lizy@aphy.iphy.ac.cn; Hu, Yi-Hua; Ju, Gui-Fang; Zhong, Xiao-Lan; Ding, Wei; Li, Zhi-Yuan E-mail: lizy@aphy.iphy.ac.cn

    2014-07-28

    Optical Tamm states (OTSs) in analogy with its electronic counterpart confined at the surface of crystals are optical surface modes at the interfaces between uniform metallic films and distributed Bragg reflectors. In this paper, OTSs are numerically investigated in two-dimensional hybrid plasmonic-photonic crystal nanobeams (HPPCN), which are constructed by inserting a metallic nanoparticle into a photonic crystal nanobeam formed by periodically etching square air holes into dielectric waveguides. The evidences of OTSs can be verified by transmission spectra and the field distribution at resonant frequency. Similar to OTSs in one-dimensional multilayer structures OTSs in HPPCN can be excited by both TE and TM polarization. The physical origin of OTSs in HPPCN is due to the combined contribution of strong reflection imposed by the photonic band gap (PBG) of the photonic crystal (PC) nanobeam and strong backward scattering exerted by the nanoparticle. For TE, incidence OTSs can be obtained at the frequency near the center of the photonic band gap. The transmissivity and the resonant frequency can be finely tuned by the dimension of nanoparticles. While for TM incidence OTSs are observed for relatively larger metallic nanoparticles compared with TE polarization. The differences between TE and TM polarization can be explained by two reasons. For one reason stronger backward scattering of nanoparticles for TE polarization can be achieved by the excitation of localized surface plasmon polariton of nanoparticles. This assumption has been proved by examining the scattering, absorption, and extinction cross section of the metallic nanoparticle. The other can be attributed to the deep and wide PBG available for TE polarization with less number of air holes compared with TM polarization. Our results show great promise in extending the application scope of OTSs from one-dimensional structures to practical integrated photonic devices and circuits.

  8. Numerical investigation of optical Tamm states in two-dimensional hybrid plasmonic-photonic crystal nanobeams

    NASA Astrophysics Data System (ADS)

    Meng, Zi-Ming; Hu, Yi-Hua; Ju, Gui-Fang; Zhong, Xiao-Lan; Ding, Wei; Li, Zhi-Yuan

    2014-07-01

    Optical Tamm states (OTSs) in analogy with its electronic counterpart confined at the surface of crystals are optical surface modes at the interfaces between uniform metallic films and distributed Bragg reflectors. In this paper, OTSs are numerically investigated in two-dimensional hybrid plasmonic-photonic crystal nanobeams (HPPCN), which are constructed by inserting a metallic nanoparticle into a photonic crystal nanobeam formed by periodically etching square air holes into dielectric waveguides. The evidences of OTSs can be verified by transmission spectra and the field distribution at resonant frequency. Similar to OTSs in one-dimensional multilayer structures OTSs in HPPCN can be excited by both TE and TM polarization. The physical origin of OTSs in HPPCN is due to the combined contribution of strong reflection imposed by the photonic band gap (PBG) of the photonic crystal (PC) nanobeam and strong backward scattering exerted by the nanoparticle. For TE, incidence OTSs can be obtained at the frequency near the center of the photonic band gap. The transmissivity and the resonant frequency can be finely tuned by the dimension of nanoparticles. While for TM incidence OTSs are observed for relatively larger metallic nanoparticles compared with TE polarization. The differences between TE and TM polarization can be explained by two reasons. For one reason stronger backward scattering of nanoparticles for TE polarization can be achieved by the excitation of localized surface plasmon polariton of nanoparticles. This assumption has been proved by examining the scattering, absorption, and extinction cross section of the metallic nanoparticle. The other can be attributed to the deep and wide PBG available for TE polarization with less number of air holes compared with TM polarization. Our results show great promise in extending the application scope of OTSs from one-dimensional structures to practical integrated photonic devices and circuits.

  9. Kristine Bonnevie, Tine Tammes and Elisabeth Schiemann in early genetics: emerging chances for a university career for women.

    PubMed

    Stamhuis, Ida H; Monsen, Arve

    2007-01-01

    The beginning of the twentieth century saw the emergence of the discipline of genetics. It is striking how many female scientists were contributing to this new field at the time. At least three female pioneers succeeded in becoming professors: Kristine Bonnevie (Norway), Elisabeth Schiemann (Germany) and the Tine Tammes (The Netherlands). The question is which factors contributed to the success of these women's careers? At the time women were gaining access to university education it had become quite the norm for universities to be sites for teaching and research. They were still expanding: new laboratories were being built and new disciplines were being established. All three women benefited from the fact that genetics was considered a new field promising in terms of its utility to society; in the case of Tammes and Schiemann in agriculture and in the case of Bonnevie in eugenics. On the other hand, the field of genetics also benefited from the fact that these first female researchers were eager for the chance to work in science and wanted to make active contributions. The all worked and studied in environments which, although different from one another, were positive towards them, at least at the start. Having a patron was generally a prerequisite. Tammes profited from her teacher's contacts and status. Bonnevie made herself indispensable through her success as a teacher and eventually made her position so strong that she was no longer dependent on a single patron. The case of Schiemann adds something new; it shows the vulnerability of such dependency. Initially, Schiemann's teacher had to rely on the first generation of university women simply because he was unable to attract ambitious young men to his institute. In those early, uncertain years of the new discipline, male scientists tended to choose other, better established, and more prestigious disciplines. However, when genetics itself had become an established field, it also became more attractive to men

  10. Effect of hybrid state of surface plasmon-polaritons, magnetic defect mode and optical Tamm state on nonreciprocal propagation

    NASA Astrophysics Data System (ADS)

    Fang, Yun-tuan; Ni, Yue-xin; He, Hang-qing; Hu, Jian-xia

    2014-06-01

    A coupled system of semi-infinite one-dimensional photonic crystal coated with metal and magnetic films is proposed. The properties of hybrid states of surface plasmon-polaritons, magnetic defect mode and optical Tamm state from the system have been studied through the Bloch theorem of periodic structure and the transfer matrix method. In the hybrid states the magneto-optical effect is amplified due to the field resonance amplification at the interface between the metal and magneto-optical material. Tunable nonreciprocal propagation can be achieved from the hybrid states through changing the thickness of magneto-optical material layer. The nonreciprocity is found to be robust to the change of metal thickness.

  11. Going beyond the Tamm-Dancoff approximation in the Bethe-Salpeter approach to the optical properties of solids

    NASA Astrophysics Data System (ADS)

    Puschnig, Peter; Ambrosch-Draxl, Claudia

    2007-03-01

    The solution of the Bethe-Salpeter equation (BSE) has turned out to be the method of choice for the ab-initio calculation of optical properties of semiconductors and insulators which is capable of correctly accounting for excitonic effects. Commonly, however, the coupling between the resonant and anti-resonant excitations is neglected, referred to as the Tamm-Dancoff approximation (TDA). This is well justified in many cases, in particular, for the working horses of theoretical solid state physics, such as bulk Si and GaAs. Here, we report on a first-principles investigation of the optical properties of organic semiconductors which are highly anisotropic systems. We find that the TDA no longer holds in such low-dimensional systems, where the exciton binding energies are no longer small compared to the band gaps. Going beyond the TDA leads to an increase of the exciton binding energy in the order of several tenths of an eV thereby considerably improving the agreement with experiment.

  12. Immunological detection of nitrosative stress-mediated modified Tamm-Horsfall glycoprotein (THP) in calcium oxalate stone formers.

    PubMed

    Pragasam, V; Kalaiselvi, P; Sumitra, K; Srinivasan, S; Anandkumar, P; Varalakshmi, P

    2006-01-01

    The generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in hyperoxaluric condition has been proved experimentally. This may result in the formation of the cytotoxic metabolite peroxynitrite, which is capable of causing lipid peroxidation and protein modification. The presence of nitrotyrosine in proteins has been associated with several pathological conditions. The present study investigated the presence of nitrotyrosine in the stone formers Tamm-Horsfall glycoprotein (THP). In vitro nitration of control THP was carried out using peroxynitrite. New Zealand white rabbits were immunized with peroxynitrated THP at 15-day intervals. Antisera collected following the third immunization were assayed for antibody titres using solid-phase ELISA. Antibodies were purified by affinity chromatography. The carbonyl content of control, stone formers and nitrated THP were determined. Western blotting was carried with control, stone formers and nitrated THPs. Immunodiffusion studies demonstrated cross-reaction with nitrated bovine serum albumin. Significant amounts (p < 0.001) of carbonyl content were present in both stone formers and nitrated THPs. Western blot analysis confirmed the presence of nitrated amino acid 3-nitrotyrosine in stone formers, which could bring about structural and functional modifications of THP in hyperoxaluric patients. A cross-reaction with nitrated bovine serum albumin confirms that the raised antibody has certain paratopes similar to the epitope of nitrated protein molecules. Detection of 3-nitrotyrosine in stone formers THP indicates that it is one of the key factors influencing the conversion of THP to a structurally and immunologically altered form during calcium oxalate stone formation.

  13. Estimation of a 2p2h effect on Gamow-Teller transitions within the second Tamm-Dancoff approximation

    NASA Astrophysics Data System (ADS)

    Minato, F.

    2016-04-01

    Two-particle two-hole (2p2h) effect on the Gamow-Teller (GT) transition for neutron-rich nuclei is studied by the second Tamm-Dancoff approximation (STDA) with the Skyrme interaction. Unstable 24O and 34Si and stable 48Ca nuclei are chosen to study the quenching and fragmentation of the GT strengths. Correlation of the 2p2h configurations causes about 20 % quenching and downward shift of GT giant resonances (GTGRs). The residual interaction changing relative angular momentum that appeared in the tensor force part gives a meaningful effect to the GT strength distributions. In this work, 17 - 26 % of the total GT strengths are brought to high-energy region above GTGRs. In particular, the tensor force brings strengths to high energy more than 50 MeV. STDA calculation within a small model space for 2p2h configuration is also performed and experimental data of 48Ca is reproduced reasonably.

  14. Direct determination of exciton couplings from subsystem time-dependent density-functional theory within the Tamm-Dancoff approximation

    NASA Astrophysics Data System (ADS)

    König, Carolin; Schlüter, Nicolas; Neugebauer, Johannes

    2013-01-01

    In subsystem time-dependent density functional theory (TDDFT) [J. Neugebauer, J. Chem. Phys. 126, 134116 (2007), 10.1063/1.2713754] localized excitations are used to calculate delocalized excitations in large chromophore aggregates. We have extended this formalism to allow for the Tamm-Dancoff approximation (TDA). The resulting response equations have a form similar to a perturbative configuration interaction singles (CIS) approach. Thus, the inter-subsystem matrix elements in subsystem TDA can, in contrast to the full subsystem-TDDFT case, directly be interpreted as exciton coupling matrix elements. Here, we present the underlying theory of subsystem TDDFT within the TDA as well as first applications. Since for some classes of pigments, such as linear polyenes and carotenoids, TDA has been reported to perform better than full TDDFT, we also report applications of this formalism to exciton couplings in dimers of such pigments and in mixed bacteriochlorophyll-carotenoid systems. The improved description of the exciton couplings can be traced back to a more balanced description of the involved local excitations.

  15. Observation of Tamm plasmon polaritons in visible regime from ZnO/Al 2O 3 distributed Bragg reflector - Ag interface

    NASA Astrophysics Data System (ADS)

    Tsang, S. H.; Yu, S. F.; Li, X. F.; Yang, H. Y.; Liang, H. K.

    2011-04-01

    Ag coated ZnO/Al2O3 distributed Bragg reflectors (DBRs), which were fabricated by a modified filtered cathodic vacuum arc technique at room temperature, shown the formation of visible Tamm plasmon polaritons (TPP). By varying the thickness of Ag and top ZnO dielectric layer of the DBR, it can be verified that the excitation of dip at the stopband of the reflection spectrum is related to TPPs. As visible light was used to excite TPPs, the corresponding effective mass can be reduced to 1.3 × 10- 5 of the free electron mass.

  16. A simplified Tamm-Dancoff density functional approach for the electronic excitation spectra of very large molecules

    NASA Astrophysics Data System (ADS)

    Grimme, Stefan

    2013-06-01

    Two approximations in the Tamm-Dancoff density functional theory approach (TDA-DFT) to electronically excited states are proposed which allow routine computations for electronic ultraviolet (UV)- or circular dichroism (CD) spectra of molecules with 500-1000 atoms. Speed-ups compared to conventional time-dependent DFT (TD-DFT) treatments of about two to three orders of magnitude in the excited state part at only minor loss of accuracy are obtained. The method termed sTDA ("s" for simplified) employs atom-centered Löwdin-monopole based two-electron repulsion integrals with the asymptotically correct 1/R behavior and perturbative single excitation configuration selection. It is formulated generally for any standard global hybrid density functional with given Fock-exchange mixing parameter ax. The method performs well for two standard benchmark sets of vertical singlet-singlet excitations for values of ax in the range 0.2-0.6. The mean absolute deviations from reference data are only 0.2-0.3 eV and similar to those from standard TD-DFT. In three cases (two dyes and one polypeptide), good mutual agreement between the electronic spectra (up to 10-11 eV excitation energy) from the sTDA method and those from TD(A)-DFT is obtained. The computed UV- and CD-spectra of a few typical systems (e.g., C60, two transition metal complexes, [7]helicene, polyalanine, a supramolecular aggregate with 483 atoms and about 7000 basis functions) compare well with corresponding experimental data. The method is proposed together with medium-sized double- or triple-zeta type atomic-orbital basis sets as a quantum chemical tool to investigate the spectra of huge molecular systems at a reliable DFT level.

  17. Electronic circular dichroism of highly conjugated π-systems: breakdown of the Tamm-Dancoff/configuration interaction singles approximation.

    PubMed

    Bannwarth, Christoph; Grimme, Stefan

    2015-04-16

    We show that the electronic circular dichroism (ECD) of delocalized π-systems represents a worst-case scenario for Tamm-Dancoff approximated (TDA) linear response methods. We mainly consider density functional theory (TDA-DFT) variants together with range-separated hybrids, but the conclusions also apply for other functionals as well as the configuration interaction singles (CIS) approaches. We study the effect of the TDA for the computation of ECD spectra in some prototypical extended π-systems. The C76 fullerene, a chiral carbon nanotube fragment, and [11]helicene serve as model systems for inherently chiral, π-chromophores. Solving the full linear response problem is inevitable in order to obtain accurate ECD spectra for these systems. For the C76 fullerene and the nanotube fragment, TDA and CIS approximated methods yield spectra in the origin-independent velocity gauge formalism of incorrect sign which would lead to the assignment of the opposite (wrong) absolute configuration. As a counterexample, we study the ECD of an α-helix polypeptide chain. Here, the lowest-energy transitions are dominated by localized excitations within the individual peptide units, and TDA methods perform satisfactorily. The results may have far-reaching implications for simple semiempirical methods which often employ TDA and CIS for huge molecules. Our recently presented simplified time-dependent DFT approach proves to be an excellent low-cost linear response method which together with range-separated density functionals like ωB97X-D3 produces ECD spectra in very good agreement with experiment.

  18. Configuration Interaction-Corrected Tamm-Dancoff Approximation: A Time-Dependent Density Functional Method with the Correct Dimensionality of Conical Intersections.

    PubMed

    Li, Shaohong L; Marenich, Aleksandr V; Xu, Xuefei; Truhlar, Donald G

    2014-01-16

    Linear response (LR) Kohn-Sham (KS) time-dependent density functional theory (TDDFT), or KS-LR, has been widely used to study electronically excited states of molecules and is the method of choice for large and complex systems. The Tamm-Dancoff approximation to TDDFT (TDDFT-TDA or KS-TDA) gives results similar to KS-LR and alleviates the instability problem of TDDFT near state intersections. However, KS-LR and KS-TDA share a debilitating feature; conical intersections of the reference state and a response state occur in F - 1 instead of the correct F - 2 dimensions, where F is the number of internal degrees of freedom. Here, we propose a new method, named the configuration interaction-corrected Tamm-Dancoff approximation (CIC-TDA), that eliminates this problem. It calculates the coupling between the reference state and an intersecting response state by interpreting the KS reference-state Slater determinant and linear response as if they were wave functions. Both formal analysis and test results show that CIC-TDA gives similar results to KS-TDA far from a conical intersection, but the intersection occurs with the correct dimensionality. We anticipate that this will allow more realistic application of TDDFT to photochemistry.

  19. A simple diagnostic method for the differentiation of Tamm-Horsfall glycoproteins from healthy probands and those from recurrent calcium oxalate renal stone formers.

    PubMed

    Schnierle, P

    1995-11-15

    Tamm-Horsfall glycoproteins (THPs)* from healthy probands, and those from a majority of recurrent calcium oxalate renal stone formers, reveal different properties when analyzed using isoelectric focusing. The pl-values of THPs from healthy probands are approximately 3.5 while THPs from recurrent renal stone formers have pl-values between 4.5 and 6. The two groups of THPs exhibit completely different protein patterns in IEF. This proves the structural difference of these THPs. The differences in IEF analysis allow the differentiation between THPs from healthy probands and those from recurrent calcium oxalate stone formers. These differences could possibly be used as a simple diagnostic method for the recognition of recurrent calcium oxalate renal stone formers.

  20. Exploring the nature of low-lying excited-states in molecular crystals from many-body perturbation theory beyond the Tamm-Dancoff Approximation

    NASA Astrophysics Data System (ADS)

    Rangel, Tonatiuh; Sharifzadeh, Sahar; Rinn, Andre; da Jornada, Felipe H.; Shao, Meiyue; Witte, Gregor; Yang, Chao; Louie, Steven G.; Chatterjee, Sangaam; Kronik, Leeor; Neaton, Jeffrey B.

    Organic semiconductors have attracted attention due to their potential for optoelectronics and novel phenomena, such as singlet fission. Here, we use many-body perturbation theory to simulate neutral excitations in acene and perylene crystals. By diagonalizing the full Bethe-Salpether (BSE) Hamiltonian beyond the Tamm Dancoff approximation (TDA), we find that both low-lying excitation energies and oscillator strengths are in improved agreement with experiments relative to the TDA. We characterize the low-lying excitons, focusing in the degree of charge-transfer and spatial delocalization, connecting their relevance to singlet fission. For perylene, we find overall good agreement with absorption measurements, and we see evidence for the formation of an ``exciton-polariton'' band in β-perylene. This work is supported by the DOE.

  1. Ultra-fast computation of electronic spectra for large systems by tight-binding based simplified Tamm-Dancoff approximation (sTDA-xTB)

    NASA Astrophysics Data System (ADS)

    Grimme, Stefan; Bannwarth, Christoph

    2016-08-01

    The computational bottleneck of the extremely fast simplified Tamm-Dancoff approximated (sTDA) time-dependent density functional theory procedure [S. Grimme, J. Chem. Phys. 138, 244104 (2013)] for the computation of electronic spectra for large systems is the determination of the ground state Kohn-Sham orbitals and eigenvalues. This limits such treatments to single structures with a few hundred atoms and hence, e.g., sampling along molecular dynamics trajectories for flexible systems or the calculation of chromophore aggregates is often not possible. The aim of this work is to solve this problem by a specifically designed semi-empirical tight binding (TB) procedure similar to the well established self-consistent-charge density functional TB scheme. The new special purpose method provides orbitals and orbital energies of hybrid density functional character for a subsequent and basically unmodified sTDA procedure. Compared to many previous semi-empirical excited state methods, an advantage of the ansatz is that a general eigenvalue problem in a non-orthogonal, extended atomic orbital basis is solved and therefore correct occupied/virtual orbital energy splittings as well as Rydberg levels are obtained. A key idea for the success of the new model is that the determination of atomic charges (describing an effective electron-electron interaction) and the one-particle spectrum is decoupled and treated by two differently parametrized Hamiltonians/basis sets. The three-diagonalization-step composite procedure can routinely compute broad range electronic spectra (0-8 eV) within minutes of computation time for systems composed of 500-1000 atoms with an accuracy typical of standard time-dependent density functional theory (0.3-0.5 eV average error). An easily extendable parametrization based on coupled-cluster and density functional computed reference data for the elements H-Zn including transition metals is described. The accuracy of the method termed sTDA-xTB is first

  2. A parallel implementation of the analytic nuclear gradient for time-dependent density functional theory within the Tamm-Dancoff approximation

    NASA Astrophysics Data System (ADS)

    Liu, Fenglai; Gan, Zhengting; Shao, Yihan; Hsu, Chao-Ping; Dreuw, Andreas; Head-Gordon, Martin; Miller, Benjamin T.; Brooks, Bernard R.; Yu, Jian-Guo; Furlani, Thomas R.; Kong, Jing

    2010-10-01

    We derived the analytic gradient for the excitation energies from a time-dependent density functional theory calculation within the Tamm-Dancoff approximation (TDDFT/TDA) using Gaussian atomic orbital basis sets, and introduced an efficient serial and parallel implementation. Some timing results are shown from a B3LYP/6-31G**/SG-1-grid calculation on zincporphyrin. We also performed TDDFT/TDA geometry optimizations for low-lying excited states of 20 small molecules, and compared adiabatic excitation energies and optimized geometry parameters to experimental values using the B3LYP and ωB97 functionals. There are only minor differences between TDDFT and TDA optimized excited state geometries and adiabatic excitation energies. Optimized bond lengths are in better agreement with experiment for both functionals than either CC2 or SOS-CIS(D0), while adiabatic excitation energies are in similar or slightly poorer agreement. Optimized bond angles with both functionals are more accurate than CIS values, but less accurate than either CC2 or SOS-CIS(D0) ones.

  3. Tamm-Horsfall protein regulates circulating and renal cytokines by affecting glomerular filtration rate and acting as a urinary cytokine trap.

    PubMed

    Liu, Yan; El-Achkar, Tarek M; Wu, Xue-Ru

    2012-05-11

    Although few organ systems play a more important role than the kidneys in cytokine catabolism, the mechanism(s) regulating this pivotal physiological function and how its deficiency affects systemic cytokine homeostasis remain unclear. Here we show that elimination of Tamm-Horsfall protein (THP) expression from mouse kidneys caused a marked elevation of circulating IFN-γ, IL1α, TNF-α, IL6, CXCL1, and IL13. Accompanying this were enlarged spleens with prominent white-pulp macrophage infiltration. Lipopolysaccharide (LPS) exacerbated the increase of serum cytokines without a corresponding increase in their urinary excretion in THP knock-out (KO) mice. This, along with the rise of serum cystatin C and the reduced inulin and creatinine clearance from the circulation, suggested that diminished glomerular filtration may contribute to reduced cytokine clearance in THP KO mice both at the baseline and under stress. Unlike wild-type mice where renal and urinary cytokines formed specific in vivo complexes with THP, this "trapping" effect was absent in THP KO mice, thus explaining why cytokine signaling pathways were activated in renal epithelial cells in such mice. Our study provides new evidence implicating an important role of THP in influencing cytokine clearance and acting as a decoy receptor for urinary cytokines. Based on these and other data, we present a unifying model that underscores the role of THP as a major regulator of renal and systemic immunity.

  4. EGF receptor-dependent mechanism may be involved in the Tamm-Horsfall glycoprotein-enhanced PMN phagocytosis via activating Rho family and MAPK signaling pathway.

    PubMed

    Li, Ko-Jen; Siao, Sue-Cien; Wu, Cheng-Han; Shen, Chieh-Yu; Wu, Tsai-Hung; Tsai, Chang-Youh; Hsieh, Song-Chou; Yu, Chia-Li

    2014-01-21

    Our previous studies showed that urinary Tamm-Horsfall glycoprotein (THP) potently enhanced polymorphonuclear neutrophil (PMN) phagocytosis. However, the domain structure(s), signaling pathway and the intracellular events responsible for THP-enhanced PMN phagocytosis remain to be elucidated. THP was purified from normal human urine. The human promyelocytic leukemia cell line HL-60 was induced to differentiate into PMNs by all-trans retinoid acid. Pretreatment with different MAPK and PI3K inhibitors was used to delineate signaling pathways in THP-enhanced PMN phagocytosis. Phosphorylation of molecules responsible for PMN phagocytosis induced by bacterial lipopolysaccharide (LPS), THP, or human recombinant epidermal growth factor (EGF) was evaluated by western blot. A p38 MAPK inhibitor, SB203580, effectively inhibited both spontaneous and LPS- and THP-induced PMN phagocytosis. Both THP and LPS enhanced the expression of the Rho family proteins Cdc42 and Rac that may lead to F-actin re-arrangement. Further studies suggested that THP and EGF enhance PMN and differentiated HL-60 cell phagocytosis in a similar pattern. Furthermore, the EGF receptor inhibitor GW2974 significantly suppressed THP- and EGF-enhanced PMN phagocytosis and p38 and ERK1/2 phosphorylation in differentiated HL-60 cells. We conclude that EGF receptor-dependent signaling may be involved in THP-enhanced PMN phagocytosis by activating Rho family and MAP kinase.

  5. Excited-State Electronic Structure with Configuration Interaction Singles and Tamm-Dancoff Time-Dependent Density Functional Theory on Graphical Processing Units.

    PubMed

    Isborn, Christine M; Luehr, Nathan; Ufimtsev, Ivan S; Martínez, Todd J

    2011-06-14

    Excited-state calculations are implemented in a development version of the GPU-based TeraChem software package using the configuration interaction singles (CIS) and adiabatic linear response Tamm-Dancoff time-dependent density functional theory (TDA-TDDFT) methods. The speedup of the CIS and TDDFT methods using GPU-based electron repulsion integrals and density functional quadrature integration allows full ab initio excited-state calculations on molecules of unprecedented size. CIS/6-31G and TD-BLYP/6-31G benchmark timings are presented for a range of systems, including four generations of oligothiophene dendrimers, photoactive yellow protein (PYP), and the PYP chromophore solvated with 900 quantum mechanical water molecules. The effects of double and single precision integration are discussed, and mixed precision GPU integration is shown to give extremely good numerical accuracy for both CIS and TDDFT excitation energies (excitation energies within 0.0005 eV of extended double precision CPU results).

  6. Linear-scaling time-dependent density-functional theory beyond the Tamm-Dancoff approximation: Obtaining efficiency and accuracy with in situ optimised local orbitals

    NASA Astrophysics Data System (ADS)

    Zuehlsdorff, T. J.; Hine, N. D. M.; Payne, M. C.; Haynes, P. D.

    2015-11-01

    We present a solution of the full time-dependent density-functional theory (TDDFT) eigenvalue equation in the linear response formalism exhibiting a linear-scaling computational complexity with system size, without relying on the simplifying Tamm-Dancoff approximation (TDA). The implementation relies on representing the occupied and unoccupied subspaces with two different sets of in situ optimised localised functions, yielding a very compact and efficient representation of the transition density matrix of the excitation with the accuracy associated with a systematic basis set. The TDDFT eigenvalue equation is solved using a preconditioned conjugate gradient algorithm that is very memory-efficient. The algorithm is validated on a small test molecule and a good agreement with results obtained from standard quantum chemistry packages is found, with the preconditioner yielding a significant improvement in convergence rates. The method developed in this work is then used to reproduce experimental results of the absorption spectrum of bacteriochlorophyll in an organic solvent, where it is demonstrated that the TDA fails to reproduce the main features of the low energy spectrum, while the full TDDFT equation yields results in good qualitative agreement with experimental data. Furthermore, the need for explicitly including parts of the solvent into the TDDFT calculations is highlighted, making the treatment of large system sizes necessary that are well within reach of the capabilities of the algorithm introduced here. Finally, the linear-scaling properties of the algorithm are demonstrated by computing the lowest excitation energy of bacteriochlorophyll in solution. The largest systems considered in this work are of the same order of magnitude as a variety of widely studied pigment-protein complexes, opening up the possibility of studying their properties without having to resort to any semiclassical approximations to parts of the protein environment.

  7. Linear-scaling time-dependent density-functional theory beyond the Tamm-Dancoff approximation: Obtaining efficiency and accuracy with in situ optimised local orbitals

    SciTech Connect

    Zuehlsdorff, T. J. Payne, M. C.; Hine, N. D. M.; Haynes, P. D.

    2015-11-28

    We present a solution of the full time-dependent density-functional theory (TDDFT) eigenvalue equation in the linear response formalism exhibiting a linear-scaling computational complexity with system size, without relying on the simplifying Tamm-Dancoff approximation (TDA). The implementation relies on representing the occupied and unoccupied subspaces with two different sets of in situ optimised localised functions, yielding a very compact and efficient representation of the transition density matrix of the excitation with the accuracy associated with a systematic basis set. The TDDFT eigenvalue equation is solved using a preconditioned conjugate gradient algorithm that is very memory-efficient. The algorithm is validated on a small test molecule and a good agreement with results obtained from standard quantum chemistry packages is found, with the preconditioner yielding a significant improvement in convergence rates. The method developed in this work is then used to reproduce experimental results of the absorption spectrum of bacteriochlorophyll in an organic solvent, where it is demonstrated that the TDA fails to reproduce the main features of the low energy spectrum, while the full TDDFT equation yields results in good qualitative agreement with experimental data. Furthermore, the need for explicitly including parts of the solvent into the TDDFT calculations is highlighted, making the treatment of large system sizes necessary that are well within reach of the capabilities of the algorithm introduced here. Finally, the linear-scaling properties of the algorithm are demonstrated by computing the lowest excitation energy of bacteriochlorophyll in solution. The largest systems considered in this work are of the same order of magnitude as a variety of widely studied pigment-protein complexes, opening up the possibility of studying their properties without having to resort to any semiclassical approximations to parts of the protein environment.

  8. Tamm-Horsfall protein in recurrent calcium kidney stone formers with positive family history: abnormalities in urinary excretion, molecular structure and function.

    PubMed

    Jaggi, Markus; Nakagawa, Yasushi; Zipperle, Ljerka; Hess, Bernhard

    2007-04-01

    Tamm-Horsfall protein (THP) powerfully inhibits calcium oxalate crystal aggregation, but structurally abnormal THPs from recurrent calcium stone formers may promote crystal aggregation. Therefore, increased urinary excretion of abnormal THP might be of relevance in nephrolithiasis. We studied 44 recurrent idiopathic calcium stone formers with a positive family history of stone disease (RCSF(fam)) and 34 age- and sex-matched healthy controls (C). Twenty-four-hour urinary THP excretion was measured by enzyme linked immunosorbent assay. Structural properties of individually purified THPs were obtained from analysis of elution patterns from a Sepharose 4B column. Sialic acid (SA) contents of native whole 24-h urines, crude salt precipitates of native urines and individually purified THPs were measured. THP function was studied by measuring inhibition of CaOx crystal aggregation in vitro (pH 5.7, 200 mM sodium chloride). Twenty-four-hour urine excretion of THP was higher in RCSF(fam) (44.0 +/- 4.0 mg/day) than in C (30.9 +/- 2.2 mg/day, P = 0.015). Upon salt precipitation and lyophilization, elution from a Sepharose 4B column revealed one major peak (peak A, cross-reacting with polyclonal anti-THP antibody) and a second minor peak (peak B, not cross-reacting). THPs from RCSF(fam) eluted later than those from C (P = 0.021), and maximum width of THP peaks was higher in RCSF(fam )than in C (P = 0.024). SA content was higher in specimens from RCSF(fam) than from C, in native 24-h urines (207.5 +/- 20.4 mg vs. 135.2 +/- 16.1 mg, P = 0.013) as well as in crude salt precipitates of 24-h urines (10.4 +/- 0.5 mg vs. 7.4 +/- 0.9 mg, P = 0.002) and in purified THPs (75.3 +/- 9.3 microg/mg vs. 48.8 +/- 9.8 microg/mg THP, P = 0.043). Finally, inhibition of calcium oxalate monohydrate crystal aggregation by 40 mg/L of THP was lower in RCSF(fam) (6.1 +/- 5.5%, range -62.0 to +84.2%) than in C (24.9 +/- 6.0%, range -39.8 to +82.7%), P = 0.022, and only 25 out of 44 (57%) THPs from RCSF

  9. Valence excitation energies of alkenes, carbonyl compounds, and azabenzenes by time-dependent density functional theory: linear response of the ground state compared to collinear and noncollinear spin-flip TDDFT with the Tamm-Dancoff approximation.

    PubMed

    Isegawa, Miho; Truhlar, Donald G

    2013-04-07

    Time-dependent density functional theory (TDDFT) holds great promise for studying photochemistry because of its affordable cost for large systems and for repeated calculations as required for direct dynamics. The chief obstacle is uncertain accuracy. There have been many validation studies, but there are also many formulations, and there have been few studies where several formulations were applied systematically to the same problems. Another issue, when TDDFT is applied with only a single exchange-correlation functional, is that errors in the functional may mask successes or failures of the formulation. Here, to try to sort out some of the issues, we apply eight formulations of adiabatic TDDFT to the first valence excitations of ten molecules with 18 density functionals of diverse types. The formulations examined are linear response from the ground state (LR-TDDFT), linear response from the ground state with the Tamm-Dancoff approximation (TDDFT-TDA), the original collinear spin-flip approximation with the Tamm-Dancoff (TD) approximation (SF1-TDDFT-TDA), the original noncollinear spin-flip approximation with the TDA approximation (SF1-NC-TDDFT-TDA), combined self-consistent-field (SCF) and collinear spin-flip calculations in the original spin-projected form (SF2-TDDFT-TDA) or non-spin-projected (NSF2-TDDFT-TDA), and combined SCF and noncollinear spin-flip calculations (SF2-NC-TDDFT-TDA and NSF2-NC-TDDFT-TDA). Comparing LR-TDDFT to TDDFT-TDA, we observed that the excitation energy is raised by the TDA; this brings the excitation energies underestimated by full linear response closer to experiment, but sometimes it makes the results worse. For ethylene and butadiene, the excitation energies are underestimated by LR-TDDFT, and the error becomes smaller making the TDA. Neither SF1-TDDFT-TDA nor SF2-TDDFT-TDA provides a lower mean unsigned error than LR-TDDFT or TDDFT-TDA. The comparison between collinear and noncollinear kernels shows that the noncollinear kernel

  10. Valence excitation energies of alkenes, carbonyl compounds, and azabenzenes by time-dependent density functional theory: Linear response of the ground state compared to collinear and noncollinear spin-flip TDDFT with the Tamm-Dancoff approximation

    NASA Astrophysics Data System (ADS)

    Isegawa, Miho; Truhlar, Donald G.

    2013-04-01

    Time-dependent density functional theory (TDDFT) holds great promise for studying photochemistry because of its affordable cost for large systems and for repeated calculations as required for direct dynamics. The chief obstacle is uncertain accuracy. There have been many validation studies, but there are also many formulations, and there have been few studies where several formulations were applied systematically to the same problems. Another issue, when TDDFT is applied with only a single exchange-correlation functional, is that errors in the functional may mask successes or failures of the formulation. Here, to try to sort out some of the issues, we apply eight formulations of adiabatic TDDFT to the first valence excitations of ten molecules with 18 density functionals of diverse types. The formulations examined are linear response from the ground state (LR-TDDFT), linear response from the ground state with the Tamm-Dancoff approximation (TDDFT-TDA), the original collinear spin-flip approximation with the Tamm-Dancoff (TD) approximation (SF1-TDDFT-TDA), the original noncollinear spin-flip approximation with the TDA approximation (SF1-NC-TDDFT-TDA), combined self-consistent-field (SCF) and collinear spin-flip calculations in the original spin-projected form (SF2-TDDFT-TDA) or non-spin-projected (NSF2-TDDFT-TDA), and combined SCF and noncollinear spin-flip calculations (SF2-NC-TDDFT-TDA and NSF2-NC-TDDFT-TDA). Comparing LR-TDDFT to TDDFT-TDA, we observed that the excitation energy is raised by the TDA; this brings the excitation energies underestimated by full linear response closer to experiment, but sometimes it makes the results worse. For ethylene and butadiene, the excitation energies are underestimated by LR-TDDFT, and the error becomes smaller making the TDA. Neither SF1-TDDFT-TDA nor SF2-TDDFT-TDA provides a lower mean unsigned error than LR-TDDFT or TDDFT-TDA. The comparison between collinear and noncollinear kernels shows that the noncollinear kernel

  11. γ-decay of {}_{8}^{16}{{\\rm{O}}}_{8}\\,{and}\\,{}_{7}^{16}{{\\rm{N}}}_{9} in proton-neutron Tamm-Dancoff and random phase approximations with optimized surface δ interaction

    NASA Astrophysics Data System (ADS)

    Pahlavani, M. R.; Firoozi, B.

    2016-09-01

    γ-ray transitions from excited states of {}16{{N}} and {}16{{O}} isomers that appear in the γ spectrum of the {}616{{{C}}}10\\to {}716{{{N}}}9\\to {}816{{{O}}}8 beta decay chain are investigated. The theoretical approach used in this research starts with a mean-field potential consisting of a phenomenological Woods-Saxon potential including spin-orbit and Coulomb terms (for protons) in order to obtain single-particle energies and wave functions for nucleons in a nucleus. A schematic residual surface delta interaction is then employed on the top of the mean field and is treated within the proton-neutron Tamm-Dancoff approximation (pnTDA) and the proton-neutron random phase approximation. The goal is to use an optimized surface delta interaction interaction, as a residual interaction, to improve the results. We have used artificial intelligence algorithms to establish a good agreement between theoretical and experimental energy spectra. The final results of the ‘optimized’ calculations are reasonable via this approach.

  12. Transcutaneous Analyte Measuring Methods (TAMM). Phase 2

    DTIC Science & Technology

    1991-11-01

    completely developed. The BI-102 is currently set up in Biotronics’ chemical laboratory. Biotronics personnel are being tested for glucose using the BI...LABRATOF INERAC ANAt2VS <Update Patient OF BLOO( IR S l odim, ChIoio- Databse wth P10bsinn oloG * aten IfoBlood Analysis DATA ENTRY . CIL Patint Ito DTA

  13. SO(4) group structure for a motivated QCD Hamiltonian: Analytic and Tamm-Dancoff solutions

    NASA Astrophysics Data System (ADS)

    Yepez-Martinez, Tochtli; Civitarese, Osvaldo; Hess, Peter O.

    2016-08-01

    Starting from the QCD Hamiltonian written in the canonical Coulomb gauge formalism, we developed a mapping onto an SO(4) representation which is suitable for the description of the QCD spectra at low energies. The mapping does not break the flavor symmetry and it preserves the singlet-colorless structure of the states. We present and discuss the structure of integer and half-integer-spin states with masses below 2 GeV. Finally, we extend the formalism in order to include particle-hole-like correlations in building excitations.

  14. Work of the Tamm-Sakharov group on the first hydrogen bomb

    NASA Astrophysics Data System (ADS)

    Ritus, V. I.

    2014-09-01

    This review is an extended version of a report delivered at a session of the Department of Physical Sciences, the Department of Energetics, Mechanical Engineering, Mechanics, and Control Processes, and the Coordination Council on Technical Sciences of the RAS devoted to the 60th anniversary of the first hydrogen bomb test. The significant physical ideas suggested by A D Sakharov and V L Ginzburg underlying our first hydrogen bomb, RDS-6s, and numerous concrete problems and difficulties that had to be solved and overcome in designing thermonuclear weapons are presented. The understanding of the country's leaders and the Atomic Project managers of the exceptional role of fundamental science in the appearance and implementation of our scientists' concrete ideas and suggestions is emphasized.

  15. Chiral optical Tamm states at the boundary of the medium with helical symmetry of the dielectric tensor

    NASA Astrophysics Data System (ADS)

    Timofeev, I. V.; Vetrov, S. Ya.

    2016-09-01

    A new optical state at the boundary of a chiral medium whose dielectric tensor has a helical symmetry is described analytically and numerically. The case of zero tangential wavenumber is considered. The state localized near the boundary does not transfer energy along this boundary and decreases exponentially with the distance from the boundary. The penetration of the field into the chiral medium is blocked at wavelengths corresponding to the photonic band gap and close to the pitch of the helix. The polarization of light near the boundary has the same sign of chirality as the helical symmetry. It is shown that the homogeneous environment or a substrate should exhibit anisotropic metallic reflection. The spectral manifestation of the state is determined by the angle between the optical axes of the media at the interface. A state at the interface between a cholesteric liquid crystal and an anisotropic metal-dielectric nanocomposite was considered as an example.

  16. Timber assessment market model (1993): Structure, projections and policy simulations. Forest Service general technical report

    SciTech Connect

    Adams, D.M.; Haynes, R.W.

    1996-11-01

    The 1993 timber assessment market model (TAMM) is a spatial model of the solid-wood and timber inventory elements of the U.S. forest products sector. The TAMM model provides annual projections of volumes and prices in the solidwood products and sawtimber stumpage markets and estimates of total timber harvest and inventory by geographic region for periods of up to 50 years. TAMM and its companion models that project pulpwood and fuelwood use were developed to support the quinquennial Resource Planning Act (RPA) timber assessments and assessment updates conducted by the USDA Forest Service. The report summaries the methods used to develop the various components of TAMM and the estimates of key behavioral parameters used in the TAMM structure, and also illustrates the use of TAMM with a base and several scenario projections.

  17. High-resolution airborne gravity imaging over James Ross Island (West Antarctica)

    USGS Publications Warehouse

    Jordan, T.A.; Ferraccioli, F.; Jones, P.C.; Smellie, J.L.; Ghidella, M.; Corr, H. F. J.; Zakrajsek, A.F.

    2007-01-01

    James Ross Island (JRI) exposes a Miocene-Recent alkaline basaltic volcanic complex that developed in a back-arc, east of the northern Antarctic Peninsula. JRI has been the focus of several geological studies because it provides a window on Neogene magmatic processes and paleoenvironments. However, little is known about its internal structure. New airborne gravity data were collected as part of the first high-resolution aerogeophysical survey flown over the island and reveal a prominent negative Bouguer gravity anomaly over Mt Haddington. This is intriguing as basaltic volcanoes are typically associated with positive Bouguer anomalies, linked to underlying mafic intrusions. The negative Bouguer anomaly may be associated with a hitherto unrecognised low-density sub-surface body, such as a breccia-filled caldera, or a partially molten magma chamber.

  18. Q-Flex Accelerometer Thermal Performance Study

    DTIC Science & Technology

    1976-09-01

    riaK». --»- -w .1 ^i«. of tha rt«v. contractor, b. .ith.riar« Sdr «Jri2; S^SLÄt^LS!* ^V^ ****" P***- Govanwant. (b) uaad In »tola or In part by thT...Govariwant, (b) uaad in whola or in part by tha Govariwant for aanufacture or, in tha caaa of co«|^ itar aoftwara doctsMntation, for preparing tha aaaa or

  19. Puget Sound Dredged Disposal Analysis: Management Plan Assessment Report. Dredged Material Management Year 1990.

    DTIC Science & Technology

    1991-03-01

    A. 4.3 Other PSDDA Program Topics Laboratory Accreditation Ecology presented during the DY 1989 ARM a summary of: o the legal authority to establish...a laboratory accreditation program (RCW 43.21 A.230 (1987)); o the purpose in establishing such a program; o the state rules which establish such a...and documenting best professional judgment considerations. Page A-1 Page A-2 CLARIFICATION ENVIRONMENTAL LABORATORY ACCREDITATION Prepared by Toi Jries

  20. Simplified Shock Design for Installation of Equipment

    DTIC Science & Technology

    1982-03-01

    Crane IN .162 NAVFA(T*ENGC0M PAC D)IV. (Kil ( COdIC 101, PeaiI Il lahrbo. I II; C UI)I 09P)J PEAlIU HARBOR IIl; (Code 2011 Pearl Harbor. I II; (’ode 402...Cambridge MA (Whitmian) NArL, ACADEMY OF ENG. ALEXAND)RIA. VA (SEARL.E. JR.)I NAT’URAL ENERGY LAB Library. Honolulu. III NEW MEXICO SOLAR ENERGY INST. Dr

  1. A Synthesis of Research on Color, Typography, and Graphics as they Relate to Readability.

    DTIC Science & Technology

    1985-09-01

    scores for groups -1crr-’ and white caper (Michael arnd Jones, 1955). On the other hand, jr.:i,3 *,e, .!r ano J. Kenneth Jones. in ;-raestudies, cite the...source of that data. Cohen, Peter A., Barbara J. Ebeling, and James A. Kulik (1981) "A meta- ainalysis of outcome studies on visual-based instruction...learning-visual testing scored significantly higher in indentifying details than did the control group. Tversky, Barbara ( 1969) "Pictorial and verbal

  2. Experimental investigation of interface states in photonic crystal heterostructures

    NASA Astrophysics Data System (ADS)

    Guo, Jiyong; Sun, Yong; Zhang, Yewen; Li, Hongqiang; Jiang, Haitao; Chen, Hong

    2008-08-01

    Optical Tamm states, a kind of interface modes, are also called Tamm plasmon-polaritons. They are experimentally observed in photonic heterostructures based on microstrip transmission lines. The position of optical Tamm states can be designed exactly under effective impedance match and effective phase shift match conditions. Our results show that the photonic band gaps can have the effect of negative-permittivity or negative-permeability media in constructing the interface modes. The simulations and experimental results agree with each other quite well.

  3. Seasonal Water Transport in the Atmosphere of Mars: Applications of a Mars General Circulation Model Using Mars Global Surveyor Data

    NASA Technical Reports Server (NTRS)

    Hollingsworth, Jeffery L.; Bridger, Alison F. C.; Haberle, Robert M.

    1999-01-01

    This is a Final Report for a Joint Research Interchange (JRI) between NASA Ames Research Center and San Jose State University, Department of Meteorology. We present below a summary of progress made during the duration of this JRI. The focus of this JRI has been to investigate seasonal water vapor transport in the atmosphere of Mars and its effects on the planet's present climate. To this end, the primary task has been to adapt a new dynamical processor for the adiabatic tendencies of the atmospheric circulation into the NASA Ames Mars general circulation model (MGCM). Using identical boundary and initial conditions, several comparative tests between the new and old MGCMs have been performed and the nature of the simulated circulations have been diagnosed. With confidence that the updated version of the Ames MGCM produces quite similar mean and eddy circulation statistics, the new climate model is well poised as a tool to pursue fundamental questions related to the spatial and seasonal variations of atmospheric water vapor on Mars, and to explore exchanges of water with non-atmospheric reservoirs and transport within its atmosphere. In particular, the role of surface sources and sinks can be explored, the range of water-vapor saturation altitudes can be investigated, and plausible precipitation mechanisms can be studied, for a range of atmospheric dust loadings, such future investigations can contribute to a comprehensive study of surface inventories, exchange mechanisms, and the relative importance of atmospheric transport Mars' water cycle. A listing of presentations made and manuscripts submitted during the course of this project is provided.

  4. Seasonal Water Transport in the Atmosphere of Mars: Applications of a Mars General Circulation Model Using Mars Global Surveyor Data

    NASA Technical Reports Server (NTRS)

    Hollingsworth, Jeffery L.; Bridger, Alison F. C.; Haberle, Robert M.

    1999-01-01

    This is a Final Report for a Joint Research Interchange (JRI) between NASA Ames Research Center and San Jose State University, Department of Meteorology. We present below a summary of progress made during the duration of this JRI. The focus of this JRI has been to investigate seasonal water vapor transport in the atmosphere of Mars and its effects on the planet's present climate. To this end, the primary task has been to adapt a new dynamical processor for the adiabatic tendencies of the atmospheric circulation into the NASA Ames Mars general circulation model (MGCM). Using identical boundary and initial conditions, several comparative tests between the new and old MGCMs have been performed and the nature of the simulated circulations have been diagnosed. With confidence that the updated version of the Ames MGCM produces quite similar mean and eddy circulation statistics, the new climate model is well poised as a tool to pursue fundamental questions related to the spatial and seasonal variations of atmospheric water vapor on Mars, and to explore exchanges of water with non-atmospheric reservoirs and transport within its atmosphere. In particular, the role of surface sources and sinks can be explored, the range of water-vapor saturation altitudes can be investigated, and plausible precipitation mechanisms can be studied, for a range of atmospheric dust loadings. Such future investigations can contribute to a comprehensive study of surface inventories, exchange mechanisms, and the relative importance of atmospheric transport Mars' water cycle. A listing of presentations made and manuscripts submitted during the course of this project is provided.

  5. Fluid Dynamics of High Performance Turbomachines.

    DTIC Science & Technology

    1986-11-01

    8217S I.m 0- :5’> _ _ _ _ __ _ _ _ a m w m (Sqpr Cn;e 0 41 cr.J 0 c 0- C) CC 0 >J Lr)) z 0 E 00 00 L. 0 * ~ ~ ~ ~ ~ ~ ~ ~ ~ www WWI-- - - - -- , -~.-- r ...JrY 𔃽i; lo10 t ce MO J07 .78 oe 14 Ose0. 1S 10 R / R ou, 3: m xr p r w mrto 0 A TIME AVG-RF8O...g R /RT % Figure 3b: Time average tracer concentration, injection near hub *~~~~~~ ~ . . . . . .--’ : 4.’*~X: ; . .:.:. ;~~s.. .~ .,. 12 VORTEX

  6. Development of New Protocol Hardware and Software for LSI-11 to Accommodate AUTODIN II ADCCP-HDLC, and X.25. Appendix D. Maintenance Manual

    DTIC Science & Technology

    1983-02-01

    hvJry in OI 3l C* j4’. ,414rW AI~ffR A,’ 1 V b~O C ECO BZ,� XCACK- I twevx- -, SriE AA 1 DXSf i C XO TCAE - It U240f 2 TUJCE - q D~fi- 15 - ItPR DV3...85’ RICE- .. CS- 02 SEL- B 5 07’ 02 SVCR- ... C3 C4’ TCACK- B 5’ TCAE - ... CS’ 02 TCSCK . . .B8- 04 02 TCSCK- B 5’ 88to TCSE- C5 .c s’. X~jE

  7. Propagation of surface waves and waveguide modes guided by a dielectric slab inserted in a sculptured nematic thin film

    SciTech Connect

    Faryad, Muhammad; Lakhtakia, Akhlesh

    2011-01-15

    Wave propagation guided by a dielectric slab inserted in a sculptured nematic thin film (SNTF) was studied theoretically. Two types of guided waves can be identified: (i) surface (Dyakonov-Tamm) waves guided by one or both of the two planar interfaces of the dielectric slab and the SNTF, and (ii) waveguide modes in the dielectric waveguide formed by the slab with the SNTF as the cladding. As the thickness of the dielectric slab is increased, the number of waveguide modes increases. If the slab thickness is less than twice the e-folding distance into the dielectric slab, the Dyakonov-Tamm waves propagate coupled to both interfaces; the coupling decreases and eventually vanishes as the slab thickness increases, so that Dyakonov-Tamm waves are guided by the individual dielectric-SNTF interfaces independently. The chosen structure supports the propagation of Dyakonov-Tamm waves in all directions, in contrast to the restricted range of propagation supported by a single SNTF-dielectric interface. Propagation of both Dyakonov-Tamm waves and waveguide modes should occur in practice with negligible attenuation, in contrast to that of surface-plasmon-polariton waves that are guided when the dielectric slab is replaced by a metal slab.

  8. Propagation of surface waves and waveguide modes guided by a dielectric slab inserted in a sculptured nematic thin film

    NASA Astrophysics Data System (ADS)

    Faryad, Muhammad; Lakhtakia, Akhlesh

    2011-01-01

    Wave propagation guided by a dielectric slab inserted in a sculptured nematic thin film (SNTF) was studied theoretically. Two types of guided waves can be identified: (i) surface (Dyakonov-Tamm) waves guided by one or both of the two planar interfaces of the dielectric slab and the SNTF, and (ii) waveguide modes in the dielectric waveguide formed by the slab with the SNTF as the cladding. As the thickness of the dielectric slab is increased, the number of waveguide modes increases. If the slab thickness is less than twice the e-folding distance into the dielectric slab, the Dyakonov-Tamm waves propagate coupled to both interfaces; the coupling decreases and eventually vanishes as the slab thickness increases, so that Dyakonov-Tamm waves are guided by the individual dielectric-SNTF interfaces independently. The chosen structure supports the propagation of Dyakonov-Tamm waves in all directions, in contrast to the restricted range of propagation supported by a single SNTF-dielectric interface. Propagation of both Dyakonov-Tamm waves and waveguide modes should occur in practice with negligible attenuation, in contrast to that of surface-plasmon-polariton waves that are guided when the dielectric slab is replaced by a metal slab.

  9. Mars Global Surveyor: Aerobraking and Observations Support Using a Mars Global Circulation Model

    NASA Technical Reports Server (NTRS)

    Hollingsworth, Jeffery L.; Bridger, Alison F. C.; Haberle, Robert M.

    1997-01-01

    This is a Final Report for a Joint Research Interchange (JRI) between NASA Ames Research Center and San Jose State University, Department of Meteorology. Using a global atmospheric circulation model for Mars, the focus of this JRI has been to provide support for the Mars Global Surveyor (MGS) spacecraft aerobraking activities and interpretation guidance of preliminary observations. The primary atmospheric model applied in this investigation has been a high-top version of the NASA Ames Mars general circulation model (MGCM). Comparisons with an atmospheric model designed primarily for engineering purposes (Mars-GRAM) has also been carried out. From a suite of MGCM simulations, we have assessed plausible spatial and temporal variability in atmospheric density at high altitudes (e.g., 70-1 10 km) for seasonal dates and locations during Phase 1 aerobraking. Diagnostic tools have been developed to analyze circulation fields from the MGCM simulations, and these tools have been applied in the creation of a Mars climate catalogue database. Throughout Phase I aerobraking activities, analysis products have been provided to the MGS aerobraking atmospheric advisory group (AAG). Analyses of circulation variability at the coupling level between the MGCM and a Mars thermospheric global circulation model (MTGCM) has also been assessed. Finally, using a quasi-geostrophic dynamical formulation with the MGCM simulations, diagnosis of breaking planetary (Rossby) waves in Mars middle atmosphere has been carried out. Titles of papers presented at scientific workshops and seminars, and a publication in the scientific literature are provided.

  10. Mars Global Surveyor: Aerobraking and Observations Support Using a Mars Global Circulation Model

    NASA Technical Reports Server (NTRS)

    Hollingsworth, Jeffery L.; Bridger, Alison F. C.; Harberle, Robert M.

    1997-01-01

    This is a Final Report for a Joint Research Interchange (JRI) between NASA Ames Research Center and San Jose State University, Department of Meteorology. Using a global atmospheric circulation model for Mars, the focus of this JRI has been to provide support for the Mars Global Surveyor (MGS) spacecraft aerobraking activities and interpretation guidance of preliminary observations. ne primary atmospheric model applied in this investigation has been a high-top version of the NASA Ames Mars general circulation model (MGCM). Comparisons with an atmospheric model designed primarily for engineering purposes (Mars-GRAM) has also been carried out. From a suite of MGCM simulations, we have assessed plausible spatial and temporal variability in atmospheric density at high altitudes (e.g., 70-110 km) for seasonal dates and locations during Phase 1 aerobraking. Diagnostic tools have been developed to analyze circulation fields from the MGCM simulations, and these tools have been applied in the creation of a Mars climate catalogue database. Throughout Phase 1 aerobraking activities, analysis products have been provided to the MGS aerobraking atmospheric advisory group (AAG). Analyses of circulation variability at the coupling level between the MGCM and a Mars thermospheric global circulation model (MTGCM) has also been assessed. Finally, using a quasi-geostrophic dynamical formulation with the MGCM simulations, diagnosis of breaking planetary (Rossby) waves in Mars' middle atmosphere has been carried out. Titles of papers presented at scientific workshops and seminars, and a publication in the scientific literature are provided.

  11. An Intercomparison of the Dynamical Cores of Global Atmospheric Circulation Models for Mars

    NASA Technical Reports Server (NTRS)

    Hollingsworth, Jeffery L.; Bridger, Alison F. C.; Haberle, Robert M.

    1998-01-01

    This is a Final Report for a Joint Research Interchange (JRI) between NASA Ames Research Center and San Jose State University, Department of Meteorology. The focus of this JRI has been to evaluate the dynamical 'cores' of two global atmospheric circulation models for Mars that are in operation at the NASA Ames Research Center. The two global circulation models in use are fundamentally different: one uses spherical harmonics in its horizontal representation of field variables; the other uses finite differences on a uniform longitude-latitude grid. Several simulations have been conducted to assess how the dynamical processors of each of these circulation models perform using identical 'simple physics' parameterizations. A variety of climate statistics (e.g., time-mean flows and eddy fields) have been compared for realistic solstitial mean basic states. Results of this research have demonstrated that the two Mars circulation models with completely different spatial representations and discretizations produce rather similar circulation statistics for first-order meteorological fields, suggestive of a tendency for convergence of numerical solutions. Second and higher-order fields can, however, vary significantly between the two models.

  12. Mars Global Surveyor: Aerobraking and Observations Support Using a Mars Global Circulation Model

    NASA Technical Reports Server (NTRS)

    Hollingsworth, Jeffery L.; Bridger, Alison F. C.; Haberle, Robert M.

    1997-01-01

    This is a Final Report for a Joint Research Interchange (JRI) between NASA Ames Research Center and San Jose State University, Department of Meteorology. Using a global atmospheric circulation model for Mars, the focus of this JRI has been to provide support for the Mars Global Surveyor (MGS) spacecraft aerobraking activities and interpretation guidance of preliminary observations. The primary atmospheric model applied in this investigation has been a high-top version of the NASA Ames Mars general circulation model (MGCM). Comparisons with an atmospheric model designed primarily for engineering purposes (Mars-GRAM) has also been carried out. From a suite of MGCM simulations, we have assessed plausible spatial and temporal variability in atmospheric density at high altitudes (e.g., 70-110 km) for seasonal dates and locations during Phase I aerobraking. Diagnostic tools have been developed to analyze circulation fields from the MGCM simulations, and these tools have been applied in the creation of a Mars climate catalogue database. Throughout Phase I aerobraking activities, analysis products have been provided to the MGS aerobraking atmospheric advisory group (AAG). Analyses of circulation variability at the coupling level between the MGCM and a Mars thermospheric global circulation model (MTGCM) has also been assessed. Finally, using a quasi-geostrophic dynamical formulation with the MGCM simulations, diagnosis of breaking planetary (Rossby) waves in Mars' middle atmosphere has been carried out. Titles of papers presented at scientific workshops and seminars, and a publication in the scientific literature are provided.

  13. Intraseasonal and Interannual Variability of Mars Present Climate

    NASA Technical Reports Server (NTRS)

    Hollingsworth, Jeffery L.; Bridger, Alison F. C.; Haberle, Robert M.

    1996-01-01

    This is a Final Report for a Joint Research Interchange (JRI) between NASA Ames Research Center and San Jose State University, Department of Meteorology. The focus of this JRI has been to investigate the nature of intraseasonal and interannual variability of Mars'present climate. We have applied a three-dimensional climate model based on the full hydrostatic primitive equations to determine the spatial, but primarily, the temporal structures of the planet's large-scale circulation as it evolves during a given seasonal advance, and, over multi-annual cycles. The particular climate model applies simplified physical parameterizations and is computationally efficient. It could thus easily be integrated in a perpetual season or advancing season configuration, as well as over many Mars years. We have assessed both high and low-frequency components of the circulation (i.e., motions having periods of Omicron(2-10 days) or greater than Omicron(10 days), respectively). Results from this investigation have explored the basic issue whether Mars' climate system is naturally 'chaotic' associated with nonlinear interactions of the large-scale circulation-regardless of any allowance for year-to-year variations in external forcing mechanisms. Titles of papers presented at scientific conferences and a manuscript to be submitted to the scientific literature are provided. An overview of a areas for further investigation is also presented.

  14. Immunological aspects of pyelonephritis.

    PubMed

    Hanson, L A; Ahlstedt, S; Fasth, A; Hagberg, M; Kaijser, B; Mattsby-Baltzer, I; Svanborg-Eden, C

    1979-01-01

    Several virulence factors, such as O and K antigens and capacity to attach to uroepithelial cells, seem to be required for Escheria coli to cause acute pyelonephritis. These factors induce an immune response, however, which can modify the course and clinical expression of the infection. During acute pyelonephritis, autoantibodies to the Tamm-Horsfall protein increase. These antibodies, which probably are evoked by a cross-reaction noted between structures of E. coli LPS and the Tamm-Horsfall protein, may add to the renal tissue engagement in interstitial nephritis caused by bacterial pyelonephritis.

  15. HARDMAN Comparability Analysis Methodology Guide. Volume 5. Analysis Support Information

    DTIC Science & Technology

    1985-04-01

    H - HWC »-I m > u CO 4-» 0 0 fl> >i JC 0) O »OÜ 4JWH>4)flJ»-i Sc«»->*HI0Oiu -H H »Ö...Identifier Soldier Training Publications Submarines Atlantic/ Submarines Pacific j.> TAMMS TASC TASO TDIS TG TOE TRADOC TRADOC Pam 71-9

  16. QSAR Study of Mosquito Repellents Using Codessa Pro

    DTIC Science & Technology

    2006-01-01

    SciFinder catalog.21 Using Codessa Pro in the normal manner gave the 3-descriptor model for the vapor pressure shown in Table 3 with the follow- ing...20. Stone, M. J. R. Stat. Soc. B. 1977, 38, 44. 21. SciFinder Scholar, American Chemical Society, 2003. 22. Katritzky, A. R.; Wang, Y.; Sild, S.; Tamm

  17. Sensitivity of ventilation and brain metabolism to ammonia exposure in rainbow trout, Oncorhynchus mykiss.

    PubMed

    Zhang, Li; Nawata, C Michele; Wood, Chris M

    2013-11-01

    Ammonia has been documented as a respiratory gas that stimulates ventilation, and is sensed by peripheral neuroepithelial cells (NECs) in the gills in ammoniotelic rainbow trout. However, the hyperventilatory response is abolished in trout chronically exposed (1+ months) to high environmental ammonia [HEA; 250 μmol l(-1) (NH4)2SO4]. This study investigates whether the brain is involved in the acute sensitivity of ventilation to ammonia, and whether changes in brain metabolism are related to the loss of hyperventilatory responses in trout chronically exposed to HEA ('HEA trout'). Hyperventilation (via increased ventilatory amplitude rather than rate) and increased total ammonia concentration ([TAmm]) in brain tissue were induced in parallel by acute HEA exposure in control trout in a concentration-series experiment [500, 750 and 1000 μmol l(-1) (NH4)2SO4], but these inductions were abolished in HEA trout. Ventilation was correlated more closely to [TAmm] in brain rather than to [TAmm] in plasma or cerebrospinal fluid. The close correlation of hyperventilation and increased brain [TAmm] also occurred in control trout acutely exposed to HEA in a time-series analysis [500 μmol l(-1) (NH4)2SO4; 15, 30, 45 and 60 min], as well as in a methionine sulfoxamine (MSOX) pre-injection experiment [to inhibit glutamine synthetase (GSase)]. These correlations consistently suggest that brain [TAmm] is involved in the hyperventilatory responses to ammonia in trout. The MSOX treatments, together with measurements of GSase activity, TAmm, glutamine and glutamate concentrations in brain tissue, were conducted in both the control and HEA trout. These experiments revealed that GSase plays an important role in transferring ammonia to glutamate to make glutamine in trout brain, thereby attenuating the elevation of brain [TAmm] following HEA exposure, and that glutamate concentration is reduced in HEA trout. The mRNAs for the ammonia channel proteins Rhbg, Rhcg1 and Rhcg2 were expressed

  18. Information on and Comments Concerning Suicide Plane Attacks

    DTIC Science & Technology

    1945-06-25

    8217JRY 8ALL .. TAIL tiF ANY BELIEVYED JET PROPELLED LiI BUBB LE CONOP¥f: ’llDILAE8 POSSIBE PILif CONTRGL X ARFMOR INDICATE D BY `ANY O8ERVED 2aM HITS X...VJIPEPR ,tOPIRT) BTOMS giNi THATES ,EWAL C: ,tOUR-RETE I i"sCiF ^ wAC TIONXT4t D I f 5 031i^0 ANDFOR A5tCIG f 40f9 X ONtV vERVA ON’ OF4 tL:AUi\\ V...s an understanding between bridge and engineroom that when engine order telegraph was rung up 5 titles on flank speed indicator , the ongineroom knew

  19. Theory and operation of the Gould 32/27 programs ABLE-2A and EBLE for the tropospheric air motion measurement system

    NASA Technical Reports Server (NTRS)

    Butler, C.

    1986-01-01

    Software development for the Trospheric Air Motion Measurement Systems (TAMMS) is documented. In July/August the TAMMS was flown on the NASA/Goddard Flight Center Electra aircraft for 19 mission for the ABLE-2A (Amazon Boundary Layer Experiment) in Brazil. In December 1985, several flights were performed to assess the contamination and boundary layer of the Electra. Position data, flow angles, pressure transducer measurements were recorded. The programs written for the ABLE-2A were modified due to timing considerations for this particular program. The 3-step programs written for EBLE (Electra Boundary Layer Experiment) are described. Power up and log-on procedures are discussed. A few editing techniques are described for modification of the programs.

  20. The role of the fano resonance in multiple exciton generation in quantum dots

    NASA Astrophysics Data System (ADS)

    Oksengendler, B. L.; Marasulov, M. B.; Nikiforov, V. N.

    2016-02-01

    The phenomenon of interference between two pathways of electron transfer from the valence to the conduction band at a quantum dot is considered. The first way is the conventional "valence band-conduction band" transition, while the second is the transition via a virtual two-electron state on the Tamm level in a quantum dot (QD) followed by the Auger effect, which ejects one electron from the Tamm level to the conduction band. In the case of a coherent addition of these ionization pathways, the Fano resonance can take place, this leading to an increase in the coefficient of photon absorption. This results in increasing internal efficiency of light conversion and can provide a basis for increasing the efficiency of solar cells due to the phenomenon of multiple exciton generation.

  1. Transport of Massless Dirac Fermions in Non-topological Type Edge States

    PubMed Central

    Latyshev, Yu I.; Orlov, A. P.; Volkov, V. A.; Enaldiev, V. V.; Zagorodnev, I. V.; Vyvenko, O. F.; Petrov, Yu V.; Monceau, P.

    2014-01-01

    There are two types of intrinsic surface states in solids. The first type is formed on the surface of topological insulators. Recently, transport of massless Dirac fermions in the band of “topological” states has been demonstrated. States of the second type were predicted by Tamm and Shockley long ago. They do not have a topological background and are therefore strongly dependent on the properties of the surface. We study the problem of the conductivity of Tamm-Shockley edge states through direct transport experiments. Aharonov-Bohm magneto-oscillations of resistance are found on graphene samples that contain a single nanohole. The effect is explained by the conductivity of the massless Dirac fermions in the edge states cycling around the nanohole. The results demonstrate the deep connection between topological and non-topological edge states in 2D systems of massless Dirac fermions. PMID:25524881

  2. Propagation and excitation of multiple surface waves

    NASA Astrophysics Data System (ADS)

    Faryad, Muhammad

    Surface waves are the solutions of the frequency-domain Maxwell equations at the planar interface of two dissimilar materials. The time-averaged Poynting vector of a surface wave (i) has a significant component parallel to the interface and (ii) decays at sufficiently large distances normal to the interface. If one of the partnering materials is a metal and the other a dielectric, the surface waves are called surface plasmon-polariton (SPP) waves. If both partnering materials are dielectric, with at least one being periodically nonhomogeneous normal to the interface, the surface waves are called Tamm waves; and if that dielectric material is also anisotropic, the surface waves are called Dyakonov--Tamm waves. SPP waves also decays along the direction of propagation, whereas Tamm and Dyakonov--Tamm waves propagate with negligible losses. The propagation and excitation of multiple SPP waves guided by the interface of a metal with a periodically nonhomogeneous sculptured nematic thin film (SNTF), and the interface of a metal with a rugate filter were theoretically investigated. The SNTF is an anisotropic material with a permittivity dyadic that is periodically nonhomogeneous in the thickness direction. A rugate filter is also a periodically nonhomogeneous dielectric material; however, it is an isotropic material. Multiple SPP waves of the same frequency but with different polarization states, phase speeds, attenuation rates, and spatial field profiles were found to be guided by a metal/SNTF interface, a metal/rugate-filter interface, and a metal slab in the SNTF. Multiple Dyakonov--Tamm waves of the same frequency but different polarization states, phase speeds, and spatial field profiles were found to be guided by a structural defect in an SNTF, and by a dielectric slab in an SNTF. The characteristics of multiple SPP and Dyakonov--Tamm waves were established by the investigations on canonical boundary-value problems. The Turbadar-Kretschmann-Raether (TKR) and the

  3. Hyperbolic resonances of metasurface cavities.

    PubMed

    Keene, D; Durach, M

    2015-07-13

    We propose a new class of optical resonator structures featuring one or two metasurface reflectors or metacavities and predict that such resonators support novel hyperbolic resonances. As an example of such resonances we introduce hyperbolic Tamm plasmons (HTPs) and hyperbolic Fabry-Perot resonances (HFPs). The hyperbolic optical modes feature low-loss incident power re-distribution over TM and TE polarization output channels, clover-leaf anisotropic dispersion, and other unique properties which are tunable and are useful for multiple applications.

  4. Nuclear Response Within a New Microscopic Multiphonon Approach

    NASA Astrophysics Data System (ADS)

    Lo Iudice, N.; Bianco, D.; Knapp, F.; Andreozzi, F.; Porrino, A.; Vesely, P.

    2013-03-01

    We have revised an equation of motion method for generating a basis of microscopic multiphonon states built of Tamm-Dancoff phonons. This new version removes the inconsistencies of the previous formulation and yields eigenvalue equations of simple structure. To test the method we have computed the electric dipole response of the neutron rich 20O in a space extending up to the three-phonon subspace.

  5. Discrete solitons in graphene metamaterials

    NASA Astrophysics Data System (ADS)

    Bludov, Yu. V.; Smirnova, D. A.; Kivshar, Yu. S.; Peres, N. M. R.; Vasilevskiy, M. I.

    2015-01-01

    We study nonlinear properties of multilayer metamaterials created by graphene sheets separated by dielectric layers. We demonstrate that such structures can support localized nonlinear modes described by the discrete nonlinear Schrödinger equation and that its solutions are associated with stable discrete plasmon solitons. We also analyze the nonlinear surface modes in truncated graphene metamaterials being a nonlinear analog of surface Tamm states.

  6. Electron transitions in the spectra of diaryl-substituted 1,3,4-oxadiazole

    SciTech Connect

    Pedash, V.F.; Pedash, Yu.F.

    1987-10-01

    This paper outlines the results of quantum-chemical calculations of the excited electron states of 2,5-diaryl-substituted 1,3,4-oxadiazole, containing phenyl and naphthyl radicals in various combinations. The characteristics of the electron transitions are calculated using the Tamm-Dankov model within whose framework the wave function of the excited state is represented as the superposition of singly excited configurations using the Hartree-Fock ground state wave function.

  7. Exciton-polariton integrated circuits

    NASA Astrophysics Data System (ADS)

    Liew, T. C. H.; Kavokin, A. V.; Ostatnický, T.; Kaliteevski, M.; Shelykh, I. A.; Abram, R. A.

    2010-07-01

    We show that logical signals encoded in bistable states in semiconductor microcavities can be generated and controlled electronically by exploiting the electrical sensitivity of Tamm-plasmon-exciton-polariton modes. The signals can be transported along polariton neurons, created with a patterned metal surface. Using the Gross-Pitaevskii equations, we simulate an electrically controlled transistor and find that high repetition rates (10 GHz) are possible.

  8. (HBCU) Light Localization and Switching with Photonic Defects and Surfaces

    DTIC Science & Technology

    2012-02-01

    papers. 6. Molding the Flow of Surface Plasmon Polaritons in Real-time Molding the flow of Surface Plasmon Polaritons (SPPs) at a subwavelength scale...routing and coupling, and (4) Tamm and Shockley-like surface states in photonic interfaces and superlattices. These studies will advance the knowledge...paves the way for ultra-compact integrated optical circuits. Traditional plasmonic elements based on either structuring metal surfaces or placing

  9. Photonic Hypercrystals

    NASA Astrophysics Data System (ADS)

    Narimanov, Evgenii E.

    2014-10-01

    We introduce a new "universality class" of artificial optical media—photonic hypercrystals. These hyperbolic metamaterials, with periodic spatial variation of dielectric permittivity on subwavelength scale, combine the features of optical metamaterials and photonic crystals. In particular, surface waves supported by a hypercrystal possess the properties of both the optical Tamm states in photonic crystals and surface-plasmon polaritons at the metal-dielectric interface.

  10. Spectral and polarization properties of a ‘cholesteric liquid crystal—phase plate—metal’ structure

    NASA Astrophysics Data System (ADS)

    Vetrov, S. Ya; Pyatnov, M. V.; Timofeev, I. V.

    2016-01-01

    We investigate the localized surface modes in a structure consisting of the cholesteric liquid crystal layer, a phase plate, and a metal layer. These modes are analogous to the optical Tamm states. The nonreciprocal transmission of polarized light propagating in the forward and backward directions is established. It is demonstrated that the transmission spectrum can be controlled by external fields acting on the cholesteric liquid crystal and by varying the plane of polarization of the incident light.

  11. Sub-lethal ammonia toxicity in largemouth bass.

    PubMed

    Suski, C D; Kieffer, J D; Killen, S S; Tufts, B L

    2007-03-01

    Guidelines for ammonia toxicity in fish are often determined using static exposure tests with immature fish over a 96-h period. These results may not be relevant to aquaculture, hauling or angling tournament scenarios where mature fish can be exposed to ammonia for shorter durations, often following additional stressors such as handling. The current study sought to quantify (1) the impact of ambient ammonia on the ability of largemouth bass to recover from exercise, (2) the behavioural response of largemouth bass to elevated ambient ammonia and (3) the concentration of ammonia that can accumulate in a live-release vessel at an angling tournament. After approximately 3 h, total ammonia (T(amm)) concentrations in a live-release vessel at an angling tournament were almost 200 muM. Exposure of fish to 1000 microM T(amm) (a value approximately 80% below the criteria maximum concentration for largemouth bass) caused significant reductions in ventilation rates, and increases in erratic swimming and irregular ventilation. Exposure to 100 microM T(amm) impaired the ability of largemouth bass to recover from exercise relative to fish recovering in fresh water. Therefore, sub-lethal ambient ammonia concentrations cause physiological disturbances that can impair the recovery of largemouth bass from exercise.

  12. Devescovinid trichomonad with axostyle-based rotary motor ("Rubberneckia"): taxonomic assignment as Caduceia versatilis sp. nov

    NASA Technical Reports Server (NTRS)

    d'Ambrosio, U.; Dolan, M.; Wier, A. M.; Margulis, L.

    1999-01-01

    An amitochondriate trichomonad cell of the family Devescovinidae (Class Parabasalia), helped demonstrate the fluid model of lipoprotein cell membranes. This wood-ingesting symbiont in the hindgut of the dry wood-eating termite Cryptotermes cavifrons is informally known to cell biologists as "Rubberneckia". As the microtubular axo-style complex generates force causing clockwise movement of the entire anterior portion of the cell at the shear zone the protist displays "head" rotation. Studies by phase contrast and videomicroscopy of live cells, of whole mounts by scanning, and thin sections by transmission electron microscopy extend the observations of Tamm and Tamm [24-26] and Tamm [19-23]. Habitat, cell shape, size, nuclear features, parabasal apparatus and other morphological details permit the assignment of "Rubberneckia" to Kirby's cosmopolitan genus Caduceia. This large-sized devescovinid has distinctive parabasal gyres, an axostylar rotary, motor, and regularly-associated nonflagellated, fusiform and flagellated rod epibiotic surface bacteria. In addition to regularly aligned epibionts intranuclear and endocytoplasmic bacteria are abundant and hydrogenosomes are Present. "Rubberneckia" is compared here to the other seven species of Caduceia. Since it is clearly sufficiently distinctive to warrant new species status, we named it C. versatilis.

  13. Climate Variability in the Antarctic Peninsula: Insights from the 2010 Bruce Plateau Ice Core

    NASA Astrophysics Data System (ADS)

    Mosley-Thompson, E. S.; Goodwin, B. P.; Sierra, R.; Lin, P.; Miller, D.; Thompson, L. G.; Kenny, D. V.

    2013-12-01

    A new ice core was drilled to bedrock (448.12 m) in 2010 on the Bruce Plateau (BP) ice field (66.03°S; 64.07°W; 1975.5 masl) in the northern Antarctic Peninsula (AP). This is the second ice core, the 2008 James Ross Island (JRI) core was the first, in the AP to reach bedrock and thereby capture the entire record preserved at the drill site. There are just a handful of multi-century long ice core records from the AP, most extending back less than 500 years. The very high annual mass accumulation on the BP (~1.8 m w.e. from 1900 to 2009 CE) allows precise layer counting back to 1400 CE and with temporal constraints by known volcanic eruptions the record is annually resolved back to 1250 CE. The δ18O of individual samples correlates well with temperature observations at Rothera Station (1977 to 2009) which allows calculation of monthly estimates of mass accumulation. These reveal a late winter/ early spring precipitation maximum which imparts a seasonal bias to the climate signals closely linked to wet deposition (e.g., δ18O, various chemical species). The annually resolved records of δ18O and mass accumulation provide proxy-based histories of temperature and precipitation. Comparison with meteorological observations indicates that the BP δ18O record provides a reliable proxy of mean annual air temperature along the west side of the AP. The resulting δ18O-inferred air temperatures for the last 600 years reveal multi-decadal scale variability with warm conditions during some periods exceeding that of the last few decades. Extracting the annual accumulation history is complicated by layer thinning at depth and to reconstruct annual layer thicknesses a Dansgaard-Johnsen model configured for flank flow was applied. The resulting record indicates that over the last 600 years the average annual mass accumulation (precipitation) rises slightly until ~1800 CE (~2.3 m w.e.) after which it declines to a minimum (~1.5 m w.e.) around 1950 CE. Accumulation then rises

  14. Soil thermal properties at two different sites on James Ross Island in the period 2012/13

    NASA Astrophysics Data System (ADS)

    Hrbáček, Filip; Láska, Kamil

    2015-04-01

    James Ross Island (JRI) is the largest island in the eastern part of the Antarctic Peninsula. Ulu Peninsula in the northern part of JRI is considered the largest ice free area in the Maritime Antarctica region. However, information about permafrost on JRI, active layer and its soil properties in general are poorly known. In this study, results of soil thermal measurements at two different sites on Ulu Peninsula are presented between 1 April 2012 and 30 April 2013. The study sites are located (1) on an old Holocene marine terrace (10 m a. s. l.) in the closest vicinity of Johann Gregor Mendel (JGM) Station and (2) on top of a volcanic plateau named Johnson Mesa (340 m a. s. l.) about 4 km south of the JGM Station. The soil temperatures were measured at 30 min interval using platinum resistance thermometers Pt100/8 in two profiles up to 200 cm at JGM Station and 75 cm at Johnson Mesa respectively. Decagon 10HS volumetric water content sensors were installed up 30 cm at Johnson Mesa to 50 cm at JGM Station, while Hukseflux HFP01 soil heat flux sensors were used for direct monitoring of soil physical properties at 2.5 cm depth at both sites. The mean soil temperature varied between -5.7°C at 50 cm and -6.3°C at 5 cm at JGM Station, while that for Johnson Mesa varied between -6.9°C at 50 cm and -7.1°C at 10 cm. Maximum active layer thickness estimated from 0 °C isotherm reached 52 cm at JGM Station and 50 cm at Johnson Mesa respectively which corresponded with maximum observed annual temperature at 50 cm at both sites. The warmest part of both profiles detected at 50 cm depth corresponded with maximum thickness of active layer, estimated from 0°C isotherm, reached 52 cm at JGM Station and 50 cm at Johnson Mesa respectively. Volumetric water content at 5 cm varied around 0.25 m3m-3 at both sites. The slight increase to 0.32 m3m-3 was observed at JGM Station at 50 cm and at Johnson Mesa at 30 cm depth. Soil texture analysis showed distinctly higher share of coarser

  15. Think tank (3) - Present activities of other representative organizations

    NASA Astrophysics Data System (ADS)

    Obara, Michio

    There were some think tank businesses in Japan before the war. South Manchuria Railway Company established its Research Department for the purpose of getting power to control Manchuria as a colony, and got the good results. Think tank business was flourishing three times after the war. This business attracts much attention when the social and economic paradigm is going to change. Among the key large-scale think tanks in Japan, Nomura Research Institute, Ltd. (NRI) was the first to enhance the system functions by the merger, and posted think tank function up in the SI business. Mitsubishi Research Institute, Inc. (MRI) intends to be an orthodox think tank, and established an advanced research institute and the laboratory for R&D. Daiwa Institute of Research, Ltd. (DIR) focuses on economic forecast by using system. Fuji Research Institute, Corp. (FUJI RIC) focuses on survey and policy proposing in macro-economics, and analyzing technology. The Japan Research Institute, Ltd. (JRI) focuses on regional development, and R&D in advanced technology.

  16. Think tank (2) Its development and the current situation of the key organizations in Japan

    NASA Astrophysics Data System (ADS)

    Obara, Michio

    There were some think tank businesses in Japan before the war. South Manchuria Railway Company established its Research Department for the purpose of getting power to control Manchuria as a colony, and got the good results. Think tank business was flourishing three times after the war. This business attracts much attention when the social and economic paradigm is going to change. Among the key large-scale think tanks in Japan, Nomura Research Institute, Ltd. (NRI) was the first to enhance the system functions by the merger, and posted think tank function up in the SI business. Mitsubishi Research Institute, Inc. (MRI) intends to be an orthodox think tank, and established an advanced research institute and the laboratory for R&D. Daiwa Institute of Research, Ltd. (DIR) focuses on economic forecast by using system. Fuji Research Institute. Corp. (FUJI RIC) focuses on survey and policy proposing in macro-economics, and analyzing technology. The Japan Research Institute, Ltd. (JRI) focuses on regional development, and R&D in advanced technology.

  17. Micro-Pressure Sensors for Future Mars Missions

    NASA Technical Reports Server (NTRS)

    Catling, David C.

    1996-01-01

    The joint research interchange effort was directed at the following principal areas: u further development of NASA-Ames' Mars Micro-meteorology mission concept as a viable NASA space mission especially with regard to the science and instrument specifications u interaction with the flight team from NASA's New Millennium 'Deep-Space 2' (DS-2) mission with regard to selection and design of micro-pressure sensors for Mars u further development of micro-pressure sensors suitable for Mars The research work undertaken in the course of the Joint Research Interchange should be placed in the context of an ongoing planetary exploration objective to characterize the climate system on Mars. In particular, a network of small probes globally-distributed on the surface of the planet has often been cited as the only way to address this particular science goal. A team from NASA Ames has proposed such a mission called the Micrometeorology mission, or 'Micro-met' for short. Surface pressure data are all that are required, in principle, to calculate the Martian atmospheric circulation, provided that simultaneous orbital measurements of the atmosphere are also obtained. Consequently, in the proposed Micro-met mission a large number of landers would measure barometric pressure at various locations around Mars, each equipped with a micro-pressure sensor. Much of the time on the JRI was therefore spent working with the engineers and scientists concerned with Micro-met to develop this particular mission concept into a more realistic proposition.

  18. Memories of David Kirzhnits

    NASA Astrophysics Data System (ADS)

    Bolotovsky, B. M.

    2013-06-01

    In the mid-1950s, a new staff member appeared at the Theory Division of the Physical Institute of the Academy of Sciences (FIAN): David Abramovich Kirzhnits. A Moscow State University alumnus, after graduation he had been assigned to a large defense plant in the city of Gorky, where he had worked for several years as an engineer. He was "liberated" from there by Igor Evgenyevich Tamm, our department head, who managed to transfer him to FIAN. Igor Evgenyevich knew D. A. Kirzhnits - they had met in Moscow before Kirzhnits finished university. At that time Kirzhnits was performing thesis work with professor A. S. Kompaneyets as academic adviser. At his adviser's suggestion, D. Kirzhnits consulted with I. E. Tamm on questions pertaining to the thesis topic. I. E. Tamm took a great liking for the diploma student, and he even wanted to recruit D. A. Kirzhnits for the Theory Division immediately after graduation. But at that time (1949) this proved impossible for several reasons. First, D. Kirzhnits was, as they say, an "invalid of the fifth group" - a Jew - which during those years of violent struggle against cosmopolitanismb often proved an obstacle in looking for work. Second, during the years of mass repressions D. Kirzhnits' father had been arrested on treason charges (according to the charges, he had wanted to sell the Far East to Japan). After intensive investigation his father was released, but he lived only a little longer. Reports of this also could have impeded his acceptance. Third, Igor Evgenyevich didn't have enough weight in officials' eyes at that time and so was unable to overcome "first" and "second."...

  19. Theoretical investigation on dye sensitizer solar cell: Spin-forbidden transition

    SciTech Connect

    Imamura, Yutaka

    2015-12-31

    We studied spin-forbidden transitions of metal polypyridyl sensitizers by two-component relativistic time-dependent density functional theory with the spin-orbit interaction based on Tamm-Dancoff approximation. The singlet-to-triplet transition, which is assigned to a metal-to-ligand charge-transfer type excitation, appears for a phosphine-coordinated Ru(II), DX1. Absorption spectra of the modified DX1 molecules, whose Ru is replaced with Fe and Os, were also calculated for examining the effects of metals on the spin-orbit interaction.

  20. On the calculation of Δ for electronic excitations in time-dependent density-functional theory

    NASA Astrophysics Data System (ADS)

    Myneni, Hemanadhan; Casida, Mark E.

    2017-04-01

    Excited states are often treated within the context of time-dependent (TD) density-functional theory (DFT), making it important to be able to assign the excited spin-state symmetry. While there is universal agreement on how Δ , the difference between for ground and excited states, should be calculated in a wave-function-like formalism such as the Tamm-Dancoff approximation (TDA), confusion persists as to how to determine the spin-state symmetry of excited states in TD-DFT. We try to clarify the origins of this confusion by examining various possibilities for the parameters (σ1 ,σ2) in the formula

  1. Projected quasiparticle calculations for the N =82 odd-proton isotones

    SciTech Connect

    Losano, L. ); Dias, H. )

    1991-12-01

    The structure of low-lying states in odd-mass {ital N}=82 isotones (135{le}{ital A}{le}145) is investigated in terms of a number-projected one- and three-quasiparticles Tamm-Dancoff approximation. A surface-delta interaction is taken as the residual nucleon-nucleon interaction. Excitation energies, dipole and quadrupole moments, and {ital B}({ital M}1) and {ital B}({ital E}2) values are calculated and compared with the experimental data.

  2. A Local CC2 and TDA-DFT Double Hybrid Study on BODIPY/aza-BODIPY Dimers as Heavy Atom Free Triplet Photosensitizers for Photodynamic Therapy Applications.

    PubMed

    Momeni, Mohammad R; Brown, Alex

    2016-04-28

    A series of 11 different boron-dipyrromethene (BODIPY) dimers is carefully examined by means of ab initio and Tamm-Dancoff approximated density functional theory methods. Vertical and 0-0 excitation energies along with the tetraradical character of these dimers are determined. Possible application of a series of linked dimers for photodynamic therapy (PDT) was investigated through computing their excitation energies, spin-orbit coupling matrix elements, and singlet-triplet energy gaps. Finally through a systematic investigation of a series of 36 different BODIPY and aza-BODIPY dimers, a new class of near-IR heavy atom free photosensitizers for PDT action is introduced.

  3. Richardson-Gaudin description of pairing in atomic nuclei

    NASA Astrophysics Data System (ADS)

    De Baerdemacker, Stijn

    2012-05-01

    The present contribution discusses a connection between the exact Bethe Ansatz eigenstates of the reduced Bardeen-Cooper-Schrieffer (BCS) Hamiltonian and the multi-phonon states of the Tamm-Dancoff Approximation (TDA). The connection is made on the algebraic level, by means of a deformed quasi-spin algebra with a bosonic Heisenberg-Weyl algebra in the contraction limit of the deformation parameter. Each exact Bethe Ansatz eigenstate is mapped on a unique TDA multi-phonon state, shedding light on the physics behind the Bethe Ansatz structure of the exact wave function. The procedure is illustrated with a model describing neutron pairing in 56Fe.

  4. Meson Structure in a Relativistic Many-Body Approach

    SciTech Connect

    Llanes-Estrada, Felipe J.; Cotanch, Stephen R.

    2000-02-07

    Results from an extensive relativistic many-body analysis utilizing a realistic effective QCD Hamiltonian are presented for the meson spectrum. A comparative numerical study of the BCS, Tamm-Dancoff (TDA), and RPA treatments provides new, significant insight into the condensate structure of the vacuum, the chiral symmetry governance of the pion, and the meson spin, orbital, and flavor mass splitting contributions. In contrast to a previous glueball application, substantial quantitative differences are computed between TDA and RPA for the light quark sector with the pion emerging as a Goldstone boson only in the RPA. (c) 2000 The American Physical Society.

  5. Investigations of the g{sub K}-factors in the {sup 175,177,179}Hf Isotopes

    SciTech Connect

    Yakut, Hakan; Kuliev, Ali; Guliyev, Ekber

    2008-11-11

    In this paper the intrinsic g{sub K} and effective spin g{sub s} factors of the odd-mass {sup 175-179}Hf isotopes have been investigated within the Tamm-Dancoff approximation by using the realistic Saxon-Woods potential. The theoretically calculated g{sub K} and g{sub s}{sup eff} values are compared with experimental data. The comparison of the measured and calculated values of the effective g{sub s} factor shows that the spin polarization explains quite well the observed reduction of g{sub s} from its free-nucleon value.

  6. Alternative simulations of forestry scenarios involving carbon sequestration options: Investigation of impacts on regional and national timber markets. Forest Service general technical report

    SciTech Connect

    Haynes, R.W.; Alig, R.J.; Moore, E.

    1994-08-01

    This report explores a number of contemporary issues as background to the emerging interest in using forest policies to mitigate global climate change. The intent of most of these policies is to sequester carbon in the forests of the United States. Most of the policies are variations on past forest policies explored as part of the Resources Planning Act (RPA) process. The analysis projects the effects of alternative scenarios on forest area, inventory, harvest, and prices (stumpage and product), as well as welfare effects of alternative mitigation strategies. The market impacts are analyzed by using the TAMM and ATLAS forest inventory modeling systems.

  7. Accidental degeneracies in nonlinear quantum deformed systems

    NASA Astrophysics Data System (ADS)

    Aleixo, A. N. F.; Balantekin, A. B.

    2011-09-01

    We construct a multi-parameter nonlinear deformed algebra for quantum confined systems that includes many other deformed models as particular cases. We demonstrate that such systems exhibit the property of accidental pairwise energy level degeneracies. We also study, as a special case of our multi-parameter deformation formalism, the extension of the Tamm-Dancoff cutoff deformed oscillator and the occurrence of accidental pairwise degeneracy in the energy levels of the deformed system. As an application, we discuss the case of a trigonometric Rosen-Morse potential, which is successfully used in models for quantum confined systems, ranging from electrons in quantum dots to quarks in hadrons.

  8. Microscopic multiphonon method for odd nuclei and its application to 17O

    NASA Astrophysics Data System (ADS)

    De Gregorio, G.; Knapp, F.; Lo Iudice, N.; Vesely, P.

    2016-12-01

    An equations of motion phonon method is extended to odd nuclei. It generates an orthonormal basis out of an odd particle coupled to n -phonon core states (n =0 ,1 ,2 ,⋯ ), built of Tamm-Dancoff phonons, and formulates the eigenvalue problem in such a multiphonon particle-core space. 17O is chosen as testing ground. An intrinsic chiral Hamiltonian is adopted in a large configuration space to perform a calculation using a Hartree-Fock (HF) basis in a space encompassing up to two and, under simplifying assumptions, three phonons. The impact of the different phonon components on spectrum, moments, transitions, and dipole cross section is discussed.

  9. Multiple responses of TPP-assisted near-perfect absorption in metal/Fibonacci quasiperiodic photonic crystal.

    PubMed

    Gong, Yongkang; Liu, Xueming; Wang, Leiran; Lu, Hua; Wang, Guoxi

    2011-05-09

    Absorption properties in one-dimensional quasiperiodic photonic crystal composed of a thin metallic layer and dielectric Fibonacci multilayers are investigated. It is found that a large number of photonic stopbands can occur at the dielectric Fibonacci multilayers. Tamm plasmon polaritons (TPPs) with the frequencies locating at each photonic stopband are excited at the interface between the metallic layer and the dielectric layer, leading to almost perfect absorption for the energy of incident wave. By adjusting the length of dielectric layer with higher refractive-index or the Fibonacci order, the number of absorption peaks can be tuned effectively and enlarged significantly.

  10. Calibration of NASA Turbulent Air Motion Measurement System

    NASA Technical Reports Server (NTRS)

    Barrick, John D. W.; Ritter, John A.; Watson, Catherine E.; Wynkoop, Mark W.; Quinn, John K.; Norfolk, Daniel R.

    1996-01-01

    A turbulent air motion measurement system (TAMMS) was integrated onboard the Lockheed 188 Electra airplane (designated NASA 429) based at the Wallops Flight Facility in support of the NASA role in global tropospheric research. The system provides air motion and turbulence measurements from an airborne platform which is capable of sampling tropospheric and planetary boundary-layer conditions. TAMMS consists of a gust probe with free-rotating vanes mounted on a 3.7-m epoxy-graphite composite nose boom, a high-resolution inertial navigation system (INS), and data acquisition system. A variation of the tower flyby method augmented with radar tracking was implemented for the calibration of static pressure position error and air temperature probe. Additional flight calibration maneuvers were performed remote from the tower in homogeneous atmospheric conditions. System hardware and instrumentation are described and the calibration procedures discussed. Calibration and flight results are presented to illustrate the overall ability of the system to determine the three-component ambient wind fields during straight and level flight conditions.

  11. Recent progress in density functional theory

    NASA Astrophysics Data System (ADS)

    Truhlar, Donald

    2014-03-01

    Ongoing work involves several areas of density functional theory: new methods for computing electronic excitation energies, including a new way to remove spin contamination in the spin-flip Tamm-Dancoff approximation and a configuration-interaction-corrected Tamm-Dancoff Approximation for treating conical intersections; new ways to treat open-shell states, including a reinterpreted broken-symmetry method and multi-configuration Kohn-Sham theory; a new exchange-correlation functional; new tests of density functional theory against databases for electronic transition energies and molecules and solids containing metal atoms; and applications. A selection of results will be presented. I am grateful to the following collaborators for contributions to the ongoing work: Boris Averkiev, Rebecca Carlson, Laura Fernandez, Laura Gagliardi, Chad Hoyer, Francesc Illas, Miho Isegawa, Shaohong Li, Giovanni Li Manni, Sijie Luo, Dongxia Ma, Remi Maurice, Rubén Means-Pañeda, Roberto Peverati, Nora Planas, Prasenjit Seal, Pragya Verma, Bo Wang, Xuefei Xu, Ke R. Yang, Haoyu Yu, Wenjing Zhang, and Jingjing Zheng. Supported in part by the AFOSR and U.S. DOE.

  12. Quantum speed limits, coherence, and asymmetry

    NASA Astrophysics Data System (ADS)

    Marvian, Iman; Spekkens, Robert W.; Zanardi, Paolo

    2016-05-01

    The resource theory of asymmetry is a framework for classifying and quantifying the symmetry-breaking properties of both states and operations relative to a given symmetry. In the special case where the symmetry is the set of translations generated by a fixed observable, asymmetry can be interpreted as coherence relative to the observable eigenbasis, and the resource theory of asymmetry provides a framework to study this notion of coherence. We here show that this notion of coherence naturally arises in the context of quantum speed limits. Indeed, the very concept of speed of evolution, i.e., the inverse of the minimum time it takes the system to evolve to another (partially) distinguishable state, is a measure of asymmetry relative to the time translations generated by the system Hamiltonian. Furthermore, the celebrated Mandelstam-Tamm and Margolus-Levitin speed limits can be interpreted as upper bounds on this measure of asymmetry by functions which are themselves measures of asymmetry in the special case of pure states. Using measures of asymmetry that are not restricted to pure states, such as the Wigner-Yanase skew information, we obtain extensions of the Mandelstam-Tamm bound which are significantly tighter in the case of mixed states. We also clarify some confusions in the literature about coherence and asymmetry, and show that measures of coherence are a proper subset of measures of asymmetry.

  13. Ammonia first? The transition from cutaneous to branchial ammonia excretion in developing rainbow trout is not altered by exposure to chronically high NaCl.

    PubMed

    Zimmer, Alex M; Wood, Chris M

    2015-05-15

    Larval rainbow trout (Oncorhynchus mykiss) were reared from hatch under control ([Na(+)]=0.60 mmol l(-1)) or high NaCl ([Na(+)]=60 mmol l(-1)) conditions to elucidate the driving force for the ontogeny of branchial Na(+)/NH4 (+) exchange, one of the earliest gill functions. We hypothesized that if Na(+) uptake is the driving force, then in high NaCl there would be a delay in the skin-to-gill shift in ammonia excretion (Jamm) and/or an elevation in whole-body total ammonia (Tamm). In both groups, however, the skin-to-gill shift for Jamm, determined using divided chambers, occurred at the same time (13 days post-hatch; dph) and whole-body Tamm was unchanged. Moreover, high NaCl larvae displayed elevated whole-body [Na(+)] relative to controls by 18 dph, suggesting that maintaining branchial Jamm occurs at the expense of Na(+) balance. Overall, these results support the 'ammonia hypothesis', which posits that ammonia excretion, probably as Na(+)/NH4 (+) exchange, is the primary function of the early fish gill.

  14. Robotic Rock Classification

    NASA Technical Reports Server (NTRS)

    Hebert, Martial

    1999-01-01

    This report describes a three-month research program undertook jointly by the Robotics Institute at Carnegie Mellon University and Ames Research Center as part of the Ames' Joint Research Initiative (JRI.) The work was conducted at the Ames Research Center by Mr. Liam Pedersen, a graduate student in the CMU Ph.D. program in Robotics under the supervision Dr. Ted Roush at the Space Science Division of the Ames Research Center from May 15 1999 to August 15, 1999. Dr. Martial Hebert is Mr. Pedersen's research adviser at CMU and is Principal Investigator of this Grant. The goal of this project is to investigate and implement methods suitable for a robotic rover to autonomously identify rocks and minerals in its vicinity, and to statistically characterize the local geological environment. Although primary sensors for these tasks are a reflection spectrometer and color camera, the goal is to create a framework under which data from multiple sensors, and multiple readings on the same object, can be combined in a principled manner. Furthermore, it is envisioned that knowledge of the local area, either a priori or gathered by the robot, will be used to improve classification accuracy. The key results obtained during this project are: The continuation of the development of a rock classifier; development of theoretical statistical methods; development of methods for evaluating and selecting sensors; and experimentation with data mining techniques on the Ames spectral library. The results of this work are being applied at CMU, in particular in the context of the Winter 99 Antarctica expedition in which the classification techniques will be used on the Nomad robot. Conversely, the software developed based on those techniques will continue to be made available to NASA Ames and the data collected from the Nomad experiments will also be made available.

  15. Exact formulation and solution of the nuclear eigenvalue problem in a microscopic multiphonon space

    SciTech Connect

    Andreozzi, F.; Iudice, N. Lo; Porrino, A.; Knapp, F.; Kvasil, J.

    2007-04-15

    We propose a method for solving exactly the nuclear eigenvalue problem within a multiphonon space constructed out of Tamm-Dancoff phonons. The method consists in deriving, within a given n-phonon subspace, a set of equations, of simple structure for any n, which are solved iteratively, starting from the particle-hole vacuum, to yield a set of states covering a multiphonon space up to an arbitrary number of phonons. The intrinsic redundancy of the set so generated is removed completely and exactly by a simple and efficient prescription. Such a multiphonon basis reduces the Hamiltonian into diagonal blocks plus residual off-diagonal terms of simple form. Its diagonalization becomes straightforward and yields exact eigensolutions. {sup 16}O is adopted as numerical test ground.

  16. Shock waves in noble gases and their mixtures

    NASA Astrophysics Data System (ADS)

    Bratos, M.; Herczynski, R.

    The shock wave structures in pure monatomic gases and in binary gas mixtures are investigated in this paper using a variational approach. The idea of Mott-Smith's distribution function (generalized in the case of a gas mixture) was combined with Tamm's method of solving the Boltzmann equation. The intermolecular potential used is of the Lennard-Jones type. The relation between the dimensionless shock wave thickness and Mach number in front of the shock wave is analyzed. Special attention was paid to the determination of shock wave structures in mixtures of gases with disparate molecular masses. The calculation performed for the shock wave in the binary gas mixture, xenon-helium, confirm the existence of a 'hump' of the density profile of the lighter component. The heavy gas component temperature overshoots its downstream equilibrium value in the case of a mixture of gases with disparate molecular masses and for a small mole fraction of the heavy gas component.

  17. First order nonadiabatic coupling matrix elements between excited states: implementation and application at the TD-DFT and pp-TDA levels.

    PubMed

    Li, Zhendong; Suo, Bingbing; Liu, Wenjian

    2014-12-28

    The recently proposed rigorous yet abstract theory of first order nonadiabatic coupling matrix elements (fo-NACME) between electronically excited states [Z. Li and W. Liu, J. Chem. Phys. 141, 014110 (2014)] is specified in detail for two widely used models: The time-dependent density functional theory and the particle-particle Tamm-Dancoff approximation. The actual implementation employs a Lagrangian formalism with atomic-orbital based direct algorithms, which makes the computation of fo-NACME very similar to that of excited-state gradients. Although the methods have great potential in investigating internal conversions and nonadiabatic dynamics between excited states of large molecules, only prototypical systems as a first pilot application are considered here to illustrate some conceptual aspects.

  18. Representation independent algorithms for molecular response calculations in time-dependent self-consistent field theories

    SciTech Connect

    Tretiak, Sergei

    2008-01-01

    Four different numerical algorithms suitable for a linear scaling implementation of time-dependent Hartree-Fock and Kohn-Sham self-consistent field theories are examined. We compare the performance of modified Lanczos, Arooldi, Davidson, and Rayleigh quotient iterative procedures to solve the random-phase approximation (RPA) (non-Hermitian) and Tamm-Dancoff approximation (TDA) (Hermitian) eigenvalue equations in the molecular orbital-free framework. Semiempirical Hamiltonian models are used to numerically benchmark algorithms for the computation of excited states of realistic molecular systems (conjugated polymers and carbon nanotubes). Convergence behavior and stability are tested with respect to a numerical noise imposed to simulate linear scaling conditions. The results single out the most suitable procedures for linear scaling large-scale time-dependent perturbation theory calculations of electronic excitations.

  19. Charge-changing particle-hole excitation of {sup 16}N and {sup 16}F nuclei

    SciTech Connect

    Taqi Al-Bayati, Ali H.; Darwesh, Sarah S.

    2013-12-16

    The nuclear structure of {sup 16}N (closed shell + ν − π) and {sup 16}F (closed shell + π − ν) nuclei is studied using particle-hole proton-neutron Tamm-Dancoff Approximation pn TDA and particle-hole proton-neutron Random Phase Approximation pn RPA. The particle-hole Hamiltonian of PSD model space is to be diagonalized in the presence of the PSDMWKPN interaction: for P-space the Cohen-Kurath interaction, for SD-space the Wildenthal Interaction, for the coupling matrix elements between P- and SD-spaces the Millener-Kurath interaction is used, spurious components were eliminated with CM contribution. The results containing energy level schemes and electromagnetic transition strength are compared with the available experimental data.

  20. Charge-changing particle-hole excitation of 16N and 16F nuclei

    NASA Astrophysics Data System (ADS)

    Taqi Al-Bayati, Ali H.; Darwesh, Sarah S.

    2013-12-01

    The nuclear structure of 16N (closed shell + ν - π) and 16F (closed shell + π - ν) nuclei is studied using particle-hole proton-neutron Tamm-Dancoff Approximation pn TDA and particle-hole proton-neutron Random Phase Approximation pn RPA. The particle-hole Hamiltonian of PSD model space is to be diagonalized in the presence of the PSDMWKPN interaction: for P-space the Cohen-Kurath interaction, for SD-space the Wildenthal Interaction, for the coupling matrix elements between P- and SD-spaces the Millener-Kurath interaction is used, spurious components were eliminated with CM contribution. The results containing energy level schemes and electromagnetic transition strength are compared with the available experimental data.

  1. Double, Rydberg and charge transfer excitations from pairing matrix fluctuation and particle-particle random phase approximation

    SciTech Connect

    Yang, Yang; Aggelen, Helen van; Yang, Weitao

    2013-12-14

    Double, Rydberg, and charge transfer (CT) excitations have been great challenges for time-dependent density functional theory (TDDFT). Starting from an (N ± 2)-electron single-determinant reference, we investigate excitations for the N-electron system through the pairing matrix fluctuation, which contains information on two-electron addition/removal processes. We adopt the particle-particle random phase approximation (pp-RPA) and the particle-particle Tamm-Dancoff approximation (pp-TDA) to approximate the pairing matrix fluctuation and then determine excitation energies by the differences of two-electron addition/removal energies. This approach captures all types of interesting excitations: single and double excitations are described accurately, Rydberg excitations are in good agreement with experimental data and CT excitations display correct 1/R dependence. Furthermore, the pp-RPA and the pp-TDA have a computational cost similar to TDDFT and consequently are promising for practical calculations.

  2. First order nonadiabatic coupling matrix elements between excited states: Implementation and application at the TD-DFT and pp-TDA levels

    NASA Astrophysics Data System (ADS)

    Li, Zhendong; Suo, Bingbing; Liu, Wenjian

    2014-12-01

    The recently proposed rigorous yet abstract theory of first order nonadiabatic coupling matrix elements (fo-NACME) between electronically excited states [Z. Li and W. Liu, J. Chem. Phys. 141, 014110 (2014)] is specified in detail for two widely used models: The time-dependent density functional theory and the particle-particle Tamm-Dancoff approximation. The actual implementation employs a Lagrangian formalism with atomic-orbital based direct algorithms, which makes the computation of fo-NACME very similar to that of excited-state gradients. Although the methods have great potential in investigating internal conversions and nonadiabatic dynamics between excited states of large molecules, only prototypical systems as a first pilot application are considered here to illustrate some conceptual aspects.

  3. Representation independent algorithms for molecular response calculations in time-dependent self-consistent field theories

    NASA Astrophysics Data System (ADS)

    Tretiak, Sergei; Isborn, Christine M.; Niklasson, Anders M. N.; Challacombe, Matt

    2009-02-01

    Four different numerical algorithms suitable for a linear scaling implementation of time-dependent Hartree-Fock and Kohn-Sham self-consistent field theories are examined. We compare the performance of modified Lanczos, Arooldi, Davidson, and Rayleigh quotient iterative procedures to solve the random-phase approximation (RPA) (non-Hermitian) and Tamm-Dancoff approximation (TDA) (Hermitian) eigenvalue equations in the molecular orbital-free framework. Semiempirical Hamiltonian models are used to numerically benchmark algorithms for the computation of excited states of realistic molecular systems (conjugated polymers and carbon nanotubes). Convergence behavior and stability are tested with respect to a numerical noise imposed to simulate linear scaling conditions. The results single out the most suitable procedures for linear scaling large-scale time-dependent perturbation theory calculations of electronic excitations.

  4. First order nonadiabatic coupling matrix elements between excited states: Implementation and application at the TD-DFT and pp-TDA levels

    SciTech Connect

    Li, Zhendong; Suo, Bingbing; Liu, Wenjian

    2014-12-28

    The recently proposed rigorous yet abstract theory of first order nonadiabatic coupling matrix elements (fo-NACME) between electronically excited states [Z. Li and W. Liu, J. Chem. Phys. 141, 014110 (2014)] is specified in detail for two widely used models: The time-dependent density functional theory and the particle-particle Tamm-Dancoff approximation. The actual implementation employs a Lagrangian formalism with atomic-orbital based direct algorithms, which makes the computation of fo-NACME very similar to that of excited-state gradients. Although the methods have great potential in investigating internal conversions and nonadiabatic dynamics between excited states of large molecules, only prototypical systems as a first pilot application are considered here to illustrate some conceptual aspects.

  5. Gamow-Teller {beta}{sup +} decay of deformed nuclei near the proton drip line

    SciTech Connect

    Frisk, F.; Hamamoto, I.; Zhang, X.Z. |

    1995-11-01

    Using a quasiparticle Tamm-Dancoff approximation (TDA) based on deformed Hartree-Fock (HF) calculations with Skyrme interactions, the distribution of the Gamow-Teller (GT) {beta}{sup +} decay strength is estimated for the HF local minima of even-even deformed nuclei near the proton drip line in the region of 28{lt}{ital Z}{lt}66. The distribution often depends sensitively on the nuclear shape (namely, oblate or prolate). In the region of {ital Z}{lt}50 the possibility of observing {beta}-delayed proton emission depends sensitively on the excess of {ital Z} over {ital Z}={ital N}. In the region of {ital Z}{gt}50 almost the entire estimated GT strength is found to lie below the ground states of the even-even mother nuclei, and the observation of the total GT strength by {beta}-delayed charged-particle(s) emission will be of essential importance.

  6. Double, Rydberg and charge transfer excitations from pairing matrix fluctuation and particle-particle random phase approximation

    NASA Astrophysics Data System (ADS)

    Yang, Yang; van Aggelen, Helen; Yang, Weitao

    2013-12-01

    Double, Rydberg, and charge transfer (CT) excitations have been great challenges for time-dependent density functional theory (TDDFT). Starting from an (N ± 2)-electron single-determinant reference, we investigate excitations for the N-electron system through the pairing matrix fluctuation, which contains information on two-electron addition/removal processes. We adopt the particle-particle random phase approximation (pp-RPA) and the particle-particle Tamm-Dancoff approximation (pp-TDA) to approximate the pairing matrix fluctuation and then determine excitation energies by the differences of two-electron addition/removal energies. This approach captures all types of interesting excitations: single and double excitations are described accurately, Rydberg excitations are in good agreement with experimental data and CT excitations display correct 1/R dependence. Furthermore, the pp-RPA and the pp-TDA have a computational cost similar to TDDFT and consequently are promising for practical calculations.

  7. Double, Rydberg and Charge Transfer Excitations from Pairing Matrix Fluctuation and Particle-Particle Random Phase Approximation

    NASA Astrophysics Data System (ADS)

    Yang, Yang; van Aggelen, Helen; Yang, Weitao

    2014-03-01

    Double, Rydberg and charge transfer (CT) excitations have been great challenges for time-dependent density functional theory (TDDFT). Starting from an (N +/- 2) -electron single-determinant reference, we investigate excitations for the N-electron system through the pairing matrix fluctuation, which contains information on two-electron addition/removal processes. We adopt the particle-particle random phase approximation (pp-RPA) and the particle-particle Tamm-Dancoff approximation (pp-TDA) to approximate the pairing matrix fluctuation and then determine excitation energies by the differences of two-electron addition/removal energies. This approach captures all types of interesting excitations: single and double excitations are described accurately, Rydberg excitations are in good agreement with experimental data and CT excitations display correct 1/R dependence. Furthermore, the pp-RPA and the pp-TDA have a computational cost similar to TDDFT and consequently are promising for practical calculations.

  8. Double, Rydberg and charge transfer excitations from pairing matrix fluctuation and particle-particle random phase approximation.

    PubMed

    Yang, Yang; van Aggelen, Helen; Yang, Weitao

    2013-12-14

    Double, Rydberg, and charge transfer (CT) excitations have been great challenges for time-dependent density functional theory (TDDFT). Starting from an (N ± 2)-electron single-determinant reference, we investigate excitations for the N-electron system through the pairing matrix fluctuation, which contains information on two-electron addition/removal processes. We adopt the particle-particle random phase approximation (pp-RPA) and the particle-particle Tamm-Dancoff approximation (pp-TDA) to approximate the pairing matrix fluctuation and then determine excitation energies by the differences of two-electron addition/removal energies. This approach captures all types of interesting excitations: single and double excitations are described accurately, Rydberg excitations are in good agreement with experimental data and CT excitations display correct 1/R dependence. Furthermore, the pp-RPA and the pp-TDA have a computational cost similar to TDDFT and consequently are promising for practical calculations.

  9. One-dimensional photonic crystals with highly Bi-substituted iron garnet defect in reflection polar geometry

    NASA Astrophysics Data System (ADS)

    Mikhailova, T. V.; Berzhansky, V. N.; Karavainikov, A. V.; Shaposhnikov, A. N.; Prokopov, A. R.; Lyashko, S. D.

    2016-08-01

    It is represented the results of modelling of magnetooptical properties in reflection polar geometry of one-dimensional photonic crystal, in which highly Bi-substituted iron garnet defect of composition Bi1.0Y0.5Gd1.5Fe4.2Al0.8O12 / Bi2.8Y0.2Fe5Oi2 is located between the dielectric Bragg mirrors (SiO2 / TiO2)m (were m is number of layer pairs) and buffer SiO2 and gold top layers of different thicknesses is placed on structure. The modification of spectral line- shapes of microcavity and Tamm plasmon-polariton modes depending on m is found.

  10. S1 and S2 excited states of gas-phase Schiff-base retinal chromophores: a time-dependent density functional theoretical investigation.

    PubMed

    Sun, Mengtao; Ding, Yong; Cui, Ganglong; Liu, Yajun

    2007-04-19

    In concert with the recent photoabsorption experiments of gas-phase Schiff-base retinal chromophores (Nielsen et al. Phys. Rev. Lett. 2006, 96, 018304), quantum chemical calculations using time-dependent density functional theory coupled with different functionals and under the Tamm-Dancoff approximation were made on the first two excited states (S1 and S2) of two retinal chromophores: 11-cis and all-trans protonated Schiff bases. The calculated vertical excitation energies (Tv) and oscillator strengths (f) are consistent with the experimental absorption bands. The experimentally observed phenomenon that the transition dipole moment (mu) of S2 is much smaller that of S1 was interpreted by 3D representation of transition densities. The different optical behaviors (linear and nonlinear optical responds) of the excited states were investigated by considering different strengths of external electric fields.

  11. Tokamaks: from A D Sakharov to the present (the 60-year history of tokamaks)

    NASA Astrophysics Data System (ADS)

    Azizov, E. A.

    2012-02-01

    The paper is prepared on the basis of the report presented at the session of the Physical Sciences Division of the Russian Academy of Sciences (RAS) at the Lebedev Physical Institute, RAS on 25 May 2011, devoted to the 90-year jubilee of Academician Andrei D Sakharov - the initiator of controlled nuclear fusion research in the USSR. The 60-year history of plasma research work in toroidal devices with a longitudinal magnetic field suggested by Andrei D Sakharov and Igor E Tamm in 1950 for the confinement of fusion plasma and known at present as tokamaks is described in brief. The recent (2006) agreement among Russia, the EU, the USA, Japan, China, the Republic of Korea, and India on the joint construction of the international thermonuclear experimental reactor (ITER) in France based on the tokamak concept is discussed. Prospects for using the tokamak as a thermonuclear (14 MeV) neutron source are examined.

  12. Mixed optical Cherenkov-Bremsstrahlung radiation in vicinity of the Cherenkov cone from relativistic heavy ions: Unusual dependence of the angular distribution width on the radiator thickness

    NASA Astrophysics Data System (ADS)

    Rozhkova, E. I.; Pivovarov, Yu. L.

    2016-07-01

    The Cherenkov radiation (ChR) angular distribution is usually described by the Tamm-Frank (TF) theory, which assumes that relativistic charged particle moves uniformly and rectilinearly in the optically transparent radiator. According to the TF theory, the full width at half maximum (FWHM) of the ChR angular distribution inversely depends on the radiator thickness. In the case of relativistic heavy ions (RHI) a slowing-down in the radiator may sufficiently change the angular distribution of optical radiation in vicinity of the Cherenkov cone, since there appears a mixed ChR-Bremsstrahlung radiation. As a result, there occurs a drastic transformation of the FWHM of optical radiation angular distribution in dependence on the radiator thickness: from inversely proportional (TF theory) to the linearly proportional one. In our paper we present the first analysis of this transformation taking account of the gradual velocity decrease of RHI penetrating through a radiator.

  13. A particle-hole calculation for pion production in relativistic heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Norbury, J. W.; Deutchman, P. A.; Townsend, L. W.

    1985-02-01

    A differential cross section for pi-meson production in peripheral heavy-ion collisions is formulated within the context of a particle-hole model in the Tamm-Dancoff approximation. This is the first attempt at a fully quantum-mechanical particle-hole calculation for pion production in relativistic heavy-ion collisions. The particular reaction studied is an O-16 projectile colliding with a C-12 target at rest. In the projectile a linear combination of isobar-hole states is formed, with the possibility of a coherent isobar giant resonance. The target can be excited to its giant M1 resonance (J-pi = 1(+), T = 1) at 15.11 MeV, or to its isobar analog neighbors, B-12 at 13.4 MeV and N-12 at 17.5 MeV. The theory is compared to recent experimental results.

  14. All-electron first-principles GW+Bethe-Salpeter calculation for optical absorption spectra of sodium clusters

    SciTech Connect

    Noguchi, Yoshifumi; Ohno, Kaoru

    2010-04-15

    The optical absorption spectra of sodium clusters (Na{sub 2n}, n{<=} 4) are calculated by using an all-electron first-principles GW+Bethe-Salpeter method with the mixed-basis approach within the Tamm-Dancoff approximation. In these small systems, the excitonic effect strongly affects the optical properties due to the confinement of exciton in the small system size. The present state-of-the-art method treats the electron-hole two-particle Green's function by incorporating the ladder diagrams up to the infinite order and therefore takes into account the excitonic effect in a good approximation. We check the accuracy of the present method by comparing the resulting spectra with experiments. In addition, the effect of delocalization in particular in the lowest unoccupied molecular orbital in the GW quasiparticle wave function is also discussed by rediagonalizing the Dyson equation.

  15. Selection of Mathematical Models of Target Acquisition by Electro- Optical Systems

    DTIC Science & Technology

    1977-01-01

    of CDR P. Chatelier (AIR-340F). The study reported here was supported by NAVAIRSYSCOM AirTask A03P.3400/008B/7F55-525-000. This report has been...imimm mm**) 1 qpi W|ll||y*r>wW tamm ’-’"’"•"■’■’■- • nr:j|"«*,i1- itWg’iW xn**-**,»#■&**’*****• M^ S ^ii^lltMäiSMäiiiällii^Miä mmmmm^vn’m-irnvm...PAGE (Whtn Data Enitrtd) ’ S . T fV^ REPORT DOCUMENTATION PAGE »i^HEPORT NI>Ma^R__ NWC1|TP’S928~7 / 2. OOVT ACCESSION NO «> T)XkLÜIUtäuWLÜ«J

  16. Kinetics of inhibition by 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole on calf thymus casein kinase II.

    PubMed

    Zandomeni, R O

    1989-09-01

    The adenosine analogue 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) is a specific inhibitor for RNA polymerase II transcription in vivo and in vitro [Tamm + Sehgal (1978) Adv. Virus Res. 22, 187-258; Zandomeni & Weinmann (1984) J. Biol. Chem. 259, 14804-14811]. The effect on RNA polymerase II-specific transcription seems to be mediated by its inhibition of nuclear casein kinase II [Zandomeni, Carrera-Zandomeni, Shugar & Weinmann (1986) J. Biol. Chem. 261, 3414-3419]. Inhibition studies indicated that DRB acted as a mixed-type inhibitor with respect to casein and as a competitive inhibitor with respect to the nucleotide phosphate donor substrates. The DRB inhibition constant is 7 microM for the calf thymus casein kinase II, with regard to both ATP and GTP.

  17. [Dynamics of the protein content of human urine during 5-day immersion].

    PubMed

    Vorontsov, A L; Nesterovskaia, A Iu; Morukov, B L; Markin, A A; Zhuravleva, O A; Zabolotskaia, I V; Vostrikova, L V

    2011-01-01

    Variations in the protein spectrum (12 groups) of native daily urine were studied during 5-day dry immersion (DI) of 14 subjects at the age of 19 to 26 years using gradient electrophoresis in polyacrylamide gel. Protein excretion with urine did not alter in the course of the experiment. However, the urine proteins spectrum trended to some shifts. Excretion of low-molecular proteins decreased and of albumin increased pointing to remodulation of tubular reabsorption initiated by the experimental conditions. Steady growth of the Tamm-Horsfall protein concentration seems to be a defense reaction. There was an incremental decrease in immunoglobulins that could be associated with a reduction of glomerular filter permeability for high-molecular proteins.

  18. Quantitative modeling of Cerenkov light production efficiency from medical radionuclides.

    PubMed

    Beattie, Bradley J; Thorek, Daniel L J; Schmidtlein, Charles R; Pentlow, Keith S; Humm, John L; Hielscher, Andreas H

    2012-01-01

    There has been recent and growing interest in applying Cerenkov radiation (CR) for biological applications. Knowledge of the production efficiency and other characteristics of the CR produced by various radionuclides would help in accessing the feasibility of proposed applications and guide the choice of radionuclides. To generate this information we developed models of CR production efficiency based on the Frank-Tamm equation and models of CR distribution based on Monte-Carlo simulations of photon and β particle transport. All models were validated against direct measurements using multiple radionuclides and then applied to a number of radionuclides commonly used in biomedical applications. We show that two radionuclides, Ac-225 and In-111, which have been reported to produce CR in water, do not in fact produce CR directly. We also propose a simple means of using this information to calibrate high sensitivity luminescence imaging systems and show evidence suggesting that this calibration may be more accurate than methods in routine current use.

  19. The Light Infantry Division Regionally Focused for Low Intensity Conflict

    DTIC Science & Technology

    1990-06-01

    daIta needed. endt coeno~tet•n n e.wn t• lV•lt he otlec¶,O’ Of eftfo’M~tso.tend• tammI[enti te11adIet this bi’dett etln~ie m¢ lay Sthe¢ aetee o UP, b | 4911...W oe f Info•matKonmn udIo .tto t foe eeuWng t04% buideeie. to Wathfttqteit beadsuartet Ser,.tv( .O rl r m I b •lfoff aOp. Opf anlo"iOnesd At•0ot. I...information, 1 June 1990. Other requests for this B aocument shall be referred to: HQs, CAC & Ft. Leavenworth, ATTN: ATZL-GOP-SEl, Ft. Leavenworth, KS 66027

  20. A particle-hole calculation for pion production in relativistic heavy-ion collisions

    NASA Technical Reports Server (NTRS)

    Norbury, J. W.; Deutchman, P. A.; Townsend, L. W.

    1985-01-01

    A differential cross section for pi-meson production in peripheral heavy-ion collisions is formulated within the context of a particle-hole model in the Tamm-Dancoff approximation. This is the first attempt at a fully quantum-mechanical particle-hole calculation for pion production in relativistic heavy-ion collisions. The particular reaction studied is an O-16 projectile colliding with a C-12 target at rest. In the projectile a linear combination of isobar-hole states is formed, with the possibility of a coherent isobar giant resonance. The target can be excited to its giant M1 resonance (J-pi = 1(+), T = 1) at 15.11 MeV, or to its isobar analog neighbors, B-12 at 13.4 MeV and N-12 at 17.5 MeV. The theory is compared to recent experimental results.

  1. Linear scaling solution of the time-dependent self-consistent-field equations with quasi-independent Rayleigh quotient iteration

    SciTech Connect

    Challacombe, Matt

    2009-01-01

    An algorithm for solution of the Time-Dependent Self-Consistent-Field (TD-SCF) equations is developed, based on dual solution channels for non-linear optimization of the Tsiper functional [J.Phys.B, 34 L401 (2001)]. This formulation poses the TD-SCF problem as two Rayleigh quotients, coupled weakly through biorthogonality. Convergence rates for the Random Phase Approximation (RPA) are found to be equivalent to the Tamm-Dancoff approximation (TDA). Moreover, the variational nature of the quotient is robust to approximation errors, allowing linear scaling solution to the bulk limit of the RPA matrix-eigenvalue and exchange operator problem for molecular wires with extended conjugation, including polyphenylene vinylene and the (4,3) nanotube.

  2. Phase-locked coherent modes in a patterned metal-organic microcavity

    NASA Astrophysics Data System (ADS)

    Brückner, R.; Zakhidov, A. A.; Scholz, R.; Sudzius, M.; Hintschich, S. I.; Fröb, H.; Lyssenko, V. G.; Leo, K.

    2012-05-01

    Organic microcavities offer tantalizing prospects for studying the interactions of light and matter. For electrical excitation of these processes, electrodes must be integrated. However, the large absorption properties of metals are generally considered fatal for optical coherence. With this in mind, we embedded a thin silver grating into an organic microcavity to generate periodic arrays of localized cavity modes and metal-based Tamm plasmon polaritons. These excited states are capable of phase coupling across the grating. At room temperature and under non-resonant pumping, we selectively stimulated coherent emission from in- and out-of-phase locked arrays. We show that an absorptive metal inside an optical cavity is compatible with coherent emission. Most importantly, the inherently low residual absorption of the organic layer enables coherence to spread over macroscopic distances, even at room temperature. Our strategy of embedding metal patterns into an organic microcavity yields a viable route towards electrically driven organic solid-state lasers.

  3. On improvements of Double Beta Decay using FQTDA Model

    NASA Astrophysics Data System (ADS)

    de Oliveira, L.; Samana, A. R.; Krmpotic, F.; Mariano, A. E.; Barbero, C. A.

    2015-07-01

    The Quasiparticle Tamm-Dancoff Approximation (QTDA) is applied to describe the nuclear double beta decay with two neutrinos. Several serious inconveniences found in the Quasiparticle Random Phase Approximation (QRPA) are not present in the QTDA, as such as the ambiguity in treating the intermediary states, and further approximations necessary for evaluation of the nuclear matrix elements (NMEs) or, the extreme sensitivity of NME with the ratio between the pn and pp + nn pairings. Some years ago, the decay 48Ca → 48Ti was discussed within the particle-hole limit of QTDA. We found some mismatch in the numerical calculations when the full QTDA was being implemented, and a new performance in the particle-hole limit of QTDA is required to guarantee the fidelity of the approximation.

  4. Quantum speed limits in open system dynamics.

    PubMed

    del Campo, A; Egusquiza, I L; Plenio, M B; Huelga, S F

    2013-02-01

    Bounds to the speed of evolution of a quantum system are of fundamental interest in quantum metrology, quantum chemical dynamics, and quantum computation. We derive a time-energy uncertainty relation for open quantum systems undergoing a general, completely positive, and trace preserving evolution which provides a bound to the quantum speed limit. When the evolution is of the Lindblad form, the bound is analogous to the Mandelstam-Tamm relation which applies in the unitary case, with the role of the Hamiltonian being played by the adjoint of the generator of the dynamical semigroup. The utility of the new bound is exemplified in different scenarios, ranging from the estimation of the passage time to the determination of precision limits for quantum metrology in the presence of dephasing noise.

  5. [Familial juvenile hyperuricemic nephropathy].

    PubMed

    Hummel, Aurélie

    2012-04-01

    Familial juvenile hyperuricemic nephropathy is a rare autosomal dominant disease. It is characterized by abnormal handling of urate responsible for hyperuricaemia often complicated of gouty arthritis. Renal failure is due to tubulointerstitial nephritis. Ultrasonography sometimes finds renal cysts of variable size and number. Renal histology, although not specific, shows interstitial fibrosis, atrophic tubules, sometimes enlarged and with irregular membrane thickening. Renal failure progresses to end stage between 30 and 60 years of age. Allopurinol treatment is recommended at the early stages of the disease, its efficacy on slowing down the progression of the disease is however not proven. There is genetic heterogeneity in familial juvenile hyperuricemic nephropathy. Uromodulin encoding Tamm-Horsfall protein is the only gene to date identified, responsible in less than half of the families. The described mutations most often concern a cystein and are clustering in exon 4. These mutations result in abnormal retention of the protein in endoplasmic reticulum of Henle loop cells and in reduction of its urinary excretion. The pathophysiology of the disease is however still dubious. Indeed, Tamm-Horsfall protein functions are not well known (anti-infectious role, cristallisation inhibition, immunomodulating role). Knock-out mice do not develop renal phenotype but are more prone to E. coli urinary infections. Uromodulin gene mutations have also been described in medullary cystic kidney disease, an autosomal dominant tubulointerstitial nephropathy, considered at first as a distinct disorder. Genetic progress allowed us to consider familial juvenile hyperuricemic nephropathy and medullary cystic kidney disease as the two facets of a same disease, we should call uromodulin associated kidney diseases. At least two other genes have been implicated in similar clinical presentation: TCF2 and the gene encoding renin.

  6. Reversible brain swelling in crucian carp (Carassius carassius) and goldfish (Carassius auratus) in response to high external ammonia and anoxia.

    PubMed

    Wilkie, Michael P; Stecyk, Jonathan A W; Couturier, Christine S; Sidhu, Sanya; Sandvik, Guro K; Nilsson, Göran E

    2015-06-01

    Increased internal ammonia (hyperammonemia) and ischemic/anoxic insults are known to result in a cascade of deleterious events that can culminate in potentially fatal brain swelling in mammals. It is less clear, however, if the brains of fishes respond to ammonia in a similar manner. The present study demonstrated that the crucian carp (Carassius carassius) was not only able to endure high environmental ammonia exposure (HEA; 2 to 22 mmol L(-1)) but that they experienced 30% increases in brain water content at the highest ammonia concentrations. This swelling was accompanied by 4-fold increases in plasma total ammonia (TAmm) concentration, but both plasma TAmm and brain water content were restored to pre-exposure levels following depuration in ammonia-free water. The closely related, ammonia-tolerant goldfish (Carassius auratus) responded similarly to HEA (up to 3.6 mmol L(-1)), which was accompanied by 4-fold increases in brain glutamine. Subsequent administration of the glutamine synthetase inhibitor, methionine sulfoximine (MSO), reduced brain glutamine accumulation by 80% during HEA. However, MSO failed to prevent ammonia-induced increases in brain water content suggesting that glutamine may not be directly involved in initiating ammonia-induced brain swelling in fishes. Although the mechanisms of brain swelling are likely different, exposure to anoxia for 96 h caused similar, but lesser (10%) increases in brain water content in crucian carp. We conclude that brain swelling in some fishes may be a common response to increased internal ammonia or lower oxygen but further research is needed to deduce the underlying mechanisms behind such responses.

  7. SU-E-T-238: Monte Carlo Estimation of Cerenkov Dose for Photo-Dynamic Radiotherapy

    SciTech Connect

    Chibani, O; Price, R; Ma, C; Eldib, A; Mora, G

    2014-06-01

    Purpose: Estimation of Cerenkov dose from high-energy megavoltage photon and electron beams in tissue and its impact on the radiosensitization using Protoporphyrine IX (PpIX) for tumor targeting enhancement in radiotherapy. Methods: The GEPTS Monte Carlo code is used to generate dose distributions from 18MV Varian photon beam and generic high-energy (45-MV) photon and (45-MeV) electron beams in a voxel-based tissueequivalent phantom. In addition to calculating the ionization dose, the code scores Cerenkov energy released in the wavelength range 375–425 nm corresponding to the pick of the PpIX absorption spectrum (Fig. 1) using the Frank-Tamm formula. Results: The simulations shows that the produced Cerenkov dose suitable for activating PpIX is 4000 to 5500 times lower than the overall radiation dose for all considered beams (18MV, 45 MV and 45 MeV). These results were contradictory to the recent experimental studies by Axelsson et al. (Med. Phys. 38 (2011) p 4127), where Cerenkov dose was reported to be only two orders of magnitude lower than the radiation dose. Note that our simulation results can be corroborated by a simple model where the Frank and Tamm formula is applied for electrons with 2 MeV/cm stopping power generating Cerenkov photons in the 375–425 nm range and assuming these photons have less than 1mm penetration in tissue. Conclusion: The Cerenkov dose generated by high-energy photon and electron beams may produce minimal clinical effect in comparison with the photon fluence (or dose) commonly used for photo-dynamic therapy. At the present time, it is unclear whether Cerenkov radiation is a significant contributor to the recently observed tumor regression for patients receiving radiotherapy and PpIX versus patients receiving radiotherapy only. The ongoing study will include animal experimentation and investigation of dose rate effects on PpIX response.

  8. Nitrogen metabolism, acid-base regulation, and molecular responses to ammonia and acid infusions in the spiny dogfish shark (Squalus acanthias).

    PubMed

    Nawata, C Michele; Walsh, Patrick J; Wood, Chris M

    2015-07-01

    Although they are ureotelic, marine elasmobranchs express Rh glycoproteins, putative ammonia channels. To address questions raised by a recent study on high environmental ammonia (HEA) exposure, dogfish were intravascularly infused for 24 h at 3 ml kg(-1) h(-1) with isosmotic NaCl (500 mmol l(-1), control), NH4HCO3 (500 mmol l(-1)), NH4Cl (500 mmol l(-1)), or HCl (as 125 mmol l(-1) HCl + 375 mmol l(-1) NaCl). While NaCl had no effect on arterial acid-base status, NH4HCO3 caused mild alkalosis, NH4Cl caused strong acidosis, and HCl caused lesser acidosis, all predominantly metabolic in nature. Total plasma ammonia (T(Amm)) and excretion rates of ammonia (J(Amm)) and urea-N (J(Urea-N)) were unaffected by NaCl or HCl. However, despite equal loading rates, plasma T(Amm) increased to a greater extent with NH4Cl, while J(Amm) increased to a greater extent with NH4HCO3 due to much greater increases in blood-to-water PNH3 gradients. As with HEA, both treatments caused large (90%) elevations of J(Urea-N), indicating that urea-N synthesis by the ornithine-urea cycle (OUC) is driven primarily by ammonia rather than HCO3(-). Branchial mRNA expressions of Rhbg and Rhp2 were unaffected by NH4HCO3 or NH4Cl, but v-type H(+)-ATPase was down-regulated by both treatments, and Rhbg and Na(+)/H(+) exchanger NHE2 were up-regulated by HCl. In the kidney, Rhbg was unresponsive to all treatments, but Rhp2 was up-regulated by HCl, and the urea transporter UT was up-regulated by HCl and NH4Cl. These responses are discussed in the context of current ideas about branchial, renal, and OUC function in this nitrogen-limited predator.

  9. Acute exposure to high environmental ammonia (HEA) triggers the emersion response in the green shore crab.

    PubMed

    Zimmer, Alex M; Wood, Chris M

    2017-02-01

    The physiological effects of high environmental ammonia (HEA) exposure have been well documented in many aquatic species. In particular, it has recently been demonstrated that exposure to ammonia in fish leads to a similar hyperventilatory response as observed during exposure to hypoxia. In littoral crabs, such as the green crab (Carcinus maenas), exposure to severe hypoxia triggers an emersion response whereby crabs escape hypoxia to breathe air. We hypothesized that exposure to HEA in green crabs would lead to a similar behavioural response which is specific to ammonia. Using an experimental arena containing a rock bed onto which crabs could emerse, we established that exposure to HEA (4mmol/l NH4HCO3) for 15min triggers emersion in crabs. In experiments utilizing NaHCO3 controls and NH4HCO3 injections, we further determined that emersion was triggered specifically by external ammonia and was independent of secondary acid-base or respiratory disturbances caused by HEA. We then hypothesized that emersion from HEA provides a physiological benefit, similar to emersion from hypoxia. Exposure to 15min of HEA without emersion (no rock bed present) caused significant increases in arterial haemolymph total ammonia (Tamm), pH, and [HCO3(-)]. When emersion was allowed, arterial haemolymph Tamm and [HCO3(-)] increased, but no alkalosis developed. Moreover, emersion decreased haemolymph partial pressure of NH3 relative to crabs which could not emerse. Overall, we demonstrate a novel behavioural response to HEA exposure in crabs which we propose may share similar mechanistic pathways with the emersion response triggered by hypoxia.

  10. The suitability of an uncemented hydroxyapatite coated (HAC) hip hemiarthroplasty stem for intra-capsular femoral neck fractures in osteoporotic elderly patients: the Metaphyseal-Diaphyseal Index, a solution to preventing intra-operative periprosthetic fracture.

    PubMed

    Chana, Rishi; Mansouri, Reza; Jack, Chris; Edwards, Max R; Singh, Ravi; Keller, Carmel; Khan, Farid

    2011-11-18

    This study will seek to identify a measurable radiographic index, the Metaphyseal-Diaphyseal Index (MDI) score to determine whether intra-operative fracture in osteoporotic bone can be predicted.A 5 year prospective cohort of 560 consecutive patients, undergoing hemiarthroplasty (cemented or uncemented), was evaluated. A nested case-control study to determine risk factors affecting intra-operative fracture was carried out. The Vancouver Classification was used to classify periprosthetic fracture. The MDI score was calculated using radiographs from the uncemented group. As a control (gold standard), Yeung et al's Canal Bone Ratio (CBR) score was also calculated. From this, a receiver operating characteristic (ROC) curve was formulated for both scores and area under the curve (AUC) compared. Intra and inter-observer correlations were determined. Cost analysis was also worked out for adverse outcomes. Four hundred and seven uncemented and one hundred and fifty-three cemented stems were implanted. The use of uncemented implants was the main risk factor for intra-operative periprosthetic fracture. Sixty-two periprosthetic fractures occurred in the uncemented group (15.2%), nine occurred in the cemented group (5.9%), P < 0.001. The revision rate for sustaining a periprosthetic fracture (uncemented group) was 17.7%, P < 0.001 and 90 day mortality 19.7%, P < 0.03. MDI's AUC was 0.985 compared to CBR's 0.948, P < 0.001. The MDI score cut-off to predict fracture was 21, sensitivity 98.3%, specificity 99.8%, positive predictive value 90.5% and negative predictive value 98%. Multivariate regression analysis ruled out any other confounding factors as being significant. The intra and inter-observer Pearson correlation scores were r = 0.99, P < 0.001. JRI uncemented hemiarthroplasty has a significantly higher intra-operative fracture rate. We recommend cemented arthroplasty for hip fractures. We propose a radiographic system that may allow surgeons to select patients who are good

  11. Tribological behavior of artificial hip joint under the effects of magnetic field in dry and lubricated sliding.

    PubMed

    Zaki, M; Aljinaidi, A; Hamed, M

    2003-01-01

    In recent years, there is an increasing utilization and demand to use magnetic fields in bioengineering applications due to its beneficial effects. Although in the last decade more attention has been given by tribologists to the electromagnetic processes taking place between sliding surfaces, which influence the tribological behaviors, but no attention has been concern with the sliding surfaces of the artificial implant joints. Therefore, the present work aims to elucidate the tribological behavior of an artificial joint implant under the effect of magnetic fields. Experimental investigation was carried out on a specially designed and constructed hip simulator on which the variations in the coefficients of friction and wear rates of the sliding surfaces were evaluated under the influence of a medium strength magnetic field suitable to apply in the human body. A realistic Ti-alloy implanted stem was used with an inserted head made from surgical grade stainless steel. This head was allowed to rub against UHMWPE sockets. The utilized type of prosthesis was "The JRI Modular Muller Standard-Total Hip Design". The performed experimental tests were conducted under both dry and lubricated sliding conditions using physiological saline solution. The designed simulator allows the coefficients of friction and the wear rates to be evaluated under realistic physiological loading and motion cycles encountered during normal walking of the human body. Comparative results are presented between the artificial joint performance in the presence and absence of the applied magnetic field. The experimental results have indicated that the presence of a medium strength magnetic field of 270 Gauss strength between rubbing surfaces resulted in high beneficial reductions in friction and wear rate of UHMWPE sliding on stainless steel either under dry or saline lubricating conditions. Therefore recommendation was forward to subject artificial implants made of stainless steel/UHMWPE combination

  12. Highly efficient implementation of pseudospectral time-dependent density-functional theory for the calculation of excitation energies of large molecules.

    PubMed

    Cao, Yixiang; Hughes, Thomas; Giesen, Dave; Halls, Mathew D; Goldberg, Alexander; Vadicherla, Tati Reddy; Sastry, Madhavi; Patel, Bhargav; Sherman, Woody; Weisman, Andrew L; Friesner, Richard A

    2016-06-15

    We have developed and implemented pseudospectral time-dependent density-functional theory (TDDFT) in the quantum mechanics package Jaguar to calculate restricted singlet and restricted triplet, as well as unrestricted excitation energies with either full linear response (FLR) or the Tamm-Dancoff approximation (TDA) with the pseudospectral length scales, pseudospectral atomic corrections, and pseudospectral multigrid strategy included in the implementations to improve the chemical accuracy and to speed the pseudospectral calculations. The calculations based on pseudospectral time-dependent density-functional theory with full linear response (PS-FLR-TDDFT) and within the Tamm-Dancoff approximation (PS-TDA-TDDFT) for G2 set molecules using B3LYP/6-31G*(*) show mean and maximum absolute deviations of 0.0015 eV and 0.0081 eV, 0.0007 eV and 0.0064 eV, 0.0004 eV and 0.0022 eV for restricted singlet excitation energies, restricted triplet excitation energies, and unrestricted excitation energies, respectively; compared with the results calculated from the conventional spectral method. The application of PS-FLR-TDDFT to OLED molecules and organic dyes, as well as the comparisons for results calculated from PS-FLR-TDDFT and best estimations demonstrate that the accuracy of both PS-FLR-TDDFT and PS-TDA-TDDFT. Calculations for a set of medium-sized molecules, including Cn fullerenes and nanotubes, using the B3LYP functional and 6-31G(**) basis set show PS-TDA-TDDFT provides 19- to 34-fold speedups for Cn fullerenes with 450-1470 basis functions, 11- to 32-fold speedups for nanotubes with 660-3180 basis functions, and 9- to 16-fold speedups for organic molecules with 540-1340 basis functions compared to fully analytic calculations without sacrificing chemical accuracy. The calculations on a set of larger molecules, including the antibiotic drug Ramoplanin, the 46-residue crambin protein, fullerenes up to C540 and nanotubes up to 14×(6,6), using the B3LYP functional and 6-31G

  13. Macroscopicity of quantum superpositions on a one-parameter unitary path in Hilbert space

    NASA Astrophysics Data System (ADS)

    Volkoff, T. J.; Whaley, K. B.

    2014-12-01

    We analyze quantum states formed as superpositions of an initial pure product state and its image under local unitary evolution, using two measurement-based measures of superposition size: one based on the optimal quantum binary distinguishability of the branches of the superposition and another based on the ratio of the maximal quantum Fisher information of the superposition to that of its branches, i.e., the relative metrological usefulness of the superposition. A general formula for the effective sizes of these states according to the branch-distinguishability measure is obtained and applied to superposition states of N quantum harmonic oscillators composed of Gaussian branches. Considering optimal distinguishability of pure states on a time-evolution path leads naturally to a notion of distinguishability time that generalizes the well-known orthogonalization times of Mandelstam and Tamm and Margolus and Levitin. We further show that the distinguishability time provides a compact operational expression for the superposition size measure based on the relative quantum Fisher information. By restricting the maximization procedure in the definition of this measure to an appropriate algebra of observables, we show that the superposition size of, e.g., NOON states and hierarchical cat states, can scale linearly with the number of elementary particles comprising the superposition state, implying precision scaling inversely with the total number of photons when these states are employed as probes in quantum parameter estimation of a 1-local Hamiltonian in this algebra.

  14. A Preliminary Study Into the Significance of Intrarenal Reflux in BK Virus Nephropathy After Kidney Transplantation

    PubMed Central

    Kawanishi, Kunio; Honda, Kazuho; Koike, Junki; Hattori, Motoshi; Fuchinoue, Shouhei; Tanabe, Kazunari; Oda, Hideaki; Nagashima, Yoji

    2016-01-01

    Background The BK virus typically colonizes the lower urinary tract and is the causative agent in BK virus nephropathy (BKVN), which can progress to allograft dysfunction and graft loss. Urinary reflux in kidney allografts is induced by vesicoureteral reflux or disturbances in intrarenal reflux (IRR), believed to be associated with BKVN. This study was designed to elucidate the relationship between BKVN and IRR. Methods We examined 30 renal transplant recipients histologically diagnosed with BKVN using anti-Simian virus 40 immunohistochemistry and 60 clinically matched control recipients. The BKVN patients were divided into stable (n = 12) and progressive (n = 18) groups according to allograft kidney function 1 year after diagnosis. Histological rejection scores according to the pathological classification of rejection in renal allografts (Banff classification), histological BKVN stages, and histological polyomavirus load levels (pvl) proposed by the Banff working group were evaluated. The IRR was quantified by histological reflux scores defined with retention and reflux of immunostained Tamm-Horsfall protein in renal tubules and glomeruli. Results Higher reflux scores were observed in the BKVN group compared with that in the control group. No differences in clinical parameters were observed between the BKVN and control groups. Reflux scores and pvl were significantly higher in the progressive group than in the stable BKVN group with no significant difference in BK stage observed between groups. Reflux scores were found to be significantly correlated with pvl. Conclusions Our preliminary study suggested that IRR might be a predisposing and prognostic factor in BKVN. PMID:27500256

  15. Long-range doublon transfer in a dimer chain induced by topology and ac fields

    PubMed Central

    Bello, M.; Creffield, C. E.; Platero, G.

    2016-01-01

    The controlled transfer of particles from one site of a spatial lattice to another is essential for many tasks in quantum information processing and quantum communication. In this work we study how to induce long-range transfer between the two ends of a dimer chain, by coupling states that are localized just on the chain’s end-points. This has the appealing feature that the transfer occurs only between the end-points – the particle does not pass through the intermediate sites–making the transfer less susceptible to decoherence. We first show how a repulsively bound-pair of fermions, known as a doublon, can be transferred from one end of the chain to the other via topological edge states. We then show how non-topological surface states of the familiar Shockley or Tamm type can be used to produce a similar form of transfer under the action of a periodic driving potential. Finally we show that combining these effects can produce transfer by means of more exotic topological effects, in which the driving field can be used to switch the topological character of the edge states, as measured by the Zak phase. Our results demonstrate how to induce long range transfer of strongly correlated particles by tuning both topology and driving. PMID:26932406

  16. General description of electromagnetic radiation processes based on instantaneous charge acceleration in ''endpoints''

    SciTech Connect

    James, Clancy W.; Falcke, Heino; Huege, Tim; Ludwig, Marianne

    2011-11-15

    We present a methodology for calculating the electromagnetic radiation from accelerated charged particles. Our formulation - the 'endpoint formulation' - combines numerous results developed in the literature in relation to radiation arising from particle acceleration using a complete, and completely general, treatment. We do this by describing particle motion via a series of discrete, instantaneous acceleration events, or 'endpoints', with each such event being treated as a source of emission. This method implicitly allows for particle creation and destruction, and is suited to direct numerical implementation in either the time or frequency domains. In this paper we demonstrate the complete generality of our method for calculating the radiated field from charged particle acceleration, and show how it reduces to the classical named radiation processes such as synchrotron, Tamm's description of Vavilov-Cherenkov, and transition radiation under appropriate limits. Using this formulation, we are immediately able to answer outstanding questions regarding the phenomenology of radio emission from ultra-high-energy particle interactions in both the earth's atmosphere and the moon. In particular, our formulation makes it apparent that the dominant emission component of the Askaryan effect (coherent radio-wave radiation from high-energy particle cascades in dense media) comes from coherent 'bremsstrahlung' from particle acceleration, rather than coherent Vavilov-Cherenkov radiation.

  17. Computing UV/vis spectra using a combined molecular dynamics and quantum chemistry approach: bis-triazin-pyridine (BTP) ligands studied in solution.

    PubMed

    Höfener, Sebastian; Trumm, Michael; Koke, Carsten; Heuser, Johannes; Ekström, Ulf; Skerencak-Frech, Andrej; Schimmelpfennig, Bernd; Panak, Petra J

    2016-03-21

    We report a combined computational and experimental study to investigate the UV/vis spectra of 2,6-bis(5,6-dialkyl-1,2,4-triazin-3-yl)pyridine (BTP) ligands in solution. In order to study molecules in solution using theoretical methods, force-field parameters for the ligand-water interaction are adjusted to ab initio quantum chemical calculations. Based on these parameters, molecular dynamics (MD) simulations are carried out from which snapshots are extracted as input to quantum chemical excitation-energy calculations to obtain UV/vis spectra of BTP ligands in solution using time-dependent density functional theory (TDDFT) employing the Tamm-Dancoff approximation (TDA). The range-separated CAM-B3LYP functional is used to avoid large errors for charge-transfer states occurring in the electronic spectra. In order to study environment effects with theoretical methods, the frozen-density embedding scheme is applied. This computational procedure allows to obtain electronic spectra calculated at the (range-separated) DFT level of theory in solution, revealing solvatochromic shifts upon solvation of up to about 0.6 eV. Comparison to experimental data shows a significantly improved agreement compared to vacuum calculations and enables the analysis of relevant excitations for the line shape in solution.

  18. Pathogenesis of urinary tract infections with normal female anatomy.

    PubMed

    Finer, Gal; Landau, Daniel

    2004-10-01

    Recurrent urinary tract infections (UTIs) are common among girls and young women who are healthy and have anatomically normal urinary tracts. These infections are a main source of morbidity and health-care costs in this population. The interaction between specific infecting bacteria and urinary tract epithelium characteristics underlies the pathogenesis of this disease. Several pathogen-related factors predispose people to recurrent UTI, including periurethral bacterial colonisation and Escherichia coli virulence. Host behavioural risk factors include voiding dysfunction, high intercourse frequency, and oral contraceptive and spermicide use. The role of vesicoureteral reflux in recurrent childhood UTI is probably overestimated in the medical literature and is important only in a small group of children with high-grade reflux. Family pedigree analysis suggests a familial genetic predisposition for UTI among young females. Animal models show the multigenic nature of recurrent UTI. Putative candidate genes for the disease include ABH blood groups, interleukin-8 receptor (CXCR1), the human leucocyte antigen locus, toll-like receptors, tumour necrosis factor, and Tamm-Horsfall protein.

  19. Analytical approach for the excited-state Hessian in time-dependent density functional theory: Formalism, implementation, and performance

    NASA Astrophysics Data System (ADS)

    Liu, Jie; Liang, WanZhen

    2011-11-01

    The paper presents the formalism, implementation, and performance of the analytical approach for the excited-state Hessian in the time-dependent density functional theory (TDDFT) that extends our previous work [J. Liu and W. Z. Liang, J. Chem. Phys. 135, 014113 (2011)] on the analytical Hessian in TDDFT within Tamm-Dancoff approximation (TDA) to full TDDFT. In contrast to TDA-TDDFT, an appreciable advantage of full TDDFT is that it maintains the oscillator strength sum rule, and therefore yields more precise results for the oscillator strength and other related physical quantities. For the excited-state harmonic vibrational frequency calculation, however, full TDDFT does not seem to be advantageous since the numerical tests demonstrate that the accuracy of TDDFT with and without TDA are comparable to each other. As a common practice, the computed harmonic vibrational frequencies are scaled by a suitable scale factor to yield good agreement with the experimental fundamental frequencies. Here we apply both the optimized ground-state and excited-state scale factors to scale the calculated excited-state harmonic frequencies and find that the scaling decreases the root-mean-square errors. The optimized scale factors derived from the excited-state calculations are slightly smaller than those from the ground-state calculations.

  20. Calculation Method for Exciton Wavefunctions with Electron--Hole Exchange Interaction: Application to Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Ajiki, Hiroshi

    2013-05-01

    A new method for calculating exciton wavefunctions in the presence of a long-range electron--hole (e--h) exchange interaction (EXI) is presented. The e--h EXI arises, for example, for cross-polarized excitons in a single-walled carbon nanotube (SWNT). Cross-polarized excitons have previously been calculated as an eigenvalue problem of a Bethe--Salpeter equation (BSE) within the Tamm--Dancoff-type approximation (TDA). The resulting wavefunctions provide quite different absorption spectra in comparison with those calculated in the self-consistent-field method [S. Uryu and T. Ando, J. Phys.: Conf. Ser. 302 (2011) 012004]. Although the self-consistent-field method is more reliable, exciton wavefunctions cannot be obtained from this method. A general method is derived here to obtain exciton wavefunctions that take the e--h EXI into account within the TDA, and the method is applied to the cross-polarized excitons of a SWNT. The absorption spectra calculated from the resulting exciton wavefunctions agree well with the spectra calculated from the self-consistent-field method within a rotating-wave approximation.

  1. QPNM calculation for the ground state magnetic moments of odd-mass deformed nuclei: 157-167Er isotopes

    NASA Astrophysics Data System (ADS)

    Yakut, H.; Guliyev, E.; Guner, M.; Tabar, E.; Zenginerler, Z.

    2012-08-01

    A new microscopic method has been developed in the framework of the Quasiparticle-Phonon Nuclear Model (QPNM) in order to investigate spin polarization effects on the magnetic properties such as magnetic moment, intrinsic magnetic moment and effective gs factor of the ground state of odd-mass 157-167Er isotopes. The calculations were performed using both Tamm-Dancoff Approximation (TDA) and Quasiparticle Random-Phase Approximation (QRPA). Reasonably good agreement has been obtained between the QRPA results and the relevant experimental data. Furthermore the variation of the intrinsic magnetic moment gK values with the mass number A exhibits similar behavior for both theoretical and experimental results. From the compression of the calculated intrinsic magnetic moment values with the experimental data the spin-spin interaction parameter has been found as χ=(30/A) MeV for odd-mass 157-167Er isotopes. Our results clarify the possibility of using this new method to describe the magnetic properties of odd-mass deformed nuclei.

  2. Relativistic Continuum Shell Model

    NASA Astrophysics Data System (ADS)

    Grineviciute, Janina; Halderson, Dean

    2011-04-01

    The R-matrix formalism of Lane and Thomas has been extended to the relativistic case so that the many-coupled channels problem may be solved for systems in which binary breakup channels satisfy a relative Dirac equation. The formalism was previously applied to the relativistic impulse approximation RIA and now we applied it to Quantum Hadrodynamics QHD in the continuum Tamm-Dancoff approximation TDA with the classical meson fields replaced by one-meson exchange potentials. None of the published QHD parameters provide a decent fit to the 15 N + p elastic cross section. The deficiency is also evident in inability of the QHD parameters with the one meson exchange potentials to reproduce the QHD single particle energies. Results with alternate parameters sets are presented. A. M. Lane and R. G. Thomas, R-Matrix Theory of Nuclear Reactions, Reviews of Modern Physics, 30 (1958) 257

  3. A visual Fortran 90 program for the two-particle or two-hole excitations of nuclei: The PPRPA program

    NASA Astrophysics Data System (ADS)

    Taqi, Ali H.

    Random Phase Approximation (RPA) is one of the main approximation tools in studying nuclear structure. Here, we present a graphical user interface (GUI) Fortran code: Particle-Particle Random Phase Approximation (PPRPA) version 1, 2015. The code performs Tamm-Dancoff approximation (TDA) and Random Phase Approximation (RPA) calculations of nuclear structure of nuclei having A ± 2 nucleons in the total angular momenta and isospin (JT) scheme. The Hamiltonian is diagonalized with a given input model space, single-particle energies and interaction. Space function has been expanded to include orbits s, p, d, f, g and h. The current version of the code allows the user to test 20 orbits only. All possible eigenvalues and amplitudes within a model space are calculated. The single-particle density, charge distribution density and transition density are calculated in the basis of the harmonic oscillator potential. The primary utility of the PPRPA code is providing a visual tool to implementation and understanding of the collective excitation techniques TDA and RPA. Impact of the program includes all students, researchers and all those interested in knowing the facts about the structure of the atom nucleus and about the success of approximation methods in different branches of science.

  4. Benign nodal lesions mimicking metastases from pediatric renal neoplasms: a report of the National Wilms' Tumor Study Pathology Center.

    PubMed

    Weeks, D A; Beckwith, J B; Mierau, G W

    1990-12-01

    Regional lymph node status is a key factor in the staging of pediatric renal tumors on the National Wilms' Tumor Study (NWTS). A review of cases entered on the NWTS has uncovered a number of cases where benign lymph node findings were mistaken for metastases. Most frequently, this was due to the presence of complexes of epithelial cells and Tamm-Horsfall protein within nodal sinuses. The epithelial cells were derived from damaged nephrons, usually resulting from obstruction by tumor. Another epithelial pseudometastic lesion, intranodal squamous epithelial cells, was found to originate from metaplastic calyceal urothelium. Benign mesothelial or coelomic inclusions similar to those previously described in pelvic and periaortic lymph nodes of adult females were found in nodes of four patients, including two boys, who are, to our knowledge, the first to be described with this finding. Other sources of confusion included protrusion of lymphoid follicles or germinal centers into nodal sinuses, thick endothelial cells of postcapillary venules mimicking epithelial tubules, nodal megakaryocytes resembling anaplastic nuclear changes, and histiocytic granulomas. Immunocytochemical methods were useful in evaluating some of these phenomena. Recognition of these pseudometastatic lesions is essential in order to avoid unnecessary and potentially hazardous therapeutic intensification.

  5. Monolayered MoSe2: a candidate for room temperature polaritonics

    NASA Astrophysics Data System (ADS)

    Lundt, N.; Maryński, A.; Cherotchenko, E.; Pant, A.; Fan, X.; Tongay, S.; Sęk, G.; Kavokin, A. V.; Höfling, S.; Schneider, C.

    2017-03-01

    Monolayered MoSe2 is a promising new material to investigate advanced light-matter coupling as it hosts stable and robust excitons with comparably narrow optical resonances. In this work, we investigate the evolution of the lowest lying excitonic transition, the so-called A-valley exciton, with temperature. We find a strong, phonon-induced temperature broadening of the resonance, and more importantly, a reduction of the oscillator strength for increased temperatures, which we describe in the framework of a microscopic model. Based on these experimentally extracted, temperature dependent parameters, we apply a coupled oscillator model to elucidate the possibility to observe the strong coupling regime between the A-exciton and a microcavity resonance in three prototypical photonic architectures with varying mode volumes. We find that the formation of exciton-polaritons up to ambient conditions in compact, monolithic dielectric and Tamm-based structures seems feasible. In contrast, a temperature-induced transition into the weak coupling regime can be expected for structures with extended effective cavity length. Based on these findings, we calculate and draw the phase diagram of polariton Bosonic condensation in a microcavity with embedded MoSe2 monolayers.

  6. Introducing constricted variational density functional theory in its relaxed self-consistent formulation (RSCF-CV-DFT) as an alternative to adiabatic time dependent density functional theory for studies of charge transfer transitions

    SciTech Connect

    Krykunov, Mykhaylo; Seth, Mike; Ziegler, Tom

    2014-05-14

    We have applied the relaxed and self-consistent extension of constricted variational density functional theory (RSCF-CV-DFT) for the calculation of the lowest charge transfer transitions in the molecular complex X-TCNE between X = benzene and TCNE = tetracyanoethylene. Use was made of functionals with a fixed fraction (α) of Hartree-Fock exchange ranging from α = 0 to α = 0.5 as well as functionals with a long range correction (LC) that introduces Hartree-Fock exchange for longer inter-electronic distances. A detailed comparison and analysis is given for each functional between the performance of RSCF-CV-DFT and adiabatic time-dependent density functional theory (TDDFT) within the Tamm-Dancoff approximation. It is shown that in this particular case, all functionals afford the same reasonable agreement with experiment for RSCF-CV-DFT whereas only the LC-functionals afford a fair agreement with experiment using TDDFT. We have in addition calculated the CT transition energy for X-TCNE with X = toluene, o-xylene, and naphthalene employing the same functionals as for X = benzene. It is shown that the calculated charge transfer excitation energies are in as good agreement with experiment as those obtained from highly optimized LC-functionals using adiabatic TDDFT. We finally discuss the relation between the optimization of length separation parameters and orbital relaxation in the RSCF-CV-DFT scheme.

  7. The effects of acute and chronic ammonia exposure during early life stages of the gulf toadfish, Opsanus beta.

    PubMed

    Barimo, John F; Walsh, Patrick J

    2005-11-10

    The gulf toadfish (Opsanus beta) is unusual among teleosts in that it is facultatively ureotelic and adults and juveniles have a particularly high tolerance to environmental ammonia. Male toadfish brood their offspring in confined nests. It has been hypothesized that the potential accumulation of ammonia in nests from the male and the offspring, coupled with suspected low ammonia tolerance in offspring would provide the selective pressure necessary for excretion of the less toxic urea by adult toadfish. This study examines this so-called 'nest-fouling' hypothesis through acute and chronic ammonia toxicity testing on early life stages of O. beta. In addition, nitrogen elimination was examined among embryos, yolk-sac larvae and juveniles where we found an ontogenic shift from ammonotely to ureotely with advancing life history stages. The acute ammonia 96 h LC50 values for embryos and larvae were 63.6 and 5.45 mmol-Nl(-1) total ammonia (TAmm), respectively. Thus, these early life stages are more tolerant to ammonia than either juveniles or adults and LC50 values are at least 2 orders of magnitude greater than concentrations naturally occurring at nest sites. Furthermore, 40 days exposures at mean and maximum NH3 concentrations normally found within nests revealed no observable detrimental effects. In fact, growth in terms of wet or dry weight was greatest at the maximum NH3 concentration. We therefore conclude that the nest-fouling hypothesis is not a viable explanation for ureotely in the gulf toadfish.

  8. Apoptosis of the Thick Ascending Limb Results in Acute Kidney Injury

    PubMed Central

    Srichai, Manakan B.; Hao, Chuanming; Davis, Linda; Golovin, Anastasia; Zhao, Min; Moeckel, Gilbert; Dunn, Steve; Bulus, Nada; Harris, Raymond C.; Zent, Roy; Breyer, Matthew D.

    2008-01-01

    Ischemia- or toxin-induced acute kidney injury is generally thought to affect the cells of the proximal tubule, but it has been difficult to define the involvement of other tubular segments because of the widespread damage caused by ischemia/reperfusion or toxin-induced injury in experimental models. For evaluation of whether thick ascending limb (TAL)-specific epithelial injury results in acute kidney injury, a novel transgenic mouse model that expresses the herpes simplex virus 1 thymidine kinase gene under the direction of the TAL-specific Tamm-Horsfall protein promoter was generated. After administration of gancyclovir, these mice demonstrated apoptosis only in TAL cells, with little evidence of neutrophil infiltration. Compared with control mice, blood urea nitrogen and creatinine levels were at least five-fold higher in the transgenic mice, which also developed oliguria and impaired urinary concentrating ability. These findings suggest that acute injury targeted only to the TAL is sufficient to cause severe acute kidney injury in mice with features similar to those observed in humans. PMID:18495962

  9. Apoptosis of the thick ascending limb results in acute kidney injury.

    PubMed

    Srichai, Manakan B; Hao, Chuanming; Davis, Linda; Golovin, Anastasia; Zhao, Min; Moeckel, Gilbert; Dunn, Steve; Bulus, Nada; Harris, Raymond C; Zent, Roy; Breyer, Matthew D

    2008-08-01

    Ischemia- or toxin-induced acute kidney injury is generally thought to affect the cells of the proximal tubule, but it has been difficult to define the involvement of other tubular segments because of the widespread damage caused by ischemia/reperfusion or toxin-induced injury in experimental models. For evaluation of whether thick ascending limb (TAL)-specific epithelial injury results in acute kidney injury, a novel transgenic mouse model that expresses the herpes simplex virus 1 thymidine kinase gene under the direction of the TAL-specific Tamm-Horsfall protein promoter was generated. After administration of gancyclovir, these mice demonstrated apoptosis only in TAL cells, with little evidence of neutrophil infiltration. Compared with control mice, blood urea nitrogen and creatinine levels were at least five-fold higher in the transgenic mice, which also developed oliguria and impaired urinary concentrating ability. These findings suggest that acute injury targeted only to the TAL is sufficient to cause severe acute kidney injury in mice with features similar to those observed in humans.

  10. Linear response theory for the density matrix renormalization group: efficient algorithms for strongly correlated excited states.

    PubMed

    Nakatani, Naoki; Wouters, Sebastian; Van Neck, Dimitri; Chan, Garnet Kin-Lic

    2014-01-14

    Linear response theory for the density matrix renormalization group (DMRG-LRT) was first presented in terms of the DMRG renormalization projectors [J. J. Dorando, J. Hachmann, and G. K.-L. Chan, J. Chem. Phys. 130, 184111 (2009)]. Later, with an understanding of the manifold structure of the matrix product state (MPS) ansatz, which lies at the basis of the DMRG algorithm, a way was found to construct the linear response space for general choices of the MPS gauge in terms of the tangent space vectors [J. Haegeman, J. I. Cirac, T. J. Osborne, I. Pižorn, H. Verschelde, and F. Verstraete, Phys. Rev. Lett. 107, 070601 (2011)]. These two developments led to the formulation of the Tamm-Dancoff and random phase approximations (TDA and RPA) for MPS. This work describes how these LRTs may be efficiently implemented through minor modifications of the DMRG sweep algorithm, at a computational cost which scales the same as the ground-state DMRG algorithm. In fact, the mixed canonical MPS form implicit to the DMRG sweep is essential for efficient implementation of the RPA, due to the structure of the second-order tangent space. We present ab initio DMRG-TDA results for excited states of polyenes, the water molecule, and a [2Fe-2S] iron-sulfur cluster.

  11. Benchmarking singlet and triplet excitation energies of molecular semiconductors for singlet fission: Tuning the amount of HF exchange and adjusting local correlation to obtain accurate functionals for singlet-triplet gaps

    NASA Astrophysics Data System (ADS)

    Brückner, Charlotte; Engels, Bernd

    2017-01-01

    Vertical and adiabatic singlet and triplet excitation energies of molecular p-type semiconductors calculated with various DFT functionals and wave-function based approaches are benchmarked against MS-CASPT2/cc-pVTZ reference values. A special focus lies on the singlet-triplet gaps that are very important in the process of singlet fission. Singlet fission has the potential to boost device efficiencies of organic solar cells, but the scope of existing singlet-fission compounds is still limited. A computational prescreening of candidate molecules could enlarge it; yet it requires efficient methods accurately predicting singlet and triplet excitation energies. Different DFT formulations (Tamm-Dancoff approximation, linear response time-dependent DFT, Δ-SCF) and spin scaling schemes along with several ab initio methods (CC2, ADC(2)/MP2, CIS(D), CIS) are evaluated. While wave-function based methods yield rather reliable singlet-triplet gaps, many DFT functionals are shown to systematically underestimate triplet excitation energies. To gain insight, the impact of exact exchange and correlation is in detail addressed.

  12. High Resolution Inelastic Electron Scattering from LEAD-208.

    NASA Astrophysics Data System (ADS)

    Connelly, James Patrick

    Inclusive electron scattering differential cross sections from ^{208}Pb have been measured with energy resolutions better than 20 keV for over 120 discrete states with excitation energies less than 7.3 MeV. The momentum-transfer dependence of these cross sections has been mapped over a range of 0.5 to 2.8 fm^{-1} in the forward direction and 1.0 to 2.9 fm^{ -1} in the backward scattering direction. Over fifty excitations have been analyzed in the Distorted Wave Born Approximation to yield transition charge, current and magnetization densities. The nuclear structure of discrete excitations are interpreted in the framework of 1p-1h transition. The nuclear structure of levels in the excitation region below 4.8 MeV is studied in detail. Above 4.8 MeV, multiplets from single particle-hole configurations coupling to high spin states (J >=q 7) are investigated. Experimental transition densities are compared to Tamm-Dancoff calculations from a correlated ground state.

  13. Loss of Urinary Macromolecules in Mice Causes Interstitial and Intratubular Renal Calcification Dependent on the Underlying Conditions

    NASA Astrophysics Data System (ADS)

    Wu, Xue-Ru; Lieske, John C.; Evan, Andrew P.; Sommer, Andre J.; Liaw, Lucy; Mo, Lan

    2008-09-01

    Urinary protein macromolecules have long been thought to play a role in influencing the various phases of urolithiasis including nucleation, growth, aggregation of mineral crystals and their subsequent adhesion to the renal epithelial cells. However, compelling evidence regarding their precise role was lacking, due partly to the fact that most prior studies were done in vitro and results were highly variable depending on the experimental conditions. The advent of genetic engineering technology has made it possible to study urinary protein macromolecules within an in vivo biological system. Indeed, recent studies have begun to shed light on the net effects of loss of one or more macromolecules on the earliest steps of urolithiasis. This paper focuses on the in vivo consequences of inactivating Tamm-Horsfall protein and/or osteopontin, two major urinary glycoproteins, using the knockout approach. The renal phenotypes of both single and double knockout mice under spontaneous or hyperoxaluric conditions will be described. The functional significance of the urinary macromolecules as critical defense factors against renal calcification will also be discussed.

  14. Direct proton decay from the Gamow-Teller resonance in {sup 208}Bi

    SciTech Connect

    Akimune, H.; Daito, I.; Fujita, Y.; Fujiwara, M.; Greenfield, M.B.; Harakeh, M.N.; Inomata, T.; Jaenecke, J.; Katori, K.; Nakayama, S.; Sakai, H.; Sakemi, Y.; Tanaka, M.; Yosoi, M. ||||||||

    1995-08-01

    Spin-isospin excitations in {sup 208}Bi have been investigated using the {sup 208}Pb ({sup 3}He,{ital t}){sup 208}Bi reaction at near {theta}{approx}0{degree} at {ital E}({sup 3}He)=450 MeV. The microscopic structure of the Gamow-Teller resonance (GTR), the isobaric analog state (IAS), and the spin-flip dipole ({Delta}{ital L}=1) resonance (SDR) in {sup 208}Bi has been studied by observing their direct proton decays to the low-lying neutron-hole states in {sup 207}Pb. Decay protons were measured at backward angles in coincidence with tritons detected at and near 0{degree}. The total branching ratio for proton decay from the GTR is determined to be only 4.9{plus_minus}1.3%. The total branching ratio for proton decay from the SDR amounts to 14.1{plus_minus}4.2%. The deduced total widths as well as the total and partial proton escape widths of the GRR and IAS are found to be in reasonable agreement with recent theoretical estimates obtained in the framework of the continuum Tamm-Dancoff approximation.

  15. Calcium Oxalate Stone Agglomeration Inhibition [tm] Reflects Renal Stone-Forming Activity.

    PubMed

    Lindberg, J S; Cole, F E; Romani, W; Husserl, F E; Fuselier, H A; Kok, D J; Erwin, D T

    2000-04-01

    Louisiana and other Gulf South states comprise a "Stone Belt" where calcium oxalate stone formers (CaOx SFs) are found at a high rate of approximately 5%. In these patients, the agglomeration of small stone crystals, which are visible in nearly all morning urine collections, forms stones that can become trapped in the renal parenchyma and the renal pelvis. Without therapy, about half of CaOx SFs repeatedly form kidney stones, which can cause excruciating pain that can be relieved by passage, fragmentation (lithotripsy), or surgical removal. The absence of stones in "normal" patients suggests that there are stone inhibitors in "normal" urines.At the Ochsner Renal Stone Clinic, 24-hour urine samples are collected by the patient and sent to the Ochsner Renal Stone Research Program where calcium oxalate stone agglomeration inhibition [tm] measurements are performed. Urine from healthy subjects and inactive stone formers has demonstrated strongly inhibited stone growth [tm] in contrast to urine from recurrent CaOx SFs. [tm] data from 1500 visits of 700 kidney stone patients have been used to evaluate the risk of recurrence in Ochsner's CaOx SF patients. These data have also been used to demonstrate the interactive roles of certain identified urinary stone-growth inhibitors, citrate and Tamm-Horsfall protein (THP), which can be manipulated with medication to diminish recurrent stone formation. Our goal is to offer patients both financial and pain relief by reducing their stones with optimized medication, using medical management to avoid costly treatments.

  16. Myeloma-like cast nephropathy caused by human recombinant soluble CD4 (sCD4) in monkeys.

    PubMed Central

    Bugelski, P. J.; Solleveld, H. A.; Fong, K. L.; Klinkner, A. M.; Hart, T. K.; Morgan, D. G.

    1992-01-01

    CD4 is the receptor for human immunodeficiency virus (HIV) on lymphocytes and macrophages. Soluble CD4 (sCD4), a recombinant truncated form of CD4, has been shown to inhibit HIV-1 in vitro and is being tested as a therapy for AIDS. Preclinical studies in cynomolgus monkeys revealed a protein cast nephropathy after four daily intravenous doses of 100 mg/kg/day. Renal lesions were not found in monkeys that received 10 mg/kg/day. The renal lesions consisted of proteinaceous tubular casts associated with multinucleate giant cells and neutrophils located in the tubules of the distal nephron. The affected tubules were surrounded by an interstitial mixed inflammatory cell infiltrate. By electron microscopy, the casts were composed of moderately electron dense, paracrystalline material. Immunostaining demonstrated that the casts contained sCD4-derived material and Tamm-Horsfall protein. Moreover, biochemical analysis of urine showed that a portion of sCD4 was excreted as intact protein. Because infection with HIV-1 can be associated with clinically significant nephropathy, these data suggest that renal function should be closely monitored in patients receiving soluble forms of CD4. Images Figure 1 Figure 2 Figure 3 PMID:1546739

  17. All-electron G W +Bethe-Salpeter calculations on small molecules

    NASA Astrophysics Data System (ADS)

    Hirose, Daichi; Noguchi, Yoshifumi; Sugino, Osamu

    2015-05-01

    Accuracy of the first-principles G W +Bethe-Salpeter equation (BSE) method is examined for low-energy excited states of small molecules. The standard formalism, which is based on the one-shot G W approximation and the Tamm-Dancoff approximation (TDA), is found to underestimate the optical gap of N2, CO, H2O ,C2H4 , and CH2O by about 1 eV. Possible origins are investigated separately for the effect of TDA and for the approximate schemes of the self-energy operator, which are known to cause overbinding of the electron-hole pair and overscreening of the interaction. By applying the known correction formula, we find the amount of the correction is too small to overcome the underestimated excitation energy. This result indicates a need for fundamental revision of the G W +BSE method rather than adjustment of the standard one. We expect that this study makes the problems in the current G W +BSE formalism clearer and provides useful information for further intrinsic development beyond the current framework.

  18. Cubic-scaling iterative solution of the Bethe-Salpeter equation for finite systems

    NASA Astrophysics Data System (ADS)

    Ljungberg, M. P.; Koval, P.; Ferrari, F.; Foerster, D.; Sánchez-Portal, D.

    2015-08-01

    The Bethe-Salpeter equation (BSE) is currently the state of the art in the description of neutral electronic excitations in both solids and large finite systems. It is capable of accurately treating charge-transfer excitations that present difficulties for simpler approaches. We present a local basis set formulation of the BSE for molecules where the optical spectrum is computed with the iterative Haydock recursion scheme, leading to a low computational complexity and memory footprint. Using a variant of the algorithm we can go beyond the Tamm-Dancoff approximation. We rederive the recursion relations for general matrix elements of a resolvent, show how they translate into continued fractions, and study the convergence of the method with the number of recursion coefficients and the role of different terminators. Due to the locality of the basis functions the computational cost of each iteration scales asymptotically as O (N3) with the number of atoms, while the number of iterations typically is much lower than the size of the underlying electron-hole basis. In practice we see that, even for systems with thousands of orbitals, the runtime will be dominated by the O (N2) operation of applying the Coulomb kernel in the atomic orbital representation.

  19. Surface aggregation of urinary proteins and aspartic acid-rich peptides on the faces of calcium oxalate monohydrate investigated by in situ force microscopy

    SciTech Connect

    Weaver, M L; Qiu, S R; Hoyer, J R; Casey, W H; Nancollas, G H; De Yoreo, J J

    2008-05-28

    The growth of calcium oxalate monohydrate in the presence of Tamm-Horsfall protein (THP), osteopontin (OPN), and the 27-residue synthetic peptides (DDDS){sub 6}DDD and (DDDG){sub 6}DDD [where D = aspartic acid and X = S (serine) or G (glycine)] was investigated via in situ atomic force microscopy (AFM). The results show that these three growth modulators create extensive deposits on the crystal faces. Depending on the modulator and crystal face, these deposits can occur as discrete aggregates, filamentary structures, or uniform coatings. These proteinaceous films can lead to either the inhibition or increase of the step speeds (with respect to the impurity-free system) depending on a range of factors that include peptide or protein concentration, supersaturation and ionic strength. While THP and the linear peptides act, respectively, to exclusively increase and inhibit growth on the (-101) face, both exhibit dual functionality on the (010) face, inhibiting growth at low supersaturation or high modulator concentration and accelerating growth at high supersaturation or low modulator concentration. Based on analyses of growth morphologies and dependencies of step speeds on supersaturation and protein or peptide concentration, we argue for a picture of growth modulation that accounts for the observations in terms of the strength of binding to the surfaces and steps and the interplay of electrostatic and solvent-induced forces at crystal surface.

  20. Analytical approach for the excited-state Hessian in time-dependent density functional theory: formalism, implementation, and performance.

    PubMed

    Liu, Jie; Liang, WanZhen

    2011-11-14

    The paper presents the formalism, implementation, and performance of the analytical approach for the excited-state Hessian in the time-dependent density functional theory (TDDFT) that extends our previous work [J. Liu and W. Z. Liang, J. Chem. Phys. 135, 014113 (2011)] on the analytical Hessian in TDDFT within Tamm-Dancoff approximation (TDA) to full TDDFT. In contrast to TDA-TDDFT, an appreciable advantage of full TDDFT is that it maintains the oscillator strength sum rule, and therefore yields more precise results for the oscillator strength and other related physical quantities. For the excited-state harmonic vibrational frequency calculation, however, full TDDFT does not seem to be advantageous since the numerical tests demonstrate that the accuracy of TDDFT with and without TDA are comparable to each other. As a common practice, the computed harmonic vibrational frequencies are scaled by a suitable scale factor to yield good agreement with the experimental fundamental frequencies. Here we apply both the optimized ground-state and excited-state scale factors to scale the calculated excited-state harmonic frequencies and find that the scaling decreases the root-mean-square errors. The optimized scale factors derived from the excited-state calculations are slightly smaller than those from the ground-state calculations.

  1. Identifying and tracing potential energy surfaces of electronic excitations with specific character via their transition origins: application to oxirane.

    PubMed

    Li, Jian-Hao; Zuehlsdorff, T J; Payne, M C; Hine, N D M

    2015-05-14

    We show that the transition origins of electronic excitations identified by quantified natural transition orbital (QNTO) analysis can be employed to connect potential energy surfaces (PESs) according to their character across a wide range of molecular geometries. This is achieved by locating the switching of transition origins of adiabatic potential surfaces as the geometry changes. The transition vectors for analysing transition origins are provided by linear response time-dependent density functional theory (TDDFT) calculations under the Tamm-Dancoff approximation. We study the photochemical CO ring opening of oxirane as an example and show that the results corroborate the traditional Gomer-Noyes mechanism derived experimentally. The knowledge of specific states for the reaction also agrees well with that given by previous theoretical work using TDDFT surface-hopping dynamics that was validated by high-quality quantum Monte Carlo calculations. We also show that QNTO can be useful for considerably larger and more complex systems: by projecting the excitations to those of a reference oxirane molecule, the approach is able to identify and analyse specific excitations of a trans-2,3-diphenyloxirane molecule.

  2. Platonic Micelles: Monodisperse Micelles with Discrete Aggregation Numbers Corresponding to Regular Polyhedra

    NASA Astrophysics Data System (ADS)

    Fujii, Shota; Yamada, Shimpei; Matsumoto, Sakiko; Kubo, Genki; Yoshida, Kenta; Tabata, Eri; Miyake, Rika; Sanada, Yusuke; Akiba, Isamu; Okobira, Tadashi; Yagi, Naoto; Mylonas, Efstratios; Ohta, Noboru; Sekiguchi, Hiroshi; Sakurai, Kazuo

    2017-03-01

    The concept of micelles was first proposed in 1913 by McBain and has rationalized numerous experimental results of the self-aggregation of surfactants. It is generally agreed that the aggregation number (Nagg) for spherical micelles has no exact value and a certain distribution. However, our studies of calix[4]arene surfactants showed that they were monodisperse with a defined Nagg whose values are chosen from 6, 8, 12, 20, and 32. Interestingly, some of these numbers coincide with the face numbers of Platonic solids, thus we named them “Platonic micelles”. The preferred Nagg values were explained in relation to the mathematical Tammes problem: how to obtain the best coverage of a sphere surface with multiple identical circles. The coverage ratio D(N) can be calculated and produces maxima at N = 6, 12, 20, and 32, coinciding with the observed Nagg values. We presume that this “Platonic nature” may hold for any spherical micelles when Nagg is sufficiently small.

  3. Thouless theorem for matrix product states and subsequent post density matrix renormalization group methods

    NASA Astrophysics Data System (ADS)

    Wouters, Sebastian; Nakatani, Naoki; Van Neck, Dimitri; Chan, Garnet Kin-Lic

    2013-08-01

    The similarities between Hartree-Fock (HF) theory and the density matrix renormalization group (DMRG) are explored. Both methods can be formulated as the variational optimization of a wave-function Ansatz. Linearization of the time-dependent variational principle near a variational minimum allows to derive the random phase approximation (RPA). We show that the nonredundant parameterization of the matrix product state (MPS) tangent space [J. Haegeman, J. I. Cirac, T. J. Osborne, I. Pižorn, H. Verschelde, and F. Verstraete, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.107.070601 107, 070601 (2011)] leads to the Thouless theorem for MPS, i.e., an explicit nonredundant parameterization of the entire MPS manifold, starting from a specific MPS reference. Excitation operators are identified, which extends the analogy between HF and DMRG to the Tamm-Dancoff approximation (TDA), the configuration interaction (CI) expansion, and coupled cluster theory. For a small one-dimensional Hubbard chain, we use a CI-MPS Ansatz with single and double excitations to improve on the ground state and to calculate low-lying excitation energies. For a symmetry-broken ground state of this model, we show that RPA-MPS allows to retrieve the Goldstone mode. We also discuss calculations of the RPA-MPS correlation energy. With the long-range quantum chemical Pariser-Parr-Pople Hamiltonian, low-lying TDA-MPS and RPA-MPS excitation energies for polyenes are obtained.

  4. Linear response theory for the density matrix renormalization group: Efficient algorithms for strongly correlated excited states

    NASA Astrophysics Data System (ADS)

    Nakatani, Naoki; Wouters, Sebastian; Van Neck, Dimitri; Chan, Garnet Kin-Lic

    2014-01-01

    Linear response theory for the density matrix renormalization group (DMRG-LRT) was first presented in terms of the DMRG renormalization projectors [J. J. Dorando, J. Hachmann, and G. K.-L. Chan, J. Chem. Phys. 130, 184111 (2009)]. Later, with an understanding of the manifold structure of the matrix product state (MPS) ansatz, which lies at the basis of the DMRG algorithm, a way was found to construct the linear response space for general choices of the MPS gauge in terms of the tangent space vectors [J. Haegeman, J. I. Cirac, T. J. Osborne, I. Pižorn, H. Verschelde, and F. Verstraete, Phys. Rev. Lett. 107, 070601 (2011)]. These two developments led to the formulation of the Tamm-Dancoff and random phase approximations (TDA and RPA) for MPS. This work describes how these LRTs may be efficiently implemented through minor modifications of the DMRG sweep algorithm, at a computational cost which scales the same as the ground-state DMRG algorithm. In fact, the mixed canonical MPS form implicit to the DMRG sweep is essential for efficient implementation of the RPA, due to the structure of the second-order tangent space. We present ab initio DMRG-TDA results for excited states of polyenes, the water molecule, and a [2Fe-2S] iron-sulfur cluster.

  5. Autoradiographic localization of benzodiazepine receptors in the rat kidney

    SciTech Connect

    Beaumont, K.; Healy, D.P.; Fanestil, D.D.

    1984-11-01

    The localization of benzodiazepine (BZD) receptors in the rat kidney was studied by autoradiography after in vitro labeling of kidney slices with flunitrazepam. The affinity, density, and rank order of displacement of (/sup 3/H)-flunitrazepam by several BZDs (RO 5-4864 > diazepam > clonazepam) demonstrated that binding was to BZD receptors of the peripheral type. In autoradiograms obtained with tritium-sensitive film, a high density of silver grains was obtained in the outer medulla, with lower densities in the cortex. Binding was absent from the inner medulla (papilla). In higher resolution autoradiograms obtained with an emulsion-coated cover slip procedure, silver grains were seen to be concentrated over a tubular element in both outer medulla and cortex, identifiable by morphology and distribution as the thick ascending limb of the loop of Henle and the distal convoluted tubule. The identity of the labeled tubules was confirmed by immunofluorescent localization in adjacent slices of Tamm-Horsfall protein, a specific marker for these segments of tubules. Investigation of the effects of peripherally specific BZDs such as RO 5-4864 on distal tubule function is indicated.

  6. Quantitative Modeling of Cerenkov Light Production Efficiency from Medical Radionuclides

    PubMed Central

    Beattie, Bradley J.; Thorek, Daniel L. J.; Schmidtlein, Charles R.; Pentlow, Keith S.; Humm, John L.; Hielscher, Andreas H.

    2012-01-01

    There has been recent and growing interest in applying Cerenkov radiation (CR) for biological applications. Knowledge of the production efficiency and other characteristics of the CR produced by various radionuclides would help in accessing the feasibility of proposed applications and guide the choice of radionuclides. To generate this information we developed models of CR production efficiency based on the Frank-Tamm equation and models of CR distribution based on Monte-Carlo simulations of photon and β particle transport. All models were validated against direct measurements using multiple radionuclides and then applied to a number of radionuclides commonly used in biomedical applications. We show that two radionuclides, Ac-225 and In-111, which have been reported to produce CR in water, do not in fact produce CR directly. We also propose a simple means of using this information to calibrate high sensitivity luminescence imaging systems and show evidence suggesting that this calibration may be more accurate than methods in routine current use. PMID:22363636

  7. Platonic Micelles: Monodisperse Micelles with Discrete Aggregation Numbers Corresponding to Regular Polyhedra

    PubMed Central

    Fujii, Shota; Yamada, Shimpei; Matsumoto, Sakiko; Kubo, Genki; Yoshida, Kenta; Tabata, Eri; Miyake, Rika; Sanada, Yusuke; Akiba, Isamu; Okobira, Tadashi; Yagi, Naoto; Mylonas, Efstratios; Ohta, Noboru; Sekiguchi, Hiroshi; Sakurai, Kazuo

    2017-01-01

    The concept of micelles was first proposed in 1913 by McBain and has rationalized numerous experimental results of the self-aggregation of surfactants. It is generally agreed that the aggregation number (Nagg) for spherical micelles has no exact value and a certain distribution. However, our studies of calix[4]arene surfactants showed that they were monodisperse with a defined Nagg whose values are chosen from 6, 8, 12, 20, and 32. Interestingly, some of these numbers coincide with the face numbers of Platonic solids, thus we named them “Platonic micelles”. The preferred Nagg values were explained in relation to the mathematical Tammes problem: how to obtain the best coverage of a sphere surface with multiple identical circles. The coverage ratio D(N) can be calculated and produces maxima at N = 6, 12, 20, and 32, coinciding with the observed Nagg values. We presume that this “Platonic nature” may hold for any spherical micelles when Nagg is sufficiently small. PMID:28290532

  8. Treatment of acute kidney injury with cast nephropathy.

    PubMed

    Walther, Carl; Podoll, Amber S; Finkel, Kevin W

    2014-07-01

    Nearly 50% of patients with multiple myeloma develop renal disease; acute kidney injury (AKI) from cast nephropathy, or "myeloma kidney" is the most common type. Development of AKI is associated with worse 1-year survival and reduces the therapeutic options available to patients. Therefore, there is a great need to develop more effective therapies. Cast nephropathy is due to the interaction and aggregation of filtered free light chains (FLCs) and Tamm- Horsfall protein (THP) causing intratubular obstruction and damage. The key to treating cast nephropathy is rapid lowering of FLCs as this correlates with renal recovery. Newer chemotherapy agents lower FLCs and have been referred to as "renoprotective". However there remains great interest in using various extracorporeal therapies to remove serum FLCs. Initially, therapeutic plasma exchange (TPE) was thought to improve renal outcomes in cast nephropathy based on small trials. The largest randomized trial of TPE, however, failed to show any benefit. A newer technique is extended high cut-off hemodialysis (HCO-HD). This modality uses a high molecular weight cut-off filter to remove FLCs. To date, trials with HCO-HD in patients with cast nephropathy have been encouraging. However, there are no randomized trials demonstrating the benefit of HCOHD when used in addition to newer chemotherapeutic regimens. Until these studies are available, HCO-HD cannot be recommended as standard of care.

  9. Electron correlation effects on photoionization time delay in atomic Ar and Xe

    NASA Astrophysics Data System (ADS)

    Ganesan, A.; Saha, S.; Decshmukh, P. C.; Manson, S. T.; Kheifets, A. S.

    2016-05-01

    Time delay studies in photoionization processes have stimulated much interest as they provide valuable dynamical information about electron correlation and relativistic effects. In a recent work on Wigner time delay in the photoionization of noble gas atoms, it was found that correlations resulting from interchannel coupling involving shells with different principal quantum numbers have significant effects on 2s and 2p photoionization of Ne, 3s photoionization of Ar, and 3d photoionization of Kr. In the present work, photoionization time delay in inner and outer subshells of the noble gases Ar and Xe are examined by including electron correlations using different many body techniques: (i) the relativistic-random-phase approximation (RRPA), (ii) RRPA with relaxation, to include relaxation effects of the residual ion and (iii) the relativistic multiconfiguration Tamm-Dancoff (RMCTD) approximation. The (sometimes substantial) effects of the inclusion of non-RPA correlations on the photoionization Wigner time delay are reported. Work supported by DOE, Office of Chemical Sciences and DST (India).

  10. Analytic derivative couplings for spin-flip configuration interaction singles and spin-flip time-dependent density functional theory

    SciTech Connect

    Zhang, Xing; Herbert, John M.

    2014-08-14

    We revisit the calculation of analytic derivative couplings for configuration interaction singles (CIS), and derive and implement these couplings for its spin-flip variant for the first time. Our algorithm is closely related to the CIS analytic energy gradient algorithm and should be straightforward to implement in any quantum chemistry code that has CIS analytic energy gradients. The additional cost of evaluating the derivative couplings is small in comparison to the cost of evaluating the gradients for the two electronic states in question. Incorporation of an exchange-correlation term provides an ad hoc extension of this formalism to time-dependent density functional theory within the Tamm-Dancoff approximation, without the need to invoke quadratic response theory or evaluate third derivatives of the exchange-correlation functional. Application to several different conical intersections in ethylene demonstrates that minimum-energy crossing points along conical seams can be located at substantially reduced cost when analytic derivative couplings are employed, as compared to use of a branching-plane updating algorithm that does not require these couplings. Application to H{sub 3} near its D{sub 3h} geometry demonstrates that correct topology is obtained in the vicinity of a conical intersection involving a degenerate ground state.

  11. Analytic derivative couplings for spin-flip configuration interaction singles and spin-flip time-dependent density functional theory.

    PubMed

    Zhang, Xing; Herbert, John M

    2014-08-14

    We revisit the calculation of analytic derivative couplings for configuration interaction singles (CIS), and derive and implement these couplings for its spin-flip variant for the first time. Our algorithm is closely related to the CIS analytic energy gradient algorithm and should be straightforward to implement in any quantum chemistry code that has CIS analytic energy gradients. The additional cost of evaluating the derivative couplings is small in comparison to the cost of evaluating the gradients for the two electronic states in question. Incorporation of an exchange-correlation term provides an ad hoc extension of this formalism to time-dependent density functional theory within the Tamm-Dancoff approximation, without the need to invoke quadratic response theory or evaluate third derivatives of the exchange-correlation functional. Application to several different conical intersections in ethylene demonstrates that minimum-energy crossing points along conical seams can be located at substantially reduced cost when analytic derivative couplings are employed, as compared to use of a branching-plane updating algorithm that does not require these couplings. Application to H3 near its D(3h) geometry demonstrates that correct topology is obtained in the vicinity of a conical intersection involving a degenerate ground state.

  12. Photonic confinement in laterally structured metal-organic microcavities

    NASA Astrophysics Data System (ADS)

    Mischok, Andreas; Brückner, Robert; Sudzius, Markas; Reinhardt, Christoph; Lyssenko, Vadim G.; Fröb, Hartmut; Leo, Karl

    2014-08-01

    We investigate the formation of optical modes in organic microcavities with an incorporated perforated silver layer. The metal leads to a formation of Tamm-plasmon-polaritons and thus separates the sample into metal-free or metal-containing areas, supporting different resonances. This mode splitting is exploited to confine photons in elliptic holes and triangular cuts, forming distinctive standing wave patterns showing the strong lateral confinement. A comparison with a Maxwell-Bloch based rate equation model clearly shows the nonlinear transition into the lasing regime. The concentration of the electric field density and inhibition of lateral loss channels in turn decreases the lasing threshold by up to one order of magnitude, to 0.1 nJ. By spectroscopic investigation of such a triangular wedge, we observe the transition from the unperturbed cavity state to a strongly confined complex transversal mode. Such a structured silver layer can be utilized in future for charge carrier injection in an electrically driven organic solid state laser.

  13. Composite surface-plasmon-polariton waves guided by a thin metal layer sandwiched between a homogeneous isotropic dielectric material and a periodically multilayered isotropic dielectric material

    NASA Astrophysics Data System (ADS)

    Chiadini, Francesco; Fiumara, Vincenzo; Scaglione, Antonio; Lakhtakia, Akhlesh

    2015-01-01

    Multiple p- and s-polarized compound surface-plasmon-polariton (SPP) waves at a fixed frequency can be guided by a structure consisting of a metal layer sandwiched between a homogeneous isotropic dielectric (HID) material and a periodic multilayered isotropic dielectric (PMLID) material. For any thickness of the metal layer, at least one compound SPP wave must exist. It possesses the p-polarization state, and is strongly bound to the metal/HID interface when the metal thickness is large but to both metal/dielectric interfaces when the metal thickness is small. When the metal layer vanishes, this compound SPP wave transmutes into a Tamm wave. Additional compound SPP waves exist, depending on the thickness of the metal layer, the relative permittivity of the HID material, and the period and composition of the PMLID material. Some of these are p-polarized, the others are s-polarized. All of them differ in phase speed, attenuation rate, and field profile, even though all are excitable at the same frequency. The multiplicity and dependence of the number of compound SPP waves on the relative permittivity of the HID material when the metal layer is thin could be useful for optical sensing applications and intrachip plasmonic optical communication.

  14. Tailoring the optical properties of wide-bandgap based microcavities via metal films

    SciTech Connect

    Sebald, K. Rahman, SK. S.; Cornelius, M.; Gutowski, J.; Klein, T.; Klembt, S.; Kruse, C.; Hommel, D.

    2015-08-10

    We report on the tuning of the optical properties of II-VI-material-based microcavity samples, which is achieved by depositing Ag films on top of the structures. The micro-reflectivity spectra show a spectral shift of the sample resonance dependent on the metal layer thickness. By comparison of the experimental findings with the theoretical calculations applying the transfer matrix method on a metal-dielectric mirror structure, the influence of the metal layer particularly with regard to its partial oxidation was explored. Tamm plasmon modes are created at the interface between an open cavity with three ZnSe quantum wells and a metal layer on top. When tuning the excitonic emission relative to the mode by changing the sample temperature, an anticrossing of the resonances was observed. This is a clear indication that the strong coupling regime has been achieved in that sample configuration yielding a Rabi splitting of 18.5 meV. These results are promising for the realization of polariton-based optical devices with a rather simple sample configuration.

  15. Photonic lattices in organic microcavities: Bloch states and control of lasing

    NASA Astrophysics Data System (ADS)

    Mischok, Andreas; Brückner, Robert; Fröb, Hartmut; Lyssenko, Vadim G.; Leo, Karl

    2015-09-01

    Organic microcavities comprising the host:guest emitter system Alq3:DCM offer an interesting playground to experimentally study the dispersion characteristics of laterally patterned microlasers due to the broad emission spectrum and large oscillator strength of the organic dye. By structuring of metallic or dielectric sublayers directly on top of the bottom mirror, we precisely manipulate the mode structure and influence the coherent emission properties of the device. Embedding silver layers into a microcavity leads to an interaction of the optical cavity-state in the organic layer and the neighboring metal which red-shifts the cavity resonance, creating a Tamm-plasmon-polariton state. A patterning of the metal can in turn be exploited to fabricate deep photonic wells of micron-size, efficiently confining light in lateral direction. In periodic arrays of silver wires, we create a Kronig-Penney-like optical potential in the cavity and in turn observe optical Bloch states spanning over several photonic wires. We modify the Kronig-Penney theory to analytically describe the full far-field emission dispersion of our cavities and show the emergence of either zero- , π-, or 2π- phase-locking in the system. By investigating periodic SiO2 patterns, we experimentally observe stimulated emission from the ground and different excited discrete states at room temperature and are able to directly control the laser emission from both extended and confined modes of the photonic wires at room-temperature.

  16. Tailoring the optical properties of wide-bandgap based microcavities via metal films

    NASA Astrophysics Data System (ADS)

    Sebald, K.; Rahman, SK. S.; Cornelius, M.; Gutowski, J.; Klein, T.; Klembt, S.; Kruse, C.; Hommel, D.

    2015-08-01

    We report on the tuning of the optical properties of II-VI-material-based microcavity samples, which is achieved by depositing Ag films on top of the structures. The micro-reflectivity spectra show a spectral shift of the sample resonance dependent on the metal layer thickness. By comparison of the experimental findings with the theoretical calculations applying the transfer matrix method on a metal-dielectric mirror structure, the influence of the metal layer particularly with regard to its partial oxidation was explored. Tamm plasmon modes are created at the interface between an open cavity with three ZnSe quantum wells and a metal layer on top. When tuning the excitonic emission relative to the mode by changing the sample temperature, an anticrossing of the resonances was observed. This is a clear indication that the strong coupling regime has been achieved in that sample configuration yielding a Rabi splitting of 18.5 meV. These results are promising for the realization of polariton-based optical devices with a rather simple sample configuration.

  17. What's on the Surface? Physics and Chemistry of Delta-Doped Surfaces

    NASA Technical Reports Server (NTRS)

    Hoenk, Michael

    2011-01-01

    Outline of presentation: 1. Detector surfaces and the problem of stability 2. Delta-doped detectors 3. Physics of Delta-doped Silicon 4. Chemistry of the Si-SiO2 Interface 5. Physics and Chemistry of Delta-doped Surfaces a. Compensation b. Inversion c. Quantum exclusion. Conclusions: 1. Quantum confinement of electrons and holes dominates the behavior of delta-doped surfaces. 2. Stability of delta-doped detectors: Delta-layer creates an approx 1 eV tunnel barrier between bulk and surface. 3. At high surface charge densities, Tamm-Shockley states form at the surface. 4. Surface passivation by quantum exclusion: Near-surface delta-layer suppresses T-S trapping of minority carriers. 5. The Si-SiO2 interface compensates the surface 6. For delta-layers at intermediate depth, surface inversion layer forms 7. Density of Si-SiO2 interface charge can be extremely high (>10(exp 14)/sq cm)

  18. TEM analysis of the initial stages of BaSO4 crystallization

    NASA Astrophysics Data System (ADS)

    Ruiz Agudo, Cristina; Putnis, Christine V.; Ruiz Agudo, Encarnación; Putnis, Andrew

    2014-05-01

    observed ex-situ in a Transmission Electron Microscope. We found that barite precipitation involves the initial formation of nanometer-size (5-10 nm) particles that fuse in an oriented way to form larger particles. Two hierarchical levels of aggregation are observed: first, the aggregation of 5-10 nm particles to form larger, but still nanometer-sized (20-60 nm) particles. In a second stage, these latter particles aggregate to produce larger single crystals (200-500 nm). No evidence of an amorphous or crystalline precursor phase previous to crystalline barite was found. These results are of importance for the design of scale prevention methods, particularly in the choice of the most suitable scale inhibitor. Gebauer D., Cölfen H., Verch A. and Antonietti M. (2009) The multiple roles of additives in CaCO3 crystallization: a quantitative case study. Adv. Mater. 21, 435-439. Gebauer D., Völkel A. and Cölfen H. (2008) Stable prenucleation calcium carbonate clusters. Science 332, 1819-1822. Van Driessche A.E.S., Benning L.G., Rodriguez-Blanco J. D., Ossorio M., Bots P. and García-Ruiz J. M. (2012) The role and implications of bassanite as a stable precursor phase to gypsum precipitation. Science 336, 69-71. Baumgartner J., Dey A., Bomans P. H. H., Le Coadou C., Fratzl P., Sommerdijk N. A. J. M. and Faivre D. (2013) Nucleation and growth of magnetite from solution. Nature 12, 310-314. Li D., Nielsen M.H., Lee J.R.I, Frandsen C., Banfield J.F. and De Yoreo J.J.(2012) Direction-Specific Interactions Control Crystal Growth by Oriented Attachment. Science 336, 1014-1018.

  19. NR2 and P3+: Accurate, Efficient Electron-Propagator Methods for Calculating Valence, Vertical Ionization Energies of Closed-Shell Molecules.

    PubMed

    Corzo, H H; Galano, Annia; Dolgounitcheva, O; Zakrzewski, V G; Ortiz, J V

    2015-08-20

    Two accurate and computationally efficient electron-propagator (EP) methods for calculating the valence, vertical ionization energies (VIEs) of closed-shell molecules have been identified through comparisons with related approximations. VIEs of a representative set of closed-shell molecules were calculated with EP methods using 10 basis sets. The most easily executed method, the diagonal, second-order (D2) EP approximation, produces results that steadily rise as basis sets are improved toward values based on extrapolated coupled-cluster singles and doubles plus perturbative triples calculations, but its mean errors remain unacceptably large. The outer valence Green function, partial third-order and renormalized partial third-order methods (P3+), which employ the diagonal self-energy approximation, produce markedly better results but have a greater tendency to overestimate VIEs with larger basis sets. The best combination of accuracy and efficiency with a diagonal self-energy matrix is the P3+ approximation, which exhibits the best trends with respect to basis-set saturation. Several renormalized methods with more flexible nondiagonal self-energies also have been examined: the two-particle, one-hole Tamm-Dancoff approximation (2ph-TDA), the third-order algebraic diagrammatic construction or ADC(3), the renormalized third-order (3+) method, and the nondiagonal second-order renormalized (NR2) approximation. Like D2, 2ph-TDA produces steady improvements with basis set augmentation, but its average errors are too large. Errors obtained with 3+ and ADC(3) are smaller on average than those of 2ph-TDA. These methods also have a greater tendency to overestimate VIEs with larger basis sets. The smallest average errors occur for the NR2 approximation; these errors decrease steadily with basis augmentations. As basis sets approach saturation, NR2 becomes the most accurate and efficient method with a nondiagonal self-energy.

  20. Validation of local hybrid functionals for TDDFT calculations of electronic excitation energies

    NASA Astrophysics Data System (ADS)

    Maier, Toni M.; Bahmann, Hilke; Arbuznikov, Alexei V.; Kaupp, Martin

    2016-02-01

    -energy dependent local hybrids, differences between spin-resolved and "common" local mixing functions in local hybrids, and the effects of the Tamm-Dancoff approximation on the excitation energies are also discussed.

  1. Neutrino mean free paths in cold symmetric nuclear matter

    SciTech Connect

    Cowell, S.; Pandharipande, V.R.

    2004-09-01

    The neutrino mean free paths (NMFP) for scattering and absorption in cold symmetric nuclear matter (SNM) are calculated using two-body effective interactions and one-body effective weak operators obtained from realistic models of nuclear forces using correlated basis theory. The infinite system is modeled in a box with periodic boundary conditions and the one particle-hole (p-h) response functions are calculated using the Tamm-Dancoff approximation (TDA). For the densities {rho}=(1/2), 1 (3/2){rho}{sub 0}, where {rho}{sub 0} is the equilibrium density of SNM, the strength of the response is shifted to higher energy transfers when compared to a noninteracting Fermi gas (FG). This and the weakness of effective operators compared to the bare operators, significantly reduces the cross sections, enhancing the NMFP by factors of {approx}2.5-3.5 at the densities considered. The NMFP at the equilibrium density {rho}{sub 0} are also calculated using the TDA and random phase approximation (RPA) using zero range Skyrme-like effective interactions with parameters chosen to reproduce the equation of state and spin-isospin susceptibilities of matter. Their results indicate that RPA corrections to correlated TDA may further increase the NMFP by {approx}25% to 3-4 times those in a noninteracting FG. Finally, the sums and the energy weighted sums of the Fermi and Gamow-Teller responses obtained from the correlated ground state are compared with those of the 1 p-h response functions to extract the sum and mean energies of multi p-h contributions to the weak response. The relatively large mean energy of the multi p-h excitations suggests that they may not contribute significantly to low energy NMFP.

  2. The role of retardation in the structure and linear response of finite nuclei

    SciTech Connect

    Crecca, M.A.

    1989-01-01

    Conventional random phase approximation (RPA) and Tamm-Dancoff approximation (TDA) calculations of nuclear structure and the linear response employ interactions between nucleons that are instantaneous. However, N-N interactions derived from the exchange of mesons between nucleons must depend on the space-time separation of the nucleons since the mesons travel at finite speeds. Furthermore, a quantum field theory that contains interacting meson and nucleon degrees of freedom employ the Feynman propagator, i{Delta}{sub F}(x - x{prime}), to connect the nucleon-meson vertices of Feynman diagrams. This raises the question of whether calculations done with space-time dependent interactions differ significantly from the conventional calculations that employ instantaneous forces, and what are the qualitative features of the difference. The inquiry into this question begins by generalizing the traditional RPA and TDA equations into the domain of retarded (space-time dependant) interactions. This entails establishing an integral equation (the Bethe-Salpeter equation) for the polarization propagator with the appropriate RPA or TDA kernel such that the integral equation reduces to the usual RPA or TDA matrix equation for the polarization propagator as the interaction becomes instantaneous. After establishing this generalization of the RPA and TDA, a TDA calculation is performed for an interaction arising from the exchange of a scalar meson. The results are compared with those obtained from the conventional instantaneous reduction of the scalar meson exchange interaction, the Yukawa potential. Upon comparing these results one finds that in general the nuclear structure obtained from scalar meson exchange differ little less than 10%.

  3. Theoretical studies on the dimerization of substituted paraphenylenediamine radical cations

    NASA Astrophysics Data System (ADS)

    Punyain, Kraiwan; Kelterer, Anne-Marie; Grampp, Günter

    2011-12-01

    Organic radical cations form dicationic dimers in solution, observed experimentally as diamagnetic species in temperature-dependent EPR and low temperature UV/Vis spectroscopy. Dimerization of paraphenylenediamine, N,N-dimethyl-paraphenylenediamine and 2,3,5,6-tetramethyl-paraphenylenediamine radical cation in ethanol/diethylether mixture was investigated theoretically according to geometry, energetics and UV/Vis spectroscopy. Density Functional Theory including dispersion correction describes stable dimers after geometry optimization with conductor-like screening model of solvation and inclusion of the counter-ion. Energy corrections were done on double-hybrid Density Functional Theory with perturbative second-order correlation (B2PLYP-D) including basis set superposition error (BSSE), and multireference Møller-Plesset second-order perturbation theory method (MRMP2) based on complete active space method (CASSCF(2,2)) single point calculation, respectively. All three dication π-dimers exhibit long multicenter π-bonds around 2.9 ± 0.1 Å with strongly interacting orbitals. Substitution with methyl groups does not influence the dimerization process substantially. Dispersion interaction and electrostatic attraction from counter-ion play an important role to stabilize the dication dimers in solution. Dispersion-corrected double hybrid functional B2PLYP-D and CASSCF(2,2) can describe the interaction energetics properly. Vertical excitations were computed with Tamm-Dancoff approximation for time-dependent Density Functional Theory (TDA-DFT) at the B3LYP level with the cc-pVTZ basis set including ethanol solvent molecules explicitly. A strong interaction of the counter-ion and the solvent ethanol with the monomeric species is observed, whereas in the dimers the strong interaction of both radical cation species is the dominating factor for the additional peak in UV/Vis spectra.

  4. Mixed time-dependent density-functional theory/classical trajectory surface hopping study of oxirane photochemistry

    NASA Astrophysics Data System (ADS)

    Tapavicza, Enrico; Tavernelli, Ivano; Rothlisberger, Ursula; Filippi, Claudia; Casida, Mark E.

    2008-09-01

    We present a mixed time-dependent density-functional theory (TDDFT)/classical trajectory surface hopping (SH) study of the photochemical ring opening in oxirane. Previous preparatory work limited to the symmetric CC ring-opening pathways of oxirane concluded that the Tamm-Dancoff approximation (TDA) is important for improving the performance of TDDFT away from the equilibrium geometry. This observation is supported by the present TDDFT TDA/SH calculations which successfully confirm the main experimentally derived Gomer-Noyes mechanism for the photochemical CO ring opening of oxirane and, in addition, provide important state-specific information not easily accessible from experiments. In particular, we find that, while one of the lowest two excited states is photochemically relatively inert, excitation into the other excited state leads predominantly to rapid ring opening, cyclic-C2H4O→C•H2CH2O•. This is followed by hopping to the electronic ground state where hot (4000K) dynamics leads to further reactions, namely, C•H2CH2O•→CH3CHO→C•H3+C•HO and CH4+CO. We note that, in the dynamics, we are not limited to following minimum energy pathways and several surface hops may actually be needed before products are finally reached. The performance of different functionals is then assessed by comparison of TDDFT and diffusion Monte Carlo potential energy curves along a typical TDDFT TDA/SH reaction path. Finally, although true (S0,S1) conical intersections are expected to be absent in adiabatic TDDFT, we show that the TDDFT TDA is able to approximate a conical intersection in this system.

  5. Mixed time-dependent density-functional theory/classical trajectory surface hopping study of oxirane photochemistry

    SciTech Connect

    Tapavicza, Enrico; Tavernelli, Ivano; Rothlisberger, Ursula; Filippi, Claudia; Casida, Mark E.

    2008-09-28

    We present a mixed time-dependent density-functional theory (TDDFT)/classical trajectory surface hopping (SH) study of the photochemical ring opening in oxirane. Previous preparatory work limited to the symmetric CC ring-opening pathways of oxirane concluded that the Tamm-Dancoff approximation (TDA) is important for improving the performance of TDDFT away from the equilibrium geometry. This observation is supported by the present TDDFT TDA/SH calculations which successfully confirm the main experimentally derived Gomer-Noyes mechanism for the photochemical CO ring opening of oxirane and, in addition, provide important state-specific information not easily accessible from experiments. In particular, we find that, while one of the lowest two excited states is photochemically relatively inert, excitation into the other excited state leads predominantly to rapid ring opening, cyclic-C{sub 2}H{sub 4}O{yields}CH{sub 2}CH{sub 2}O. This is followed by hopping to the electronic ground state where hot (4000 K) dynamics leads to further reactions, namely, CH{sub 2}CH{sub 2}O{yields}CH{sub 3}CHO{yields}CH{sub 3}+CHO and CH{sub 4}+CO. We note that, in the dynamics, we are not limited to following minimum energy pathways and several surface hops may actually be needed before products are finally reached. The performance of different functionals is then assessed by comparison of TDDFT and diffusion Monte Carlo potential energy curves along a typical TDDFT TDA/SH reaction path. Finally, although true (S{sub 0},S{sub 1}) conical intersections are expected to be absent in adiabatic TDDFT, we show that the TDDFT TDA is able to approximate a conical intersection in this system.

  6. Lead absorption and renal dysfunction in a South African battery factory

    PubMed Central

    Ehrlich, R.; Robins, T.; Jordaan, E.; Miller, S.; Mbuli, S.; Selby, P.; Wynchank, S.; Cantrell, A.; De Broe, M.; D'Haese, P.; Todd, A.; Landrigan, P.

    1998-01-01

    OBJECTIVES: To test the association between inorganic lead (Pb) exposure, blood pressure, and renal function in South African battery factory workers, with both conventional and newer measures of renal function and integrity. METHODS: Renal function measures included serum creatinine, urea, and urate (n = 382). Urinary markers (n = 199) included urinary N-acetyl-beta-D-glucosaminidase (NAG), retinol binding protein, intestinal alkaline phosphatase, tissue non-specific alkaline phosphatase, Tamm-Horsfall glycoprotein, epidermal growth factor, and microalbuminuria. RESULTS: Mean current blood Pb was 53.5 micrograms/dl (range 23 to 110), median zinc protoporphyrin 10.9 micrograms/g haemoglobin (range 1.9 to 104), and mean exposure duration 11.6 years (range 0.5 to 44.5). Mean historical blood Pb, available on 246 workers, was 57.3 micrograms/dl (range 14 to 96.3). After adjustment for age, weight and height, positive exposure response relations were found between current blood Pb, historical blood Pb, zinc protoporphyrin (ZPP), and serum creatinine and urate. Blood pressure was not associated with Pb exposure. Among the urinary markers, only NAG showed a positive association with current and historical blood Pb. CONCLUSION: An exposure-response relation between Pb and renal dysfunction across the range from < 40 to > 70 micrograms/dl blood Pb was found in this workforce, with conventional measures of short and long term Pb exposure and of renal function. This could not be explained by an effect on blood pressure, which was not associated with Pb exposure. The findings probably reflect a higher cumulative renal burden of Pb absorption in this workforce in comparison with those in recent negative studies. The results also confirm the need for strategies to reduce Pb exposure among industrial workers in South Africa.   PMID:9816378

  7. Comparative evaluation of Na(+) uptake in Cyprinodon variegatus variegatus (Lacepede) and Cyprinodon variegatus hubbsi (Carr) (Cyprinodontiformes, Teleostei): Evaluation of NHE function in high and low Na(+) freshwater.

    PubMed

    Brix, Kevin V; Esbaugh, Andrew J; Mager, Edward M; Grosell, Martin

    2015-07-01

    The euryhaline pupfish, Cyprinodon variegatus variegatus (Cvv), can successfully osmoregulate in ≥2 mM Na(+) and a freshwater population (Cyprinodon variegatus hubbsi; Cvh) osmoregulates at ≥0.1mM Na(+). We previously demonstrated that Cvv relies on an apical NKCC and NHE in the gill for Na(+) uptake in high (7mM) and intermediate (2 mM) Na(+) concentrations, while Cvh relies only on NHE for Na(+) uptake. This study investigated whether differential NHE isoform use explains differences in Na(+) uptake kinetics between these two populations. We further studied whether Cvh uses a NHE-Rh metabolon or carbonic anhydrase (CA) to overcome thermodynamic challenges of NHE function in dilute freshwater. Transfer to more dilute freshwater resulted in upregulation of nhe-2 (Cvv only) and nhe-3 (Cvv and Cvh). Relative expression of nhe-3 compared to nhe-2 was 2-fold higher in Cvv, but 200-fold higher in Cvh suggesting that nhe-3 expression is an important freshwater adaptation for Cvh. Simultaneous measurement of Na(+) and Tamm flux under various conditions provided no support for a NHE-Rh metabolon in either population. Carbonic anhydrase activity in Cvv was comparable in 7 and 2 mM Na(+) acclimated fish. In Cvh, CA activity increased by 75% in 0.1 mM Na(+) acclimated fish compared to 7 mM Na(+) fish. Ethoxzolamide had variable effects, stimulating and reducing Na(+) uptake in Cvv acclimated to 7 and 2 mM Na(+), while reducing Na(+) uptake in 7 and 0.1mM Na(+) acclimated Cvh. This suggests that CA plays important, but different roles in regulating Na(+) uptake in Cvv and Cvh.

  8. Differential expression of claudin tight junction proteins in the human cortical nephron

    PubMed Central

    Kirk, Adam; Campbell, Sara; Bass, Paul; Mason, Juan; Collins, Jane

    2010-01-01

    Background. In renal tubules, paracellular permeability is tightly controlled to facilitate solute absorption and urinary concentration and is regulated by tight junctions, which incorporate claudin proteins. There is very limited information confirming the localization of these proteins in the human renal cortex. Most data is inferred from mouse, bovine and rabbit studies and differences exist between mouse and other species. Methods. A survey of claudin staining was performed on human kidney cortex embedded in glycolmethacrylate resin to enhance tissue morphology and facilitate the cutting of 2 µm serial sections. Results. Claudin-2, -10 and -11 antibodies labelled renal tubular epithelial cells, correlating with Lotus tetragonolobus and N-cadherin positive proximal tubules. Claudin-3, -10, -11 and -16 antibodies strongly stained a population of tubules that were positive for Tamm Horsfall protein on adjacent sections, confirming expression in the thick ascending limb of the Loop of Henle. Claudin-3, -4 and -8 antibodies reacted with tubules that correlated with the distal nephron markers, E-cadherin, epithelial membrane antigen and Dolichos biflorus and claudin-3, -4, -7 and -8 with the distal tubule marker, calbindin, and the collecting duct marker, aquaporin-2. Claudin-14 was localized in distal convoluted tubules, correlating positively with calbindin but negatively with aquaporin-2, whereas claudin-1 staining was identified in the parietal epithelium of Bowman's capsule, distal convoluted tubule and collecting duct. Cellular and tight junction localization of claudin staining in renal tubules was heterogeneous and is discussed. Conclusions. Complex variation in the expression of human claudins likely determines paracellular permeability in the kidney. Altered claudin expression may influence pathologies involving abnormalities of absorption. PMID:20124215

  9. Coherent phenomena in terahertz 2D plasmonic structures: strong coupling, plasmonic crystals, and induced transparency by coupling of localized modes

    NASA Astrophysics Data System (ADS)

    Dyer, Gregory C.; Aizin, Gregory R.; Allen, S. James; Grine, Albert D.; Bethke, Don; Reno, John L.; Shaner, Eric A.

    2014-05-01

    The device applications of plasmonic systems such as graphene and two dimensional electron gases (2DEGs) in III-V heterostructures include terahertz detectors, mixers, oscillators and modulators. These two dimensional (2D) plasmonic systems are not only well-suited for device integration, but also enable the broad tunability of underdamped plasma excitations via an applied electric field. We present demonstrations of the coherent coupling of multiple voltage tuned GaAs/AlGaAs 2D plasmonic resonators under terahertz irradiation. By utilizing a plasmonic homodyne mixing mechanism to downconvert the near field of plasma waves to a DC signal, we directly detect the spectrum of coupled plasmonic micro-resonator structures at cryogenic temperatures. The 2DEG in the studied devices can be interpreted as a plasmonic waveguide where multiple gate terminals control the 2DEG kinetic inductance. When the gate tuning of the 2DEG is spatially periodic, a one-dimensional finite plasmonic crystal forms. This results in a subwavelength structure, much like a metamaterial element, that nonetheless Bragg scatters plasma waves from a repeated crystal unit cell. A 50% in situ tuning of the plasmonic crystal band edges is observed. By introducing gate-controlled defects or simply terminating the lattice, localized states arise in the plasmonic crystal. Inherent asymmetries at the finite crystal boundaries produce an induced transparency-like phenomenon due to the coupling of defect modes and crystal surface states known as Tamm states. The demonstrated active control of coupled plasmonic resonators opens previously unexplored avenues for sensitive direct and heterodyne THz detection, planar metamaterials, and slow-light devices.

  10. Regulation of macromolecular modulators of urinary stone formation by reactive oxygen species: transcriptional study in an animal model of hyperoxaluria.

    PubMed

    Khan, Saeed R; Joshi, Sunil; Wang, Wei; Peck, Ammon B

    2014-06-01

    We used an unbiased approach of gene expression profiling to determine differential gene expression of all the macromolecular modulators (MMs) considered to be involved in stone formation, in hyperoxaluric rats, with and without treatment with the NADPH oxidase inhibitor apocynin. Male rats were fed rat chow or chow supplemented with 5% wt/wt hydroxy-l-proline (HLP) with or without apocynin-supplemented water. After 28 days, rats were euthanized and their kidneys explanted. Total RNA was isolated and microarray analysis was conducted using the Illumina bead array reader. Gene ontology analysis and the pathway analyses of the genes were done using Database for Annotation, Visualization of Integrated Discovery enrichment analysis tool. Quantitative RT-PCR of selected genes was carried out to verify the microarray results. Expression of selected gene products was confirmed using immunohistochemistry. Administration of HLP led to crystal deposition. Genes encoding for fibronectin, CD 44, fetuin B, osteopontin, and matrix-gla protein were upregulated while those encoding for heavy chains of inter-alpha-inhibitor 1, 3, and 4, calgranulin B, prothrombin, and Tamm-Horsfall protein were downregulated. HLP-fed rats receiving apocynin had a significant reversal in gene expression profiles: those that were upregulated came down while those that were downregulated stepped up. Apocynin treatment resulted in near complete absence of crystals. Clearly, there are two types of MMs; one is downregulated while the other is upregulated during hyperoxaluria and crystal deposition. Apparently gene and protein expressions of known macromolecular modulators of CaOx crystallization are likely regulated by ROS produced in part through the activation of NADPH oxidase.

  11. Self-consistent quasiparticle formulation of a multiphonon method and its application to the neutron-rich O20 nucleus

    NASA Astrophysics Data System (ADS)

    De Gregorio, G.; Knapp, F.; Lo Iudice, N.; Vesely, P.

    2016-04-01

    A Bogoliubov quasiparticle formulation of an equation-of-motion phonon method, suited for open-shell nuclei, is derived. Like its particle-hole version, it consists of deriving a set of equations of motions whose iterative solution generates an orthonormal basis of n -phonon states (n =0 ,1 ,2 ,... ), built of quasiparticle Tamm-Dancoff phonons, which simplifies the solution of the eigenvalue problem. The method is applied to the open-shell neutron-rich O20 for illustrative purposes. A Hartree-Fock-Bogoliubov canonical basis, derived from an intrinsic two-body optimized chiral Hamiltonian, is used to derive and solve the eigenvalue equations in a space encompassing a truncated two-phonon basis. The spurious admixtures induced by the violation of the particle number and the center-of-mass motion are eliminated to a large extent by a Gram-Schmidt orthogonalization procedure. The calculation takes into account the Pauli principle, is self-consistent, and is parameter free except for the energy cutoff used to truncate the two-phonon basis, which induces an increasing depression of the ground state through its strong coupling to the quasiparticle vacuum. Such a cutoff is fixed so as to reproduce the first 1- level. The two-phonon states are shown to enhance the level density of the low-energy spectrum, consistently with the data, and to induce a fragmentation of the E 1 strength which, while accounting for the very low E 1 transitions, is not sufficient to reproduce the experimental cross section in the intermediate energy region. This and other discrepancies suggest the need of including the three-phonon states. These are also expected to offset the action of the two phonons on the quasiparticle vacuum and, therefore, free the calculation from any parameter.

  12. Isolation of urinary exosomes for RNA biomarker discovery using a simple, fast, and highly scalable method.

    PubMed

    Alvarez, M Lucrecia

    2014-01-01

    Urinary exosomes are nanovesicles (40-100 nm) of endocytic origin that are secreted into the urine when a multivesicular body fuses with the membrane of cells from all nephron segments. Interest in urinary exosomes intensified after the discovery that they contain not only protein and mRNA but also microRNA (miRNA) markers of renal dysfunction and structural injury. Currently, the most widely used protocol for the isolation of urinary exosomes is based on ultracentrifugation, a method that is time consuming, requires expensive equipment, and has low scalability, which limits its applicability in the clinical practice. In this chapter, a simple, fast, and highly scalable step-by-step method for isolation of urinary exosomes is described. This method starts with a 10-min centrifugation of 10 ml urine, then the supernatant is saved (SN1), and the pellet is treated with dithiothreitol and heat to release and recover those exosomes entrapped by polymeric Tamm-Horsfall protein. The treated pellet is then resuspended and centrifuged, and the supernatant obtained (SN2) is combined with the first supernatant, SN1. Next, 3.3 ml of ExoQuick-TC, a commercial exosome precipitation reagent, is added to the total supernatant (SN1 + SN2), mixed well, and saved for at least 12 h at 4 °C. Finally, a pellet of exosomes is obtained after a 30-min centrifugation of the supernatant/ExoQuick-TC mix. We previously compared this method with five others used to isolate urinary exosomes and found that this is the simplest, fastest, and most effective alternative to ultracentrifugation-based protocols if the goal of the study is RNA profiling. A method for isolation and quantification of miRNAs and mRNAs from urinary exosomes is also described here. In addition, we provide a step-by-step description of exosomal miRNA profiling using universal reverse transcription and SYBR qPCR.

  13. Soil microstructure and factors of its formation

    NASA Astrophysics Data System (ADS)

    Alekseeva, T. V.

    2007-06-01

    The microstructural stability of soils of different geneses (steppe soils, tropical soils, and subtropical soils) developed from marine clay, loess, and weathering crusts was studied by the method of successive treatments with chemical reagents destroying the particular clay-aggregating components. The following dispersing agents were used: (1) H2O (pH 5.5), (2) 0.1 N NaCl (pH 6), (3) 0.002% Na2CO3 (pH 8.7), (4) 0.1 N NaOH (pH 11.5), (5) the Tamm reagent (pH 3.2), and (6) 0.1 N NaOH (pH 11.5). The properties of the clay subfractions obtained in the course of these treatments were studied by a set of analytical methods, including X-ray diffractometry, Mössbauer spectroscopy, and magnetic measurements. It was shown that soil microaggregates are formed under the impact of a number of physicochemical processes; the content and properties of inorganic components (clay minerals in soils with a high CEC and iron oxides in soils with a low CEC) are the controlling factors. The structure of the parent materials is transformed to different degrees to form the soil structure. For example, autonomous nondifferentiated soils inherit, to some extent, the specific microorganization of the parent material. At the same time, the redistribution of substances in the soil profile and in the landscape may exert a substantial influence on the soil structure and microstructure. This is particularly true for autonomous differentiated soils, turbated soils, accumulative soils, polylithogenic soils, and polygenetic soils. The properties of the obtained subfractions of the clay (the mineralogical composition, the Fe2+/(Fe2+ + Fe3+) ratio, the magnetic susceptibility, and the Cha/Cfa ratio) attest to the spatial heterogeneity of the composition and properties of the mineral and organic aggregated compounds in soils.

  14. Multiresolution quantum chemistry in multiwavelet bases: excited states from time-dependent Hartree-Fock and density functional theory via linear response.

    PubMed

    Yanai, Takeshi; Fann, George I; Beylkin, Gregory; Harrison, Robert J

    2015-12-21

    A fully numerical method for the time-dependent Hartree-Fock and density functional theory (TD-HF/DFT) with the Tamm-Dancoff (TD) approximation is presented in a multiresolution analysis (MRA) approach. From a reformulation with effective use of the density matrix operator, we obtain a general form of the HF/DFT linear response equation in the first quantization formalism. It can be readily rewritten as an integral equation with the bound-state Helmholtz (BSH) kernel for the Green's function. The MRA implementation of the resultant equation permits excited state calculations without virtual orbitals. The integral equation is efficiently and adaptively solved using a numerical multiresolution solver with multiwavelet bases. Our implementation of the TD-HF/DFT methods is applied for calculating the excitation energies of H2, Be, N2, H2O, and C2H4 molecules. The numerical errors of the calculated excitation energies converge in proportion to the residuals of the equation in the molecular orbitals and response functions. The energies of the excited states at a variety of length scales ranging from short-range valence excitations to long-range Rydberg-type ones are consistently accurate. It is shown that the multiresolution calculations yield the correct exponential asymptotic tails for the response functions, whereas those computed with Gaussian basis functions are too diffuse or decay too rapidly. We introduce a simple asymptotic correction to the local spin-density approximation (LSDA) so that in the TDDFT calculations, the excited states are correctly bound.

  15. Recent Progress in GW-based Methods for Excited-State Calculations of Reduced Dimensional Systems

    NASA Astrophysics Data System (ADS)

    da Jornada, Felipe H.

    2015-03-01

    Ab initio calculations of excited-state phenomena within the GW and GW-Bethe-Salpeter equation (GW-BSE) approaches allow one to accurately study the electronic and optical properties of various materials, including systems with reduced dimensionality. However, several challenges arise when dealing with complicated nanostructures where the electronic screening is strongly spatially and directionally dependent. In this talk, we discuss some recent developments to address these issues. First, we turn to the slow convergence of quasiparticle energies and exciton binding energies with respect to k-point sampling. This is very effectively dealt with using a new hybrid sampling scheme, which results in savings of several orders of magnitude in computation time. A new ab initio method is also developed to incorporate substrate screening into GW and GW-BSE calculations. These two methods have been applied to mono- and few-layer MoSe2, and yielded strong environmental dependent behaviors in good agreement with experiment. Other issues that arise in confined systems and materials with reduced dimensionality, such as the effect of the Tamm-Dancoff approximation to GW-BSE, and the calculation of non-radiative exciton lifetime, are also addressed. These developments have been efficiently implemented and successfully applied to real systems in an ab initio framework using the BerkeleyGW package. I would like to acknowledge collaborations with Diana Y. Qiu, Steven G. Louie, Meiyue Shao, Chao Yang, and the experimental groups of M. Crommie and F. Wang. This work was supported by Department of Energy under Contract No. DE-AC02-05CH11231 and by National Science Foundation under Grant No. DMR10-1006184.

  16. Excited states with internally contracted multireference coupled-cluster linear response theory

    NASA Astrophysics Data System (ADS)

    Samanta, Pradipta Kumar; Mukherjee, Debashis; Hanauer, Matthias; Köhn, Andreas

    2014-04-01

    In this paper, the linear response (LR) theory for the variant of internally contracted multireference coupled cluster (ic-MRCC) theory described by Hanauer and Köhn [J. Chem. Phys. 134, 204211 (2011)] has been formulated and implemented for the computation of the excitation energies relative to a ground state of pronounced multireference character. We find that straightforward application of the linear-response formalism to the time-averaged ic-MRCC Lagrangian leads to unphysical second-order poles. However, the coupling matrix elements that cause this behavior are shown to be negligible whenever the internally contracted approximation as such is justified. Hence, for the numerical implementation of the method, we adopt a Tamm-Dancoff-type approximation and neglect these couplings. This approximation is also consistent with an equation-of-motion based derivation, which neglects these couplings right from the start. We have implemented the linear-response approach in the ic-MRCC singles-and-doubles framework and applied our method to calculate excitation energies for a number of molecules ranging from CH2 to p-benzyne and conjugated polyenes (up to octatetraene). The computed excitation energies are found to be very accurate, even for the notoriously difficult case of doubly excited states. The ic-MRCC-LR theory is also applicable to systems with open-shell ground-state wavefunctions and is by construction not biased towards a particular reference determinant. We have also compared the linear-response approach to the computation of energy differences by direct state-specific ic-MRCC calculations. We finally compare to Mk-MRCC-LR theory for which spurious roots have been reported [T.-C. Jagau and J. Gauss, J. Chem. Phys. 137, 044116 (2012)], being due to the use of sufficiency conditions to solve the Mk-MRCC equations. No such problem is present in ic-MRCC-LR theory.

  17. Double excitations and state-to-state transition dipoles in π-π∗ excited singlet states of linear polyenes: Time-dependent density-functional theory versus multiconfigurational methods

    NASA Astrophysics Data System (ADS)

    Mikhailov, Ivan A.; Tafur, Sergio; Masunov, Artëm E.

    2008-01-01

    The effect of static and dynamic electron correlation on the nature of excited states and state-to-state transition dipole moments is studied with a multideterminant wave function approach on the example of all-trans linear polyenes ( C4H6 , C6H8 , and C8H10 ). Symmetry-forbidden singlet nAg states were found to separate into three groups: purely single, mostly single, and mostly double excitations. The excited-state absorption spectrum is dominated by two bright transitions: 1Bu-2Ag and 1Bu-mAg , where mAg is the state, corresponding to two-electron excitation from the highest occupied to lowest unoccupied molecular orbital. The richness of the excited-state absorption spectra and strong mixing of the doubly excited determinants into lower- nAg states, reported previously at the complete active space self-consistent field level of theory, were found to be an artifact of the smaller active space, limited to π orbitals. When dynamic σ-π correlation is taken into account, single- and double-excited states become relatively well separated at least at the equilibrium geometry of the ground state. This electronic structure is closely reproduced within time-dependent density-functional theory (TD DFT), where double excitations appear in a second-order coupled electronic oscillator formalism and do not mix with the single excitations obtained within the linear response. An extension of TD DFT is proposed, where the Tamm-Dancoff approximation (TDA) is invoked after the linear response equations are solved (a posteriori TDA). The numerical performance of this extension is validated against multideterminant-wave-function and quadratic-response TD DFT results. It is recommended for use with a sum-over-states approach to predict the nonlinear optical properties of conjugated molecules.

  18. Interactive chemistry of coal-petroleum processing: Quarterly progress report for March 15, 1987-June 15, 1987. [Effect of coal or resid on reaction

    SciTech Connect

    Curtis, C.W.; Guin, J.A.; Tarrer, A.R.

    1987-01-01

    The thermal reactions of model compounds NAPH, DMC, PN, BZT, and QN with Maya TLR (topped long resid) showed no reactions. The presence of Maya TLR blocked the intermediate hydrogenation pathway from QN to THQ compared to the reaction without Maya TLR where 13% THQ was formed. Maya TLR served as a strong inhibitor in the catalytic hydrogenations of model compounds, being more detrimental to the hydrogenation and heteroatom removal reactions than coal. The severe inhibition of Maya TLR is caused by the chemical composition of the resid. The resid contains large refractory hydrocarbon species and substantial amounts of metals. Maya TLR was most likely deactivating the NiMo/Al/sub 2/O/sub 3/ catalyst as well as possibly interacting with model species present. Catalyst deactivation due to pore-plugging by petroleum crude and residua reaction products from hydrotreating, i.e., metal sulfides and coke has been studied by Newson. In crude oils and residua, vanadium and nickel compounds are the most abundant organometallic constituents and cause major problems in hydrotreating of residuum oils. At hydroprocessing conditions, these metal compounds deposit on and deactivate the catalyst. Pore mouth plugging in the catalyst by the metal deposit has been known as the major cause in the catalyst deactivation. Tamm and co-workers studied two mechanisms of catalyst deactivation by petroleum feed metals: (1) poisoning of the active surface and (2) physical obstruction of the pore structure. Thus, two possible reasons for the severe deactivation observed in the Maya TLR are metal deposition and carbon laydown on the catalyst surface. Another reason why the Maya TLR had a stronger inhibiting effect than coal is that these reactions are at 350/sup 0/C, where the coal was only partially dissolved; therefore, all the bad actors from coal were not available in the system, while those from the resid were. 3 refs., 4 figs., 36 tabs.

  19. Involvement of urinary proteins in the rat strain difference in sensitivity to ethylene glycol-induced renal toxicity.

    PubMed

    Li, Yan; McLaren, Marie C; McMartin, Kenneth E

    2010-09-01

    Ethylene glycol (EG) exposure is a common model for kidney stones, because animals accumulate calcium oxalate monohydrate (COM) in kidneys. Wistar rats are more sensitive to EG than Fischer 344 (F344) rats, with greater COM deposition in kidneys. The mechanisms by which COM accumulates differently among strains are poorly understood. Urinary proteins inhibit COM adhesion to renal cells, which could alter COM deposition in kidneys. We hypothesize that COM accumulates more in Wistar rat kidneys because of lower levels of inhibitory proteins in urine. Wistar and F344 rats were treated with 0.75% EG in drinking water for 8 wk. Twenty-four-hour urine was collected every 2 wk for analysis of urinary proteins. Similar studies were conducted for 2 wk using 2% hydroxyproline (HP) as an alternative oxalate source. Total urinary protein was higher in F344 than Wistar rats at all times. Tamm-Horsfall protein was not different between strains. Osteopontin (OPN) levels in Wistar urine and kidney tissue were higher and were further increased by EG treatment. This increase in OPN occurred before renal COM accumulation. Untreated F344 rats showed greater CD45 and ED-1 staining in kidneys than untreated Wistars; in contrast, EG treatment increased CD45 and ED-1 staining in Wistars more than in F344 rats, indicating macrophage infiltration. This increase occurred in parallel with the increase in OPN and before COM accumulation. Like EG, HP induced markedly greater oxalate concentrations in the plasma and urine of Wistar rats compared with F344 rats. These results suggest that OPN upregulation and macrophage infiltration do not completely protect against COM accumulation and may be a response to crystal retention. Because the two oxalate precursors, EG and HP, produced similar elevations of oxalate, the strain difference in COM accumulation may result more so from metabolic differences between strains than from differences in urinary proteins or inflammatory responses.

  20. High Sodium-Induced Oxidative Stress and Poor Anticrystallization Defense Aggravate Calcium Oxalate Crystal Formation in Rat Hyperoxaluric Kidneys.

    PubMed

    Huang, Ho-Shiang; Ma, Ming-Chieh

    2015-01-01

    Enhanced sodium excretion is associated with intrarenal oxidative stress. The present study evaluated whether oxidative stress caused by high sodium (HS) may be involved in calcium oxalate crystal formation. Male rats were fed a sodium-depleted diet. Normal-sodium and HS diets were achieved by providing drinking water containing 0.3% and 3% NaCl, respectively. Rats were fed a sodium-depleted diet with 5% hydroxyl-L-proline (HP) for 7 and 42 days to induce hyperoxaluria and/or calcium oxalate deposition. Compared to normal sodium, HS slightly increased calcium excretion despite diuresis; however, the result did not reach statistical significance. HS did not affect the hyperoxaluria, hypocalciuria or supersaturation caused by HP; however, it increased calcium oxalate crystal deposition soon after 7 days of co-treatment. Massive calcium oxalate formation and calcium crystal excretion in HS+HP rats were seen after 42 days of treatment. HP-mediated hypocitraturia was further exacerbated by HS. Moreover, HS aggravated HP-induced renal injury and tubular damage via increased apoptosis and oxidative stress. Increased urinary malondialdehyde excretion, in situ superoxide production, NAD(P)H oxidase and xanthine oxidase expression and activity, and decreased antioxidant enzyme expression or activity in the HS+HP kidney indicated exaggerated oxidative stress. Interestingly, this redox imbalance was associated with reduced renal osteopontin and Tamm-Horsfall protein expression (via increased excretion) and sodium-dependent dicarboxylate cotransporter NaDC-1 upregulation. Collectively, our results demonstrate that a HS diet induces massive crystal formation in the hyperoxaluric kidney; this is not due to increased urinary calcium excretion but is related to oxidative injury and loss of anticrystallization defense.

  1. Perturbation theory in light-cone quantization

    SciTech Connect

    Langnau, A.

    1992-01-01

    A thorough investigation of light-cone properties which are characteristic for higher dimensions is very important. The easiest way of addressing these issues is by analyzing the perturbative structure of light-cone field theories first. Perturbative studies cannot be substituted for an analysis of problems related to a nonperturbative approach. However, in order to lay down groundwork for upcoming nonperturbative studies, it is indispensable to validate the renormalization methods at the perturbative level, i.e., to gain control over the perturbative treatment first. A clear understanding of divergences in perturbation theory, as well as their numerical treatment, is a necessary first step towards formulating such a program. The first objective of this dissertation is to clarify this issue, at least in second and fourth-order in perturbation theory. The work in this dissertation can provide guidance for the choice of counterterms in Discrete Light-Cone Quantization or the Tamm-Dancoff approach. A second objective of this work is the study of light-cone perturbation theory as a competitive tool for conducting perturbative Feynman diagram calculations. Feynman perturbation theory has become the most practical tool for computing cross sections in high energy physics and other physical properties of field theory. Although this standard covariant method has been applied to a great range of problems, computations beyond one-loop corrections are very difficult. Because of the algebraic complexity of the Feynman calculations in higher-order perturbation theory, it is desirable to automatize Feynman diagram calculations so that algebraic manipulation programs can carry out almost the entire calculation. This thesis presents a step in this direction. The technique we are elaborating on here is known as light-cone perturbation theory.

  2. Transition matrices and orbitals from reduced density matrix theory

    SciTech Connect

    Etienne, Thibaud

    2015-06-28

    In this contribution, we report two different methodologies for characterizing the electronic structure reorganization occurring when a chromophore undergoes an electronic transition. For the first method, we start by setting the theoretical background necessary to the reinterpretation through simple tensor analysis of (i) the transition density matrix and (ii) the natural transition orbitals in the scope of reduced density matrix theory. This novel interpretation is made more clear thanks to a short compendium of the one-particle reduced density matrix theory in a Fock space. The formalism is further applied to two different classes of excited states calculation methods, both requiring a single-determinant reference, that express an excited state as a hole-particle mono-excited configurations expansion, to which particle-hole correlation is coupled (time-dependent Hartree-Fock/time-dependent density functional theory) or not (configuration interaction single/Tamm-Dancoff approximation). For the second methodology presented in this paper, we introduce a novel and complementary concept related to electronic transitions with the canonical transition density matrix and the canonical transition orbitals. Their expression actually reflects the electronic cloud polarisation in the orbital space with a decomposition based on the actual contribution of one-particle excitations from occupied canonical orbitals to virtual ones. This approach validates our novel interpretation of the transition density matrix elements in terms of the Euclidean norm of elementary transition vectors in a linear tensor space. A proper use of these new concepts leads to the conclusion that despite the different principles underlying their construction, they provide two equivalent excited states topological analyses. This connexion is evidenced through simple illustrations of (in)organic dyes electronic transitions analysis.

  3. Excited states with internally contracted multireference coupled-cluster linear response theory.

    PubMed

    Samanta, Pradipta Kumar; Mukherjee, Debashis; Hanauer, Matthias; Köhn, Andreas

    2014-04-07

    In this paper, the linear response (LR) theory for the variant of internally contracted multireference coupled cluster (ic-MRCC) theory described by Hanauer and Köhn [J. Chem. Phys. 134, 204211 (2011)] has been formulated and implemented for the computation of the excitation energies relative to a ground state of pronounced multireference character. We find that straightforward application of the linear-response formalism to the time-averaged ic-MRCC Lagrangian leads to unphysical second-order poles. However, the coupling matrix elements that cause this behavior are shown to be negligible whenever the internally contracted approximation as such is justified. Hence, for the numerical implementation of the method, we adopt a Tamm-Dancoff-type approximation and neglect these couplings. This approximation is also consistent with an equation-of-motion based derivation, which neglects these couplings right from the start. We have implemented the linear-response approach in the ic-MRCC singles-and-doubles framework and applied our method to calculate excitation energies for a number of molecules ranging from CH2 to p-benzyne and conjugated polyenes (up to octatetraene). The computed excitation energies are found to be very accurate, even for the notoriously difficult case of doubly excited states. The ic-MRCC-LR theory is also applicable to systems with open-shell ground-state wavefunctions and is by construction not biased towards a particular reference determinant. We have also compared the linear-response approach to the computation of energy differences by direct state-specific ic-MRCC calculations. We finally compare to Mk-MRCC-LR theory for which spurious roots have been reported [T.-C. Jagau and J. Gauss, J. Chem. Phys. 137, 044116 (2012)], being due to the use of sufficiency conditions to solve the Mk-MRCC equations. No such problem is present in ic-MRCC-LR theory.

  4. Internal photoemission from plasmonic nanoparticles: comparison between surface and volume photoelectric effects.

    PubMed

    Uskov, Alexander V; Protsenko, Igor E; Ikhsanov, Renat S; Babicheva, Viktoriia E; Zhukovsky, Sergei V; Lavrinenko, Andrei V; O'Reilly, Eoin P; Xu, Hongxing

    2014-05-07

    We study the emission of photoelectrons from plasmonic nanoparticles into a surrounding matrix. We consider two mechanisms of electron emission from the nanoparticles--surface and volume ones--and use models for these two mechanisms which allow us to obtain analytical results for the photoelectron emission rate from a nanoparticle. Calculations have been carried out for a step potential at the surface of a spherical nanoparticle, and a simple model for the hot electron cooling has been used. We highlight the effect of the discontinuity of the dielectric permittivity at the nanoparticle boundary in the surface mechanism, which leads to a substantial (by ∼5 times) increase of the internal photoelectron emission rate from a nanoparticle compared to the case when such a discontinuity is absent. For a plasmonic nanoparticle, a comparison of the two photoeffect mechanisms was undertaken for the first time which showed that the surface photoeffect can in the general case be larger than the volume one, which agrees with the results obtained for a flat metal surface first formulated by Tamm and Schubin in their pioneering development of a quantum-mechanical theory of photoeffect in 1931. In accordance with our calculations, this possible predominance of the surface effect is based on two factors: (i) effective cooling of hot carriers during their propagation from the volume of the nanoparticle to its surface in the scenario of the volume mechanism and (ii) strengthening of the surface mechanism through the effect of the discontinuity of the dielectric permittivity at the nanoparticle boundary. The latter is stronger at relatively lower photon energies and correspondingly is more substantial for internal photoemission than for an external one. We show that in the general case, it is essential to take both mechanisms into account in the development of devices based on the photoelectric effect and when considering hot electron emission from a plasmonic nanoantenna.

  5. Interstitial Calcinosis in Renal Papillae of Genetically Engineered Mouse Models: Relation to Randall’s Plaques

    PubMed Central

    Wu, Xue-Ru

    2014-01-01

    Genetically engineered mouse models (GEMMs) have been highly instrumental in elucidating gene functions and molecular pathogenesis of human diseases, although their use in studying kidney stone formation or nephrolithiasis remains relatively limited. This review intends to provide an overview of several knockout mouse models that develop interstitial calcinosis in the renal papillae. Included herein are mice deficient for Tamm-Horsfall protein (THP; also named uromodulin), osteopontin (OPN), both THP and OPN, Na+-phosphate cotransporter Type II (Npt2a) and Na+/H+ exchanger regulatory factor (NHERF-1). The baseline information of each protein is summarized, along with key morphological features of the interstitial calcium deposits in mice lacking these proteins. Attempts are made to correlate the papillary interstitial deposits found in GEMMs with Randall’s plaques, the latter considered precursors of idiopathic calcium stones in patients. The pathophysiology that underlies the renal calcinosis in the knockout mice are also discussed wherever information is available. Not all the knockout models are allocated equal space because some are more extensively characterized than others. Despite the inroads already made, the exact physiological underpinning, origin, evolution and fate of the papillary interstitial calcinosis in the GEMMs remain incompletely defined. Greater investigative efforts are warranted in order to pin down the precise role of the papillary interstitial calcinosis in nephrolithiasis using the existing models. Additionally, more sophisticated, second-generation GEMMs that allow gene inactivation in a time-controlled manner and “compound mice” that bear several genetic alterations are urgently needed, in light of mounting evidence that nephrolithiasis is a multifactorial, multi-stage and polygenic disease. PMID:25096800

  6. [Mechanisms of urinary tract sterility maintenance].

    PubMed

    Okrągła, Emilia; Szychowska, Katarzyna; Wolska, Lidia

    2014-06-02

    Physiologically, urine and the urinary tract are maintained sterile because of physical and chemical properties of urine and the innate immune system's action. The urinary tract is constantly exposed to the invasion of microorganisms from the exterior environment, also because of the anatomical placement of the urethra, in the vicinity of the rectum. Particularly vulnerable to urinary tract infections (UTI) are women (an additional risk factor is pregnancy), but also the elderly and children. The main pathogens causing UTI are bacteria; in 70-95% of cases it is the bacterium Escherichia coli. Infections caused by viruses and fungi are less common and are associated with decreased immunity, pharmacotherapy, or some diseases. Bacteria have evolved a number of factors that facilitate the colonization of the urinary tract: the cover and cell membrane antigens O and K1, lipopolysaccharide (LPS), fimbriae, pile and cilia. On the other hand, the human organism has evolved mechanisms to hinder colonization of the urinary tract: mechanisms arising from the anatomical structure of the urinary tract, the physicochemical properties of the urine and the activity of the innate immune system, also known as non-specific, which isolates and destroys pathogens using immunological processes, and the mechanisms for release of antimicrobial substances such as Tamm-Horsfall protein, mucopolysaccharides, immunoglobulins IgA and IgG, lactoferrin, lipocalin, neutrophils, cytokines and antimicrobial peptides. This review aims to analyze the state of knowledge on the mechanisms to maintain the sterility of the urinary tract used by the human organism and bacterial virulence factors to facilitate the colonization of the urinary tract.

  7. Characterization of renal biomarkers for use in clinical trials: biomarker evaluation in healthy volunteers

    PubMed Central

    Brott, David A; Adler, Scott H; Arani, Ramin; Lovick, Susan C; Pinches, Mark; Furlong, Stephen T

    2014-01-01

    Background Several preclinical urinary biomarkers have been qualified and accepted by the health authorities (US Food and Drug Administration, European Medicines Agency, and Pharmaceuticals and Medical Devices Agency) for detecting drug-induced kidney injury during preclinical toxicologic testing. Validated human assays for many of these biomarkers have become commercially available, and this study was designed to characterize some of the novel clinical renal biomarkers. The objective of this study was to evaluate clinical renal biomarkers in a typical Phase I healthy volunteer population to determine confidence intervals (pilot reference intervals), intersubject and intrasubject variability, effects of food intake, effect of sex, and vendor assay comparisons. Methods Spot urine samples from 20 male and 19 female healthy volunteers collected on multiple days were analyzed using single analyte and multiplex assays. The following analytes were measured: α-1-microglobulin, β-2-microglobulin, calbindin, clusterin, connective tissue growth factor, creatinine, cystatin C, glutathione S-transferase-α, kidney injury marker-1, microalbumin, N-acetyl-β-(D) glucosaminidase, neutrophil gelatinase-associated lipocalin, osteopontin, Tamm-Horsfall urinary glycoprotein, tissue inhibitor of metalloproteinase 1, trefoil factor 3, and vascular endothelial growth factor. Results Confidence intervals were determined from the single analyte and multiplex assays. Intersubject and intrasubject variability ranged from 38% to 299% and from 29% to 82% for biomarker concentration, and from 24% to 331% and from 10% to 67% for biomarker concentration normalized to creatinine, respectively. There was no major effect of food intake or sex. Single analyte and multiplex assays correlated with r2≥0.700 for five of six biomarkers when evaluating biomarker concentration, but for only two biomarkers when evaluating concentration normalized to creatinine. Conclusion Confidence intervals as well as

  8. Threshold reduction by multidimensional photonic confinement in metal-organic microcavities

    NASA Astrophysics Data System (ADS)

    Mischok, Andreas; Brückner, Robert; Reinhardt, Christoph; Sudzius, Markas; Lyssenko, Vadim G.; Fröb, Hartmut; Leo, Karl

    2014-05-01

    Due to their geometry, optical microcavities allow strong confinement of light between the mirrors and promise single mode operation at lowest possible lasing thresholds. Nevertheless, such devices suffer from losses not only due to parasitic absorption of the active or mirror layers, but especially via outcoupling of leaky and waveguided modes within the active layer. In this work, we present an organic microcavity sandwiched between high quality dielectric distributed Bragg reflectors. A highly conductive silver layer of 40nm thickness is added next to the active layer, leading to the formation of Tamm-Plasmon-Polaritons (TPP), one replacing the original cavity mode and shifting its resonance to the red, another one emerging from the long-wavelength sideband and moving to the blue. To avoid parasitic absorption introduced by such contacts, the silver layer is structured on the micrometer-scale using photolithography, yielding separated areas supporting either original cavity mode or red shifted TPP-resonances. This separation leads to a strong spatial trapping of the modes to only their resonant regions on the sample and can in turn be exploited to achieve complete three-dimensional confinement of photons. In elliptic holes produced in the metal layer, we observe the formation of Mathieu-Modes, leading to a reduction of the lasing threshold by six times. Facilitating triangular cuts in the silver layer, highly confined standing modes develop in the system, allowing a precise optimization of the spatial mode extension and reducing the threshold even further down to one order of magnitude below the threshold of an unstructured organic cavity. These results show that the introduction of absorptive metals, needed for the realization of an electrically driven laser, can in turn be harnessed to improve the characteristics of the device.

  9. DFT-based methods in the design of two-photon operated molecular switches.

    PubMed

    Mikhailov, Ivan A; Belfield, Kevin D; Masunov, Artëm E

    2009-06-25

    Conjugated organic molecules with photochromic properties are being extensively studied as prospective optical switching and data storage materials. Among different photochromic compounds, diarylethenes demonstrate thermal stability, fatigue resistance, and high quantum yield. The mechanism of photoswitching in diarylethenes involves a symmetry-allowed conrotatory electrocyclic reaction, initiated by UV light. Replacement of one UV photon with two near-IR ones would offer a number of practical advantages, including drastic increase in storage capacity via three-dimensional multilayer design. For this purpose we designed a prototype molecule with a two-photon absorbing (2PA) pendant substituent, attached to the photochromic diarylethene moiety. However, this molecule was experimentally shown to have lost the photoswitching properties. We analyze reasons for this loss using quantum chemistry tools. Analysis of the nodal structure of the frontier Kohn-Sham orbitals, allowed us to trace the route of the problem to the lone pair orbital of the 2PA substituent falling within the HOMO-LUMO (highest occupied molecular orbital-lowest unoccupied molecular orbital) gap of the photoreactive diarylethene moiety. We suggest a chemical modification of the 2PA substituent in order to restore the order of the orbitals. Potential energy plots along the reaction coordinate at the M05-2X/6-31G* theory level for the prototype 2PA photochromic molecule before and after the modification confirm the predictive capability of the proposed orbital approach. The Slater transition state method was used to obtain geometries along the reaction pathway by the constrained optimization of excited states, whereas potential energy curves were plotted using the recently proposed (Mikhailov, I. A.; Tafur, S.; Masunov, A. E. Phys. Rev. A 2008, 77 (1), 012510) a posteriori Tamm-Dancoff approximation to the time-dependent density functional theory in second order of the external field. We show that this

  10. The instructive role of metanephric mesenchyme in ureteric bud patterning, sculpting, and maturation and its potential ability to buffer ureteric bud branching defects.

    PubMed

    Shah, Mita M; Tee, James B; Meyer, Tobias; Meyer-Schwesinger, Catherine; Choi, Yohan; Sweeney, Derina E; Gallegos, Thomas F; Johkura, Kohei; Rosines, Eran; Kouznetsova, Valentina; Rose, David W; Bush, Kevin T; Sakurai, Hiroyuki; Nigam, Sanjay K

    2009-11-01

    Kidney organogenesis depends on reciprocal interactions between the ureteric bud (UB) and the metanephric mesenchyme (MM) to form the UB-derived collecting system and MM-derived nephron. With the advent of in vitro systems, it is clear that UB branching can occur independently of MM contact; however, little has been done to detail the role of MM cellular contact in this process. Here, a model system in which the cultured isolated UB is recombined with uninduced MM is used to isolate the effects of the MM progenitor tissue on the development and maturation of the collecting system. By morphometrics, we demonstrate that cellular contact with the MM is required for vectorial elongation of stalks and tapering of luminal caliber of UB-derived tubules. Expression analysis of developmentally significant genes indicates the cocultured tissue is most similar to an embryonic day 19 (E19) kidney. The likely major contributor to this is the functional maturation of the collecting duct and proximal nephron segments in the UB-induced MM, as measured by quantitative PCR, of the collecting duct-specific arginine vasopressin receptor and the nephron tubule segment-specific organic anion transporter OAT1, Na-P(i) type 2 cotransporter, and Tamm-Horsfall protein gene expressions. However, expression of aquaporin-2 is upregulated similarly in isolated UB and cocultured tissue, suggesting that some aspects of functional maturation can occur independently of MM cellular contact. In addition to its sculpting effects, the MM normalized a "branchless" UB morphology induced by FGF7 or heregulin in isolated UB culture. The morphological changes induced by the MM were accompanied by a reassignment of GFRalpha1 (a receptor for GDNF) to tips. Such "quality control" by the MM of UB morphology may provide resiliency to the branching program. This may help to explain a number of knockout phenotypes in which branching and/or cystic defects are less impressive than expected. A second hit in the MM

  11. Molecular basis of Escherichia coli colonization of the upper urinary tract in BALB/c mice. Gal-Gal pili immunization prevents Escherichia coli pyelonephritis in the BALB/c mouse model of human pyelonephritis.

    PubMed Central

    O'Hanley, P; Lark, D; Falkow, S; Schoolnik, G

    1985-01-01

    Most human pyelonephritis Escherichia coli isolates express both mannose (MS)- and globoside (Gal-Gal)-binding pili. An ascending E. coli urinary tract infection model was established in the 16-wk-old female BALB/c mouse to compare the pathogenic significance of MS and Gal-Gal pili and their efficacy as vaccines for the prevention of pyelonephritis. The distribution and density of pilus receptor compounds in urogenital tissues and as soluble compounds in urine were determined with antibodies to the synthetic receptor analogues, alpha D-Gal(1----4) beta D-Gal and alpha D-Man(1----2) alpha D-Man. Both carbohydrates were detected in vagina, bladder, ureter, and renal pelvis epithelium and in collecting duct and tubular cells. A pilus receptor compound also was detected in urine. It competitively inhibited the binding capacity of MS pili and was found to be physically, chemically, and immunologically related to Tamm-Horsfall uromucoid. Infectivity and invasiveness were quantitatively and histologically characterized for four E. coli strains: J96, a human pyelonephritis strain that expresses both MS and Gal-Gal pili; two recombinant strains prepared from J96 chromosomal DNA encoding MS pili or Gal-Gal pili; and the nonpiliated K12 recipient. Intravesicular administration of J96 (10(6) colony-forming units [CFU]) resulted in renal colonization and invasion in each of nine mice. The Gal-Gal clone (10(6) CFU) colonized the kidneys in each of 10 mice but did not invade. In contrast, the MS clone (10(6) CFU) did not colonize renal epithelium or invade. This effect was superceded when larger doses (greater than or equal to 10(10) CFU) of the MS clone were administered in volumes that cause acute vesicoureteric reflux. The efficacy was determined of vaccines composed of pure MS or Gal-Gal pili or the lipopolysaccharide containing O somatic antigen of the challenge strain, J96. The Gal-Gal pilus vaccine blocked renal colonization in 19 of 22 mice and renal invasion in 10 of 11

  12. Testing Noncollinear Spin-Flip, Collinear Spin-Flip, and Conventional Time-Dependent Density Functional Theory for Predicting Electronic Excitation Energies of Closed-Shell Atoms.

    PubMed

    Xu, Xuefei; Yang, Ke R; Truhlar, Donald G

    2014-05-13

    Conventional time-dependent density functional theory (TDDFT) is based on a closed-shell Kohn-Sham (KS) singlet ground state with the adiabatic approximation, using either linear response (KS-LR) or the Tamm-Dancoff approximation (KS-TDA); these methods can only directly predict singly excited states. This deficiency can be overcome by using a triplet state as the reference in the KS-TDA approximation and "exciting" the singlet by a spin flip (SF) from the triplet; this is the method suggested by Krylov and co-workers, and we abbreviate this procedure as SF-KS-TDA. SF-KS-TDA can be applied either with the original collinear kernel of Krylov and co-workers or with a noncollinear kernel, as suggested by Wang and Ziegler. The SF-KS-TDA method does bring some new practical difficulties into play, but it can at least formally model doubly excited states and states with double-excitation character, so it might be more useful than conventional TDDFT (both KS-LR and KS-TDA) for photochemistry if these additional difficulties can be surmounted and if it is accurate with existing approximate exchange-correlation functionals. In the present work, we carried out calculations specifically designed to understand better the accuracy and limitations of the conventional TDDFT and SF-KS-TDA methods; we did this by studying closed-shell atoms and closed-shell monatomic cations because they provide a simple but challenging testing ground for what we might expect in studying the photochemistry of molecules with closed-shell ground states. To test their accuracy, we applied conventional KS-LR and KS-TDA and 18 versions of SF-KS-TDA (nine collinear and nine noncollinear) to the same set of vertical excitation energies (including both Rydberg and valence excitations) of Be, B(+), Ne, Na(+), Mg, and Al(+). We did this for 10 exchange-correlation functionals of various types, both local and nonlocal. We found that the GVWN5 and M06 functionals with nonlocal kernels in spin-flip calculations

  13. The electronic states of 1,2,5-oxadiazole studied by VUV absorption spectroscopy and CI, CCSD(T) and DFT methods

    NASA Astrophysics Data System (ADS)

    Palmer, Michael H.

    2009-06-01

    The 1,2,5-oxadiazole VUV absorption spectrum in the range 5-11.5 eV, shows broad bands centred near 6.2, 7.1, 8.3, 8.8, 10.6 and 11.3 eV. Rydberg states associated with three ionisation energies (IE) were identified in the complex fine structure above 8.7 eV. Electronic vertical excitation energies for singlet and triplet valence, and Rydberg states were computed using ab initio multi-reference multi-root CI methods. There is generally a good correlation between the envelope of the theoretical intensities and the experimental spectrum. The nature of the more intense calculated Rydberg states, and positions of the main valence and Rydberg bands are discussed. The lowest triplet, singlet and Rydberg 3s excited states have equilibrium structures that are non-planar with CS symmetry, in a chair-like orientation where the O and H atoms lie out of the NCCN plane. This finding is consistent with the doubling of the low energy UV spectral lines [B.J. Forrest, A.W. Richardson, Can. J. Chem., 50 (1972) 2088]. The nearly degenerate IE of the UV-photoelectron spectrum (UV-PES, Palmer et al. 1977) makes analysis of the VUV spectrum difficult, leading to the necessity for reinvestigation. Vertical studies (IEV) using CI, Tamm-Dancoff (TDA) and Green's Function (GF) methods all gave similar results, with near degeneracy of the first 3IEV confirming the earlier study. Studies of the adiabatic IE (IEA) using CCSD(T) and B3LYP methods, showed the energy sequence 2A2 < 2B1 < 2B2, but these states are all saddle points, in contrast to the 4th state (2A1) which is a minimum. In contrast, MP2 study of the 2B2 state showed a minimum, with only two saddle points. Complete minima were found after minor twisting of the structures. The lowest energy cationic state is 2A″ (CS), which closely resembles the 2B2 state. The O-N-C-C skeleton is twisted by 8°. The corresponding 2A‧ state (CS) is effectively identical to the 2B1 state. Attempts to find minima for other symmetry states were

  14. Efficient time-dependent density functional theory approximations for hybrid density functionals: Analytical gradients and parallelization

    NASA Astrophysics Data System (ADS)

    Petrenko, Taras; Kossmann, Simone; Neese, Frank

    2011-02-01

    In this paper, we present the implementation of efficient approximations to time-dependent density functional theory (TDDFT) within the Tamm-Dancoff approximation (TDA) for hybrid density functionals. For the calculation of the TDDFT/TDA excitation energies and analytical gradients, we combine the resolution of identity (RI-J) algorithm for the computation of the Coulomb terms and the recently introduced "chain of spheres exchange" (COSX) algorithm for the calculation of the exchange terms. It is shown that for extended basis sets, the RIJCOSX approximation leads to speedups of up to 2 orders of magnitude compared to traditional methods, as demonstrated for hydrocarbon chains. The accuracy of the adiabatic transition energies, excited state structures, and vibrational frequencies is assessed on a set of 27 excited states for 25 molecules with the configuration interaction singles and hybrid TDDFT/TDA methods using various basis sets. Compared to the canonical values, the typical error in transition energies is of the order of 0.01 eV. Similar to the ground-state results, excited state equilibrium geometries differ by less than 0.3 pm in the bond distances and 0.5° in the bond angles from the canonical values. The typical error in the calculated excited state normal coordinate displacements is of the order of 0.01, and relative error in the calculated excited state vibrational frequencies is less than 1%. The errors introduced by the RIJCOSX approximation are, thus, insignificant compared to the errors related to the approximate nature of the TDDFT methods and basis set truncation. For TDDFT/TDA energy and gradient calculations on Ag-TB2-helicate (156 atoms, 2732 basis functions), it is demonstrated that the COSX algorithm parallelizes almost perfectly (speedup ˜26-29 for 30 processors). The exchange-correlation terms also parallelize well (speedup ˜27-29 for 30 processors). The solution of the Z-vector equations shows a speedup of ˜24 on 30 processors. The

  15. Failures of TDDFT in describing the lowest intramolecular charge-transfer excitation in para-nitroaniline

    NASA Astrophysics Data System (ADS)

    Eriksen, Janus J.; Sauer, Stephan P. A.; Mikkelsen, Kurt V.; Christiansen, Ove; Jensen, Hans Jørgen Aa.; Kongsted, Jacob

    2013-07-01

    We investigate the failure of time-dependent density functional theory (TDDFT) with the CAM-B3LYP exchange-correlation (xc) functional coupled to the polarisable embedding (PE) scheme (PE-CAM-B3LYP) in reproducing the solvatochromic shift of the lowest intense charge-transfer excitation in para-nitroaniline (pNA) in water by comparing with results obtained with the coupled cluster singles and doubles (CCSD) model also coupled to the polarisable embedding scheme (PE-CCSD). We determine the amount of charge separation in the ground and excited charge-transfer state with both methods by calculating the electric dipole moments in the gas phase and for 100 solvent configurations. We find that CAM-B3LYP overestimates the amount of charge separation inherent in the ground state and TDDFT/CAM-B3LYP drastically underestimates this amount in the excited charge-transfer state. As the errors in the solvatochromatic shift are found to be inverse proportional to the change in dipole moment upon excitation, we conclude that the flaws in the description of the solvatochromic shift of this excitation are related to TDDFT itself and how it responds to the solvent effects modelled by the PE scheme. We recommend therefore to benchmark results of TDDFT calculations with CAM-B3LYP for intramolecular charge-transfer excitations in molecular systems similar to pNA against higher level ab initio wave function methods, like, e.g. CCSD, prior to their use. Using the calculated change in dipole moment upon excitation as a measure for charge-transfer character, we furthermore confirm that the difference between excitation energies calculated with TDDFT and with the Tamm-Dancoff approximation (TDA) to TDDFT is indeed correlated with the charge-transfer character of a given electronic transition both in vacuo and in solution. This is supported by a corresponding correlation between the change in dipole moment and the size of the Λ index diagnostic for the investigated CT excitation.

  16. The role of macromolecules in the formation of kidney stones.

    PubMed

    Rimer, Jeffrey D; Kolbach-Mandel, Ann M; Ward, Michael D; Wesson, Jeffrey A

    2017-02-01

    The formation of crystal aggregates, one of the critical processes in kidney stone pathogenesis, involves interactions between crystals (predominantly calcium oxalate monohydrate, COM) and urinary constituents (e.g., proteins), which serve as an adhesive "glue" between crystals in stones. To develop a better understanding of the protein-crystal interactions that lead to crystal aggregation, we have measured the effect of model proteins on bulk COM crystal properties as well as their adsorption on crystal surfaces using three synthetic polyanions: poly(aspartic acid) (polyD), poly(glutamic acid) (polyE), and poly(acrylic acid) (polyAA). These anionic macromolecules reduced the amount of COM crystal aggregation in bulk solution to an extent similar to that observed for mixture of proteins from normal urine, with little difference between the polymers. In contrast, the polymers exhibited differences in measures of COM crystal growth. Polycations such as poly(arginine) (polyR) and poly(lysine) (polyK) reduced aggregation weakly and exerted negligible effects on crystal growth. All polyions were found to associate with COM crystal surfaces, as evidenced by changes in the zeta potential of COM crystals in electrophoretic mobility measurements. On the other hand, COM aggregation and possibly growth can be promoted by many binary mixtures of polycations and polyanions, which appeared to be mediated by polymer aggregate formation rather than loss of crystal charge stabilization. Similarly, crystal aggregation promotion behavior can be driven by forming aggregates of weakly charged polyanions, like Tamm-Horsfall protein, suggesting that polymer (protein) aggregation may play a critical role in stone formation. Sensitivity of polyanion-COM crystal surface interactions to the chemical composition of polymer side groups were demonstrated by large differences in crystal aggregation behavior between polyD and polyE, which correlated with atomic force microscopy (AFM) measurements

  17. Low Na intake suppresses expression of CYP2C23 and arachidonic acid-induced inhibition of ENaC.

    PubMed

    Sun, Peng; Lin, Dao-Hong; Wang, Tong; Babilonia, Elisa; Wang, Zhijian; Jin, Yan; Kemp, Rowena; Nasjletti, Alberto; Wang, Wen-Hui

    2006-12-01

    We previously demonstrated that arachidonic acid (AA) inhibits epithelial Na channels (ENaC) through the cytochrome P-450 (CYP) epoxygenase-dependent pathway (34). In the present study, we tested the hypothesis that low Na intake suppresses the expression of CYP2C23, which is mainly responsible for converting AA to epoxyeicosatrienoic acid (EET) in the kidney (11) and attenuates the AA-induced inhibition of ENaC. Immunostaining showed that CYP2C23 is expressed in the Tamm-Horsfall protein (THP)-positive and aquaporin 2 (AQP2)-positive tubules. This suggests that CYP2C23 is expressed in the thick ascending limb (TAL) and collecting duct (CD). Na restriction significantly suppressed the expression of CYP2C23 in the TAL and CD. Western blot also demonstrated that the expression of CYP2C23 in renal cortex and outer medulla diminished in rats on Na-deficient diet (Na-D) but increased in those on high-Na diet (4%). Moreover, the content of 11,12-epoxyeicosatrienoic acid (EET) decreased in the isolated cortical CD from rats on Na-D compared with those on a normal-Na diet (0.5%). Patch-clamp study showed that application of 15 microM AA inhibited the activity of ENaC by 77% in the CCD of rats on a Na-D for 3 days. However, the inhibitory effect of AA on ENaC was significantly attenuated in rats on Na-D for 14 days. Furthermore, inhibition of CYP epoxygenase with MS-PPOH increased the ENaC activity in the CCD of rats on a control Na diet. We also used microperfusion technique to examine the effect of MS-PPOH on Na transport in the distal nephron. Application of MS-PPOH significantly increased Na absorption in the distal nephron of control rats but had no significant effect on Na absorption in rats on Na-D for 14 days. We conclude that low Na intake downregulates the activity and expression of CYP2C23 and attenuates the inhibitory effect of AA on Na transport.

  18. pH-induced conformational changes of membrane-bound influenza hemagglutinin and its effect on target lipid bilayers.

    PubMed Central

    Gray, C.; Tamm, L. K.

    1998-01-01

    Influenza virus hemagglutinin (HA) has served as a paradigm for both pH-dependent and -independent viral membrane fusion. Although large conformational changes were observed by X-ray crystallography when soluble fragments of HA were subjected to fusion-pH conditions, it is not clear whether the same changes occur in membrane-bound HA, what the spatial relationship is between the conformationally changed HA and the target and viral membranes, and in what way HA perturbs the target membrane at low pH. We have taken a spectroscopic approach using an array of recently developed FTIR techniques to address these questions. Difference attenuated total reflection FTIR spectroscopy was employed to reveal reversible and irreversible components of the pH-induced conformational change of the membrane-bound bromelain fragment of HA, BHA. Additional proteolytic fragments of BHA were produced which permitted a tentative assignment of the observed changes to the HA1 and HA2 subunits, respectively. The membrane-bound HA1 subunit undergoes a reversible conformational change, which most likely involves the loss of a small proportion of beta-sheet at low pH. BHA was found to undergo a partially reversible tilting motion relative to the target membrane upon exposure to pH 5, indicating a previously undescribed hinge near the anchoring point to the target membrane. Time-resolved amide H/D exchange experiments revealed a more dynamic (tertiary) structure of membrane-bound BHA and its HA2, but not its HA1, subunit. Finally BHA and, to a lesser degree, HA1 perturbed the lipid bilayer of the target membrane at the interface, as assessed by spectral changes of the lipid ester carbonyl groups. These results are discussed in the context of a complementary study of HA that was bound to viral membranes through its transmembrane peptide (Gray C, Tamm LK, 1997, Protein Sci 6:1993-2006). A distinctive role for the HA1 subunit in the conformational change of HA becomes apparent from these combined

  19. PREFACE: Preface

    NASA Astrophysics Data System (ADS)

    2011-10-01

    The International Conference Alt100 - 'Resonances in Condensed Matter' was held in Kazan, Russian Federation, from 21-25 June, at Kazan (Volga Region) Federal University. The conference was devoted to the centenary of Professor, Corresponding member of Academy of Sciences of the USSR S A Altshuler (24.09.1911-24.01.1983), well known for his pioneer works together with E K Zavoiskii on EPR, prediction of neutron magnetic moment (with I E Tamm) and acoustic magnetic resonance. The program of the conference covered experimental and theoretical studies of (i) electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), ferromagnetic and antiferromagnetic resonances (FMR, AFMR) in condensed matter, enhanced nuclear magnetic resonance in Van-Vleck paramagnets (ENMR), optical spectroscopy of paramagnetic crystals; (ii) magnetic relaxation; (iii) bulk and local magnetic properties of transition metal oxides and intermetallic compounds; (iv) modern applications of magnetic resonance techniques and methods. The conference attracted 120 participants from 14 countries. There were 26 invited talks and 36 regular oral talks in the morning and afternoon sessions, and 70 poster presentations. A book of Abstracts is available on the conference website (http://alt100.ksu.ru). The Memorial Session involved talks from B I Kochelaev (Chairman of the Organizing Committee) and A A Manenkov and reminiscences about S A Altshuler given by A A Kaplyanskii, V A Kutuzov, Yu R Pol_skii and I N Pen_kov. The memorial talks and Kaplyanskii_ speech are presented in this volume. The papers submitted for this Proceedings were carefully considered by at least two referees, and we are very grateful to referees for their quick and very thoughtful responses. A few papers were eliminated because of referee reports. Finally 41 papers have been included. We thank the international advisory committee members very much for their recommendations of speakers for Alt100 and especially members of the

  20. On spacetime structure and electrodynamics

    NASA Astrophysics Data System (ADS)

    Ni, Wei-Tou

    2016-10-01

    Electrodynamics is the most tested fundamental physical theory. Relativity arose from the completion of Maxwell-Lorentz electrodynamics. Introducing the metric gij as gravitational potential in 1913, versed in general (coordinate-)covariant formalism in 1914 and shortly after the completion of general relativity, Einstein put the Maxwell equations in general covariant form with only the constitutive relation between the excitation and the field dependent on and connected by the metric in 1916. Further clarification and developments by Weyl in 1918, Murnaghan in 1921, Kottler in 1922 and Cartan in 1923 together with the corresponding developments in electrodynamics of continuous media by Bateman in 1910, Tamm in 1924, Laue in 1952 and Post in 1962 established the premetric formalism of electrodynamics. Since almost all phenomena electrodynamics deal with have energy scales much lower than the Higgs mass energy and intermediate boson energy, electrodynamics of continuous media should be applicable and the constitutive relation of spacetime/vacuum should be local and linear. What is the key characteristic of the spacetime/vacuum? It is the Weak Equivalence Principle I (WEP I) for photons/wave packets of light which states that the spacetime trajectory of light in a gravitational field depends only on its initial position and direction of propagation, and does not depend on its frequency (energy) and polarization, i.e. nonbirefringence of light propagation in spacetime/vacuum. With this principle it is proved by the author in 1981 in the weak field limit, and by Lammerzahl and Hehl in 2004 together with Favaro and Bergamin in 2011 without assuming the weak-field condition that the constitutive tensor must be of the core metric form with only two additional degrees of freedom — the pseudoscalar (Abelian axion or EM axion) degree of freedom and the scalar (dilaton) degree of freedom (i.e. metric with axion and dilaton). In this paper, we review this connection and the

  1. A. Sakharov and Fusion Research

    NASA Astrophysics Data System (ADS)

    Coppi, Bruno

    2012-02-01

    In the landmark paper by Tamm and Sakharov [1], a controlled nuclear fusion reactor based on an axisymmetric magnetic confinement configuration whose principles remain valid to this day, was proposed. In the light of present understanding of plasma physics the virtues (e.g. that of considering the D-D reaction) and the shortcomings of this paper are pointed out. In fact, relatively recent results of theoretical plasma physics (e.g. discovery of the so called second stability region) and advances in high field magnet technology have made it possible to identify the parameters of meaningful experiments capable of exploring D-D and D-^3He burn conditions. At the same time an experimental program (IGNIR) has been undertaken through a (funded) collaboration between Italy and Russia to investigate D-T plasmas close to ignition conditions based on an advanced high field toroidal confinement configuration. A. Sakharov envisioned a bolder approach to fusion research than that advocated by some of his contemporaries. The time taken to design and decide to fabricate the first experiment capable of reaching ignition conditions is due in part to the problem of gaining an adequate understanding the expected physics of fusion burning plasmas. However, most of the relevant financial effort has gone in the pursuit of slow and indirect enterprises complying with the ``playing it safe'' tendencies of large organizations or motivated by the purpose to develop technologies or maintain a high level of expertise in plasma physics to the expected benefit of other kinds of endeavors. The creativity demonstrated by A. Sakharov in dealing with civil rights and disarmament issues is needed, while maintaining our concerns for energy and the environment on a global scale, to orient the funding for fusion research toward a direct and well based scientific effort on concepts for which a variety of developments can be envisioned. These can span from uncovering new physics relevant, for instance

  2. Membrane-associated aquaporin-1 facilitates osmotically driven water flux across the basolateral membrane of the thick ascending limb

    PubMed Central

    Cabral, Pablo D.

    2012-01-01

    The thick ascending limb of the loop of Henle (TAL) reabsorbs ∼30% of filtered NaCl but is impermeable to water. The observation that little water traverses the TAL indicates an absence of water channels at the apical membrane. Yet TAL cells swell when peritubular osmolality decreases indicating that water channels must be present in the basolateral side. Consequently, we hypothesized that the water channel aquaporin-1 (AQP1) facilitates water flux across the basolateral membrane of TALs. Western blotting revealed AQP1 expression in microdissected rat and mouse TALs. Double immunofluorescence showed that 95 ± 2% of tubules positive for the TAL-specific marker Tamm-Horsfall protein were also positive for AQP1 (n = 6). RT-PCR was used to demonstrate presence of AQP1 mRNA and the TAL-specific marker NKCC2 in microdissected TALs. Cell surface biotinylation assays showed that 23 ± 3% of the total pool of AQP1 was present at the TAL basolateral membrane (n = 7). To assess the functional importance of AQP1 in the basolateral membrane, we measured the rate of cell swelling initiated by decreasing peritubular osmolality as an indicator of water flux in microdissected TALs. Water flux was decreased by ∼50% in Aqp1 knockout mice compared with wild-types (4.0 ± 0.8 vs. 8.9 ± 1.7 fluorescent U/s, P < 0.02; n = 7). Furthermore, arginine vasopressin increased TAL AQP1 expression by 135 ± 17% (glycosylated) and 41 ± 11% (nonglycosylated; P < 0.01; n =5). We conclude that 1) the TAL expresses AQP1, 2) ∼23% of the total pool of AQP1 is localized to the basolateral membrane, 3) AQP1 mediates a significant portion of basolateral water flux, and 4) AQP1 is upregulated in TALs of rats infused with dDAVP. AQP1 could play an important role in regulation of TAL cell volume during changes in interstitial osmolality, such as during a high-salt diet or water deprivation. PMID:22674028

  3. Time-dependent density functional study of the electronic potential energy curves and excitation spectrum of the oxygen molecule.

    PubMed

    Guan, Jingang; Wang, Fan; Ziegler, Tom; Cox, Hazel

    2006-07-28

    Orbital energies, ionization potentials, molecular constants, potential energy curves, and the excitation spectrum of O(2) are calculated using time-dependent density functional theory (TDDFT) with Tamm-Dancoff approximation (TDA). The calculated negative highest occupied molecular orbital energy (-epsilon(HOMO)) is compared with the energy difference ionization potential for five exchange correlation functionals consisting of the local density approximation (LDAxc), gradient corrected Becke exchange plus Perdew correlation (B(88X)+P(86C)), gradient regulated asymptotic correction (GRAC), statistical average of orbital potentials (SAOP), and van Leeuwen and Baerends asymptotically correct potential (LB94). The potential energy curves calculated using TDDFT with the TDA at internuclear distances from 1.0 to 1.8 A are divided into three groups according to the electron configurations. The 1pi(u) (4)1pi(g) (2) electron configuration gives rise to the X (3)Sigma(g) (-), a (1)Delta(g), and b (1)Sigma(g) (+) states; the 1pi(u) (3)1pi(g) (3) electron configuration gives rise to the c (1)Sigma(u) (-), C (3)Delta(u), and A (3)Sigma(u) (+) states; and the B (3)Sigma(u) (-), A (1)Delta(u), and f (1)Sigma(u) (+) states are determined by the mixing of two or more electron configurations. The excitation spectrum of the oxygen molecule, calculated with the aforementioned exchange correlation functionals, shows that the results are quite sensitive to the choice of functional. The LDAxc and the B(88X)+P(86C) functionals produce similar spectroscopic patterns with a single strongly absorbing band positioned at 19.82 and 19.72 eV, respectively, while the asymptotically corrected exchange correlation functionals of the SAOP and the LB94 varieties yield similar excitation spectra where the computed strongly absorbing band is located at 16.09 and 16.42 eV, respectively. However, all of the exchange correlation functionals yield only one strongly absorbing band (oscillator strength

  4. Critical Assessment of Time-Dependent Density Functional Theory for Excited States of Open-Shell Systems: II. Doublet-Quartet Transitions.

    PubMed

    Li, Zhendong; Liu, Wenjian

    2016-06-14

    Compared with closed-shell systems, open-shell systems place three additional challenges to time-dependent density functional theory (TD-DFT) for electronically excited states: (a) the spin-contamination problem is a serious issue; (b) the exchange-correlation (XC) kernel may be numerically instable; and (c) the single-determinant description of open-shell ground states readily becomes energetically instable. Confined to flip-up single excitations, the spin-contamination problem can largely be avoided by using the spin-flip TD-DFT (SF-TD-DFT) formalism, provided that a noncollinear XC kernel is employed. As for the numerical instabilities associated with such a kernel, only an ad hoc scheme has been proposed so far, viz., the ALDA0 kernel, which amounts to setting the divergent components (arising from density gradients and kinetic energy density) simply to zero. The ground-state instability problem can effectively be avoided by introducing the Tamm-Dancoff approximation (TDA) to TD-DFT. Therefore, on a general basis, the SF-TDA/ALDA0 Ansatz is so far the only promising means within the TD-DFT framework for flip-up single excitations of open-shell systems. To assess systematically the performance of SF-TDA/ALDA0, in total 61 low-lying quartet excited states of the benchmark set of 11 small radicals [J. Chem. Theory Comput. 2016, 12, 238] are investigated with various XC functionals. Taking the MRCISD+Q (multireference configuration interaction with singles and doubles plus the Davidson correction) results as benchmark, it is found that the mean absolute errors of SF-TDA/ALDA0 with the SAOP (statistical averaging of model orbital potentials), global hybrid, and range-separated hybrid functionals are in the range of 0.2-0.4 eV. This is in line not only with the typical accuracy of TD-DFT for singlet and triplet excited states of closed-shell systems but also with the gross accuracy of spin-adapted TD-DFT for spin-conserving excited states of open-shell systems.

  5. Efficient time-dependent density functional theory approximations for hybrid density functionals: analytical gradients and parallelization.

    PubMed

    Petrenko, Taras; Kossmann, Simone; Neese, Frank

    2011-02-07

    In this paper, we present the implementation of efficient approximations to time-dependent density functional theory (TDDFT) within the Tamm-Dancoff approximation (TDA) for hybrid density functionals. For the calculation of the TDDFT/TDA excitation energies and analytical gradients, we combine the resolution of identity (RI-J) algorithm for the computation of the Coulomb terms and the recently introduced "chain of spheres exchange" (COSX) algorithm for the calculation of the exchange terms. It is shown that for extended basis sets, the RIJCOSX approximation leads to speedups of up to 2 orders of magnitude compared to traditional methods, as demonstrated for hydrocarbon chains. The accuracy of the adiabatic transition energies, excited state structures, and vibrational frequencies is assessed on a set of 27 excited states for 25 molecules with the configuration interaction singles and hybrid TDDFT/TDA methods using various basis sets. Compared to the canonical values, the typical error in transition energies is of the order of 0.01 eV. Similar to the ground-state results, excited state equilibrium geometries differ by less than 0.3 pm in the bond distances and 0.5° in the bond angles from the canonical values. The typical error in the calculated excited state normal coordinate displacements is of the order of 0.01, and relative error in the calculated excited state vibrational frequencies is less than 1%. The errors introduced by the RIJCOSX approximation are, thus, insignificant compared to the errors related to the approximate nature of the TDDFT methods and basis set truncation. For TDDFT/TDA energy and gradient calculations on Ag-TB2-helicate (156 atoms, 2732 basis functions), it is demonstrated that the COSX algorithm parallelizes almost perfectly (speedup ~26-29 for 30 processors). The exchange-correlation terms also parallelize well (speedup ~27-29 for 30 processors). The solution of the Z-vector equations shows a speedup of ~24 on 30 processors. The

  6. Urinary antigens as markers of papillary toxicity. I. Identification and characterization of rat kidney papillary antigens with monoclonal antibodies.

    PubMed

    Falkenberg, F W; Hildebrand, H; Lutte, L; Schwengberg, S; Henke, B; Greshake, D; Schmidt, B; Friederich, A; Rinke, M; Schlüter, G; Bomhard, E

    1996-01-01

    Monoclonal antibodies were prepared in an attempt to develop diagnostic tools for the identification of toxic damage to the rat renal papilla. One IgG and five IgM monoclonal antibodies, reacting with antigens localized in the papilla were obtained. Three of the IgM class and the IgG class monoclonal antibodies were found to be specific for antigens localized in collecting ducts, two of them staining papillary collecting ducts more intensely than cortical collecting ducts. The IgG class antibody, termed Pap X 5C10, recognizes an antigen located at high density on the luminal side of papillary collecting duct epithelial cells and at lower density in cortical collecting duct cells. One of the IgM class monoclonal antibodies reacts with an antigen localized in epithelial cells as ascending and descending loops of Henle and of connecting tubules. Another of the IgM class monoclonal antibodies reacts with an antigen localized in the interstices of the inner medulla. All these monoclonal antibodies react with their antigens in native frozen as well as in Bouin-fixed and paraffin-embedded tissue slices. Molecular properties of the Pap X 5C10 antigen have been investigated by gel permeation chromatography, SDS-PAGE, Western blotting, and isoelectric focusing. The results indicate that the antigen in both its tissue-derived and urinary form is of large (150-200 kDa) molecular size and can be separated into two molecular species with isoelectric points of pH 7.2 and 7.3 respectively. In the urine the antigens recognized by the monoclonal antibodies form large complexes with Tamm-Horsfall protein. The antigen-containing complexes can be extracted from urine by adsorption to diatomaceous earth and elution with SDS-containing buffer. Using sandwich ELISA-type assays it is possible to determine the concentration of the antigens. In preliminary experiments we were able to show that at least three of the antigens are detected in the urine following toxic insults to the kidney. The

  7. Primary stroke prevention for sickle cell disease in north-east Italy: the role of ethnic issues in establishing a Transcranial Doppler screening program

    PubMed Central

    Colombatti, Raffaella; Meneghetti, Giorgio; Ermani, Mario; Pierobon, Marta; Sainati, Laura

    2009-01-01

    Background Stroke is a serious complication of sickle cell disease (SCD) in children. Transcranic Doppler (TCD) is a well-established predictor of future cerebrovascular symptoms: a blood flow velocity >200 cm/sec in the Middle Cerebral Artery (MCA) correlates with a high risk of stroke in cohorts of African-american HbS/HbS patients. In North-East Italy the recent increase in SCD patients is mainly due to immigration from Africa. A comprehensive care program for children with SCD was established in our Center since 2004, but a wide and routine screening for Primary stroke prevention needs to be developed. Methods In order to verify the feasibility of TCD and Transcranial color coded Sonography (TCCS) screening in our setting and the applicability of international reference values of blood velocities to our population of African immigrants with HbS/HbS SCD, we performed TCD and TCCD in 12 HbS/HbS African children and two groups of age-matched controls of Caucasian and African origin respectively. TCD and TCCS were performed on the same day of the scheduled routine hematologic visit after parental education. Results All parents accepted to perform the sonography to their children. TCD and TCCD were performed in all patients and an adequate temporal window could be obtained in all of them. Pulsatility index and depth values in both the MCA and the Basilar Artery (BA) were similar at TCD and TCCS evaluation in the three groups while time-average maximum velocities (TAMM), peak systolic velocity and diastolic velocity in the MCA and BA were higher in the patients' group on both TCD and TCCS evaluation. African and Caucasian healthy controls had similar lower values. Conclusion Our preliminary data set the base to further evaluate the implementation of a primary stroke prevention program in our setting of HbS/HbS African immigrants and HbS/beta thalassemia Italians. Parental education-preferably in the native language- on stroke risk and prevention in SCD increases

  8. Frequency Standards and Metrology

    NASA Astrophysics Data System (ADS)

    Maleki, Lute

    2009-04-01

    imaging an event horizon (Invited) / S. Doeleman. Optically-pumped space cesium clock for Galileo: results of the breadboard / R. Ruffieux ... [et al.] -- pt. IV. Optical clocks I: lattice clocks. Optical lattice clock: seven years of progress and next steps (Invited) / H. Katori, M. Takamoto and T. Akatsuka. The Yb optical lattice clock (Invited) / N. D. Demke ... [et al.]. Optical Lattice clock with Sr atoms (Invited) / P. G. Westergaard ... [et al.]. Development of an optical clock based on neutral strontium atoms held in a lattice trap / E. A. Curtis ... [et al.]. Decoherence and losses by collisions in a [symbol]Sr lattice clock / J. S. R. Vellore Winfred ... [et al.]. Lattice Yb optical clock and cryogenic Cs fountain at INRIM / F. Levi ... [et al.] -- pt. V. Optical clocks II: ion clocks. [Symbol]Yb+ single-ion optical frequency standards (Invited) / Chr. Tamm ... [et al.]. An optical clock based on a single trapped [symbol]Sr+ ion (Invited) / H. S. Margolis ... [et al.]. A trapped [symbol]Yb+ ion optical frequency standard based on the [symbol] transition (Invited) / P. Gill ... [et al.]. Overview of highly accurate RF and optical frequency standards at the National Research Council of Canada (Invited) / A. A. Madej ... [et al.] -- pt. VI. Optical frequency combs. Extreme ultraviolet frequency combs for spectroscopy (Invited) / A. Ozawa ... [et al.]. Development of an optical clockwork for the single trapped strontium ion standard at 445 THz / J. E. Bernard ... [et al.]. A phase-coherent link between the visible and infrared spectral ranges using a combination of CW OPO and femtosecond laser frequency comb / E. V. Kovalchuk and A. Peters. Improvements to the robustness of a TI: sapphire-based femtosecond comb at NPL / V. Tsatourian ... [et al.] -- pt. VII. Atomic microwave standards. NIST FI and F2 (Invited) / T. P. Heavner ... [et al.]. Atomic fountains for the USNO master clock (Invited) / C. Ekstrom ... [et al.]. The transportable cesium fountain clock NIM5

  9. “The Marshall Rosenbluth International Summer School – 2007: Plasma Thermonuclear Fusion and Plasma Astrophysics – 2007”

    SciTech Connect

    Stefan, Vladislav Alexander

    2007-10-01

    plasma instabilities, together with pioneering works of A. Sakharov, I. Tamm, L. Spitzer, Jr., L. A. Artsimovich, and others, led to the design of the TOKAMAK, the principal configuration used for contemporary magnetic fusion experiments. In addition to his research achievements, he has made significant administrative contributions as a scientific advisor in the fields of energy policy and national defense. He is the founder and the first director of The Institute for Fusion Studies at Austin, Texas. M. N. Rosenbluth has been the recipient of the E. O. Lawrence Memorial Award (1964),the Albert Einstein Award (1967),the James Clerk Maxwell prize in Plasma Physics(1976),and the Enrico Fermi Award (1986). M. N. Rosenbluth had been Science Advisor for the INSTITUTE for ADVANCED PHYSICS STUDIES (presently a division of The Stefan University) since 1989. He is the editor-in-chief of the FSRC, (Frontier Science Research Conferences) Book: "NEW IDEAS in TOKAMAK CONFINEMENT" Published by the American Institute of Physics (August 1994) in the Research Trends in Physics Series founded and edited by V. Alexander Stefan in 1989. M. N. Rosenbluth was a member of the American Academy of Arts and Sciences and the National Academy of Sciences of the USA, a Professor Emeritus at the University of California, San Diego, and a Senior Scientist at General Atomics, San Diego.

  10. Identification and quantification of nitrogen cycling processes in cryptogamic covers

    NASA Astrophysics Data System (ADS)

    Weber, Bettina; Wu, Dianming; Lenhart, Katharina; Tamm, Alexandra; Ruckteschler, Nina; Rodríguez-Caballero, Emilio; Elbert, Wolfgang; Burrows, Susannah; Clough, Tim; Steinkamp, Jörg; Meusel, Hannah; Behrendt, Thomas; Büdel, Burkhard; Andreae, Meinrat O.; Sörgel, Matthias; Cheng, Yafang; Crutzen, Paul; Keppler, Frank; Su, Hang; Pöschl, Ulrich

    2016-04-01

    budget from natural terrestrial sources (Lenhart et al., 2015). 15N isotope labeling experiments revealed that nitrate (NO3-) was a precursor of N2O, suggesting that N2O may be formed during denitrification. Thus, our experiments revealed that CC play a prominent role in different steps of the N cycle, being relevant in terrestrial biogeochemistry, atmospheric chemistry and air quality. Literature Elbert W, Weber B, Burrows S, Steinkamp J, Büdel B, Andreae MO, Pöschl U (2012) Contribution of cryptogamic covers to the global cycles of carbon and nitrogen. Nature Geosciences 5: 459-462. Lenhart K, Weber B, Elbert W, Steinkamp J, Clough T, Crutzen P, Pöschl U, Keppler F (2015) Nitrous oxide and methane emissions from cryptogamic covers. Global Change Biology 21(10): 3889-3900. Weber B, Wu D, Tamm A, Ruckteschler N, Rodríguez-Caballero E, Steinkamp J, Meusel H, Elbert W, Behrendt T, Sörgel M, Cheng Y, Crutzen P, Su H, Pöschl U (2015) Biological soil crusts accelerate the nitrogen cycle through large NO and HONO emissions in drylands. Proceedings of the National Academy of Sciences 112(50): 15384-15389.

  11. Electronic structure of CuTPP and CuTPP(F) complexes: a combined experimental and theoretical study II.

    PubMed

    Mangione, Giulia; Sambi, Mauro; Carlotto, Silvia; Vittadini, Andrea; Ligorio, Giovanni; Timpel, Melanie; Pasquali, Luca; Giglia, Angelo; Nardi, Marco Vittorio; Casarin, Maurizio

    2016-09-28

    The unoccupied electronic structure of thick films of tetraphenylporphyrin and tetrakis(pentafluorophenyl)porphyrin Cu(ii) complexes (hereafter, CuTPP and CuTPP(F)) deposited on Au(111) has been studied by combining the outcomes of near-edge X-ray absorption fine structure (NEXAFS) spectroscopy with those of spin-unrestricted time-dependent density functional (TD-DFT) calculations carried out either within the scalar relativistic zeroth order regular approximation (ZORA) framework (C, N and F K-edges) or by using the Tamm-Dancoff approximation coupled to ZORA and including spin-orbit effects (Cu L2,3-edges). Similarly to the modelling of NEXAFS outcomes pertaining to other Cu(ii) complexes, the agreement between theory and experiment is more than satisfactory, thus confirming the open-shell TD-DFT to be a useful tool to look into NEXAFS results pertinent to Cu(ii) compounds. The combined effect of metalation and phenyl (Ph) fluorine decoration is found to favour an extensive mixing between (Ph)σ* and pristine porphyrin macrocyle (pmc) (pmc)π* virtual levels. The lowest lying excitation in the C and N K-edge spectra of both CuTPP and CuTPP(F) is associated with a ligand-to-metal-charge-transfer transition, unambiguously revealed in the (CuTPP)N K-edge spectral pattern. Moreover, the comparison with literature data pertaining to the modelling of the (Cu(II))L2,3 features in the phthalocyanine-Cu(ii) (CuPc) complex provided further insights into how metal-to-ligand-charge-transfer transitions associated with excitations from 2p(Cu(II)) AOs to low-lying, ligand-based π* MOs may contribute to the Cu(ii) L2,3-edge intensity and thus weaken its believed relationship with the Cu(ii)-ligand symmetry-restricted covalency. Despite the coordinative pocket of CuTPP/CuTPP(F) mirroring CuPc, the ligand-field strength exerted by the phthalocyanine ligand on the Cu(ii) centre is experimentally found and theoretically confirmed to be slightly stronger than that experienced by Cu