Time-dependent density-functional tight-binding method with the third-order expansion of electron density

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nishimoto, Yoshio, E-mail: nishimoto.yoshio@fukui.kyoto-u.ac.jp

2015-09-07

We develop a formalism for the calculation of excitation energies and excited state gradients for the self-consistent-charge density-functional tight-binding method with the third-order contributions of a Taylor series of the density functional theory energy with respect to the fluctuation of electron density (time-dependent density-functional tight-binding (TD-DFTB3)). The formulation of the excitation energy is based on the existing time-dependent density functional theory and the older TD-DFTB2 formulae. The analytical gradient is computed by solving Z-vector equations, and it requires one to calculate the third-order derivative of the total energy with respect to density matrix elements due to the inclusion of themore » third-order contributions. The comparison of adiabatic excitation energies for selected small and medium-size molecules using the TD-DFTB2 and TD-DFTB3 methods shows that the inclusion of the third-order contributions does not affect excitation energies significantly. A different set of parameters, which are optimized for DFTB3, slightly improves the prediction of adiabatic excitation energies statistically. The application of TD-DFTB for the prediction of absorption and fluorescence energies of cresyl violet demonstrates that TD-DFTB3 reproduced the experimental fluorescence energy quite well.« less

Time-dependent density-functional tight-binding method with the third-order expansion of electron density.

PubMed

Nishimoto, Yoshio

2015-09-07

We develop a formalism for the calculation of excitation energies and excited state gradients for the self-consistent-charge density-functional tight-binding method with the third-order contributions of a Taylor series of the density functional theory energy with respect to the fluctuation of electron density (time-dependent density-functional tight-binding (TD-DFTB3)). The formulation of the excitation energy is based on the existing time-dependent density functional theory and the older TD-DFTB2 formulae. The analytical gradient is computed by solving Z-vector equations, and it requires one to calculate the third-order derivative of the total energy with respect to density matrix elements due to the inclusion of the third-order contributions. The comparison of adiabatic excitation energies for selected small and medium-size molecules using the TD-DFTB2 and TD-DFTB3 methods shows that the inclusion of the third-order contributions does not affect excitation energies significantly. A different set of parameters, which are optimized for DFTB3, slightly improves the prediction of adiabatic excitation energies statistically. The application of TD-DFTB for the prediction of absorption and fluorescence energies of cresyl violet demonstrates that TD-DFTB3 reproduced the experimental fluorescence energy quite well.

Coherent fifth-order visible-infrared spectroscopies: ultrafast nonequilibrium vibrational dynamics in solution.

PubMed

Lynch, Michael S; Slenkamp, Karla M; Cheng, Mark; Khalil, Munira

2012-07-05

Obtaining a detailed description of photochemical reactions in solution requires measuring time-evolving structural dynamics of transient chemical species on ultrafast time scales. Time-resolved vibrational spectroscopies are sensitive probes of molecular structure and dynamics in solution. In this work, we develop doubly resonant fifth-order nonlinear visible-infrared spectroscopies to probe nonequilibrium vibrational dynamics among coupled high-frequency vibrations during an ultrafast charge transfer process using a heterodyne detection scheme. The method enables the simultaneous collection of third- and fifth-order signals, which respectively measure vibrational dynamics occurring on electronic ground and excited states on a femtosecond time scale. Our data collection and analysis strategy allows transient dispersed vibrational echo (t-DVE) and dispersed pump-probe (t-DPP) spectra to be extracted as a function of electronic and vibrational population periods with high signal-to-noise ratio (S/N > 25). We discuss how fifth-order experiments can measure (i) time-dependent anharmonic vibrational couplings, (ii) nonequilibrium frequency-frequency correlation functions, (iii) incoherent and coherent vibrational relaxation and transfer dynamics, and (iv) coherent vibrational and electronic (vibronic) coupling as a function of a photochemical reaction.

Aberration design of zoom lens systems using thick lens modules.

PubMed

Zhang, Jinkai; Chen, Xiaobo; Xi, Juntong; Wu, Zhuoqi

2014-12-20

A systematic approach for the aberration design of a zoom lens system using a thick lens module is presented. Each component is treated as a thick lens module at the beginning of the design. A thick lens module refers to a thick lens component with a real lens structure, like lens materials, lens curvatures, lens thicknesses, and lens interval distances. All nine third-order aberrations of a thick lens component are considered during the design. The relationship of component aberrations in different zoom positions can be approximated from the aberration shift. After minimizing the aberrations of the zoom lens system, the nine third-order aberrations of every lens component can be determined. Then the thick lens structure of every lens component can be determined after optimization according to their first-order properties and third-order aberration targets. After a third optimization for minimum practical third-order aberrations of a zoom lens system, the aberration design using the thick lens module is complete, which provides a practical zoom lens system with thick lens structures. A double-sided telecentric zoom lens system is designed using the thick lens module in this paper, which shows that this method is practical for zoom lens design.

Scale-by-scale energy budgets which account for the coherent motion

NASA Astrophysics Data System (ADS)

F, Thiesset; L, Danaila; A, Antonia R.; T, Zhou

2011-12-01

Scale-by-scale energy budget equations are written for flows where coherent structures may be prominent. Both general and locally isotropic formulations are provided. In particular, the contribution to the production, diffusion and energy transfer terms associated with the coherent motion is highlighted. Preliminary results are presented in the intermediate wake of a circular cylinder for phase-averaged second-and third-order structure functions. The experimental data provide adequate support for the scale-by-scale budgets.

Close encounters of the third kind: disordered domains and the interactions of proteins.

PubMed

Tompa, Peter; Fuxreiter, Monika; Oldfield, Christopher J; Simon, Istvan; Dunker, A Keith; Uversky, Vladimir N

2009-03-01

Protein-protein interactions are thought to be mediated by domains, which are autonomous folding units of proteins. Recently, a second type of interaction has been suggested, mediated by short segments termed linear motifs, which are related to recognition elements of intrinsically disordered regions. Here, we propose a third kind of protein-protein recognition mechanism, mediated by disordered regions longer than 20-30 residues. Bioinformatics predictions and well-characterized examples, such as the kinase-inhibitory domain of Cdk inhibitors and the Wiskott-Aldrich syndrome protein (WASP)-homology domain 2 of actin-binding proteins, show that these disordered regions conform to the definition of domains rather than motifs, i.e., they represent functional, evolutionary, and structural units. Their functions are distinct from those of short motifs and ordered domains, and establish a third kind of interaction principle. With these points, we argue that these long disordered regions should be recognized as a distinct class of biologically functional protein domains.

On the lattice dynamics of metallic hydrogen and other Coulomb systems

NASA Technical Reports Server (NTRS)

Beck, H.; Straus, D.

1975-01-01

Numerical results for the phonon spectra of metallic hydrogen and other Coulomb systems in cubic lattices are presented. In second order in the electron-ion interaction, the behavior of the dielectric function of the interacting electron gas for arguments around the seond Fermi harmonic leads to drastic Kohn anomalies and even to imaginary phonon frequencies. Third-order band-structure corrections are also calculated. Properties of self-consistent phonons and the validity of the adiabatic approximation are discussed.

An efficient and accurate two-stage fourth-order gas-kinetic scheme for the Euler and Navier-Stokes equations

NASA Astrophysics Data System (ADS)

Pan, Liang; Xu, Kun; Li, Qibing; Li, Jiequan

2016-12-01

For computational fluid dynamics (CFD), the generalized Riemann problem (GRP) solver and the second-order gas-kinetic scheme (GKS) provide a time-accurate flux function starting from a discontinuous piecewise linear flow distributions around a cell interface. With the adoption of time derivative of the flux function, a two-stage Lax-Wendroff-type (L-W for short) time stepping method has been recently proposed in the design of a fourth-order time accurate method for inviscid flow [21]. In this paper, based on the same time-stepping method and the second-order GKS flux function [42], a fourth-order gas-kinetic scheme is constructed for the Euler and Navier-Stokes (NS) equations. In comparison with the formal one-stage time-stepping third-order gas-kinetic solver [24], the current fourth-order method not only reduces the complexity of the flux function, but also improves the accuracy of the scheme. In terms of the computational cost, a two-dimensional third-order GKS flux function takes about six times of the computational time of a second-order GKS flux function. However, a fifth-order WENO reconstruction may take more than ten times of the computational cost of a second-order GKS flux function. Therefore, it is fully legitimate to develop a two-stage fourth order time accurate method (two reconstruction) instead of standard four stage fourth-order Runge-Kutta method (four reconstruction). Most importantly, the robustness of the fourth-order GKS is as good as the second-order one. In the current computational fluid dynamics (CFD) research, it is still a difficult problem to extend the higher-order Euler solver to the NS one due to the change of governing equations from hyperbolic to parabolic type and the initial interface discontinuity. This problem remains distinctively for the hypersonic viscous and heat conducting flow. The GKS is based on the kinetic equation with the hyperbolic transport and the relaxation source term. The time-dependent GKS flux function provides a dynamic process of evolution from the kinetic scale particle free transport to the hydrodynamic scale wave propagation, which provides the physics for the non-equilibrium numerical shock structure construction to the near equilibrium NS solution. As a result, with the implementation of the fifth-order WENO initial reconstruction, in the smooth region the current two-stage GKS provides an accuracy of O ((Δx) 5 ,(Δt) 4) for the Euler equations, and O ((Δx) 5 ,τ2 Δt) for the NS equations, where τ is the time between particle collisions. Many numerical tests, including difficult ones for the Navier-Stokes solvers, have been used to validate the current method. Perfect numerical solutions can be obtained from the high Reynolds number boundary layer to the hypersonic viscous heat conducting flow. Following the two-stage time-stepping framework, the third-order GKS flux function can be used as well to construct a fifth-order method with the usage of both first-order and second-order time derivatives of the flux function. The use of time-accurate flux function may have great advantages on the development of higher-order CFD methods.

Synthesis, Hirshfeld surface analysis, laser damage threshold, third-order nonlinear optical property and DFT computation studies of Dichlorobis(DL-valine)zinc(II): A spectroscopic approach

NASA Astrophysics Data System (ADS)

Chitrambalam, S.; Manimaran, D.; Hubert Joe, I.; Rastogi, V. K.; Ul Hassan, Israr

2018-01-01

The organometallic crystal of Dichlorobis(DL-valine)zinc(II) was grown by solution growth method. The computed structural geometry, vibrational wavenumbers and UV-visible spectra were compared with experimental results. Hirshfeld surface map was used to locate electron density and the fingerprint plots percentages are responsible for the stabilization of intermolecular interactions in molecular crystal. The second-order hyperpolarizability value of the molecule was also calculated at density functional theory method. The surface resistance and third-order nonlinear optical property of the crystal were studied by laser induced surface damage threshold and Z-scan techniques, respectively using Nd:YAG laser with wavelength 532 nm. The open aperture result exhibits the reverse saturation absorption, which indicate that this material has potential candidate for optical limiting and optoelectronic applications.

Similarity of Turbulent Energy Scale Budget Equation of a Round Turbulent Jet

NASA Astrophysics Data System (ADS)

Sadeghi, Hamed; Lavoie, Philippe; Pollard, Andrew

2014-11-01

A novel extension to the similarity-based form of the transport equation for the second-order velocity structure function of <(δq) 2 > along the jet centreline (see Danaila et al., 2004) has been obtained. This new self-similar equation has the desirable benefit of requiring less extensive measurements to calculate the inhomogeneous (decay and production) terms of the transport equation. According to this equation, the normalized third-order structure function can be uniquely determined when the normalized second-order structure function, the power-law exponent of and the decay rate constants of and are available. In addition, on the basis of the current similarity analysis, the similarity assumptions in combination with power-law decay of mean velocity (U ~(x -x0) - 1) are strong enough to imply power-law decay of fluctuations ( ~(x -x0) m). The similarity solutions are then tested against new experimental data, which were taken along the centreline of a round jet at ReD = 50 , 000 . For the present set of initial conditions, exhibits a power-law behaviour with m = - 1 . 83 . This work was supported by grants from NSERC (Canada).

A clock steering method: using a third-order type 3 DPLL equivalent to a Kalman filter with a delay

NASA Astrophysics Data System (ADS)

Wu, Yiwei; Gong, Hang; Zhu, Xiangwei; Ou, Gang

2015-12-01

In this paper we propose a new clock steering method, which uses a third-order type 3 digital phase locked loop (DPLL) which is equivalent to a Kalman filter with a delay. A general overview of the theoretical framework is described in detail including the transfer functions, the structure and control values, the specifications, and the approach to choosing a parameter. Simulations show that the performance of the time and frequency steering errors and the frequency stability are quite desirable. Comparing with traditional clock steering methods, it is easier to work with just one parameter. The DPLL method satisfies the requirements of generating a local representation of universal time coordinated and the system time of a global navigation satellite system.

Studies on the growth aspects, structural, thermal, dielectric and third order nonlinear optical properties of solution grown 4-methylpyridinium p-nitrophenolate single crystal

NASA Astrophysics Data System (ADS)

Devi, S. Reena; Kalaiyarasi, S.; Zahid, I. MD.; Kumar, R. Mohan

2016-11-01

An ionic organic optical crystal of 4-methylpyridinium p-nitrophenolate was grown from methanol by slow evaporation method at ambient temperature. Powder and single crystal X-ray diffraction studies revealed the crystal system and its crystalline perfection. The rocking curve recorded from HRXRD study confirmed the crystal quality. FTIR spectral analysis confirmed the functional groups present in the title compound. UV-visible spectral study revealed the optical window and band gap of grown crystal. The thermal, electrical and surface laser damage threshold properties of harvested crystal were examined by using TGA/DTA, LCR/Impedance Analyzer and Nd:YAG laser system respectively. The third order nonlinear optical property of grown crystal was elucidated by Z-scan technique.

Airy structure in 16O+14C nuclear rainbow scattering

NASA Astrophysics Data System (ADS)

Ohkubo, S.; Hirabayashi, Y.

2015-08-01

The Airy structure in 16 O +14 C rainbow scattering is studied with an extended double-folding (EDF) model that describes all the diagonal and off-diagonal coupling potentials derived from the microscopic realistic wave functions for 16 O by using a density-dependent nucleon-nucleon force. The experimental angular distributions at EL=132 , 281, and 382.2 MeV are well reproduced by the calculations. By studying the energy evolution of the Airy structure, the Airy minimum around θ =76∘ in the angular distribution at EL=132 MeV is assigned as the second-order Airy minimum A 2 in contrast to the recent literature which assigns it as the third order A 3 . The Airy minima in the 90∘ excitation function is investigated in comparison with well-known 16 O +16 O and 12 C +12 C systems. Evolution of the Airy structure into the molecular resonances with the 16 O +14 C cluster structure in the low-energy region around Ec .m .=30 MeV is discussed. It is predicted theoretically for the first time for a non-4 N 16O +14 C system that Airy elephants in the 90∘ excitation function are present.

Dependence of the third-order coefficients in Landau free energies for bcc --> fcc structural transition on hydrogen concentration in zirconium hydrides

NASA Astrophysics Data System (ADS)

Ashida, Yuh; Yamamoto, Masahiro; Naito, Shizuo; Mabuchi, Mahito; Hashino, Tomoyasu

1997-08-01

Young's modulus E and the modulus of rigidity G of zirconium hydrides ZrHx(0.9⩽x⩽1.65) at 941 and 1001 K have been obtained as a function of hydrogen concentration c by measuring resonance frequencies for bending and torsion vibrations of a polycrystalline wire. As c increases, observed E and G increase in the bcc β phase, slightly increase linearly in the β+δ phase, and then decrease in the fcc δ phase. On the basis of a phenomenological free energy in terms of strain components taking account of space group symmetry, two types of Landau expansion of the free energies for the β phase in terms of the strain components which play an important role in the structural phase transition between the β and the δ phases are examined. The observed E and G are assumed to be the same as the second-order coefficients of the free energy for the Bain distortions, which occur at the structural phase transition. The dependence of the third-order coefficients on c permits the expanded free energies to describe the fact that the β phase is more stable than the δ phase at low c.

A Kramers-Moyal approach to the analysis of third-order noise with applications in option valuation.

PubMed

Popescu, Dan M; Lipan, Ovidiu

2015-01-01

We propose the use of the Kramers-Moyal expansion in the analysis of third-order noise. In particular, we show how the approach can be applied in the theoretical study of option valuation. Despite Pawula's theorem, which states that a truncated model may exhibit poor statistical properties, we show that for a third-order Kramers-Moyal truncation model of an option's and its underlier's price, important properties emerge: (i) the option price can be written in a closed analytical form that involves the Airy function, (ii) the price is a positive function for positive skewness in the distribution, (iii) for negative skewness, the price becomes negative only for price values that are close to zero. Moreover, using third-order noise in option valuation reveals additional properties: (iv) the inconsistencies between two popular option pricing approaches (using a "delta-hedged" portfolio and using an option replicating portfolio) that are otherwise equivalent up to the second moment, (v) the ability to develop a measure R of how accurately an option can be replicated by a mixture of the underlying stocks and cash, (vi) further limitations of second-order models revealed by introducing third-order noise.

A Kramers-Moyal Approach to the Analysis of Third-Order Noise with Applications in Option Valuation

PubMed Central

Popescu, Dan M.; Lipan, Ovidiu

2015-01-01

We propose the use of the Kramers-Moyal expansion in the analysis of third-order noise. In particular, we show how the approach can be applied in the theoretical study of option valuation. Despite Pawula’s theorem, which states that a truncated model may exhibit poor statistical properties, we show that for a third-order Kramers-Moyal truncation model of an option’s and its underlier’s price, important properties emerge: (i) the option price can be written in a closed analytical form that involves the Airy function, (ii) the price is a positive function for positive skewness in the distribution, (iii) for negative skewness, the price becomes negative only for price values that are close to zero. Moreover, using third-order noise in option valuation reveals additional properties: (iv) the inconsistencies between two popular option pricing approaches (using a “delta-hedged” portfolio and using an option replicating portfolio) that are otherwise equivalent up to the second moment, (v) the ability to develop a measure R of how accurately an option can be replicated by a mixture of the underlying stocks and cash, (vi) further limitations of second-order models revealed by introducing third-order noise. PMID:25625856

Structural and electronic properties of GaAs and GaP semiconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rani, Anita; Kumar, Ranjan

2015-05-15

The Structural and Electronic properties of Zinc Blende phase of GaAs and GaP compounds are studied using self consistent SIESTA-code, pseudopotentials and Density Functional Theory (DFT) in Local Density Approximation (LDA). The Lattice Constant, Equillibrium Volume, Cohesive Energy per pair, Compressibility and Band Gap are calculated. The band gaps calcultated with DFT using LDA is smaller than the experimental values. The P-V data fitted to third order Birch Murnaghan equation of state provide the Bulk Modulus and its pressure derivatives. Our Structural and Electronic properties estimations are in agreement with available experimental and theoretical data.

Semi-local machine-learned kinetic energy density functional with third-order gradients of electron density

NASA Astrophysics Data System (ADS)

Seino, Junji; Kageyama, Ryo; Fujinami, Mikito; Ikabata, Yasuhiro; Nakai, Hiromi

2018-06-01

A semi-local kinetic energy density functional (KEDF) was constructed based on machine learning (ML). The present scheme adopts electron densities and their gradients up to third-order as the explanatory variables for ML and the Kohn-Sham (KS) kinetic energy density as the response variable in atoms and molecules. Numerical assessments of the present scheme were performed in atomic and molecular systems, including first- and second-period elements. The results of 37 conventional KEDFs with explicit formulae were also compared with those of the ML KEDF with an implicit formula. The inclusion of the higher order gradients reduces the deviation of the total kinetic energies from the KS calculations in a stepwise manner. Furthermore, our scheme with the third-order gradient resulted in the closest kinetic energies to the KS calculations out of the presented functionals.

Exploiting structure: Introduction and motivation

NASA Technical Reports Server (NTRS)

Xu, Zhong Ling

1994-01-01

This annual report summarizes the research activities that were performed from 26 Jun. 1993 to 28 Feb. 1994. We continued to investigate the Robust Stability of Systems where transfer functions or characteristic polynomials are affine multilinear functions of parameters. An approach that differs from 'Stability by Linear Process' and that reduces the computational burden of checking the robust stability of the system with multilinear uncertainty was found for low order, 2-order, and 3-order cases. We proved a crucial theorem, the so-called Face Theorem. Previously, we have proven Kharitonov's Vertex Theorem and the Edge Theorem by Bartlett. The detail of this proof is contained in the Appendix. This Theorem provides a tool to describe the boundary of the image of the affine multilinear function. For SPR design, we have developed some new results. The third objective for this period is to design a controller for IHM by the H-infinity optimization technique. The details are presented in the Appendix.

Multi-Lagrangians for integrable systems

NASA Astrophysics Data System (ADS)

Nutku, Y.; Pavlov, M. V.

2002-03-01

We propose a general scheme to construct multiple Lagrangians for completely integrable nonlinear evolution equations that admit multi-Hamiltonian structure. The recursion operator plays a fundamental role in this construction. We use a conserved quantity higher/lower than the Hamiltonian in the potential part of the new Lagrangian and determine the corresponding kinetic terms by generating the appropriate momentum map. This leads to some remarkable new developments. We show that nonlinear evolutionary systems that admit N-fold first order local Hamiltonian structure can be cast into variational form with 2N-1 Lagrangians which will be local functionals of Clebsch potentials. This number increases to 3N-2 when the Miura transformation is invertible. Furthermore we construct a new Lagrangian for polytropic gas dynamics in 1+1 dimensions which is a free, local functional of the physical field variables, namely density and velocity, thus dispensing with the necessity of introducing Clebsch potentials entirely. This is a consequence of bi-Hamiltonian structure with a compatible pair of first and third order Hamiltonian operators derived from Sheftel's recursion operator.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, Cheong R.

The structural changes of kinetic Alfvén solitary waves (KASWs) due to higher-order terms are investigated. While the first-order differential equation for KASWs provides the dispersion relation for kinetic Alfvén waves, the second-order differential equation describes the structural changes of the solitary waves due to higher-order nonlinearity. The reductive perturbation method is used to obtain the second-order and third-order partial differential equations; then, Kodama and Taniuti's technique [J. Phys. Soc. Jpn. 45, 298 (1978)] is applied in order to remove the secularities in the third-order differential equations and derive a linear second-order inhomogeneous differential equation. The solution to this new second-ordermore » equation indicates that, as the amplitude increases, the hump-type Korteweg-de Vries solution is concentrated more around the center position of the soliton and that dip-type structures form near the two edges of the soliton. This result has a close relationship with the interpretation of the complex KASW structures observed in space with satellites.« less

Function does not follow form in gene regulatory circuits.

PubMed

Payne, Joshua L; Wagner, Andreas

2015-08-20

Gene regulatory circuits are to the cell what arithmetic logic units are to the chip: fundamental components of information processing that map an input onto an output. Gene regulatory circuits come in many different forms, distinct structural configurations that determine who regulates whom. Studies that have focused on the gene expression patterns (functions) of circuits with a given structure (form) have examined just a few structures or gene expression patterns. Here, we use a computational model to exhaustively characterize the gene expression patterns of nearly 17 million three-gene circuits in order to systematically explore the relationship between circuit form and function. Three main conclusions emerge. First, function does not follow form. A circuit of any one structure can have between twelve and nearly thirty thousand distinct gene expression patterns. Second, and conversely, form does not follow function. Most gene expression patterns can be realized by more than one circuit structure. And third, multifunctionality severely constrains circuit form. The number of circuit structures able to drive multiple gene expression patterns decreases rapidly with the number of these patterns. These results indicate that it is generally not possible to infer circuit function from circuit form, or vice versa.

Structural characterizations, Hirshfeld surface analyses, and third-order nonlinear optical properties of two novel chalcone derivatives

NASA Astrophysics Data System (ADS)

Maidur, Shivaraj R.; Jahagirdar, Jitendra R.; Patil, Parutagouda Shankaragouda; Chia, Tze Shyang; Quah, Ching Kheng

2018-01-01

We report synthesis, characterizations, structure-property relationships, and third-order nonlinear optical studies for two new chalcone derivatives, (2E)-1-(anthracen-9-yl)-3-(4-bromophenyl)prop-2-en-1-one (Br-ANC) and (2E)-1-(anthracen-9-yl)-3-(4-chlorophenyl)prop-2-en-1-one (Cl-ANC). These derivatives were crystallized in the centrosymmetric monoclinic P21/c crystal structure. The intermolecular interactions of both the crystals were visualized by Hirshfeld surface analyses (HSA). The crystals are thermally stable up to their melting points (180.82 and 191.16 °C for Cl-ANC and Br-ANC, respectively). The geometry optimizations, FT-IR spectra, 1H and 13C NMR spectra, electronic absorption spectra, electronic transitions, and HOMO-LUMO energy gaps were studied by Density Functional Theory (DFT) at B3LYP/6-311+G(d, p) level. The theoretical results provide excellent agreement with experimental findings. The electric dipole moments, static polarizabilities, molecular electrostatic potentials (MEP) and global chemical reactivity descriptors (GCRD) were also theoretically computed. The materials exhibited good nonlinear absorption (NLA), nonlinear refraction (NLR) and optical limiting (OL) behavior under diode-pumped solid-state (DPSS) continuous wave (CW) laser excitation (532 nm and 200 mW). The NLO parameters such as NLA coefficient (β∼10-5 cmW-1), NLR index (n2∼10-10 cm2 W-1) and third-order NLO susceptibilities (χ(3) ∼10-7 esu) were measured. Further, we estimated one-photon and two-photon figures of merit, which satisfy the demands (W > 1 and T < 1) for all-optical switching. Thus, the present chalcone derivatives with anthracene moiety are potential materials for OL and optical switching applications.

Microscopic cascading of second-order molecular nonlinearity: New design principles for enhancing third-order nonlinearity.

PubMed

Baev, Alexander; Autschbach, Jochen; Boyd, Robert W; Prasad, Paras N

2010-04-12

Herein, we develop a phenomenological model for microscopic cascading and substantiate it with ab initio calculations. It is shown that the concept of local microscopic cascading of a second-order nonlinearity can lead to a third-order nonlinearity, without introducing any new loss mechanisms that could limit the usefulness of our approach. This approach provides a new molecular design protocol, in which the current great successes achieved in producing molecules with extremely large second-order nonlinearity can be used in a supra molecular organization in a preferred orientation to generate very large third-order response magnitudes. The results of density functional calculations for a well-known second-order molecule, (para)nitroaniline, show that a head-to-tail dimer configuration exhibits enhanced third-order nonlinearity, in agreement with the phenomenological model which suggests that such an arrangement will produce cascading due to local field effects.

Filter for third order phase locked loops

NASA Technical Reports Server (NTRS)

Crow, R. B.; Tausworthe, R. C. (Inventor)

1973-01-01

Filters for third-order phase-locked loops are used in receivers to acquire and track carrier signals, particularly signals subject to high doppler-rate changes in frequency. A loop filter with an open-loop transfer function and set of loop constants, setting the damping factor equal to unity are provided.

Structural expansions for the ground state energy of a simple metal

NASA Technical Reports Server (NTRS)

Hammerberg, J.; Ashcroft, N. W.

1973-01-01

A structural expansion for the static ground state energy of a simple metal is derived. An approach based on single particle band structure which treats the electron gas as a non-linear dielectric is presented, along with a more general many particle analysis using finite temperature perturbation theory. The two methods are compared, and it is shown in detail how band-structure effects, Fermi surface distortions, and chemical potential shifts affect the total energy. These are of special interest in corrections to the total energy beyond third order in the electron ion interaction, and hence to systems where differences in energies for various crystal structures are exceptionally small. Preliminary calculations using these methods for the zero temperature thermodynamic functions of atomic hydrogen are reported.

Structure and Stability of Molecular Crystals with Many-Body Dispersion-Inclusive Density Functional Tight Binding.

PubMed

Mortazavi, Majid; Brandenburg, Jan Gerit; Maurer, Reinhard J; Tkatchenko, Alexandre

2018-01-18

Accurate prediction of structure and stability of molecular crystals is crucial in materials science and requires reliable modeling of long-range dispersion interactions. Semiempirical electronic structure methods are computationally more efficient than their ab initio counterparts, allowing structure sampling with significant speedups. We combine the Tkatchenko-Scheffler van der Waals method (TS) and the many-body dispersion method (MBD) with third-order density functional tight-binding (DFTB3) via a charge population-based method. We find an overall good performance for the X23 benchmark database of molecular crystals, despite an underestimation of crystal volume that can be traced to the DFTB parametrization. We achieve accurate lattice energy predictions with DFT+MBD energetics on top of vdW-inclusive DFTB3 structures, resulting in a speedup of up to 3000 times compared with a full DFT treatment. This suggests that vdW-inclusive DFTB3 can serve as a viable structural prescreening tool in crystal structure prediction.

Spin-lattice relaxation-rate anomaly at structural phase transitions

NASA Astrophysics Data System (ADS)

Levanyuk, A. P.; Minyukov, S. A.; Etrillard, J.; Toudic, B.

1997-12-01

The theory of spin-lattice relaxation (SLR)-rate anomaly at structural phase transitions proposed about 30 years ago is reconsidered taking into account that knowledge about the relevant lattice response functions has changed considerably. We use both the results of previous authors and perform original calculations of the response functions when it is necessary. We consider displacive systems and use the perturbation theory to treat the lattice anharmonicities in a broad temperature region whenever possible. Some comments about the order-disorder systems are made as well. The possibility of linear coupling of the order parameter and the resonance frequency is always assumed. It is found that in the symmetrical phase the anomaly is due to the one-phonon processes, the anomalous part being proportional to either (T-Tc)-1 or (T-Tc)-1/2 depending on some condition on the soft-mode dispersion. In both cases the value of the SLR rate at the boundary of applicabity of the theory (close to the phase transition) is estimated to be 102-103 times more than the typical value of the SLR rate in an ideal crystal. An essential specific feature of the nonsymmetrical phase is appearance of third-order anharmonicities that are well known to lead to a low-frequency dispersion of the order-parameter damping constant. We have found that this constant exhibits, in addition, a strong wave-vector dispersion, so that the damping constant determing the SLR rate is quite different from that at zero wave vector. In the case of two-component order parameter the damping constant for the component with nonzero equilibrium value is different from that for the other component, the difference is of the same order of magnitude as the damping constants themselves. In the case of the incommensurate phase a part of the mentioned third-order anharmonicity is responsible for longitudinal-transversal interaction that is well known to influence the static longitudinal response function. We calculate as well the dynamic response function to find that for the SLR calculations the imaginary part is of main importance. Due to this interaction the longitudinal SLR rate acquires a dependence on the Larmor frequency. This dependence is however, fairly weak: a logarithmic one. The implications of the obtained results for interpretation of the experimental data on SLR in incommensurate phase are discussed as well.

β-Octakis(methylthio)porphycenes: synthesis, characterisation and third order nonlinear optical studies.

PubMed

Rana, Anup; Lee, Sangsu; Kim, Dongho; Panda, Pradeepta K

2015-05-04

A novel electron deficient β-octakis(methylthio)porphycene, along with its Zn(ii) and Ni(ii) derivatives, was synthesized for the first time. The macrocyclic structure exhibits core ruffling with a largely red shifted absorption band (∼750 nm) and also a large enhancement in the third order nonlinear optical response.

PERSONAL RECOLLECTIONS OF DR. HANS SELYE AND OF HIS INSTITUT DE MèDECINE ET DE CHIRURGIE EXPèRIMENTALES (IMCE).

PubMed

Salas-Prato, Milagros

2014-03-30

This article is a short personal recollection of Dr. Hans Selye (HS) and of his institute in order to show, first, why and how he influenced us; second, who he was as a person, human being, physician, scientist, professor, mentor; third, what was the structure and functioning of the Institut de Mèdecine et Chirurgie Expèrimentales (IMCE) and fourth, what HS' contributions and accomplishments were.

Global and critical test of the perturbation density-functional theory based on extensive simulation of Lennard-Jones fluid near an interface and in confined systems.

PubMed

Zhou, Shiqi; Jamnik, Andrej

2005-09-22

The structure of a Lennard-Jones (LJ) fluid subjected to diverse external fields maintaining the equilibrium with the bulk LJ fluid is studied on the basis of the third-order+second-order perturbation density-functional approximation (DFA). The chosen density and potential parameters for the bulk fluid correspond to the conditions situated at "dangerous" regions of the phase diagram, i.e., near the critical temperature or close to the gas-liquid coexistence curve. The accuracy of DFA predictions is tested against the results of a grand canonical ensemble Monte Carlo simulation. It is found that the DFA theory presented in this work performs successfully for the nonuniform LJ fluid only on the condition of high accuracy of the required bulk second-order direct correlation function. The present report further indicates that the proposed perturbation DFA is efficient and suitable for both supercritical and subcritical temperatures.

Conservation laws and rogue waves for a higher-order nonlinear Schrödinger equation with variable coefficients in the inhomogeneous fiber

NASA Astrophysics Data System (ADS)

Du, Zhong; Tian, Bo; Wu, Xiao-Yu; Liu, Lei; Sun, Yan

2017-07-01

Subpicosecond or femtosecond optical pulse propagation in the inhomogeneous fiber can be described by a higher-order nonlinear Schrödinger equation with variable coefficients, which is investigated in the paper. Via the Ablowitz-Kaup-Newell-Segur system and symbolic computation, the Lax pair and infinitely-many conservation laws are deduced. Based on the Lax pair and a modified Darboux transformation technique, the first- and second-order rogue wave solutions are constructed. Effects of the groupvelocity dispersion and third-order dispersion on the properties of the first- and second-order rouge waves are graphically presented and analyzed: The groupvelocity dispersion and third-order dispersion both affect the ranges and shapes of the first- and second-order rogue waves: The third-order dispersion can produce a skew angle of the first-order rogue wave and the skew angle rotates counterclockwise with the increase of the groupvelocity dispersion, when the groupvelocity dispersion and third-order dispersion are chosen as the constants; When the groupvelocity dispersion and third-order dispersion are taken as the functions of the propagation distance, the linear, X-shaped and parabolic trajectories of the rogue waves are obtained.

Microgravity Processing and Photonic Applications of Organic and Polymeric Materials

NASA Technical Reports Server (NTRS)

Frazier, Donald 0; Penn, Benjamin G.; Smith, David; Witherow, William K.; Paley, M. S.; Abdeldayem, Hossin A.

1998-01-01

In recent years, a great deal of interest has been directed toward the use of organic materials in the development of high-efficiency optoelectronic and photonic devices. There is a myriad of possibilities among organic which allow flexibility in the design of unique structures with a variety of functional groups. The use of nonlinear optical (NLO) organic materials such as thin-film waveguides allows full exploitation of their desirable qualities by permitting long interaction lengths and large susceptibilities allowing modest power input. There are several methods in use to prepare thin films, such as Langmuir-Blodgett (LB) and self-assembly techniques, vapor deposition, growth from sheared solution or melt, and melt growth between glass plates. Organics have many features that make Abstract: them desirable for use in optical devices such as high second- and third-order nonlinearities, flexibility of molecular design, and damage resistance to optical radiation. However, their use in devices has been hindered by processing difficulties for crystals and thin films. In this chapter, we discuss photonic and optoelectronic applications of a few organic materials and the potential role of microgravity on processing these materials. It is of interest to note how materials with second- and third-order nonlinear optical behavior may be improved in a diffusion-limited environment and ways in which convection may be detrimental to these materials. We focus our discussion on third-order materials for all-optical switching, and second-order materials for all-optical switching, and second-order materials for frequency conversion and electrooptics.

Statistical anisotropy in free turbulence for mixing layers at high Reynolds numbers

NASA Astrophysics Data System (ADS)

Gardner, Patrick J.; Roggemann, Michael C.; Welsh, Byron M.; Bowersox, Rodney D.; Luke, Theodore E.

1996-08-01

A lateral shearing interferometer was used to measure the slope of perturbed wave fronts after propagating through free turbulent mixing layers. Shearing interferometers provide a two-dimensional flow visualization that is nonintrusive. Slope measurements were used to reconstruct the phase of the turbulence-corrupted wave front. The random phase fluctuations induced by the mixing layer were captured in a large ensemble of wave-front measurements. Experiments were performed on an unbounded, plane shear mixing layer of helium and nitrogen gas at fixed velocities and high Reynolds numbers for six locations in the flow development. Statistical autocorrelation functions and structure functions were computed on the reconstructed phase maps. The autocorrelation function results indicated that the turbulence-induced phase fluctuations were not wide-sense stationary. The structure functions exhibited statistical homogeneity, indicating that the phase fluctuations were stationary in first increments. However, the turbulence-corrupted phase was not isotropic. A five-thirds power law is shown to fit orthogonal slices of the structure function, analogous to the Kolmogorov model for isotropic turbulence. Strehl ratios were computed from the phase structure functions and compared with classical estimates that assume isotropy. The isotropic models are shown to overestimate the optical degradation by nearly 3 orders of magnitude compared with the structure function calculations.

Scientific Practices in Elementary Classrooms: Third-Grade Students' Scientific Explanations for Seed Structure and Function

ERIC Educational Resources Information Center

Zangori, Laura; Forbes, Cory T.

2014-01-01

Elementary science standards emphasize that students should develop conceptual understanding of the characteristics and life cycles of plants (National Research Council, 2012), yet few studies have focused on early learners' reasoning about seed structure and function. The purpose of this study is twofold: to (a) examine third-grade…

Lump solutions and interaction phenomenon to the third-order nonlinear evolution equation

NASA Astrophysics Data System (ADS)

Kofane, T. C.; Fokou, M.; Mohamadou, A.; Yomba, E.

2017-11-01

In this work, the lump solution and the kink solitary wave solution from the (2 + 1) -dimensional third-order evolution equation, using the Hirota bilinear method are obtained through symbolic computation with Maple. We have assumed that the lump solution is centered at the origin, when t = 0 . By considering a mixing positive quadratic function with exponential function, as well as a mixing positive quadratic function with hyperbolic cosine function, interaction solutions like lump-exponential and lump-hyperbolic cosine are presented. A completely non-elastic interaction between a lump and kink soliton is observed, showing that a lump solution can be swallowed by a kink soliton.

Synthesis, optical, experimental and theoretical investigation of third order nonlinear optical properties of 8-hydroxyquinolinium 2-carboxy-6-nitrophthalate monohydrate single crystal

NASA Astrophysics Data System (ADS)

Bharathi, M. Divya; Bhuvaneswari, R.; Srividya, J.; Vinitha, G.; Prithiviraajan, R. N.; Anbalagan, G.

2018-02-01

Single crystals of 8-hydroxyquinolinium 2-carboxy-6-nitrophthalate monohydrate (8HQNP) were obtained from slow evaporation solution growth method using methanol-water (1:1) as a solvent. Powder X-ray diffraction was utilized to compute the unit cell parameters and dislocation density of 8HQNP crystal. The crystalline perfection of the as-grown crystal was investigated by high-resolution X-ray diffraction at room temperature. The molecular structure was analyzed by identifying the functional groups from FT-IR and FT-Raman spectra. The cut-off wavelength and the corresponding optical band gap obtained from an optical spectrum were 376 nm and 3.29 eV respectively. The dispersion nature of refractive index was investigated by the single-oscillator Wemple and Di-Domenico model. Red emission was observed in the photoluminescence spectrum when excited with 376 nm. The low birefringence and high laser damage threshold (8.538 GW/cm2) values dictate the suitability of the crystal for optical devices. Z-scan studies revealed the third order nonlinear absorption coefficient (β) and refractive index (n2) of the 8HQNP crystal. The theoretical value of third order nonlinear susceptibility obtained from density function theory is good accordance with the experimental value. The frontier molecular orbital energy gap decreases with increasing external electric field in different directions which attributed to the enhancement of the second hyperpolarizability. The grown title crystal is thermally stable up to 102 °C which was identified using thermal analysis. Mechanical strength of 8HQNP was estimated by using Vicker's microhardness studies.

Significance of third-order elasticity for determination of the pressure coefficient of the light emission in strained quantum wells

NASA Astrophysics Data System (ADS)

Łepkowski, S. P.

2008-10-01

We investigate the contribution arising from third-order elasticity to the pressure coefficient of the light emission (dEE/dP) in strained zinc-blende InGaAs/GaAs and InGaN/GaN quantum wells (QWs) grown in a (001) direction. In the framework of the third-order elasticity theory, we develop a model of pressure tuning of strains in these structures, which is then used to determine the coefficient dEE/dP . In the calculations of dEE/dP , we use a consistent set of the second- and third-order elastic constants which has been obtained from ab initio calculations. Our results indicate that the usage of third-order elasticity leads to significant reduction in dEE/dP in strained (001)-oriented InGaAs/GaAs and InGaN/GaN QWs, in comparison to the values of dEE/dP obtained by using the linear theory of elasticity. In the case of InGaAs/GaAs QWs, the values of dEE/dP calculated using third-order elasticity are in reasonable agreement with experimental data. For InGaN/GaN QWs, better agreement between theoretical and experimental values of dEE/dP is obtained when instead of third-order elasticity, pressure dependence of the second-order elastic constants is taken into account.

Ground-state energies of simple metals

NASA Technical Reports Server (NTRS)

Hammerberg, J.; Ashcroft, N. W.

1974-01-01

A structural expansion for the static ground-state energy of a simple metal is derived. Two methods are presented, one an approach based on single-particle band structure which treats the electron gas as a nonlinear dielectric, the other a more general many-particle analysis using finite-temperature perturbation theory. The two methods are compared, and it is shown in detail how band-structure effects, Fermi-surface distortions, and chemical-potential shifts affect the total energy. These are of special interest in corrections to the total energy beyond third order in the electron-ion interaction and hence to systems where differences in energies for various crystal structures are exceptionally small. Preliminary calculations using these methods for the zero-temperature thermodynamic functions of atomic hydrogen are reported.

Enhanced third-order nonlinear optical properties determined in thin films using the Z-scan technique: bis(μ-4,4'-oxydibenzoato)bis[(4'-phenyl-2,2':6',2''-terpyridine)cobalt(II)].

PubMed

Liu, Runqiang; Zhao, Ning; Liu, Ping; An, Caixia; Lian, Zhaoxun

2016-05-01

π-Conjugated organic materials exhibit high and tunable nonlinear optical (NLO) properties, and fast response times. 4'-Phenyl-2,2':6',2''-terpyridine (PTP) is an important N-heterocyclic ligand involving π-conjugated systems, however, studies concerning the third-order NLO properties of terpyridine transition metal complexes are limited. The title binuclear terpyridine Co(II) complex, bis(μ-4,4'-oxydibenzoato)-κ(3)O,O':O'';κ(3)O'':O,O'-bis[(4'-phenyl-2,2':6',2''-terpyridine-κ(3)N,N',N'')cobalt(II)], [Co2(C14H8O5)2(C21H15N3)2], (1), has been synthesized under hydrothermal conditions. In the crystal structure, each Co(II) cation is surrounded by three N atoms of a PTP ligand and three O atoms, two from a bidentate and one from a symmetry-related monodentate 4,4'-oxydibenzoate (ODA(2-)) ligand, completing a distorted octahedral coordination geometry. Neighbouring [Co(PTP)](2+) units are bridged by ODA(2-) ligands to form a ring-like structure. The third-order nonlinear optical (NLO) properties of (1) and PTP were determined in thin films using the Z-scan technique. The title compound shows a strong third-order NLO saturable absorption (SA), while PTP exhibits a third-order NLO reverse saturable absorption (RSA). The absorptive coefficient β of (1) is -37.3 × 10(-7) m W(-1), which is larger than that (8.96 × 10(-7) m W(-1)) of PTP. The third-order NLO susceptibility χ((3)) values are calculated as 6.01 × 10(-8) e.s.u. for (1) and 1.44 × 10(-8) e.s.u. for PTP.

Systems of conservation laws with third-order Hamiltonian structures

NASA Astrophysics Data System (ADS)

Ferapontov, Evgeny V.; Pavlov, Maxim V.; Vitolo, Raffaele F.

2018-06-01

We investigate n-component systems of conservation laws that possess third-order Hamiltonian structures of differential-geometric type. The classification of such systems is reduced to the projective classification of linear congruences of lines in P^{n+2} satisfying additional geometric constraints. Algebraically, the problem can be reformulated as follows: for a vector space W of dimension n+2, classify n-tuples of skew-symmetric 2-forms A^{α } \\in Λ^2(W) such that φ _{β γ }A^{β }\\wedge A^{γ }=0, for some non-degenerate symmetric φ.

Disentangling neighbors and extended range density oscillations in monatomic amorphous semiconductors.

PubMed

Roorda, S; Martin, C; Droui, M; Chicoine, M; Kazimirov, A; Kycia, S

2012-06-22

High energy x-ray diffraction measurements of pure amorphous Ge were made and its radial distribution function (RDF) was determined at high resolution, revealing new information on the atomic structure of amorphous semiconductors. Fine structure in the second peak in the RDF provides evidence that a fraction of third neighbors are closer than some second neighbors; taking this into account leads to a narrow distribution of tetrahedral bond angles, (8.5 ± 0.1)°. A small peak which appears near 5 Å upon thermal annealing shows that some ordering in the dihedral bond-angle distribution takes place during structural relaxation. Extended range order is detected (in both a-Ge and a-Si) which persists to beyond 20 Å, and both the periodicity and its decay length increase upon thermal annealing. Previously, the effect of structural relaxation was only detected at intermediate range, involving reduced tetrahedral bond-angle distortions. These results enhance our understanding of the atomic order in continuous random networks and place significantly more stringent requirements on computer models intending to describe these networks, or their alternatives which attempt to describe the structure in terms of an arrangement of paracrystals.

Domain structure of the ribozyme from eubacterial ribonuclease P.

PubMed Central

Loria, A; Pan, T

1996-01-01

Large RNAs can be composed of discrete domains that fold independently. One such "folding domain" has been identified previously in the ribozyme from Bacillus subtilis ribonuclease P (denoted P RNA). This domain contains roughly one-third of all residues. Folding of an RNA construct consisting of the remaining two-thirds of B. subtilis P RNA was examined by Fe(II)-EDTA hydroxyl radical protection. This molecule folds into the proper higher-order structure under identical conditions as the full-length P RNA, suggesting the presence of a second folding domain in B. subtilis P RNA. Folding analysis of the Escherichia coli P RNA by hydroxyl radical protection shows that this P RNA is completely folded at 5-6 mM Mg2+. In order to analyze the structural organization of folding domains in E. coli P RNA, constructs were designed based on the domain structure of B. subtilis P RNA. Fe(II)-EDTA protection indicates that E. coli P RNA also contains two folding domains. Despite the significant differences at the secondary structure level, both P RNAs appear to converge structurally at the folding domain level. The pre-tRNA substrate, localized in previous studies, may bind across the folding domains with the acceptor stem/3'CCA contacting the domain including the active site and the T stem-loop contacting the other. Because all eubacterial P RNAs share considerable homology in secondary structure to either B. subtilis or E. coli P RNA, these results suggest that this domain structure may be applicable for most, if not all, eubacterial P RNAs. Identification of folding domains should be valuable in dissecting structure-function relationship of large RNAs. PMID:8718684

Studies on the growth, structural, spectral and third-order nonlinear optical properties of ammonium 3-carboxy-4-hydroxy benzenesulfonate monohydrate single crystal.

PubMed

Silambarasan, A; Krishna Kumar, M; Thirunavukkarasu, A; Mohan Kumar, R; Umarani, P R

2015-01-25

An organic nonlinear optical bulk single crystal, Ammonium 3-carboxy-4-hydroxy benzenesulfonate monohydrate (ACHBS) was successfully grown by solution growth technique. Single crystal X-ray diffraction study confirms that, the grown crystal belongs to P21/c space group. Powder X-ray diffraction and high resolution X-ray diffraction analyses revealed the crystallinity of the grown crystal. Infrared spectral analysis showed the vibrational behavior of chemical bonds and its functional groups. The thermal stability and decomposition stages of the grown crystal were studied by TG-DTA analysis. UV-Visible transmittance studies showed the transparency region and cut-off wavelength of the grown crystal. The third-order nonlinear optical susceptibility of the grown crystal was estimated by Z-scan technique using He-Ne laser source. The mechanical property of the grown crystal was studied by using Vicker's microhardness test. Copyright © 2014 Elsevier B.V. All rights reserved.

Optical nonlinearities of excitons in monolayer MoS2

NASA Astrophysics Data System (ADS)

Soh, Daniel B. S.; Rogers, Christopher; Gray, Dodd J.; Chatterjee, Eric; Mabuchi, Hideo

2018-04-01

We calculate linear and nonlinear optical susceptibilities arising from the excitonic states of monolayer MoS2 for in-plane light polarizations, using second-quantized bound and unbound exciton operators. Optical selection rules are critical for obtaining the susceptibilities. We derive the valley-chirality rule for the second-order harmonic generation in monolayer MoS2 and find that the third-order harmonic process is efficient only for linearly polarized input light while the third-order two-photon process (optical Kerr effect) is efficient for circularly polarized light using a higher order exciton state. The absence of linear absorption due to the band gap and the unusually strong two-photon third-order nonlinearity make the monolayer MoS2 excitonic structure a promising resource for coherent nonlinear photonics.

The influence of aggregation on the third-order nonlinear optical property of π-conjugated chromophores: the case of cyanine dyes.

PubMed

Wang, Chao; Yuan, Yizhong

2018-06-20

The external molecular environment like the aggregation of molecules can significantly change the intrinsic third-order nonlinear optical (NLO) property of π-conjugated chromophores. A combined experimental and theoretical study was performed to understand the influence of the aggregation of cyanines on the third-order NLO property in spin-coated thin films. Our result indicates that the H and J type cyanine dimers prefer the polyene-like structures and the P type dimer displays a comparatively smaller bond length alternation (BLA). The polarizable continuum model (PCM)-tuned, range-separated (RSE) density functional approach was used to describe the screening effect of the cyanine aggregation. In the thin film, the P aggregate has very small positive isotropic averaged second hyperpolarizability γ, while the J aggregate has the largest positive γ due to the most polarized face-to-tail cyanine-cyanine interaction. Hence, the γ of the isolated cyanines (negative γ) may get cancelled against that of the cyanine aggregates (positive γ) in the thin film. The forward degenerate four-wave mixing technique also confirms a decrease in the magnitude of γ with an increase in the aggregation degree of cyanines. Since the large positive γ of the cyanine also implies strong two-photon absorption (TPA), the J aggregation of cyanines can be used as a potential fabrication method for applications involving TPA.

Theory of plasmonic effects in nonlinear optics: the case of graphene

NASA Astrophysics Data System (ADS)

Rostami, Habib; Katsnelson, Mikhail I.; Polini, Marco; Mikhail I. Katsnelson Collaboration; Habib Rostami; Marco Polini Collaboration

The nonlinear optical properties of two-dimensional electronic systems are beginning to attract considerable interest both in the theoretical and experimental sectors. Recent experiments on the nonlinear optical properties of graphene reveal considerably strong third harmonic generation and four-wave mixing of this single-atomic-layer electronic system. We develop a large-N theory of electron-electron interaction corrections to multi-legged Feynman diagrams describing second- and third-order nonlinear response functions. Our theory is completely general and is useful to understand all second- and third-order nonlinear effects, including harmonic generation, wave mixing, and photon drag. We apply our theoretical framework to the case of graphene, by carrying out microscopic calculations of the second- and third-order nonlinear response functions of an interacting two-dimensional gas of massless Dirac fermions. We compare our results with recent measurements, where all-optical launching of graphene plasmons has been achieved. This work was supported by Fondazione Istituto Italiano di Tecnologia, the European Union's Horizon 2020 research and innovation programme under Grant agreement No. 696656 GrapheneCore, and the ERC Advanced Grant 338957 FEMTO/NANO (M.I.K.).

Transfer function of radio over fiber multimode fiber optic links considering third-order dispersion.

PubMed

Capmany, J; Gasulla, Ivana

2007-08-20

Although a considerable number of multimode fiber (MMF) links operate in a wavelength region around 850 nm where chromatic dispersion of a given modal group mu is described adequately by the second derivative beta(mu) (2) of the propagation constant beta(mu)(omega), there is also an increasing interest in MMF links transmitting in the second spectral window (@1300nm) where this second derivative vanishes being thus necessary to consider the third derivative beta(mu) (3) in the evaluation of the transfer function of the multimode fiber link. We present in this paper, for the first time to our knowledge, an analytical model for the transfer function of a multimode fiber (MMF) optic link taken into account the impact of third-order dispersion. The model extends the operation of a previously reported one for second-order dispersion. Our results show that the performance of broadband radio over fiber transmission through middle-reach distances can be improved by working at the minimum-dispersion wavelength as long as low-linewidth lasers are employed.

Statistical characterization of short wind waves from stereo images of the sea surface

NASA Astrophysics Data System (ADS)

Mironov, Alexey; Yurovskaya, Maria; Dulov, Vladimir; Hauser, Danièle; Guérin, Charles-Antoine

2013-04-01

We propose a methodology to extract short-scale statistical characteristics of the sea surface topography by means of stereo image reconstruction. The possibilities and limitations of the technique are discussed and tested on a data set acquired from an oceanographic platform at the Black Sea. The analysis shows that reconstruction of the topography based on stereo method is an efficient way to derive non-trivial statistical properties of surface short- and intermediate-waves (say from 1 centimer to 1 meter). Most technical issues pertaining to this type of datasets (limited range of scales, lacunarity of data or irregular sampling) can be partially overcome by appropriate processing of the available points. The proposed technique also allows one to avoid linear interpolation which dramatically corrupts properties of retrieved surfaces. The processing technique imposes that the field of elevation be polynomially detrended, which has the effect of filtering out the large scales. Hence the statistical analysis can only address the small-scale components of the sea surface. The precise cut-off wavelength, which is approximatively half the patch size, can be obtained by applying a high-pass frequency filter on the reference gauge time records. The results obtained for the one- and two-points statistics of small-scale elevations are shown consistent, at least in order of magnitude, with the corresponding gauge measurements as well as other experimental measurements available in the literature. The calculation of the structure functions provides a powerful tool to investigate spectral and statistical properties of the field of elevations. Experimental parametrization of the third-order structure function, the so-called skewness function, is one of the most important and original outcomes of this study. This function is of primary importance in analytical scattering models from the sea surface and was up to now unavailable in field conditions. Due to the lack of precise reference measurements for the small-scale wave field, we could not quantify exactly the accuracy of the retrieval technique. However, it appeared clearly that the obtained accuracy is good enough for the estimation of second-order statistical quantities (such as the correlation function), acceptable for third-order quantities (such as the skwewness function) and insufficient for fourth-order quantities (such as kurtosis). Therefore, the stereo technique in the present stage should not be thought as a self-contained universal tool to characterize the surface statistics. Instead, it should be used in conjunction with other well calibrated but sparse reference measurement (such as wave gauges) for cross-validation and calibration. It then completes the statistical analysis in as much as it provides a snapshot of the three-dimensional field and allows for the evaluation of higher-order spatial statistics.

Key functions analysis of a novel nonlinear optical D-π-A bridge type (2E)-3-(4-Methylphenyl)-1-(3-nitrophenyl) prop-2-en-1-one chalcone: An experimental and theoretical approach

NASA Astrophysics Data System (ADS)

Patil, Parutagouda Shankaragouda; Shkir, Mohd; Maidur, Shivaraj R.; AlFaify, S.; Arora, M.; Rao, S. Venugopal; Abbas, Haider; Ganesh, V.

2017-10-01

In the current work a new third-order nonlinear optical organic single crystal of (2E)-3-(4-Methylphenyl)-1-(3-nitrophenyl) prop-2-en-1-one (ML3NC) has been grown with well-defined morphology using the slow evaporation solution growth technique. X-ray diffraction technique was used to confirm the crystal system. The presence of functional groups in the molecular structure was identified by robust FT-IR and FT-Raman spectra by experimental and theoretical analysis. The ultraviolet-visible-near infrared and photoluminescence studies shows that the grown crystals possess excellent transparency window and green emission band (∼560 nm) confirms their use in green OLEDs. The third-order nonlinear and optical limiting studies have been performed using femtosecond (fs) Z-scan technique. The third-order nonlinear optical susceptibility (χ(3)), second-order hyperpolarizability (γ), nonlinear refractive index (n2) and limiting threshold values are found to be 4.03 × 10-12 esu, 14.2 × 10-32 esu, -4.33 × 10-14 cm2/W and 2.41 mJ/cm2, respectively. Furthermore, the quantum chemical studies were carried out to achieve the ground state molecular geometry and correlate with experimental results. The experimental value of absorption wavelength (λabs = 328 nm) is found to be in excellent accord with the theoretical value (λabs = 328 nm) at TD-DFT/B3LYP/6-31G* level of theory. To understand the static and dynamic NLO behavior, the polarizability (α) and second hyperpolarizability (γ) values were determined using TD-HF method. The computed second hyperpolarizability γ(-3ω; ω,ω,ω) at 800 nm wavelength was found to be 0.499 × 10-32 esu which is in good agreement with experimental value at the same wavelength. These results confirms the applied nature of title molecule in optoelectronic and nonlinear optical devices.

Molecular Static Third-Order Polarizabilities of Carbon-Cage Fullerene and Their Correlation with Three Geometric Properties: Symmetry, Aromaticity, and Size

NASA Technical Reports Server (NTRS)

Moore, C. E.; Cardelino, B. H.; Frazier, D. O.; Niles, J.; Wang, X.-Q.

1998-01-01

The static third-order polarizabilities (gamma) of C60, C70, five isomers of C78 and two isomers of C84 were analyzed in terms of three properties, from a geometric point of view: symmetry, aromaticity and size. The polarizability values were based on the finite field approximation using a semiempirical Hamiltonian (AM1) and applied to molecular structures obtained from density functional theory calculations. Symmetry was characterized by the molecular group order. The selection of 6-member rings as aromatic was determined from an analysis of bond lengths. Maximum interatomic distance and surface area were the parameters considered with respect to size. Based on triple linear regression analysis, it was found that the static linear polarizability (alpha) and gamma in these molecules respond differently to geometrical properties: alpha depends almost exclusively on surface area while gamma is affected by a combination of number of aromatic rings, length and group order, in decreasing importance. In the case of alpha, valence electron contributions provide the same information as all-electron estimates. For gamma, the best correlation coefficients are obtained when all-electron estimates are used and when the dependent parameter is ln(gamma) instead of gamma.

Leadership: validation of a self-report scale.

PubMed

Dussault, Marc; Frenette, Eric; Fernet, Claude

2013-04-01

The aim of this paper was to propose and test the factor structure of a new self-report questionnaire on leadership. A sample of 373 school principals in the Province of Quebec, Canada completed the initial 46-item version of the questionnaire. In order to obtain a questionnaire of minimal length, a four-step procedure was retained. First, items analysis was performed using Classical Test Theory. Second, Rasch analysis was used to identify non-fitting or overlapping items. Third, a confirmatory factor analysis (CFA) using structural equation modelling was performed on the 21 remaining items to verify the factor structure of the scale. Results show that the model with a single third-order dimension (leadership), two second-order dimensions (transactional and transformational leadership), and one first-order dimension (laissez-faire leadership) provides a good fit to the data. Finally, invariance of factor structure was assessed with a second sample of 222 vice-principals in the Province of Quebec, Canada. This model is in agreement with the theoretical model developed by Bass (1985), upon which the questionnaire is based.

Second and third order nonlinear optical properties of conjugated molecules and polymers

NASA Technical Reports Server (NTRS)

Perry, Joseph W.; Stiegman, Albert E.; Marder, Seth R.; Coulter, Daniel R.; Beratan, David N.; Brinza, David E.

1988-01-01

Second- and third-order nonlinear optical properties of some newly synthesized organic molecules and polymers are reported. Powder second-harmonic-generation efficiencies of up to 200 times urea have been realized for asymmetric donor-acceptor acetylenes. Third harmonic generation chi(3)s have been determined for a series of small conjugated molecules in solution. THG chi(3)s have also been determined for a series of soluble conjugated copolymers prepared using ring-opening metathesis polymerization. The results are discussed in terms of relevant molecular and/or macroscopic structural features of these conjugated organic materials.

Tuning of active vibration controllers for ACTEX by genetic algorithm

NASA Astrophysics Data System (ADS)

Kwak, Moon K.; Denoyer, Keith K.

1999-06-01

This paper is concerned with the optimal tuning of digitally programmable analog controllers on the ACTEX-1 smart structures flight experiment. The programmable controllers for each channel include a third order Strain Rate Feedback (SRF) controller, a fifth order SRF controller, a second order Positive Position Feedback (PPF) controller, and a fourth order PPF controller. Optimal manual tuning of several control parameters can be a difficult task even though the closed-loop control characteristics of each controller are well known. Hence, the automatic tuning of individual control parameters using Genetic Algorithms is proposed in this paper. The optimal control parameters of each control law are obtained by imposing a constraint on the closed-loop frequency response functions using the ACTEX mathematical model. The tuned control parameters are then uploaded to the ACTEX electronic control electronics and experiments on the active vibration control are carried out in space. The experimental results on ACTEX will be presented.

A Survey of Protein Structures from Archaeal Viruses

PubMed Central

Dellas, Nikki; Lawrence, C. Martin; Young, Mark J.

2013-01-01

Viruses that infect the third domain of life, Archaea, are a newly emerging field of interest. To date, all characterized archaeal viruses infect archaea that thrive in extreme conditions, such as halophilic, hyperthermophilic, and methanogenic environments. Viruses in general, especially those replicating in extreme environments, contain highly mosaic genomes with open reading frames (ORFs) whose sequences are often dissimilar to all other known ORFs. It has been estimated that approximately 85% of virally encoded ORFs do not match known sequences in the nucleic acid databases, and this percentage is even higher for archaeal viruses (typically 90%–100%). This statistic suggests that either virus genomes represent a larger segment of sequence space and/or that viruses encode genes of novel fold and/or function. Because the overall three-dimensional fold of a protein evolves more slowly than its sequence, efforts have been geared toward structural characterization of proteins encoded by archaeal viruses in order to gain insight into their potential functions. In this short review, we provide multiple examples where structural characterization of archaeal viral proteins has indeed provided significant functional and evolutionary insight. PMID:25371334

Computation of turbulent pipe and duct flow using third order upwind scheme

NASA Technical Reports Server (NTRS)

Kawamura, T.

1986-01-01

The fully developed turbulence in a circular pipe and in a square duct is simulated directly without using turbulence models in the Navier-Stokes equations. The utilized method employs a third-order upwind scheme for the approximation to the nonlinear term and the second-order Adams-Bashforth method for the time derivative in the Navier-Stokes equation. The computational results appear to capture the large-scale turbulent structures at least qualitatively. The significance of the artificial viscosity inherent in the present scheme is discussed.

Photon echo spectroscopy reveals structure-dynamics relationships in carotenoids

NASA Astrophysics Data System (ADS)

Christensson, N.; Polivka, T.; Yartsev, A.; Pullerits, T.

2009-06-01

Based on simultaneous analysis of the frequency-resolved transient grating, peak shift, and echo width signals, we present a model for the third-order optical response of carotenoids including population dynamics and system-bath interactions. Our frequency-resolved photon echo experiments show that the model needs to incorporate the excited-state absorption from both the S2 and the S1 states. We apply our model to analyze the experimental results on astaxanthin and lycopene, aiming to elucidate the relation between structure and system-bath interactions. Our analysis allows us to relate structural motifs to changes in the energy-gap correlation functions. We find that the terminal rings of astaxanthin lead to increased coupling between slow molecular motions and the electronic transition. We also find evidence for stronger coupling to higher frequency overdamped modes in astaxanthin, pointing to the importance of the functional groups in providing coupling to fluctuations influencing the dynamics in the passage through the conical intersection governing the S2-S1 relaxation.

Computer-Aided Design of RNA Origami Structures.

PubMed

Sparvath, Steffen L; Geary, Cody W; Andersen, Ebbe S

2017-01-01

RNA nanostructures can be used as scaffolds to organize, combine, and control molecular functionalities, with great potential for applications in nanomedicine and synthetic biology. The single-stranded RNA origami method allows RNA nanostructures to be folded as they are transcribed by the RNA polymerase. RNA origami structures provide a stable framework that can be decorated with functional RNA elements such as riboswitches, ribozymes, interaction sites, and aptamers for binding small molecules or protein targets. The rich library of RNA structural and functional elements combined with the possibility to attach proteins through aptamer-based binding creates virtually limitless possibilities for constructing advanced RNA-based nanodevices.In this chapter we provide a detailed protocol for the single-stranded RNA origami design method using a simple 2-helix tall structure as an example. The first step involves 3D modeling of a double-crossover between two RNA double helices, followed by decoration with tertiary motifs. The second step deals with the construction of a 2D blueprint describing the secondary structure and sequence constraints that serves as the input for computer programs. In the third step, computer programs are used to design RNA sequences that are compatible with the structure, and the resulting outputs are evaluated and converted into DNA sequences to order.

Nonlinear optical behavior of DNA-functionalized gold nanoparticles

NASA Astrophysics Data System (ADS)

Kulyk, B.; Krupka, O.; Smokal, V.; Figà, V.; Czaplicki, R.; Sahraoui, B.

2018-03-01

The third-order nonlinear optical properties of gold nanoparticles embedded in the DNA-based composites were investigated by means of the third harmonic generation. With this purpose, the thin films comprising DNA-based complexes and Au nanoparticles were spin-deposited on glass substrate and their optical and nonlinear optical features were studied using the Maker-fringe technique at a laser fundamental wavelength of 1064 nm. The values of the third-order susceptibility χ (3)(- 3ω; ω, ω, ω) of the composite films based on DNA complex doped with 5 wt% of N-ethyl-N-(2-hydroxyethyl)-4-(4-nitrophenylazo)aniline were found to be significantly higher than those for pure composite films. Meanwhile, the presence of Au nanoparticles noticeable decreases the third-order nonlinear response of DNA-based composite mainly due to the enhanced absorption and scattering of laser and generated beam, respectively.

Structure Effect of Squarylium Cyanine Dyes on Third-Order Optical Nonlinearities in Ground and Excited States

NASA Astrophysics Data System (ADS)

Liu, Xu-chun; Xu, Gang; Si, Jin-hai; Ye, Pei-xian; Lin, Tong; Peng, Bi-xian

1999-08-01

A series of squarylium cyanine dyes with different substituents were synthesized and the third-order optical nonlinearities of their ground and excited states were investigated by backward degenerate four-wave-mixing. For the ground state, the molecular hyperpolarizability γg increases with the red-shift of the absorption peak λmaxab of the squaraine with different substituents, whereas for the excited-state molecular hyperpolarizability γe, the nonlinear enhancement γe/γg decreases, which may indicate that in the excited state the electron accepting-donating ability of different substituents changes in the reverse order compared with the order in the ground state.

Molecular Static Third-Order Polarizabilities of Carbon-Cage Fullerenes and their Correlation with Three Geometric Parameters: Group Order, Aromaticity, and Size

NASA Technical Reports Server (NTRS)

Moore, Craig E.; Cardelino, Beatriz H.; Frazier, Donald O.; Niles, Julian; Wang, Xian-Qiang

1997-01-01

Calculations were performed on the valence contribution to the static molecular third-order polarizabilities (gamma) of thirty carbon-cage fullerenes (C60, C70, five isomers of C78, and twenty-three isomers of C84). The molecular structures were obtained from B3LYP/STO-3G calculations. The values of the tensor elements and an associated numerical uncertainty were obtained using the finite-field approach and polynomial expansions of orders four to eighteen of polarization versus static electric field data. The latter information was obtained from semiempirical calculations using the AM1 hamiltonian.

Algebraic diagrammatic construction formalism with three-body interactions

NASA Astrophysics Data System (ADS)

Raimondi, Francesco; Barbieri, Carlo

2018-05-01

Background: Self-consistent Green's function theory has recently been extended to the basic formalism needed to account for three-body interactions [Carbone, Cipollone, Barbieri, Rios, and Polls, Phys. Rev. C 88, 054326 (2013), 10.1103/PhysRevC.88.054326]. The contribution of three-nucleon forces has so far been included in ab initio calculations on nuclear matter and finite nuclei only as averaged two-nucleon forces. Purpose: We derive the working equations for all possible two- and three-nucleon terms that enter the expansion of the self-energy up to the third order, thus including the interaction-irreducible (i.e., not averaged) diagrams with three-nucleon forces that have been previously neglected. Methods: We employ the algebraic diagrammatic construction up to the third order as an organization scheme for generating a nonperturbative self-energy, in which ring (particle-hole) and ladder (particle-particle) diagrams are resummed to all orders. Results: We derive expressions of the static and dynamic self-energy up to the third order, by taking into account the set of diagrams required when either the skeleton or nonskeleton expansions of the single-particle propagator are assumed. A hierarchy of importance among different diagrams is revealed, and a particular emphasis is given to a third-order diagram [see Fig. 2(c)] that is expected to play a significant role among those featuring an interaction-irreducible three-nucleon force. Conclusion: A consistent formalism to resum at infinite order correlations induced by three-nucleon forces in the self-consistent Green's function theory is now available and ready to be implemented in the many-body solvers.

Birth Order and Susceptibility to Peer Modeling Influences in Young Boys

ERIC Educational Resources Information Center

Finley, Gordon E.; Cheyne, James A.

1976-01-01

Susceptibility to peer modeling influences as a function of birth order was studied by examining the data of 390 boys from kindergarten through third grade who previously had participated in moral transgression experiments. (MS)

Adaptive neural output-feedback control for nonstrict-feedback time-delay fractional-order systems with output constraints and actuator nonlinearities.

PubMed

Zouari, Farouk; Ibeas, Asier; Boulkroune, Abdesselem; Cao, Jinde; Mehdi Arefi, Mohammad

2018-06-01

This study addresses the issue of the adaptive output tracking control for a category of uncertain nonstrict-feedback delayed incommensurate fractional-order systems in the presence of nonaffine structures, unmeasured pseudo-states, unknown control directions, unknown actuator nonlinearities and output constraints. Firstly, the mean value theorem and the Gaussian error function are introduced to eliminate the difficulties that arise from the nonaffine structures and the unknown actuator nonlinearities, respectively. Secondly, the immeasurable tracking error variables are suitably estimated by constructing a fractional-order linear observer. Thirdly, the neural network, the Razumikhin Lemma, the variable separation approach, and the smooth Nussbaum-type function are used to deal with the uncertain nonlinear dynamics, the unknown time-varying delays, the nonstrict feedback and the unknown control directions, respectively. Fourthly, asymmetric barrier Lyapunov functions are employed to overcome the violation of the output constraints and to tune online the parameters of the adaptive neural controller. Through rigorous analysis, it is proved that the boundedness of all variables in the closed-loop system and the semi global asymptotic tracking are ensured without transgression of the constraints. The principal contributions of this study can be summarized as follows: (1) based on Caputo's definitions and new lemmas, methods concerning the controllability, observability and stability analysis of integer-order systems are extended to fractional-order ones, (2) the output tracking objective for a relatively large class of uncertain systems is achieved with a simple controller and less tuning parameters. Finally, computer-simulation studies from the robotic field are given to demonstrate the effectiveness of the proposed controller. Copyright © 2018 Elsevier Ltd. All rights reserved.

Organizing for the Third Mission: Structural Conditions for Outreach and Relevance at Two Swedish HEIs

ERIC Educational Resources Information Center

Hellstrom, Tomas; Jacob, Merle; Wigren-Kristoferson, Caroline

2013-01-01

The authors investigate how Third Mission activities at universities, such as the outreach and technology transfer functions, are anchored in organizational structures and practices, and discuss the implications of this relationship for the success of the activities. They draw on case studies of two Swedish university colleges to illustrate the…

Off-resonant third-order optical nonlinearities of squarylium and croconium dyes

NASA Astrophysics Data System (ADS)

Li, Zhongyu; Xu, Song; Niu, Lihong; Zhang, Zhi; Chen, Zihui; Zhang, Fushi

2008-01-01

The magnitude and dynamic response of the third-order optical nonlinearities of squarylium and croconium dyes in methanol solution were measured by femtosecond degenerate four-wave mixing (DFWM) technique at 800 nm. Ultrafast nonlinear optical responses have been observed, and the magnitude of the second-order hyperpolarizabilities was evaluated to be 5.80 × 10 -31 esu for the squarylium dye and 8.69 × 10 -31 esu for the croconium dye, respectively. The large optical nonlinearities of the dyes can be attributed to their rigid and intramolecular charge transfer structure, and the instantaneous NLO responses of dyes are shorter than the experimental time resolution (50 fs), which is mainly contributed from the electron delocalization. The fast nonlinear response and large third-order optical nonlinearities show that the studied squarylium and croconium dyes might a kind of promising materials for the applications in all-optical switching and modulator.

Bulk strain solitons as a tool for determination of the third order elastic moduli of composite materials

NASA Astrophysics Data System (ADS)

Semenova, I. V.; Belashov, A. V.; Garbuzov, F. E.; Samsonov, A. M.; Semenov, A. A.

2017-06-01

We demonstrate an alternative approach to determination of the third order elastic moduli of materials based on registration of nonlinear bulk strain waves in three basic structural waveguides (rod, plate and shell) and further calculation of the Murnaghan moduli from the recorded wave parameters via simple algebra. These elastic moduli are available in literature for a limited number of materials and are measured with considerable errors, that evidences a demand in novel approaches to their determination.

Atomically-thick two-dimensional crystals: electronic structure regulation and energy device construction.

PubMed

Sun, Yongfu; Gao, Shan; Xie, Yi

2014-01-21

Atomically-thick two-dimensional crystals can provide promising opportunities to satisfy people's requirement of next-generation flexible and transparent nanodevices. However, the characterization of these low-dimensional structures and the understanding of their clear structure-property relationship encounter many great difficulties, owing to the lack of long-range order in the third dimensionality. In this review, we survey the recent progress in fine structure characterization by X-ray absorption fine structure spectroscopy and also overview electronic structure modulation by density-functional calculations in the ultrathin two-dimensional crystals. In addition, we highlight their structure-property relationship, transparent and flexible device construction as well as wide applications in photoelectrochemical water splitting, photodetectors, thermoelectric conversion, touchless moisture sensing, supercapacitors and lithium ion batteries. Finally, we outline the major challenges and opportunities that face the atomically-thick two-dimensional crystals. It is anticipated that the present review will deepen people's understanding of this field and hence contribute to guide the future design of high-efficiency energy-related devices.

Novel third-order Lovelock wormhole solutions

NASA Astrophysics Data System (ADS)

Mehdizadeh, Mohammad Reza; Lobo, Francisco S. N.

2016-06-01

In this work, we consider wormhole geometries in third-order Lovelock gravity and investigate the possibility that these solutions satisfy the energy conditions. In this framework, by applying a specific equation of state, we obtain exact wormhole solutions, and by imposing suitable values for the parameters of the theory, we find that these geometries satisfy the weak energy condition in the vicinity of the throat, due to the presence of higher-order curvature terms. Finally, we trace out a numerical analysis, by assuming a specific redshift function, and find asymptotically flat solutions that satisfy the weak energy condition throughout the spacetime.

Evidence of a forward energy cascade and Kolmogorov self-similarity in submesoscale ocean surface drifter observations

NASA Astrophysics Data System (ADS)

Poje, Andrew C.; Ã-zgökmen, Tamay M.; Bogucki, Darek J.; Kirwan, A. D.

2017-02-01

Using two-point velocity and position data from the near-simultaneous release of O(100) GPS-tracked surface drifters in the northern Gulf of Mexico, we examine the applicability of classical turbulent scaling laws to upper ocean velocity fields. The dataset allows direct estimates of both velocity structure functions and the temporal evolution of the distribution of particle pair separations. On 100 m-10 km spatial scales, and time scales of order 1-10 days, all metrics of the observed surface fluctuations are consistent with standard Kolmogorov turbulence theory in an energy cascade inertial-range regime. The sign of the third-order structure function is negative and proportional to the separation distance for scales ≲10 km where local, fluctuating Rossby numbers are found to be larger than 0.1. The scale-independent energy dissipation rate, or downscale spectral flux, estimated from Kolmogorov's 4/5th law in this regime closely matches nearby microscale dissipation measurements in the near-surface. In contrast, similar statistics derived from a like-sized set of synthetic drifters advected by purely geostrophic altimetric AVISO data agree well with Kolmogorov-Kraichnan scaling for 2D turbulence in the forward enstrophy cascade range.

Finite-temperature phase transitions of third and higher order in gauge theories at large N

DOE PAGES

Nishimura, Hiromichi; Pisarski, Robert D.; Skokov, Vladimir V.

2018-02-15

We study phase transitions in SU(∞) gauge theories at nonzero temperature using matrix models. Our basic assumption is that the effective potential is dominated by double trace terms for the Polyakov loops. As a function of the various parameters, related to terms linear, quadratic, and quartic in the Polyakov loop, the phase diagram exhibits a universal structure. In a large region of this parameter space, there is a continuous phase transition whose order is larger than second. This is a generalization of the phase transition of Gross, Witten, and Wadia (GWW). Depending upon the detailed form of the matrix model,more » the eigenvalue density and the behavior of the specific heat near the transition differ drastically. Here, we speculate that in the pure gauge theory, that although the deconfining transition is thermodynamically of first order, it can be nevertheless conformally symmetric at infnite N.« less

Finite-temperature phase transitions of third and higher order in gauge theories at large N

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nishimura, Hiromichi; Pisarski, Robert D.; Skokov, Vladimir V.

We study phase transitions in SU(∞) gauge theories at nonzero temperature using matrix models. Our basic assumption is that the effective potential is dominated by double trace terms for the Polyakov loops. As a function of the various parameters, related to terms linear, quadratic, and quartic in the Polyakov loop, the phase diagram exhibits a universal structure. In a large region of this parameter space, there is a continuous phase transition whose order is larger than second. This is a generalization of the phase transition of Gross, Witten, and Wadia (GWW). Depending upon the detailed form of the matrix model,more » the eigenvalue density and the behavior of the specific heat near the transition differ drastically. Here, we speculate that in the pure gauge theory, that although the deconfining transition is thermodynamically of first order, it can be nevertheless conformally symmetric at infnite N.« less

Triphenylamine Derived 3-Acetyl and 3-Benzothiazolyl Bis and Tris Coumarins: Synthesis, Photophysical and DFT Assisted Hyperpolarizability Study

NASA Astrophysics Data System (ADS)

Erande, Yogesh; Kothavale, Shantaram; Sreenath, Mavila C.; Chitrambalam, Subramaniyan; Joe, Isaac H.; Sekar, Nagaiyan

2018-02-01

Triphenylamine derived bis- and tris-branched donor-pi-acceptor coumarins with acetyl and benzothiazolyl acceptors are studied for their linear and nonlinear optical properties that originate from their photophysical and molecular structure. Plots of solvent polarities versus the Stokes shift, frontier molecular orbital analysis and Generalised Mulliken Hush analysis have established their strong charge transfer character supported by the strong emission solvatochromism of these chromophores. On the basis of excited state intramolecular charge transfer, the first-, second- and third-order polarizability of these dyes are determined by a solvatochromic method and supported by density functional theory calculations using CAM-B3LYP/6-31g(d). Compared to the acetyl group, the benzothiazolyl group is a strong acceptor, and its corresponding derivatives show enhanced absorption, emission maxima and non-linear optical response. Bond length alternation and bond order alternation analysis reveals that these chromophores approach the cyanine-like framework which is responsible for maximum perturbation to produce high nonlinear optical response. Third order nonlinear susceptibility for dyes 1 and 2 is determined by Z-scan measurement. All of these methods are used to determine the nonlinear optical properties, and thermogravimetric analysis suggests that these chromophores are thermally robust and efficient nonlinear optical materials.

Crystal growth and DFT insight on sodium para-nitrophenolate para-nitrophenol dihydrate single crystal for NLO applications

NASA Astrophysics Data System (ADS)

Selvakumar, S.; Boobalan, Maria Susai; Anthuvan Babu, S.; Ramalingam, S.; Leo Rajesh, A.

2016-12-01

Single crystals of sodium para-nitrophenolate para-nitrophenol dihydrate (SPPD) were grown by slow evaporation technique and its structure has been studied by FT-IR, FT-Raman and single crystal X-ray diffraction techniques. The optical and electrical properties were characterized by UV-Vis spectrum, and dielectric studies respectively. SPPD was thermally stable up to 128 °C as determined by TG-DTA curves. Using the Kurtz-Perry powder method, the second-harmonic generation efficiency was found to be five times to that of KDP. Third-order nonlinear response was studied using Z-scan technique with a He-Ne laser (632.8 nm) and NLO parameters such as intensity dependent refractive index, nonlinear absorption coefficient and third-order susceptibility were also estimated. The molecular geometry from X-ray experiment in the ground state has been compared using density functional theory (DFT) with appropriate basis set. The first-order hyperpolarizability also calculated using DFT approaches. Stability of the molecule arising from hyperconjugative interactions leading to its nonlinear optical activity and charge delocalization were analyzed using natural bond orbital technique. HOMO-LUMO energy gap value suggests the possibility of charge transfer within the molecule. Based on optimized ground state geometries, Natural bond orbital (NBO) analysis was performed to study donor-acceptor interactions.

Synthesis, growth, structural and optical studies of a new organic three dimensional framework: 4-(aminocarbonyl)pyridine 4-(aminocarbonyl)pyridinium hydrogen L-malate

NASA Astrophysics Data System (ADS)

Vijayalakshmi, A.; Vidyavathy, B.; Peramaiyan, G.; Vinitha, G.

2017-02-01

4-(aminocarbonyl)pyridine 4-(aminocarbonyl)pyridinium hydrogen L-malate [(4ACP)(4ACP).(LM)] a new organic nonlinear optical (NLO) crystal was grown by the slow evaporation method. Single crystal X-ray diffraction analysis revealed that the [(4ACP)(4ACP).(LM)] crystal belongs to monoclinic crystal system, space group P21/n, with a three dimensional network. Thermogravimetry (TG) and differential thermal (DT) analyses showed that [(4ACP)(4ACP).(LM)] is thermally stable up to 165 °C. The optical transmittance window and the lower cut-off wavelength of [(4ACP)(4ACP).(LM)] were found out by UV-vis-NIR spectral study. The molecular structure of [(4ACP)(4ACP).(LM)] was further confirmed by FTIR spectral studies. The relative dielectric permittivity and dielectric loss were determined as function of frequency and temperature. The third order nonlinear optical property of [(4ACP)(4ACP).(LM)] was studied by the Z-scan technique using a 532 nm diode pumped CW Nd:YAG laser. Nonlinear refractive index, nonlinear absorption coefficient and third order nonlinear susceptibility of the grown crystal were found to be 7.38×10-8 cm2/W, 0.08×10-4 cm/W and 5.36×10-6 esu, respectively. The laser damage threshold value is found to be 1.75 GW/cm2

Chiral behaviour of the wave functions for three wave guides in the vicinity of an exceptional point of third order

NASA Astrophysics Data System (ADS)

Heiss, Walter Dieter; Wunner, Günter

2017-12-01

A matrix model that has been used to describe essential features of a parity-time symmetric set-up of three coupled wave guides is investigated. The emphasis of the study lies on the occurrence of an exceptional point of third order. It is demonstrated that the eigenfunctions in close vicinity of the exceptional point have a distinctive chiral behaviour. Using data describing realistic situations it is argued that such chiral behaviour can be tested experimentally.

A compact and realistic cerebral cortical layout derived from prewhitened resting-state fMRI time series: Cherniak's adjacency rule, size law, and metamodule grouping upheld

PubMed Central

Lewis, Scott M.; Christova, Peka; Jerde, Trenton A.; Georgopoulos, Apostolos P.

2012-01-01

We used hierarchical tree clustering to derive a functional organizational chart of 52 human cortical areas (26 per hemisphere) from zero-lag correlations calculated between single-voxel, prewhitened, resting-state BOLD fMRI time series in 18 subjects. No special “resting-state networks” were identified. There were four major features in the resulting tree (dendrogram). First, there was a strong clustering of homotopic, left-right hemispheric areas. Second, cortical areas were concatenated in multiple, partially overlapping clusters. Third, the arrangement of the areas revealed a layout that closely resembled the actual layout of the cerebral cortex, namely an orderly progression from anterior to posterior. And fourth, the layout of the cortical areas in the tree conformed to principles of efficient, compact layout of components proposed by Cherniak. Since the tree was derived on the basis of the strength of neural correlations, these results document an orderly relation between functional interactions and layout, i.e., between structure and function. PMID:22973198

Third order LPF type compensator for flexible rotor suspension

NASA Technical Reports Server (NTRS)

Matsushita, Osami; Takahashi, Naohiko; Takagi, Michiyuki

1994-01-01

The tuning job of the compensator for levitating flexible rotors supported by active magnetic bearings (AMB) concerns providing a good damping effect to the critical speed modes while avoiding the spillover problem on the instability of higher bending modes. In this paper, an idea for design of the control law of the compensator based on utilizing a third order low pass filter (LPF) is proposed to essentially enable elimination of the spillover instability. According to the proposed design method, good damping effects for the critical speeds are obtained by the usual phase lead/lag function. Stabilization for all of higher bending modes is completed by the additional function of the 3rd order LPF due to its phase lag approaching about -270 degrees in the high frequency domain. This idea is made clear by experiments and simulations.

Modeling and Density Estimation of an Urban Freeway Network Based on Dynamic Graph Hybrid Automata

PubMed Central

Chen, Yangzhou; Guo, Yuqi; Wang, Ying

2017-01-01

In this paper, in order to describe complex network systems, we firstly propose a general modeling framework by combining a dynamic graph with hybrid automata and thus name it Dynamic Graph Hybrid Automata (DGHA). Then we apply this framework to model traffic flow over an urban freeway network by embedding the Cell Transmission Model (CTM) into the DGHA. With a modeling procedure, we adopt a dual digraph of road network structure to describe the road topology, use linear hybrid automata to describe multi-modes of dynamic densities in road segments and transform the nonlinear expressions of the transmitted traffic flow between two road segments into piecewise linear functions in terms of multi-mode switchings. This modeling procedure is modularized and rule-based, and thus is easily-extensible with the help of a combination algorithm for the dynamics of traffic flow. It can describe the dynamics of traffic flow over an urban freeway network with arbitrary topology structures and sizes. Next we analyze mode types and number in the model of the whole freeway network, and deduce a Piecewise Affine Linear System (PWALS) model. Furthermore, based on the PWALS model, a multi-mode switched state observer is designed to estimate the traffic densities of the freeway network, where a set of observer gain matrices are computed by using the Lyapunov function approach. As an example, we utilize the PWALS model and the corresponding switched state observer to traffic flow over Beijing third ring road. In order to clearly interpret the principle of the proposed method and avoid computational complexity, we adopt a simplified version of Beijing third ring road. Practical application for a large-scale road network will be implemented by decentralized modeling approach and distributed observer designing in the future research. PMID:28353664

Modeling and Density Estimation of an Urban Freeway Network Based on Dynamic Graph Hybrid Automata.

PubMed

Chen, Yangzhou; Guo, Yuqi; Wang, Ying

2017-03-29

In this paper, in order to describe complex network systems, we firstly propose a general modeling framework by combining a dynamic graph with hybrid automata and thus name it Dynamic Graph Hybrid Automata (DGHA). Then we apply this framework to model traffic flow over an urban freeway network by embedding the Cell Transmission Model (CTM) into the DGHA. With a modeling procedure, we adopt a dual digraph of road network structure to describe the road topology, use linear hybrid automata to describe multi-modes of dynamic densities in road segments and transform the nonlinear expressions of the transmitted traffic flow between two road segments into piecewise linear functions in terms of multi-mode switchings. This modeling procedure is modularized and rule-based, and thus is easily-extensible with the help of a combination algorithm for the dynamics of traffic flow. It can describe the dynamics of traffic flow over an urban freeway network with arbitrary topology structures and sizes. Next we analyze mode types and number in the model of the whole freeway network, and deduce a Piecewise Affine Linear System (PWALS) model. Furthermore, based on the PWALS model, a multi-mode switched state observer is designed to estimate the traffic densities of the freeway network, where a set of observer gain matrices are computed by using the Lyapunov function approach. As an example, we utilize the PWALS model and the corresponding switched state observer to traffic flow over Beijing third ring road. In order to clearly interpret the principle of the proposed method and avoid computational complexity, we adopt a simplified version of Beijing third ring road. Practical application for a large-scale road network will be implemented by decentralized modeling approach and distributed observer designing in the future research.

Trend-surface analysis of the structure of the Ste. Genevieve limestone in the Effingham, Illinois, area

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stevenson, D.

1970-01-01

Recent studies of oil accumulations in the Ste. Genevieve Limestone Formation in Illinois demonstrate the usefulness of fitting third-order trend surfaces to structural data and analyzing the residuals calculated by subtracting the trend surface from the structure surface. Known oil pools are located in areas having positive residual values. This type of investigation, supplemented by conventional structural and stratigraphic studies, was performed on a 9-township (approx. 324 sq miles) area in Effingham and Shelby counties, Illinois. The known oil pools in the oolite and sandstone lenses of the Ste. Genevieve Formation lie within positive residuals resulting from the difference betweenmore » a third-order trend surface and the structural surface on top of the Ste. Genevieve. A composite map outlining areas where present anticlinal noses, sandstone lenses, and positive residuals lie in close proximity to each other is included in this report to indicate places where future exploration for Ste. Genevieve oil would have the greatest chance for success.« less

The trispectrum in the Effective Field Theory of Large Scale Structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bertolini, Daniele; Schutz, Katelin; Solon, Mikhail P.

2016-06-01

We compute the connected four point correlation function (the trispectrum in Fourier space) of cosmological density perturbations at one-loop order in Standard Perturbation Theory (SPT) and the Effective Field Theory of Large Scale Structure (EFT of LSS). This paper is a companion to our earlier work on the non-Gaussian covariance of the matter power spectrum, which corresponds to a particular wavenumber configuration of the trispectrum. In the present calculation, we highlight and clarify some of the subtle aspects of the EFT framework that arise at third order in perturbation theory for general wavenumber configurations of the trispectrum. We consistently incorporatemore » vorticity and non-locality in time into the EFT counterterms and lay out a complete basis of building blocks for the stress tensor. We show predictions for the one-loop SPT trispectrum and the EFT contributions, focusing on configurations which have particular relevance for using LSS to constrain primordial non-Gaussianity.« less

Cascading second-order nonlinear processes in a lithium niobate-on-insulator microdisk.

PubMed

Liu, Shijie; Zheng, Yuanlin; Chen, Xianfeng

2017-09-15

Whispering-gallery-mode (WGM) microcavities are very important in both fundamental science and practical applications, among which on-chip second-order nonlinear microresonators play an important role in integrated photonic functionalities. Here we demonstrate resonant second-harmonic generation (SHG) and cascaded third-harmonic generation (THG) in a lithium niobate-on-insulator (LNOI) microdisk resonator. Efficient SHG in the visible range was obtained with only several mW input powers at telecom wavelengths. THG was also observed through a cascading process, which reveals simultaneous phase matching and strong mode coupling in the resonator. Cascading of second-order nonlinear processes gives rise to an effectively large third-order nonlinearity, which makes on-chip second-order nonlinear microresonators a promising frequency converter for integrated nonlinear photonics.

Ab-initio and DFT methodologies for computing hyperpolarizabilities and susceptibilities of highly conjugated organic compounds for nonlinear optical applications

NASA Astrophysics Data System (ADS)

Karakas, A.; Karakaya, M.; Ceylan, Y.; El Kouari, Y.; Taboukhat, S.; Boughaleb, Y.; Sofiani, Z.

2016-06-01

In this talk, after a short introduction on the methodologies used for computing dipole polarizability (α), second and third-order hyperpolarizability and susceptibility; the results of theoretical studies performed on density functional theory (DFT) and ab-initio quantum mechanical calculations of nonlinear optical (NLO) properties for a few selected organic compounds and polymers will be explained. The electric dipole moments (μ) and dispersion-free first hyperpolarizabilities (β) for a family of azo-azulenes and a styrylquinolinium dye have been determined by DFT at B3LYP level. To reveal the frequency-dependent NLO behavior, the dynamic α, second hyperpolarizabilities (γ), second (χ(2)) and third-order (χ(3)) susceptibilites have been evaluated using time-dependent HartreeFock (TDHF) procedure. To provide an insight into the third-order NLO phenomena of a series of pyrrolo-tetrathiafulvalene-based molecules and pushpull azobenzene polymers, two-photon absorption (TPA) characterizations have been also investigated by means of TDHF. All computed results of the examined compounds are compared with their previous experimental findings and the measured data for similar structures in the literature. The one-photon absorption (OPA) characterizations of the title molecules have been theoretically obtained by configuration interaction (CI) method. The highest occupied molecular orbitals (HOMO), the lowest unoccupied molecular orbitals (LUMO) and the HOMO-LUMO band gaps have been revealed by DFT at B3LYP level for azo-azulenes, styrylquinolinium dye, push-pull azobenzene polymers and by parametrization method 6 (PM6) for pyrrolo-tetrathiafulvalene-based molecules.

Theoretical limit of spatial resolution in diffuse optical tomography using a perturbation model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Konovalov, A B; Vlasov, V V

2014-03-28

We have assessed the limit of spatial resolution of timedomain diffuse optical tomography (DOT) based on a perturbation reconstruction model. From the viewpoint of the structure reconstruction accuracy, three different approaches to solving the inverse DOT problem are compared. The first approach involves reconstruction of diffuse tomograms from straight lines, the second – from average curvilinear trajectories of photons and the third – from total banana-shaped distributions of photon trajectories. In order to obtain estimates of resolution, we have derived analytical expressions for the point spread function and modulation transfer function, as well as have performed a numerical experiment onmore » reconstruction of rectangular scattering objects with circular absorbing inhomogeneities. It is shown that in passing from reconstruction from straight lines to reconstruction using distributions of photon trajectories we can improve resolution by almost an order of magnitude and exceed the accuracy of reconstruction of multi-step algorithms used in DOT. (optical tomography)« less

Simulation of Shallow Cumuli and Their Transition to Deep Convective Clouds by Cloud-resolving Models with Different Third-order Turbulence Closures

NASA Technical Reports Server (NTRS)

Cheng, Anning; Xu, Kuan-Man

2006-01-01

The abilities of cloud-resolving models (CRMs) with the double-Gaussian based and the single-Gaussian based third-order closures (TOCs) to simulate the shallow cumuli and their transition to deep convective clouds are compared in this study. The single-Gaussian based TOC is fully prognostic (FP), while the double-Gaussian based TOC is partially prognostic (PP). The latter only predicts three important third-order moments while the former predicts all the thirdorder moments. A shallow cumulus case is simulated by single-column versions of the FP and PP TOC models. The PP TOC improves the simulation of shallow cumulus greatly over the FP TOC by producing more realistic cloud structures. Large differences between the FP and PP TOC simulations appear in the cloud layer of the second- and third-order moments, which are related mainly to the underestimate of the cloud height in the FP TOC simulation. Sensitivity experiments and analysis of probability density functions (PDFs) used in the TOCs show that both the turbulence-scale condensation and higher-order moments are important to realistic simulations of the boundary-layer shallow cumuli. A shallow to deep convective cloud transition case is also simulated by the 2-D versions of the FP and PP TOC models. Both CRMs can capture the transition from the shallow cumuli to deep convective clouds. The PP simulations produce more and deeper shallow cumuli than the FP simulations, but the FP simulations produce larger and wider convective clouds than the PP simulations. The temporal evolutions of cloud and precipitation are closely related to the turbulent transport, the cold pool and the cloud-scale circulation. The large amount of turbulent mixing associated with the shallow cumuli slows down the increase of the convective available potential energy and inhibits the early transition to deep convective clouds in the PP simulation. When the deep convective clouds fully develop and the precipitation is produced, the cold pools produced by the evaporation of the precipitation are not favorable to the formation of shallow cumuli.

Theory of Mind Development in Adolescence and Early Adulthood: The Growing Complexity of Recursive Thinking Ability

PubMed Central

Valle, Annalisa; Massaro, Davide; Castelli, Ilaria; Marchetti, Antonella

2015-01-01

This study explores the development of theory of mind, operationalized as recursive thinking ability, from adolescence to early adulthood (N = 110; young adolescents = 47; adolescents = 43; young adults = 20). The construct of theory of mind has been operationalized in two different ways: as the ability to recognize the correct mental state of a character, and as the ability to attribute the correct mental state in order to predict the character’s behaviour. The Imposing Memory Task, with five recursive thinking levels, and a third-order false-belief task with three recursive thinking levels (devised for this study) have been used. The relationship among working memory, executive functions, and linguistic skills are also analysed. Results show that subjects exhibit less understanding of elevated recursive thinking levels (third, fourth, and fifth) compared to the first and second levels. Working memory is correlated with total recursive thinking, whereas performance on the linguistic comprehension task is related to third level recursive thinking in both theory of mind tasks. An effect of age on third-order false-belief task performance was also found. A key finding of the present study is that the third-order false-belief task shows significant age differences in the application of recursive thinking that involves the prediction of others’ behaviour. In contrast, such an age effect is not observed in the Imposing Memory Task. These results may support the extension of the investigation of the third order false belief after childhood. PMID:27247645

Reassessing the Dlx code: the genetic regulation of branchial arch skeletal pattern and development

PubMed Central

Depew, Michael J; Simpson, Carol A; Morasso, Maria; Rubenstein, John LR

2005-01-01

The branchial arches are meristic vertebrate structures, being metameric both between each other within the rostrocaudal series along the ventrocephalic surface of the embryonic head and within each individual arch: thus, just as each branchial arch must acquire a unique identity along the rostrocaudal axis, each structure within the proximodistal axis of an arch must also acquire a unique identity. It is believed that regional specification of metameric structures is controlled by the nested expression of related genes resulting in a regional code, a principal that is though to be demonstrated by the regulation of rostrocaudal axis development in animals exerted by the nested HOM-C/Hox homeobox genes. The nested expression pattern of the Dlx genes within the murine branchial arch ectomesenchyme has more recently led to the proposal of a Dlx code for the regional specification along the proximodistal axis of the branchial arches (i.e. it establishes intra-arch identity). This review re-examines this hypothesis, and presents new work on an allelic series of Dlx loss-of-function mouse mutants that includes various combinations of Dlx1, Dlx2, Dlx3, Dlx5 and Dlx6. Although we confirm fundamental aspects of the hypothesis, we further report a number of novel findings. First, contrary to initial reports, Dlx1, Dlx2 and Dlx1/2 heterozygotes exhibit alterations of branchial arch structures and Dlx2−/− and Dlx1/2−/− mutants have slight alterations of structures derived from the distal portions of their branchial arches. Second, we present evidence for a role for murine Dlx3 in the development of the branchial arches. Third, analysis of compound Dlx mutants reveals four grades of mandibular arch transformations and that the genetic interactions of cis first-order (e.g. Dlx5 and Dlx6), trans second-order (e.g. Dlx5 and Dlx2) and trans third-order paralogues (e.g. Dlx5 and Dlx1) result in significant and distinct morphological differences in mandibular arch development. We conclude by integrating functions of the Dlx genes within the context of a hypothesized general mechanism for the establishment of pattern and polarity in the first branchial arch of gnathostomes that includes regionally secreted growth factors such as Fgf8 and Bmp and other transcription factors such as Msx1, and is consistent both with the structure of the conserved gnathostome jaw bauplan and the elaboration of this bauplan to meet organismal end-point designs. PMID:16313391

Theory of third-order spectroscopic methods to extract detailed molecular orientational dynamics for planar surfaces and other uniaxial systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nishida, Jun; Fayer, Michael D., E-mail: fayer@stanford.edu

Functionalized organic monolayers deposited on planar two-dimensional surfaces are important systems for studying ultrafast orientational motions and structures of interfacial molecules. Several studies have successfully observed the orientational relaxation of functionalized monolayers by fluorescence depolarization experiments and recently by polarization-resolved heterodyne detected vibrational transient grating (HDTG) experiments. In this article we provide a model-independent theory to extract orientational correlation functions unique to interfacial molecules and other uniaxial systems based on polarization-resolved resonant third-order spectroscopies, such as pump-probe spectroscopy, HDTG spectroscopy, and fluorescence depolarization experiment. It will be shown (in the small beam-crossing angle limit) that five measurements are necessary tomore » completely characterize the monolayer's motions: I{sub ∥}(t) and I{sub ⊥}(t) with the incident beams normal to the surface, I{sub ∥}(t) and I{sub ⊥}(t) with a non-zero incident angle, and a time averaged linear dichroism measurement. Once these measurements are performed, two orientational correlation functions corresponding to in-plane and out-of-plane motions are obtained. The procedure is applicable not only for monolayers on flat surfaces, but any samples with uniaxial symmetry such as uniaxial liquid crystals and aligned planar bilayers. The theory is valid regardless of the nature of the actual molecular motions on interface. We then apply the general results to wobbling-in-a-cone model, in which molecular motions are restricted to a limited range of angles. Within the context of the model, the cone angle, the tilt of the cone relative to the surface normal, and the orientational diffusion constant can be determined. The results are extended to describe analysis of experiments where the beams are not crossing in the small angle limit.« less

Nonlinear damping model for flexible structures. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Zang, Weijian

1990-01-01

The study of nonlinear damping problem of flexible structures is addressed. Both passive and active damping, both finite dimensional and infinite dimensional models are studied. In the first part, the spectral density and the correlation function of a single DOF nonlinear damping model is investigated. A formula for the spectral density is established with O(Gamma(sub 2)) accuracy based upon Fokker-Planck technique and perturbation. The spectral density depends upon certain first order statistics which could be obtained if the stationary density is known. A method is proposed to find the approximate stationary density explicitly. In the second part, the spectral density of a multi-DOF nonlinear damping model is investigated. In the third part, energy type nonlinear damping model in an infinite dimensional setting is studied.

The optimal community detection of software based on complex networks

NASA Astrophysics Data System (ADS)

Huang, Guoyan; Zhang, Peng; Zhang, Bing; Yin, Tengteng; Ren, Jiadong

2016-02-01

The community structure is important for software in terms of understanding the design patterns, controlling the development and the maintenance process. In order to detect the optimal community structure in the software network, a method Optimal Partition Software Network (OPSN) is proposed based on the dependency relationship among the software functions. First, by analyzing the information of multiple execution traces of one software, we construct Software Execution Dependency Network (SEDN). Second, based on the relationship among the function nodes in the network, we define Fault Accumulation (FA) to measure the importance of the function node and sort the nodes with measure results. Third, we select the top K(K=1,2,…) nodes as the core of the primal communities (only exist one core node). By comparing the dependency relationships between each node and the K communities, we put the node into the existing community which has the most close relationship. Finally, we calculate the modularity with different initial K to obtain the optimal division. With experiments, the method OPSN is verified to be efficient to detect the optimal community in various softwares.

Theoretical study on the spectroscopic and third-order nonlinear optical properties of two-dimensional charge-transfer pyrazine derivatives

NASA Astrophysics Data System (ADS)

Li, Haipeng; Zhang, Yi; Bi, Zetong; Xu, Runfeng; Li, Mingxue; Shen, Xiaopeng; Tang, Gang; Han, Kui

2017-12-01

In this paper, density functional theory method was employed to study the electronic absorption spectrum and electronic static second hyperpolarisability of X-shaped pyrazine derivatives with two-dimensional charge-transfer structures. Computational results show that the push-pull electron abilities of the substituent groups and the length of the conjugated chains affect the electronic spectrum and static second hyperpolarisability of the pyrazine derivatives. As the push-pull electron abilities of the substituent groups or the length of the conjugated chains increases, the frontier molecular orbital energy gap decreases, resulting in increased second hyperpolarisability and redshift of the electronic absorption bands. The electronic absorption spectra of the pyrazine derivatives maintain good transparency in the blue light band. The electronic static second hyperpolarisability exhibits a linear relationship to the frontier molecular orbital energy gap. Particularly, increasing/decreasing the push-pull electron abilities of the substituent groups considerably affect the static second hyperpolarisability in long conjugated systems, which is important to the modulation of molecular organic nonlinear optical (NLO) properties. The studied pyrazine derivatives show large third-order NLO response and good transparency in the blue light band and are thus promising candidates as NLO materials for photonics applications.

Optical properties of the Tietz-Hua quantum well under the applied external fields

NASA Astrophysics Data System (ADS)

Kasapoglu, E.; Sakiroglu, S.; Ungan, F.; Yesilgul, U.; Duque, C. A.; Sökmen, I.

2017-12-01

In this study, the effects of the electric and magnetic fields as well as structure parameter- γ on the total absorption coefficient, including linear and third order nonlinear absorption coefficients for the optical transitions between any two subband in the Tietz-Hua quantum well have been investigated. The optical transitions were investigated by using the density matrix formalism and the perturbation expansion method. The Tietz-Hua quantum well becomes narrower (wider) when the γ - structure parameter increases (decreases) and so the energies of the bound states will be functions of this parameter. Therefore, we can provide the red or blue shift in the peak position of the absorption coefficient by changing the strength of the electric and magnetic fields as well as the structure parameters and these results can be used to adjust and control the optical properties of the Tietz-Hua quantum well.

A finite-element method for large-amplitude, two-dimensional panel flutter at hypersonic speeds

NASA Technical Reports Server (NTRS)

Mei, Chuh; Gray, Carl E.

1989-01-01

The nonlinear flutter behavior of a two-dimensional panel in hypersonic flow is investigated analytically. An FEM formulation based unsteady third-order piston theory (Ashley and Zartarian, 1956; McIntosh, 1970) and taking nonlinear structural and aerodynamic phenomena into account is derived; the solution procedure is outlined; and typical results are presented in extensive tables and graphs. A 12-element finite-element solution obtained using an alternative method for linearizing the assumed limit-cycle time function is shown to give predictions in good agreement with classical analytical results for large-amplitude vibration in a vacuum and large-amplitude panel flutter, using linear aerodynamics.

Chebyshev collocation approach for vibration analysis of functionally graded porous beams based on third-order shear deformation theory

NASA Astrophysics Data System (ADS)

Wattanasakulpong, Nuttawit; Chaikittiratana, Arisara; Pornpeerakeat, Sacharuck

2018-06-01

In this paper, vibration analysis of functionally graded porous beams is carried out using the third-order shear deformation theory. The beams have uniform and non-uniform porosity distributions across their thickness and both ends are supported by rotational and translational springs. The material properties of the beams such as elastic moduli and mass density can be related to the porosity and mass coefficient utilizing the typical mechanical features of open-cell metal foams. The Chebyshev collocation method is applied to solve the governing equations derived from Hamilton's principle, which is used in order to obtain the accurate natural frequencies for the vibration problem of beams with various general and elastic boundary conditions. Based on the numerical experiments, it is revealed that the natural frequencies of the beams with asymmetric and non-uniform porosity distributions are higher than those of other beams with uniform and symmetric porosity distributions.

Extreme brain events: Higher-order statistics of brain resting activity and its relation with structural connectivity

NASA Astrophysics Data System (ADS)

Amor, T. A.; Russo, R.; Diez, I.; Bharath, P.; Zirovich, M.; Stramaglia, S.; Cortes, J. M.; de Arcangelis, L.; Chialvo, D. R.

2015-09-01

The brain exhibits a wide variety of spatiotemporal patterns of neuronal activity recorded using functional magnetic resonance imaging as the so-called blood-oxygenated-level-dependent (BOLD) signal. An active area of work includes efforts to best describe the plethora of these patterns evolving continuously in the brain. Here we explore the third-moment statistics of the brain BOLD signals in the resting state as a proxy to capture extreme BOLD events. We find that the brain signal exhibits typically nonzero skewness, with positive values for cortical regions and negative values for subcortical regions. Furthermore, the combined analysis of structural and functional connectivity demonstrates that relatively more connected regions exhibit activity with high negative skewness. Overall, these results highlight the relevance of recent results emphasizing that the spatiotemporal location of the relatively large-amplitude events in the BOLD time series contains relevant information to reproduce a number of features of the brain dynamics during resting state in health and disease.

Nonlinear susceptibilities of finite conjugated organic polymers

NASA Technical Reports Server (NTRS)

Beratan, David N.; Onuchic, Jose Nelson; Perry, Joseph W.

1987-01-01

Tight-binding calculations of the length dependence of the third-order molecular hyperpolarizability for polyenes and polyynes are reported. The pi-electron wave functions were determined by exploiting the limited translational symmetry of the molecules. Perturbation theory was used to calculate the longitudinal component of the electronic nonresonant hyperpolarizability. This is the first two-'band' calculation of third-order hyperpolarizabilities on finite pi-electron systems of varying length. In contrast to the results of the one-'band' models, the hyperpolarizability densities increase rapidly and then, after about 10-15 repeating units, approach an asymptotic value.

A reference-modified density functional theory: An application to solvation free-energy calculations for a Lennard-Jones solution.

PubMed

Sumi, Tomonari; Maruyama, Yutaka; Mitsutake, Ayori; Koga, Kenichiro

2016-06-14

In the conventional classical density functional theory (DFT) for simple fluids, an ideal gas is usually chosen as the reference system because there is a one-to-one correspondence between the external field and the density distribution function, and the exact intrinsic free-energy functional is available for the ideal gas. In this case, the second-order density functional Taylor series expansion of the excess intrinsic free-energy functional provides the hypernetted-chain (HNC) approximation. Recently, it has been shown that the HNC approximation significantly overestimates the solvation free energy (SFE) for an infinitely dilute Lennard-Jones (LJ) solution, especially when the solute particles are several times larger than the solvent particles [T. Miyata and J. Thapa, Chem. Phys. Lett. 604, 122 (2014)]. In the present study, we propose a reference-modified density functional theory as a systematic approach to improve the SFE functional as well as the pair distribution functions. The second-order density functional Taylor series expansion for the excess part of the intrinsic free-energy functional in which a hard-sphere fluid is introduced as the reference system instead of an ideal gas is applied to the LJ pure and infinitely dilute solution systems and is proved to remarkably improve the drawbacks of the HNC approximation. Furthermore, the third-order density functional expansion approximation in which a factorization approximation is applied to the triplet direct correlation function is examined for the LJ systems. We also show that the third-order contribution can yield further refinements for both the pair distribution function and the excess chemical potential for the pure LJ liquids.

Third-order polynomial model for analyzing stickup state laminated structure in flexible electronics

NASA Astrophysics Data System (ADS)

Meng, Xianhong; Wang, Zihao; Liu, Boya; Wang, Shuodao

2018-02-01

Laminated hard-soft integrated structures play a significant role in the fabrication and development of flexible electronics devices. Flexible electronics have advantageous characteristics such as soft and light-weight, can be folded, twisted, flipped inside-out, or be pasted onto other surfaces of arbitrary shapes. In this paper, an analytical model is presented to study the mechanics of laminated hard-soft structures in flexible electronics under a stickup state. Third-order polynomials are used to describe the displacement field, and the principle of virtual work is adopted to derive the governing equations and boundary conditions. The normal strain and the shear stress along the thickness direction in the bi-material region are obtained analytically, which agree well with the results from finite element analysis. The analytical model can be used to analyze stickup state laminated structures, and can serve as a valuable reference for the failure prediction and optimal design of flexible electronics in the future.

The structure and function of the American beekeeping industry

USDA-ARS?s Scientific Manuscript database

America has had a long history with beekeeping and plays a leadership role in global beekeeping industry, which provides critical pollination services to agricultural crops constituting one-third of the world’s consumed foods. This article aims to provide an overview of the structure and function of...

Extension of the self-consistent-charge density-functional tight-binding method: third-order expansion of the density functional theory total energy and introduction of a modified effective coulomb interaction.

PubMed

Yang, Yang; Yu, Haibo; York, Darrin; Cui, Qiang; Elstner, Marcus

2007-10-25

The standard self-consistent-charge density-functional-tight-binding (SCC-DFTB) method (Phys. Rev. B 1998, 58, 7260) is derived by a second-order expansion of the density functional theory total energy expression, followed by an approximation of the charge density fluctuations by charge monopoles and an effective damped Coulomb interaction between the atomic net charges. The central assumptions behind this effective charge-charge interaction are the inverse relation of atomic size and chemical hardness and the use of a fixed chemical hardness parameter independent of the atomic charge state. While these approximations seem to be unproblematic for many covalently bound systems, they are quantitatively insufficient for hydrogen-bonding interactions and (anionic) molecules with localized net charges. Here, we present an extension of the SCC-DFTB method to incorporate third-order terms in the charge density fluctuations, leading to chemical hardness parameters that are dependent on the atomic charge state and a modification of the Coulomb scaling to improve the electrostatic treatment within the second-order terms. These modifications lead to a significant improvement in the description of hydrogen-bonding interactions and proton affinities of biologically relevant molecules.

78 FR 60356 - Self-Regulatory Organizations; The Options Clearing Corporation; Order Approving Proposed Rule...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-10-01

... choose an alternative reduction method. Third, in order to better reflect technological advancements as well as the decentralized operational structures and remote access adopted to address business... clear confirmed trades and otherwise conduct all of its business with OCC on any given day. Fourth, OCC...

Synthesis and characterization of d10 metal complexes of 3-Me-5-FcPz: Structural, theoretical and third order nonlinear optical properties

NASA Astrophysics Data System (ADS)

Senthilkumar, Kabali; Thirumoorthy, Krishnan; Vinitha, G.; Soni, Kiran; Bhuvanesh, Nattamai S. P.; Palanisami, Nallasamy

2017-01-01

The d10 metal complexes based on 3-methyl-5-ferrocenyl-1H-pyrazole (L = 3-Me-5-FcPz) ligand [M(L)4(NO3)2] Zn=(1) and Cd=(2), [Hg(L)4(NO3)2].dmf (3) have been synthesized and characterized by FT-IR, NMR, UV-Vis and elemental analysis. The molecular structure of compound 2 and its crystal packing were determined by single crystal X-ray diffraction. The nitrate anions are also involved in intermolecular hydrogen bonding with adjacent ferrocene units and it forms zig-zag one-dimensional polymeric structure. UV-Vis investigations on the positive solvatochromic behavior of 1-3 revealed that the solvation of the push-pull character increases with increasing polarity. The third-order nonlinear optical (NLO) properties of 1-3 have been determined by Z-scan technique and the results indicate that compounds 1-3 exhibits the strong self-defocusing effect. The nonlinear susceptibility χ(3) values are calculated in the order of 10-6 esu.

Algebro-geometric Solutions for the Derivative Burgers Hierarchy

NASA Astrophysics Data System (ADS)

Hou, Yu; Fan, Engui; Qiao, Zhijun; Wang, Zhong

2015-02-01

Though completely integrable Camassa-Holm (CH) equation and Degasperis-Procesi (DP) equation are cast in the same peakon family, they possess the second- and third-order Lax operators, respectively. From the viewpoint of algebro-geometrical study, this difference lies in hyper-elliptic and non-hyper-elliptic curves. The non-hyperelliptic curves lead to great difficulty in the construction of algebro-geometric solutions of the DP equation. In this paper, we study algebro-geometric solutions for the derivative Burgers (DB) equation, which is derived by Qiao and Li (2004) as a short wave model of the DP equation with the help of functional gradient and a pair of Lenard operators. Based on the characteristic polynomial of a Lax matrix for the DB equation, we introduce a third order algebraic curve with genus , from which the associated Baker-Akhiezer functions, meromorphic function, and Dubrovin-type equations are constructed. Furthermore, the theory of algebraic curve is applied to derive explicit representations of the theta function for the Baker-Akhiezer functions and the meromorphic function. In particular, the algebro-geometric solutions are obtained for all equations in the whole DB hierarchy.

Quadratic electroabsorption studies of molecular motion in dye-doped polymers

NASA Astrophysics Data System (ADS)

Poga, Constantina; Kuzyk, Mark G.; Dirk, Carl W.

1993-02-01

This paper reports on quadratic electroabsorption studies of thin-film solid solutions of squarylium dye molecules in poly(methylmethacrylate) polymer with the aim of understanding the role of electronic and reorientational mechanisms in the third-order nonlinear-optical susceptibility. We present a generalized theory of the quadratic electrooptic response that includes both electronic mechanisms and molecular reorientation and show that the ratio of two independent third-order susceptibility tensor components, namely (chi) (3)3333/(chi) (3)1133, determines the relative contribution of each mechanism. Based on these theoretical results, we have designed and built an experiment that determines this ratio as a function of temperature and wavelength. Results show that at room temperature and near the first electronic transition wavelength, the response is dominated by the electronic mechanism, and that the reorientational contribution dominates when the sample is heated above its glass transition temperature. Furthermore, results show that, off-resonance, the sign of the imaginary part of the third-order susceptibility is positive. Quadratic electroabsorption is thus shown to be a versatile tool for measuring the imaginary part of the third-order nonlinear-optical susceptibility which yields information about the interaction of polymer and dopant molecule.

Tensor hypercontraction density fitting. I. Quartic scaling second- and third-order Møller-Plesset perturbation theory

NASA Astrophysics Data System (ADS)

Hohenstein, Edward G.; Parrish, Robert M.; Martínez, Todd J.

2012-07-01

Many approximations have been developed to help deal with the O(N4) growth of the electron repulsion integral (ERI) tensor, where N is the number of one-electron basis functions used to represent the electronic wavefunction. Of these, the density fitting (DF) approximation is currently the most widely used despite the fact that it is often incapable of altering the underlying scaling of computational effort with respect to molecular size. We present a method for exploiting sparsity in three-center overlap integrals through tensor decomposition to obtain a low-rank approximation to density fitting (tensor hypercontraction density fitting or THC-DF). This new approximation reduces the 4th-order ERI tensor to a product of five matrices, simultaneously reducing the storage requirement as well as increasing the flexibility to regroup terms and reduce scaling behavior. As an example, we demonstrate such a scaling reduction for second- and third-order perturbation theory (MP2 and MP3), showing that both can be carried out in O(N4) operations. This should be compared to the usual scaling behavior of O(N5) and O(N6) for MP2 and MP3, respectively. The THC-DF technique can also be applied to other methods in electronic structure theory, such as coupled-cluster and configuration interaction, promising significant gains in computational efficiency and storage reduction.

Recent improvements to Binding MOAD: a resource for protein–ligand binding affinities and structures

PubMed Central

Ahmed, Aqeel; Smith, Richard D.; Clark, Jordan J.; Dunbar, James B.; Carlson, Heather A.

2015-01-01

For over 10 years, Binding MOAD (Mother of All Databases; http://www.BindingMOAD.org) has been one of the largest resources for high-quality protein–ligand complexes and associated binding affinity data. Binding MOAD has grown at the rate of 1994 complexes per year, on average. Currently, it contains 23 269 complexes and 8156 binding affinities. Our annual updates curate the data using a semi-automated literature search of the references cited within the PDB file, and we have recently upgraded our website and added new features and functionalities to better serve Binding MOAD users. In order to eliminate the legacy application server of the old platform and to accommodate new changes, the website has been completely rewritten in the LAMP (Linux, Apache, MySQL and PHP) environment. The improved user interface incorporates current third-party plugins for better visualization of protein and ligand molecules, and it provides features like sorting, filtering and filtered downloads. In addition to the field-based searching, Binding MOAD now can be searched by structural queries based on the ligand. In order to remove redundancy, Binding MOAD records are clustered in different families based on 90% sequence identity. The new Binding MOAD, with the upgraded platform, features and functionalities, is now equipped to better serve its users. PMID:25378330

Hybrid Methods Reveal Multiple Flexibly Linked DNA Polymerases within the Bacteriophage T7 Replisome

DOE PAGES

Wallen, Jamie R.; Zhang, Hao; Weis, Caroline; ...

2017-01-03

The physical organization of DNA enzymes at a replication fork enables efficient copying of two antiparallel DNA strands, yet dynamic protein interactions within the replication complex complicate replisome structural studies. We employed a combination of crystallographic, native mass spectrometry and small-angle X-ray scattering experiments to capture alternative structures of a model replication system encoded by bacteriophage T7. then, the two molecules of DNA polymerase bind the ring-shaped primase-helicase in a conserved orientation and provide structural insight into how the acidic C-terminal tail of the primase-helicase contacts the DNA polymerase to facilitate loading of the polymerase onto DNA. A third DNA polymerasemore » binds the ring in an offset manner that may enable polymerase exchange during replication. Alternative polymerase binding modes are also detected by small-angle X-ray scattering with DNA substrates present. The collective results unveil complex motions within T7 replisome higher-order structures that are underpinned by multivalent protein-protein interactions with functional implications.« less

Hybrid Methods Reveal Multiple Flexibly Linked DNA Polymerases within the Bacteriophage T7 Replisome

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wallen, Jamie R.; Zhang, Hao; Weis, Caroline

The physical organization of DNA enzymes at a replication fork enables efficient copying of two antiparallel DNA strands, yet dynamic protein interactions within the replication complex complicate replisome structural studies. We employed a combination of crystallographic, native mass spectrometry and small-angle X-ray scattering experiments to capture alternative structures of a model replication system encoded by bacteriophage T7. then, the two molecules of DNA polymerase bind the ring-shaped primase-helicase in a conserved orientation and provide structural insight into how the acidic C-terminal tail of the primase-helicase contacts the DNA polymerase to facilitate loading of the polymerase onto DNA. A third DNA polymerasemore » binds the ring in an offset manner that may enable polymerase exchange during replication. Alternative polymerase binding modes are also detected by small-angle X-ray scattering with DNA substrates present. The collective results unveil complex motions within T7 replisome higher-order structures that are underpinned by multivalent protein-protein interactions with functional implications.« less

Thermally stimulated nonlinear refraction in gelatin stabilized Cu-PVP nanocomposite thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tamgadge, Y. S., E-mail: ystamgadge@gmail.com; Atkare, D. V.; Pahurkar, V. G.

2016-05-06

This article illustrates investigations on thermally stimulated third order nonlinear refraction of Cu-PVP nanocomposite thin films. Cu nanoparticles have been synthesized using chemical reduction method and thin films in PVP matrix have been obtained using spin coating technique. Thin films have been characterized by X-ray diffraction (XRD) and Ultraviolet-visible (UV-vis) spectroscopyfor structural and linear optical studies. Third order nonlinear refraction studies have been performed using closed aperture z-scan technique under continuous wave (CW) He-Ne laser. Cu-PVP nanocomposites are found to exhibit strong nonlinear refractive index stimulated by thermal lensing effect.

Resolving the structure of Ti 3C 2T x MXenes through multilevel structural modeling of the atomic pair distribution function

DOE PAGES

Wesolowski, David J.; Wang, Hsiu -Wen; Page, Katharine L.; ...

2015-12-08

MXenes are a recently discovered family of two-dimensional (2D) early transition metal carbides and carbonitrides, which have already shown many attractive properties and great promise in energy storage and many other applications. But, a complex surface chemistry and small coherence length have been obstacles in some applications of MXenes, also limiting the accuracy of predictions of their properties. In this study, we describe and benchmark a novel way of modeling layered materials with real interfaces (diverse surface functional groups and stacking order between the adjacent monolayers) against experimental data. The structures of three kinds of Ti 3C 2T x MXenesmore » (T stands for surface terminating species, including O, OH, and F) produced under different synthesis conditions were resolved for the first time using atomic pair distribution function obtained by high-quality neutron total scattering. We present the true nature of the material can be easily captured with the sensitivity of neutron scattering to the surface species of interest and the detailed “third-generation” structure model. The modeling approach leads to new understanding of MXene structural properties and can replace the currently used idealized models in predictions of a variety of physical, chemical, and functional properties of Ti 3C 2-based MXenes. Moreover, the developed models can be employed to guide the design of new MXene materials with selected surface termination and controlled contact angle, catalytic, optical, electrochemical, and other properties. Finally, we suggest that the multilevel structural modeling should form the basis for a generalized methodology on modeling diffraction and pair distribution function data for 2D and layered materials.« less

Investigating the Structure of the WJ-III Cognitive at School Age

ERIC Educational Resources Information Center

Dombrowski, Stefan C.

2013-01-01

During its development, the Woodcock-Johnson, Third Edition Cognitive (WJ-III Cognitive; McGrew & Woodcock, 2001) was never subjected to structural analysis using exploratory and higher order factor analyses. Instead, confirmatory factor analyses were conducted on separate sets of WJ-III correlation matrices, yielding a seven-factor model…

Quasi-phase-matched χ(3 )-parametric interactions in sinusoidally tapered waveguides

NASA Astrophysics Data System (ADS)

Saleh, Mohammed F.

2018-01-01

In this article, I show how periodically tapered waveguides can be employed as efficient quasi-phase-matching schemes for four-wave mixing parametric processes in third-order nonlinear materials. As an example, a thorough study of enhancing third-harmonic generation in sinusoidally tapered fibers has been conducted. The quasi-phase-matching condition has been obtained for nonlinear parametric interactions in these structures using Fourier-series analysis. The dependencies of the conversion efficiency of the third harmonic on the modulation amplitude, tapering period, longitudinal-propagation direction, and pump wavelength have been studied. In comparison to uniform waveguides, the conversion efficiency has been enhanced by orders of magnitudes. I envisage that this work will have a great impact in the field of guided nonlinear optics using centrosymmetric materials.

Synthesis, growth, structural and optical studies of a new organic three dimensional framework: 4-(aminocarbonyl)pyridine 4-(aminocarbonyl)pyridinium hydrogen L-malate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vijayalakshmi, A.; Vidyavathy, B., E-mail: vidyavathybalraj@gmail.com; Peramaiyan, G.

2017-02-15

4-(aminocarbonyl)pyridine 4-(aminocarbonyl)pyridinium hydrogen L-malate [(4ACP)(4ACP).(LM)] a new organic nonlinear optical (NLO) crystal was grown by the slow evaporation method. Single crystal X-ray diffraction analysis revealed that the [(4ACP)(4ACP).(LM)] crystal belongs to monoclinic crystal system, space group P2{sub 1}/n, with a three dimensional network. Thermogravimetry (TG) and differential thermal (DT) analyses showed that [(4ACP)(4ACP).(LM)] is thermally stable up to 165 °C. The optical transmittance window and the lower cut-off wavelength of [(4ACP)(4ACP).(LM)] were found out by UV–vis–NIR spectral study. The molecular structure of [(4ACP)(4ACP).(LM)] was further confirmed by FTIR spectral studies. The relative dielectric permittivity and dielectric loss were determined asmore » function of frequency and temperature. The third order nonlinear optical property of [(4ACP)(4ACP).(LM)] was studied by the Z-scan technique using a 532 nm diode pumped CW Nd:YAG laser. Nonlinear refractive index, nonlinear absorption coefficient and third order nonlinear susceptibility of the grown crystal were found to be 7.38×10{sup −8} cm{sup 2}/W, 0.08×10{sup −4} cm/W and 5.36×10{sup −6} esu, respectively. The laser damage threshold value is found to be 1.75 GW/cm{sup 2} - Graphical abstract: In the crystal structure of the title complex, the asymmetric unit contains one hydrogen L-malate anion, 4-(aminocarbonyl)pyridinium cation and a neutral isonicotinamide molecule. It is stabilized by intermolecular N-H…O, C-H…O and O-H…O hydrogen bonds which generate a three dimensional network.« less

U(1) current from the AdS/CFT: diffusion, conductivity and causality

NASA Astrophysics Data System (ADS)

Bu, Yanyan; Lublinsky, Michael; Sharon, Amir

2016-04-01

For a holographically defined finite temperature theory, we derive an off-shell constitutive relation for a global U(1) current driven by a weak external non-dynamical electromagnetic field. The constitutive relation involves an all order gradient expansion resummed into three momenta-dependent transport coefficient functions: diffusion, electric conductivity, and "magnetic" conductivity. These transport functions are first computed analytically in the hydrodynamic limit, up to third order in the derivative expansion, and then numerically for generic values of momenta. We also compute a diffusion memory function, which, as a result of all order gradient resummation, is found to be causal.

The Effects of Land Surface Heating And Roughness Elements on the Structure and Scaling Laws of Atmospheric Boundary Layer Turbulence

NASA Astrophysics Data System (ADS)

Ghannam, Khaled

The atmospheric boundary-layer is the lowest 500-2000 m of the Earth's atmosphere where much of human life and ecosystem services reside. This layer responds to land surface (e.g. buoyancy and roughness elements) and slowly evolving free tropospheric (e.g. temperature and humidity lapse rates) conditions that arguably mediate and modulate biosphere-atmosphere interactions. Such response often results in spatially- and temporally-rich turbulence scales that continue to be the subject of inquiry given their significance to a plethora of applications in environmental sciences and engineering. The work here addresses key aspects of boundary layer turbulence with a focus on the role of roughness elements (vegetation canopies) and buoyancy (surface heating) in modifying the well-studied picture of shear-dominated wall-bounded turbulence. A combination of laboratory channel experiments, field experiments, and numerical simulations are used to explore three distinct aspects of boundary layer turbulence. These are: • The concept of ergodicity in turbulence statistics within canopies: It has been long-recognized that homogeneous and stationary turbulence is ergodic, but less is known about the effects of inhomogeneity introduced by the presence of canopies on the turbulence statistics. A high resolution (temporal and spatial) flume experiment is used here to test the convergence of the time statistics of turbulent scalar concentrations to their ensemble (spatio-temporal) counterpart. The findings indicate that within-canopy scalar statistics have a tendency to be ergodic, mostly in shallow layers (close to canopy top) where the sweeping flow events appear to randomize the statistics. Deeper layers within the canopy are dominated by low-dimensional (quasi-deterministic) von Karman vortices that tend to break ergodicity. • Scaling laws of turbulent velocity spectra and structure functions in near-surface atmospheric turbulence: the existence of a logarithmic scaling in the structure function of the longitudinal and vertical velocity components is examined using five experimental data sets that span the roughness sub-layer above vegetation canopies, the atmospheric surface-layer above a lake and a grass field, and an open channel experiment. The results indicate that close to the wall/surface, this scaling exists in the longitudinal velocity structure function only, with the vertical velocity counterpart exhibiting a much narrower extent of this range due to smaller separation of scales. Phenomenological aspects of the large-scale eddies show that the length scale formed by the friction velocity and energy dissipation acts as a dominant similarity length scale in collapsing experimental data at different heights, mainly due to the imbalance between local production and dissipation of turbulence kinetic energy. • Nonlocal heat transport in the convective atmospheric boundary-layer: Failure of the mean gradient-diffusion (K-theory) in the convective boundary-layer is explored. Using large eddy simulation runs for the atmospheric boundary layer spanning weakly to strongly convective conditions, a generic diagnostic framework that encodes the role of third-order moments in nonlocal heat transport is developed and tested. The premise is that these nonlocal effects are responsible for the inherent asymmetry in vertical transport, and hence the necessary non-Gaussian nature of the joint probability density function (JPDF) of vertical velocity and potential temperature must account for these effects. Conditional sampling (quadrant analysis) of this function and the imbalance between the flow mechanisms of ejections and sweeps are used to characterize this asymmetry, which is then linked to the third-order moments using a cumulant-discard method for the Gram-Charlier expansion of the JPDF. The connection between the ejection-sweep events and the third-order moments shows that the concepts of bottom-up/top-down diffusion, or updraft/downdraft models, are accounted for by various quadrants of this joint probability density function. To this end, future research directions that build upon this work are also discussed.

Propagation of waves in elliptic ducts. A theoretical study. [in view of jet engine compressor noise reduction

NASA Technical Reports Server (NTRS)

Baskaran, S.

1974-01-01

The cut-off frequencies for high order circumferential modes were calculated for various eccentricities of an elliptic duct section. The problem was studied with a view to the reduction of jet engine compressor noise by elliptic ducts, instead of circular ducts. The cut-off frequencies for even functions decrease with increasing eccentricity. The third order eigen frequencies are oscillatory as the eccentricity increases for odd functions. The eigen frequencies decrease for higher order odd functions inasmuch as, for higher orders, they assume the same values as those for even functions. Deformation of a circular pipe into an elliptic one of sufficiently large eccentricity produces only a small reduction in the cut-off frequency, provided the area of the pipe section is kept invariable.

An X-ray diffractometer using mirage diffraction

PubMed Central

Fukamachi, Tomoe; Jongsukswat, Sukswat; Ju, Dongying; Negishi, Riichirou; Hirano, Keiichi; Kawamura, Takaaki

2014-01-01

Some characteristics are reported of a triple-crystal diffractometer with a (+, −, +) setting of Si(220) using mirage diffraction. The first crystal is flat, while the second and third crystals are bent. Basically, the first crystal is used as a collimator, the second as a monochromator and the third as the sample. The third crystal also works as an analyzer. The advantages of this diffractometer are that its setup is easy, its structure is simple, the divergence angle from the second crystal is small and the energy resolution of the third crystal is high, of the order of sub-meV. PMID:25242911

Nonlinear optical studies and structure-activity relationship of chalcone derivatives with in silico insights

NASA Astrophysics Data System (ADS)

Kar, Swayamsiddha; Adithya, K. S.; Shankar, Pruthvik; Jagadeesh Babu, N.; Srivastava, Sailesh; Nageswara Rao, G.

2017-07-01

Nine chalcones were prepared via Claisen-Schmidt condensation, and characterized by UV-vis, IR, 1H NMR, 13C NMR and mass spectrometry. One of the representative member 4-NDM-TC has been studied via single crystal XRD and the TGA/DTA technique. SHG efficiency and NLO susceptibilities of the chalcones have been evaluated by the Kurtz and Perry method and Degenerate Four Wave Mixing techniques respectively. 3-Cl-4‧-HC was noted to possess SHG efficiency 1.37 times that of urea while 4-NDM-TC returned the highest third order NLO susceptibilities with respect to CS2. In silico studies help evaluate various physical parameters, in correlating the observed activities. In conclusion, the structure-activity relationship was derived based on the in silico and experimental results for the third order NLO susceptibilities.

Tuning the third-order nonlinear optical properties of In:ZnO thin films by 8 MeV electron beam irradiation

NASA Astrophysics Data System (ADS)

Shettigar, Nayana; Pramodini, S.; Kityk, I. V.; Abd-Lefdil, M.; Eljald, E. M.; Regragui, M.; Antony, Albin; Rao, Ashok; Sanjeev, Ganesh; Ajeyakashi, K. C.; Poornesh, P.

2017-11-01

We report the third-order nonlinear optical properties of electron beam treated Indium doped ZnO (Zn1-xInxO (x = 0.03) thin films at different dose rate. Zn1-xInxO (x = 0.03) thin films prepared by spray pyrolysis deposition technique were irradiated using 8 MeV electron beam at dose rates ranging from 1 kGy to 4 kGy. X-ray diffraction patterns were obtained to examine the structural changes, The transformation from sphalerite to wurtzite structure of ZnO was observed which indicates occurrence of structural changes due to irradiation. Morphology of irradiated thin films examined using atomic force microscopy (AFM) technique indicates the surface roughness varying with irradiation dose rate. The switching over from Saturable Absorption (SA) to Reverse Saturable Absorption (RSA) behaviour was noted when the irradiation dose rate was increased from 1 kGy to 4 kGy. The significant changes observed in the third-order nonlinear optical susceptibility χ(3) of the Zn1-xInxO (x = 0.03) thin films is attributed mainly due to electron beam irradiation. The study indicates that nonlinear optical parameters can be controlled by electron beam irradiation by choosing appropriate dose rate which is very much essential for device applications. Hence Zn1-xInxO (x = 0.03) materialize as a promising material for use in nonlinear optical device applications.

Evaluation of polymer based third order nonlinear integrated optics devices

NASA Astrophysics Data System (ADS)

Driessen, A.; Hoekstra, H. J. W. M.; Blom, F. C.; Horst, F.; Krijnen, G. J. M.; van Schoot, J. B. P.; Lambeck, P. V.; Popma, Th. J. A.; Diemeer, M. B.

1998-01-01

Nonlinear polymers are promising materials for high speed active integrated optics devices. In this paper we evaluate the perspectives polymer based nonlinear optical devices can offer. Special attention is directed to the materials aspects. In our experimental work we applied mainly Akzo Nobel DANS side-chain polymer that exhibits large second and third order coefficients. This material has been characterized by third harmonic generation, z-scan and pump-probe measurements. In addition, various waveguiding structures have been used to measure the nonlinear absorption (two photon absorption) on a ps time-scale. Finally an integrated optics Mach Zehnder interferometer has been realized and evaluated. It is shown that the DANS side-chain polymer has many of the desired properties: the material is easily processable in high-quality optical waveguiding structures, has low linear absorption and its nonlinearity has a pure electronic origin. More materials research has to be done to arrive at materials with higher nonlinear coefficients to allow switching at moderate light intensity ( < 1 W peak power) and also with lower nonlinear absorption coefficients.

Remarks on non-maximal integral elements of the Cartan plane in jet spaces

NASA Astrophysics Data System (ADS)

Bächtold, M.; Moreno, G.

2014-11-01

There is a natural filtration on the space of degree-k homogeneous polynomials in n independent variables with coefficients in the algebra of smooth functions on the Grassmannian Gr (n,s), determined by the tautological bundle. In this paper we show that the space of s-dimensional integral elements of a Cartan plane on J(E,n), with dimE=n+m, has an affine bundle structure modeled by the so-obtained bundles over Gr (n,s), and we study a natural distribution associated with it. As an example, we show that a third-order nonlinear PDE of Monge-Ampère type is not contact-equivalent to a quasi-linear one.

Third-order nonlinear electro-optic measurements in the smectic-? phase

NASA Astrophysics Data System (ADS)

Nowicka, Kamila; Bielejewska, Natalia

2018-02-01

The chiral smectic subphase with three-layer structure, ?, is now of great interest from the point of view of device technologies such as multistate or symmetric switching. We report that the unique nonlinear electro-optic response can serve as precise mark of the phase transition into three-layer structure. The problem is illustrated with the first and third harmonic electro-optic spectra. Furthermore, the characteristic response of the helical liquid crystal phases correlated with particular collective modes using the Debye-type relaxation method for the well-known prototype liquid crystal material (MHPOBC) are presented.

Recognition of functional sites in protein structures.

PubMed

Shulman-Peleg, Alexandra; Nussinov, Ruth; Wolfson, Haim J

2004-06-04

Recognition of regions on the surface of one protein, that are similar to a binding site of another is crucial for the prediction of molecular interactions and for functional classifications. We first describe a novel method, SiteEngine, that assumes no sequence or fold similarities and is able to recognize proteins that have similar binding sites and may perform similar functions. We achieve high efficiency and speed by introducing a low-resolution surface representation via chemically important surface points, by hashing triangles of physico-chemical properties and by application of hierarchical scoring schemes for a thorough exploration of global and local similarities. We proceed to rigorously apply this method to functional site recognition in three possible ways: first, we search a given functional site on a large set of complete protein structures. Second, a potential functional site on a protein of interest is compared with known binding sites, to recognize similar features. Third, a complete protein structure is searched for the presence of an a priori unknown functional site, similar to known sites. Our method is robust and efficient enough to allow computationally demanding applications such as the first and the third. From the biological standpoint, the first application may identify secondary binding sites of drugs that may lead to side-effects. The third application finds new potential sites on the protein that may provide targets for drug design. Each of the three applications may aid in assigning a function and in classification of binding patterns. We highlight the advantages and disadvantages of each type of search, provide examples of large-scale searches of the entire Protein Data Base and make functional predictions.

Adaptive interference cancel filter for evoked potential using high-order cumulants.

PubMed

Lin, Bor-Shyh; Lin, Bor-Shing; Chong, Fok-Ching; Lai, Feipei

2004-01-01

This paper is to present evoked potential (EP) processing using adaptive interference cancel (AIC) filter with second and high order cumulants. In conventional ensemble averaging method, people have to conduct repetitively experiments to record the required data. Recently, the use of AIC structure with second statistics in processing EP has proved more efficiency than traditional averaging method, but it is sensitive to both of the reference signal statistics and the choice of step size. Thus, we proposed higher order statistics-based AIC method to improve these disadvantages. This study was experimented in somatosensory EP corrupted with EEG. Gradient type algorithm is used in AIC method. Comparisons with AIC filter on second, third, fourth order statistics are also presented in this paper. We observed that AIC filter with third order statistics has better convergent performance for EP processing and is not sensitive to the selection of step size and reference input.

Evaluation of the Third Class Science Text Book from the Teacher's Perspective at Madaba Municipality

ERIC Educational Resources Information Center

Kraishan, Osama M.; Almaamah, Ismail

2016-01-01

This study aimed at evaluating the science textbook of the third grade primary school in Jordan from the point of view of the teachers who have taught this textbook, in order to find out how suitable and relevant this textbook is to the structure of the curriculum and its guidelines, by trying to answer this question: What is the evaluation of…

Magic trees in mammalians respiration or when evolution selected clever physical systems

NASA Astrophysics Data System (ADS)

Sapoval, B.; Filoche, M.

2014-03-01

The respiratory system of mammalians is made of two successive branched structures with different physiological functions. The upper structure, or bronchial tree, is a fluid transportation system made of approximately 15 generations of bifurcations leading to the order of 215= 30.000 bronchioles with a diameter of order 0.5 mm in the human lung.1 The branching pattern continues up to generation 23 but the structure and function of each of the subsequent structures, called the acini, is different. Each acinus is made of a branched system of ducts surrounded by alveolae and play the role of a diffusion cell where oxygen and carbon dioxide are exchanged with blood across the alveolar membrane.2 We show in this letter that the bronchial tree present simultaneously several optimal properties of totally different nature. It is first energy efficient3-6, second, it is space filling;7 and third it is "rapid" as discussed here. It is this multi-optimality that is qualified here as magic. The multioptimality physical characteristic suggests that, in the course of evolution, an organ selected against one criterion could have been later used later for a totally different reason. For example, once energetic efficiency for the transport of a viscous fluid like blood has been selected, the same genetic material could have been used for its optimized rapidity. This would have allowed the emergence of mammalian respiration made of inspiration-expiration cycles. For this phenomenon to exist, the rapid character is essential, as fresh air has to reach the gas exchange organs, the pulmonary acini, before the start of expiration.

Magic Trees in Mammalians Respiration or when Evolution Selected Clever Physical Systems

NASA Astrophysics Data System (ADS)

Sapoval, B.; Filoche, M.

2013-01-01

The respiratory system of mammalians is made of two successive branched structures with different physiological functions. The upper structure, or bronchial tree, is a fluid transportation system made of approximately 15 generations of bifurcations leading to the order of 215 = 30,000 bronchioles with a diameter of order 0.5 mm in the human lung.1 The branching pattern continues up to generation 23 but the structure and function of each of the subsequent structures, called the acini, is different. Each acinus is made of a branched system of ducts surrounded by alveolae and play the role of a diffusion cell where oxygen and carbon dioxide are exchanged with blood across the alveolar membrane.2 We show in this paper that the bronchial tree presents simultaneously several optimal properties of totally different nature. It is first energy efficient;3-6 second, it is space filling;7 and third it is "rapid" as discussed here. It is this multi-optimality that is qualified here as magic. The multi-optimality physical characteristic suggests that, in the course of evolution, an organ selected against one criterion could have been later used for a totally different reason. For example, once energetic efficiency for the transport of a viscous fluid like blood has been selected, the same genetic material could have been used for its optimized rapidity. This would have allowed the emergence of mammalian respiration made of inspiration-expiration cycles. For this phenomenon to exist, the rapid character is essential, as fresh air has to reach the gas exchange organs, the pulmonary acini, before the start of expiration.

Metastability and structural polymorphism in noble metals: the role of composition and metal atom coordination in mono- and bimetallic nanoclusters.

PubMed

Sanchez, Sergio I; Small, Matthew W; Bozin, Emil S; Wen, Jian-Guo; Zuo, Jian-Min; Nuzzo, Ralph G

2013-02-26

This study examines structural variations found in the atomic ordering of different transition metal nanoparticles synthesized via a common, kinetically controlled protocol: reduction of an aqueous solution of metal precursor salt(s) with NaBH₄ at 273 K in the presence of a capping polymer ligand. These noble metal nanoparticles were characterized at the atomic scale using spherical aberration-corrected scanning transmission electron microscopy (C(s)-STEM). It was found for monometallic samples that the third row, face-centered-cubic (fcc), transition metal [(3M)-Ir, Pt, and Au] particles exhibited more coherently ordered geometries than their second row, fcc, transition metal [(2M)-Rh, Pd, and Ag] analogues. The former exhibit growth habits favoring crystalline phases with specific facet structures while the latter samples are dominated by more disordered atomic arrangements that include complex systems of facets and twinning. Atomic pair distribution function (PDF) measurements further confirmed these observations, establishing that the 3M clusters exhibit longer ranged ordering than their 2M counterparts. The assembly of intracolumn bimetallic nanoparticles (Au-Ag, Pt-Pd, and Ir-Rh) using the same experimental conditions showed a strong tendency for the 3M atoms to template long-ranged, crystalline growth of 2M metal atoms extending up to over 8 nm beyond the 3M core.

Third-Order Optical Nonlinearities of Squarylium Dyes with Benzothiazole Donor Groups Measured Using the Picosecond Z-Scan Technique

NASA Astrophysics Data System (ADS)

Li, Zhong-Yu; Xu, Song; Chen, Zi-Hui; Zhang, Fu-Shi; Kasatani, Kazuo

2011-08-01

Third-order optical nonlinearities of two squarylium dyes with benzothiazole donor groups (BSQ1 and BSQ2) in chloroform solution are measured by a picosecond Z-scan technique at 532 nm. It is found that the two compounds show the saturation absorption and nonlinear self-focus refraction effect. The molecular second hyperpolarizabilities are calculated to be 7.46 × 10-31 esu and 5.01 × 10-30 esu for BSQ1 and BSQ2, respectively. The large optical nonlinearities of squarylium dyes can be attributed to their rigid and intramolecular charge transfer structure. The difference in γ values is attributed to the chloro group of benzene rings of BSQ2 and the one-photon resonance effect. It is found that the third-order nonlinear susceptibilities of two squarylium dyes are mainly determined by the real parts of χ(3), and the large optical nonlinearities of studied squarylium dyes can be attributed to the nonlinear refraction.

Correlation Scales of the Turbulent Cascade at 1 au

NASA Astrophysics Data System (ADS)

Smith, Charles W.; Vasquez, Bernard J.; Coburn, Jesse T.; Forman, Miriam A.; Stawarz, Julia E.

2018-05-01

We examine correlation functions of the mixed, third-order expressions that, when ensemble-averaged, describe the cascade of energy in the inertial range of magnetohydrodynamic turbulence. Unlike the correlation function of primitive variables such as the magnetic field, solar wind velocity, temperature, and density, the third-order expressions decorrelate at a scale that is approximately 20% of the lag. This suggests the nonlinear dynamics decorrelate in less than one wavelength. Therefore, each scale can behave differently from one wavelength to the next. In the same manner, different scales within the inertial range can behave independently at any given time or location. With such a cascade that can be strongly patchy and highly variable, it is often possible to obtain negative cascade rates for short periods of time, as reported earlier for individual samples of data.

Strong anharmonicity in the phonon spectra of PbTe and SnTe from first principles

NASA Astrophysics Data System (ADS)

Ribeiro, Guilherme A. S.; Paulatto, Lorenzo; Bianco, Raffaello; Errea, Ion; Mauri, Francesco; Calandra, Matteo

2018-01-01

At room temperature, PbTe and SnTe are efficient thermoelectrics with a cubic structure. At low temperature, SnTe undergoes a ferroelectric transition with a critical temperature strongly dependent on the hole concentration, while PbTe is an incipient ferroelectric. By using the stochastic self-consistent harmonic approximation, we investigate the anharmonic phonon spectra and the occurrence of a ferroelectric transition in both systems. We find that vibrational spectra strongly depend on the approximation used for the exchange-correlation kernel in density-functional theory. If gradient corrections and the theoretical volume are employed, then the calculation of the phonon frequencies as obtained from the diagonalization of the free-energy Hessian leads to phonon spectra in good agreement with experimental data for both systems. In PbTe we evaluate the linear thermal expansion coefficient γ =2.3 ×10-5K-1 , finding it to be in good agreement with experimental value of γ =2.04 ×10-5K-1 . Furthermore, we study the phonon spectrum and we do reproduce the transverse optical mode phonon satellite detected in inelastic neutron scattering and the crossing between the transverse optical and the longitudinal acoustic modes along the Γ X direction. The phonon satellite becomes broader at high temperatures but its energy is essentially temperature independent, in agreement with experiments. We decompose the self-consistent harmonic free energy in second-, third-, and fourth-order anharmonic terms. We find that the third- and fourth-order terms are small. However, treating the third-order term perturbatively on top of the second-order self-consistent harmonic free energy overestimates the energy of the satellite associated with the transverse optical mode. On the contrary, a perturbative treatment on top of the harmonic Hamiltonian breaks down and leads to imaginary phonon frequencies already at 300 K. In the case of SnTe, we describe the occurrence of a ferroelectric transition from the high-temperature F m 3 ¯m structure to the low-temperature R 3 m one. The transition temperature is, however, underestimated with respect to the experimental one. No satellites are present in the SnTe phonon spectra despite a not negligible anharmonic broadening of the zone-center TO mode.

Microgravity Processing and Photonic Applications of Organic and Polymeric Materials

NASA Technical Reports Server (NTRS)

Frazier, Donald O.; Penn, Benjamin G.; Smith, David D.; Witherow, William K.; Paley, Mark S.; Abdeldayem, Hossin A.

1997-01-01

In recent years, a great deal of interest has been directed toward the use of organic materials in the development of high-efficiency optoelectronic and photonic devices. There is a myriad of possibilities among organics which allow flexibility in the design of unique structures with a variety of functional groups. The use of nonlinear optical (NLO) organic materials such as thin-film waveguides allows full exploitation of their desirable qualities by permitting long interaction lengths and large susceptibilities allowing modest power input. There are several methods in use to prepare thin films, such as Langmuir-Blodgett (LB) and self-assembly techniques, vapor deposition, growth from sheared solution or melt, and melt growth between glass plates. Organics have many features that make them desirable for use in optical devices such as high second- and third-order nonlinearities, flexibility of molecular design, and damage resistance to optical radiation. However, their use in devices has been hindered by processing difficulties for crystals and thin films. In this chapter, we discuss photonic and optoelectronic applications of a few organic materials and the potential role of microgravity on processing these materials. It is of interest to note how materials with second- and third-order nonlinear optical behavior may be improved in a diffusion-limited environment and ways in which convection may be detrimental to these materials.

Which one among the Pt-containing anticancer drugs more easily forms monoadducts with G and A DNA bases? A comparative study among oxaliplatin, nedaplatin, and carboplatin.

PubMed

Alberto, Marta E; Butera, Valeria; Russo, Nino

2011-08-01

The platination processes of DNA bases with second- and third-generation Pt(II) anticancer drugs have been investigated using density functional theory (DFT) combined with the conductor-like dielectric continuum model (CPCM) approach, in order to describe their binding mechanisms and to obtain detailed data on the reaction energy profiles. Although there is no doubt that a Pt-N7 bond forms during initial attack, the energetic profiles for the formation of the monofunctional adducts are not known. Herein, a direct comparison between the rate of formation of the monofunctional adducts of the second- and third-generation anticancer drugs with guanine (G) and adenine (A) DNA bases has been made in order to spotlight possible common or different behavior. The guanine as target for platination process is confirmed to be preferred over adenine for all the investigated compounds and for both the hydrolyzed forms considered in our investigation. The preference for G purine base is dominated by electronic factors and promoted by a more favorable hydrogen-bonds pattern, confirming the important role played by H-bonds in determining both structural and kinetic control on the purine platination process. © 2011 American Chemical Society

Effect of third-order aberrations on dynamic accommodation.

PubMed

López-Gil, Norberto; Rucker, Frances J; Stark, Lawrence R; Badar, Mustanser; Borgovan, Theodore; Burke, Sean; Kruger, Philip B

2007-03-01

We investigate the potential for the third-order aberrations coma and trefoil to provide a signed cue to accommodation. It is first demonstrated theoretically (with some assumptions) that the point spread function is insensitive to the sign of spherical defocus in the presence of odd-order aberrations. In an experimental investigation, the accommodation response to a sinusoidal change in vergence (1-3D, 0.2Hz) of a monochromatic stimulus was obtained with a dynamic infrared optometer. Measurements were obtained in 10 young visually normal individuals with and without custom contact lenses that induced low and high values of r.m.s. trefoil (0.25, 1.03 microm) and coma (0.34, 0.94 microm). Despite variation between subjects, we did not find any statistically significant increase or decrease in the accommodative gain for low levels of trefoil and coma, although effects approached or reached significance for the high levels of trefoil and coma. Theoretical and experimental results indicate that the presence of Zernike third-order aberrations on the eye does not seem to play a crucial role in the dynamics of the accommodation response.

Non-Effective National Territory: A Characteristic of Third World States.

ERIC Educational Resources Information Center

Walter, Bob J.

In an effort to improve understanding and to provide better solutions to the world's political problems, this paper examines national territory or states in terms of their functional processes and their spatial structures. Examples from Third World states are provided. The author first presents a model of political territory. It has a boundary…

Synthesis of stable ZnO nanocolloids with enhanced optical limiting properties via simple solution method

NASA Astrophysics Data System (ADS)

Ramya, M.; Nideep, T. K.; Vijesh, K. R.; Nampoori, V. P. N.; Kailasnath, M.

2018-07-01

In present work, we report the synthesis of stable ZnO nanocolloids through a simple solution method which exhibit enhanced optical limiting threshold. The influences of reaction temperature on the crystal structure as well as linear and nonlinear optical properties of prepared ZnO nanoparticles were carried out. The XRD and Raman analysis reveal that the prepared ZnO nanoparticles retain the hexagonal wurtzite crystal structure. HRTEM analysis confirms the effect of reaction temperature, solvent effect on crystallinity as well as nanostructure of ZnO nanoparticles. It has been found that crystallinity and average diameter increase with reaction temperature where ethylene glycol act as both solvent and growth inhibiter. EDS spectra shows formation of pure ZnO nanoparticles. The direct energy band gap of the nanoparticles increases with decrease in particle size due to quantum confinement effect. The third order nonlinear optical properties of ZnO nanoparticles were investigated by z scan technique using a frequency doubled Nd-YAG nanosecond laser at 532 nm wavelength. The z-scan result reveals that the prepared ZnO nanoparticles exhibit self - defocusing nonlinearity. The two photon absorption coefficient and third - order nonlinear optical susceptibility increases with increasing particle size. The third-order susceptibility of the ZnO nanoparticles is found to be in the order of 10-10 esu, which is at least three order magnitude greater than the bulk ZnO. The optical limiting threshold of the nanoparticles varies in the range of 54 to 17 MW/cm2. The results suggest that ZnO nanoparticles considered as a promising candidates for the future photonic devices.

Third order nonlinearity in pulsed laser deposited LiNbO{sub 3} thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tumuluri, Anil; Rapolu, Mounika; Rao, S. Venugopal, E-mail: kcjrsp@uohyd.ernet.in, E-mail: svrsp@uohyd.ernet.in

2016-05-06

Lithium niobate (LiNbO{sub 3}) thin films were prepared using pulsed laser deposition technique. Structural properties of the same were examined from XRD and optical band gap of the thin films were measured from transmittance spectra recorded using UV-Visible spectrophotometer. Nonlinear optical properties of the thin films were recorded using Z-Scan technique. The films were exhibiting third order nonlinearity and their corresponding two photon absorption, nonlinear refractive index, real and imaginary part of nonlinear susceptibility were calculated from open aperture and closed aperture transmission curves. From these studies, it suggests that these films have potential applications in nonlinear optical devices.

Analysis of SAW properties in ZnO/AlxGa1-xN/c-Al2O3 structures.

PubMed

Chen, Ying; Emanetoglu, Nuri William; Saraf, Gaurav; Wu, Pan; Lu, Yicheng; Parekh, Aniruddh; Merai, Vinod; Udovich, Eric; Lu, Dong; Lee, Dong S; Armour, Eric A; Pophristic, Milan

2005-07-01

Piezoelectric thin films on high acoustic velocity nonpiezoelectric substrates, such as ZnO, AlN, or GaN deposited on diamond or sapphire substrates, are attractive for high frequency and low-loss surface acoustic wave devices. In this work, ZnO films are deposited on AlxGa1-xN/c-Al2O3 (0 < or = chi < or = 1) substrates using the radio frequency (RF) sputtering technique. In comparison with a single AlxGa1-xN layer deposited on c-Al2O3 with the same total film thickness, a ZnO/AlxGa1-xN/c-Al2O3 multilayer structure provides several advantages, including higher order wave modes with higher velocity and larger electromechanical coupling coefficient (K2). The surface acoustic wave (SAW) velocities and coupling coefficients of the ZnO/AlxGa1-xN/c-Al2O3 structure are tailored as a function of the Al mole percentage in AlxGa1-xN films, and as a function of the ZnO (h1) to AlxGa1-xN (h2) thickness ratio. It is found that a wide thickness-frequency product (hf) region in which coupling is close to its maximum value, K(2)max, can be obtained. The K(2)max of the second order wave mode (h1 = h2) is estimated to be 4.3% for ZnO/GaN/c-Al2O3, and 3.8% for ZnO/AlN/c-Al2O3. The bandwidth of second and third order wave modes, in which the coupling coefficient is within +/- 0.3% of K(2)max, is calculated to be 820 hf for ZnO/GaN/c-Al2O3, and 3620 hf for ZnO/AlN/c-Al2O3. Thus, the hf region in which the coupling coefficient is close to the maximum value broadens with increasing Al content, while K(2)max decreases slightly. When the thickness ratio of AlN to ZnO increases, the K(2)max and hf bandwidth of the second and third higher wave modes increases. The SAW test devices are fabricated and tested. The theoretical and experimental results of velocity dispersion in the ZnO/AlxGa1-xN/c-Al2O3 structures are found to be well matched.

Multidimensionally constrained relativistic mean-field study of triple-humped barriers in actinides

NASA Astrophysics Data System (ADS)

Zhao, Jie; Lu, Bing-Nan; Vretenar, Dario; Zhao, En-Guang; Zhou, Shan-Gui

2015-01-01

Background: Potential energy surfaces (PES's) of actinide nuclei are characterized by a two-humped barrier structure. At large deformations beyond the second barrier, the occurrence of a third barrier was predicted by macroscopic-microscopic model calculations in the 1970s, but contradictory results were later reported by a number of studies that used different methods. Purpose: Triple-humped barriers in actinide nuclei are investigated in the framework of covariant density functional theory (CDFT). Methods: Calculations are performed using the multidimensionally constrained relativistic mean field (MDC-RMF) model, with the nonlinear point-coupling functional PC-PK1 and the density-dependent meson exchange functional DD-ME2 in the particle-hole channel. Pairing correlations are treated in the BCS approximation with a separable pairing force of finite range. Results: Two-dimensional PES's of 226,228,230,232Th and 232,235,236,238U are mapped and the third minima on these surfaces are located. Then one-dimensional potential energy curves along the fission path are analyzed in detail and the energies of the second barrier, the third minimum, and the third barrier are determined. The functional DD-ME2 predicts the occurrence of a third barrier in all Th nuclei and 238U . The third minima in 230 ,232Th are very shallow, whereas those in 226 ,228Th and 238U are quite prominent. With the functional PC-PK1 a third barrier is found only in 226 ,228 ,230Th . Single-nucleon levels around the Fermi surface are analyzed in 226Th, and it is found that the formation of the third minimum is mainly due to the Z =90 proton energy gap at β20≈1.5 and β30≈0.7 . Conclusions: The possible occurrence of a third barrier on the PES's of actinide nuclei depends on the effective interaction used in multidimensional CDFT calculations. More pronounced minima are predicted by the DD-ME2 functional, as compared to the functional PC-PK1. The depth of the third well in Th isotopes decreases with increasing neutron number. The origin of the third minimum is due to the proton Z =90 shell gap at relevant deformations.

Effets optiques et structurels de l'implantation ionique dans des couches minces polymeres

NASA Astrophysics Data System (ADS)

Cottin, Pierre

The main goal of this work is to highlight the effect of ion implantation---a widely spread technique to modify chemical, electrical or optical properties of materials---on the third order nonlinear optical properties (chi (3)) of polymers. This study was limited to four polymers (PMMA, PVK, PVA, CA) for which we developed a fabrication process to obtain high optical quality thin films and controlled thickness compatible with ion implantation depth. Moreover, these polymers show different chemical structures and have in common to have very low nonlinear optical properties. Two faces of the problem were studied. First, the chemical structure of these polymers was characterized using ultraviolet and infrared spectroscopy before and after ion implantation and then was compared with which of intrinsic nonlinear optical polymers. These analysis have clearly shown that from one hand, ion implantation leads to a great number of bond breaks but from the other hand, it creates a high concentration of conjugated bonds characteristic of nonlinear optical polymers. Second, the third order nonlinear optical properties of ion implanted polymers were measured by nonlinear waveguide coupling and by third harmonic generation. For the first method, the coupling function was performed by a diffraction grating etched in a glass substrate whose fabrication process was developed in this particular case. In both cases, the used laser wave-length was 1064 nm with pulse duration of 30 ps and 5 ns respectively. The corresponding modelization for each of these techniques was established and numerically implemented. Both techniques have shown an increase of chi(3) for these polymers after ion implantation but however, they can not reach the performance of chemically designed nonlinear optical polymers. The best results were obtained for 50 keV helium implanted PMMA given |chi(3)(-3o; o, o, o)| = 7.2 x 10-21 m2.V-2 which is six time greater than the pristine material.

Label-free super-resolution with coherent nonlinear structured-illumination microscopy

NASA Astrophysics Data System (ADS)

Huttunen, Mikko J.; Abbas, Aazad; Upham, Jeremy; Boyd, Robert W.

2017-08-01

Structured-illumination microscopy enables up to a two-fold lateral resolution improvement by spatially modulating the intensity profile of the illumination beam. We propose a novel way to generalize the concept of structured illumination to nonlinear widefield modalities by spatially modulating, instead of field intensities, the phase of the incident field while interferometrically measuring the complex-valued scattered field. We numerically demonstrate that for second-order and third-order processes an almost four- and six-fold increase in lateral resolution is achievable, respectively. This procedure overcomes the conventional Abbe diffraction limit and provides new possibilities for label-free super-resolution microscopy.

Study of high-performance canonical molecular orbitals calculation for proteins

NASA Astrophysics Data System (ADS)

Hirano, Toshiyuki; Sato, Fumitoshi

2017-11-01

The canonical molecular orbital (CMO) calculation can help to understand chemical properties and reactions in proteins. However, it is difficult to perform the CMO calculation of proteins because of its self-consistent field (SCF) convergence problem and expensive computational cost. To certainly obtain the CMO of proteins, we work in research and development of high-performance CMO applications and perform experimental studies. We have proposed the third-generation density-functional calculation method of calculating the SCF, which is more advanced than the FILE and direct method. Our method is based on Cholesky decomposition for two-electron integrals calculation and the modified grid-free method for the pure-XC term evaluation. By using the third-generation density-functional calculation method, the Coulomb, the Fock-exchange, and the pure-XC terms can be given by simple linear algebraic procedure in the SCF loop. Therefore, we can expect to get a good parallel performance in solving the SCF problem by using a well-optimized linear algebra library such as BLAS on the distributed memory parallel computers. The third-generation density-functional calculation method is implemented to our program, ProteinDF. To achieve computing electronic structure of the large molecule, not only overcoming expensive computation cost and also good initial guess for safe SCF convergence are required. In order to prepare a precise initial guess for the macromolecular system, we have developed the quasi-canonical localized orbital (QCLO) method. The QCLO has the characteristics of both localized and canonical orbital in a certain region of the molecule. We have succeeded in the CMO calculations of proteins by using the QCLO method. For simplified and semi-automated calculation of the QCLO method, we have also developed a Python-based program, QCLObot.

Structural developmental psychology and health promotion in the third age.

PubMed

Bauger, Lars; Bongaardt, Rob

2017-01-12

In response to the ever-increasing longevity in Western societies, old age has been divided into two different periods, labelled the third and fourth age. Where the third age, with its onset at retirement, mostly involves positive aspects of growing old, the fourth age involves functional decline and increased morbidity. This article focuses on the entry to the third age and its potential for health promotion initiatives. Well-being is an important factor to emphasize in such health promotion, and this article views the lifestyle of third agers as essential for their well-being. The structural developmental theory of Robert Kegan delineates how a person's way of knowing develops throughout the life course. This theory is an untapped and salient perspective for health promotion initiatives in the third age. This article outlines Kegan's approach as a tool for developing psychologically spacious health promotion, and suggests future directions for research on the topic. © The Author 2017. Published by Oxford University Press.

Anomalous current from the covariant Wigner function

NASA Astrophysics Data System (ADS)

Prokhorov, George; Teryaev, Oleg

2018-04-01

We consider accelerated and rotating media of weakly interacting fermions in local thermodynamic equilibrium on the basis of kinetic approach. Kinetic properties of such media can be described by covariant Wigner function incorporating the relativistic distribution functions of particles with spin. We obtain the formulae for axial current by summation of the terms of all orders of thermal vorticity tensor, chemical potential, both for massive and massless particles. In the massless limit all the terms of fourth and higher orders of vorticity and third order of chemical potential and temperature equal zero. It is shown, that axial current gets a topological component along the 4-acceleration vector. The similarity between different approaches to baryon polarization is established.

Structural and thermodynamic properties of the Cm III ion solvated by water and methanol

DOE PAGES

Kelley, Morgan P.; Yang, Ping; Clark, Sue B.; ...

2016-04-27

The geometric and electronic structures of the 9-coordinate Cm 3+ ion solvated with both water and methanol are systematically investigated in the gas phase at each possible solvent-shell composition and configuration using density functional theory and second-order Møller–Plesset perturbation theory. Ab initio molecular dynamics simulations are employed to assess the effects of second and third solvent shells on the gas-phase structure. The ion–solvent dissociation energy for methanol is greater than that of water, potentially because of increased charge donation to the ion made possible by the electron-rich methyl group. Further, the ion–solvent dissociation energy and the ion–solvent distance are shownmore » to be dependent on the solvent-shell composition. Furthermore, this has implications for solvent exchange, which is generally the rate-limiting step in complexation reactions utilized in the separation of curium from complex metal mixtures that derive from the advanced nuclear fuel cycle.« less

Third order nonlinear optical properties of Mn doped CeO2 nanostructures

NASA Astrophysics Data System (ADS)

Mani Rahulan, K.; Angeline Little Flower, N.; Annie Sujatha, R.; Mohana Priya, P.; Gopalakrishnan, C.

2018-05-01

Mn doped CeO2 nanoparticles with different ratios of Mn were synthesized by hydrothermal method and their structural properties were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). XRD patterns revealed that the peaks are highly crystalline structure with no segregation of Mn. The surface morphology from SEM reveals that particle size decreases with increase in Mn concentration. Nonlinear optical studies of the samples were measured by single-beam open aperture Z-scan technique using 5 ns laser pulses at 532 nm. The measured optical nonlinearity of all the samples exhibit typical third order nonlinear optical behavior including two-photon absorption (2 PA) and reverse saturable absorption (RSA). The experimental results show that the presence of RSA in these nanoparticles makes them a promising material for the fabrication of optical limiting devices. .

Four-Photon Imaging with Thermal Light

NASA Astrophysics Data System (ADS)

Wen, Feng; Xue, Xinxin; Zhang, Xun; Yuan, Chenzhi; Sun, Jia; Song, Jianping; Zhang, Yanpeng

2014-10-01

In a near-field four-photon correlation measurement, ghost imaging with classical incoherent light is investigated. By applying the Klyshko advanced-wave picture, we consider the properties of four-photon spatial correlation and find that the fourth-order spatial correlation function can be decomposed into multiple lower-order correlation functions. On the basis of the spatial correlation properties, a proof-of-principle four-photon ghost imaging is proposed, and the effect of each part in a fourth-order correlation function on imaging is also analyzed. In addition, the similarities and differences among ghost imaging by fourth-, second-, and third-order correlations are also discussed. It is shown that the contrast and visibility of fourth-order correlated imaging are improved significantly, while the resolution is unchanged. Such studies can be very useful in better understanding multi photon interference and multi-channel correlation imaging.

Basement-involved faults and deep structures in the West Philippine Basin: constrains from gravity field

NASA Astrophysics Data System (ADS)

Wang, Gang; Jiang, Suhua; Li, Sanzhong; Zhang, Huixuan; Lei, Jianping; Gao, Song; Zhao, Feiyu

2017-06-01

To reveal the basement-involved faults and deep structures of the West Philippine Basin (WPB), the gravitational responses caused by these faults are observed and analyzed based on the latest spherical gravity model: WGM2012 Model. By mapping the free-air and Bouguer gravity anomalies, several main faults and some other linear structures are located and observed in the WPB. Then, by conducting a 2D discrete multi-scale wavelet decomposition, the Bouguer anomalies are decomposed into the first- to eighth-order detail and approximation fields (the first- to eighth-order Details and Approximations). The first- to third-order Details reflect detailed and localized geological information of the crust at different depths, and of which the higher-order reflects gravity field of the deeper depth. The first- to fourth-order Approximations represent the regional gravity fields at different depths of the crust, respectively. The fourth-order Approximation represents the regional gravity fluctuation caused by the density inhomogeneity of Moho interface. Therefore, taking the fourth-order Approximation as input, and adopting Parker-Oldenburg interactive inversion, We calculated the depth of Moho interface in the WPB. Results show that the Moho interface depth in the WPB ranges approximately from 8 to 12 km, indicating that there is typical oceanic crust in the basin. In the Urdaneta Plateau and the Benham Rise, the Moho interface depths are about 14 and 16 km, respectively, which provides a piece of evidence to support that the Banham Rise could be a transitional crust caused by a large igneous province. The second-order vertical derivative and the horizontal derivatives in direction 0° and 90° are computed based on the data of the third-order Detail, and most of the basement-involved faults and structures in the WPB, such as the Central Basin Fault Zone, the Gagua Ridge, the Luzon-Okinawa Fault Zone, and the Mindanao Fault Zone are interpreted by the gravity derivatives.

A stochastic-dynamic model for global atmospheric mass field statistics

NASA Technical Reports Server (NTRS)

Ghil, M.; Balgovind, R.; Kalnay-Rivas, E.

1981-01-01

A model that yields the spatial correlation structure of atmospheric mass field forecast errors was developed. The model is governed by the potential vorticity equation forced by random noise. Expansion in spherical harmonics and correlation function was computed analytically using the expansion coefficients. The finite difference equivalent was solved using a fast Poisson solver and the correlation function was computed using stratified sampling of the individual realization of F(omega) and hence of phi(omega). A higher order equation for gamma was derived and solved directly in finite differences by two successive applications of the fast Poisson solver. The methods were compared for accuracy and efficiency and the third method was chosen as clearly superior. The results agree well with the latitude dependence of observed atmospheric correlation data. The value of the parameter c sub o which gives the best fit to the data is close to the value expected from dynamical considerations.

Analyses of Third Order Bose-Einstein Correlation by Means of Coulomb Wave Function

DOE Office of Scientific and Technical Information (OSTI.GOV)

Biyajima, Minoru; Mizoguchi, Takuya; Suzuki, Naomichi

2006-04-11

In order to include a correction by the Coulomb interaction in Bose-Einstein correlation (BEC), the wave function for the Coulomb scattering were introduced in the quantum optical approach to BEC in the previous work. If we formulate the amplitude written by Coulomb wave functions according to the diagram for BEC in the plane wave formulation, the formula for 3{pi} -BEC becomes simpler than that of our previous work. We re-analyze the raw data of 3{pi} -BEC by NA44 and STAR Collaborations by this formula. Results are compared with the previous ones.

Recent improvements to Binding MOAD: a resource for protein-ligand binding affinities and structures.

PubMed

Ahmed, Aqeel; Smith, Richard D; Clark, Jordan J; Dunbar, James B; Carlson, Heather A

2015-01-01

For over 10 years, Binding MOAD (Mother of All Databases; http://www.BindingMOAD.org) has been one of the largest resources for high-quality protein-ligand complexes and associated binding affinity data. Binding MOAD has grown at the rate of 1994 complexes per year, on average. Currently, it contains 23,269 complexes and 8156 binding affinities. Our annual updates curate the data using a semi-automated literature search of the references cited within the PDB file, and we have recently upgraded our website and added new features and functionalities to better serve Binding MOAD users. In order to eliminate the legacy application server of the old platform and to accommodate new changes, the website has been completely rewritten in the LAMP (Linux, Apache, MySQL and PHP) environment. The improved user interface incorporates current third-party plugins for better visualization of protein and ligand molecules, and it provides features like sorting, filtering and filtered downloads. In addition to the field-based searching, Binding MOAD now can be searched by structural queries based on the ligand. In order to remove redundancy, Binding MOAD records are clustered in different families based on 90% sequence identity. The new Binding MOAD, with the upgraded platform, features and functionalities, is now equipped to better serve its users. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

Hopf bifurcation and chaos in a third-order phase-locked loop

NASA Astrophysics Data System (ADS)

Piqueira, José Roberto C.

2017-01-01

Phase-locked loops (PLLs) are devices able to recover time signals in several engineering applications. The literature regarding their dynamical behavior is vast, specifically considering that the process of synchronization between the input signal, coming from a remote source, and the PLL local oscillation is robust. For high-frequency applications it is usual to increase the PLL order by increasing the order of the internal filter, for guarantying good transient responses; however local parameter variations imply structural instability, thus provoking a Hopf bifurcation and a route to chaos for the phase error. Here, one usual architecture for a third-order PLL is studied and a range of permitted parameters is derived, providing a rule of thumb for designers. Out of this range, a Hopf bifurcation appears and, by increasing parameters, the periodic solution originated by the Hopf bifurcation degenerates into a chaotic attractor, therefore, preventing synchronization.

Spherically Symmetric Gravitational Collapse of a Dust Cloud in Third-Order Lovelock Gravity

NASA Astrophysics Data System (ADS)

Zhou, Kang; Yang, Zhan-Ying; Zou, De-Cheng; Yue, Rui-Hong

We investigate the spherically symmetric gravitational collapse of an incoherent dust cloud by considering a LTB-type spacetime in third-order Lovelock Gravity without cosmological constant, and give three families of LTB-like solutions which separately corresponding to hyperbolic, parabolic and elliptic. Notice that the contribution of high-order curvature corrections have a profound influence on the nature of the singularity, and the global structure of spacetime changes drastically from the analogous general relativistic case. Interestingly, the presence of high order Lovelock terms leads to the formation of massive, naked and timelike singularities in the 7D spacetime, which is disallowed in general relativity. Moveover, we point out that the naked singularities in the 7D case may be gravitational weak therefore may not be a serious threat to the cosmic censorship hypothesis, while the naked singularities in the D ≥ 8 inhomogeneous collapse violate the cosmic censorship hypothesis seriously.

Green synthesis and third-order nonlinear optical properties of 6-(9H-carbazol-9-yl) hexyl acetate

NASA Astrophysics Data System (ADS)

Chen, Baili; Geng, Feng; Luo, Xuan; Zhong, Quanjie; Zhang, Qingjun; Fang, Yu; Huang, Chuanqun; Yang, Ruizhuang; Shao, Ting; Chen, Shufan

2016-10-01

An extremely simple and green approach for the synthesis of photoelectric material 6-(9H-carbazol-9-yl) hexy-acetate (CHA) has been described in detail. The molecular structure of CHA was identified with Fourier transform infrared (FT-IR) spectra and 1H Nuclear Magnetic Resonance (1H NMR) spectroscopy. The optical absorption of CHA was recorded using ultraviolet-visible (UV-vis) spectrum. Notably, the reaction was accomplished in water medium instead of traditional toxic solvents (e.g., benzene and chloroform). The yield of CHA is up to 99%, which is increased by 13% compared with the traditional method. The approach developed by us makes it possible to achieve commercial production of CHA. Moreover, the thermal stability of CHA was studied with thermogravimetric (TG) and derivative thermogravimetric (DTG) method. The third-order nonlinear optical (NLO) properties of CHAn (obtained by new method) and CHAt (obtained by traditional method) have been studied by a Z-scan technique at 440 nm. The thermal decomposition temperature is above 200 °C. The third-order NLO of CHAn and CHAt are the same. The third-order NLO susceptibility χ (3) and two photon Figures of Merit (FOMs) of CHA are 1.58 × 10-8 (esu) and 4.55, respectively. The results reveal that CHA may be a promising candidate for all-optical switching application.

Fast large scale structure perturbation theory using one-dimensional fast Fourier transforms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmittfull, Marcel; Vlah, Zvonimir; McDonald, Patrick

The usual fluid equations describing the large-scale evolution of mass density in the universe can be written as local in the density, velocity divergence, and velocity potential fields. As a result, the perturbative expansion in small density fluctuations, usually written in terms of convolutions in Fourier space, can be written as a series of products of these fields evaluated at the same location in configuration space. Based on this, we establish a new method to numerically evaluate the 1-loop power spectrum (i.e., Fourier transform of the 2-point correlation function) with one-dimensional fast Fourier transforms. This is exact and a fewmore » orders of magnitude faster than previously used numerical approaches. Numerical results of the new method are in excellent agreement with the standard quadrature integration method. This fast model evaluation can in principle be extended to higher loop order where existing codes become painfully slow. Our approach follows by writing higher order corrections to the 2-point correlation function as, e.g., the correlation between two second-order fields or the correlation between a linear and a third-order field. These are then decomposed into products of correlations of linear fields and derivatives of linear fields. In conclusion, the method can also be viewed as evaluating three-dimensional Fourier space convolutions using products in configuration space, which may also be useful in other contexts where similar integrals appear.« less

Fast large scale structure perturbation theory using one-dimensional fast Fourier transforms

DOE PAGES

Schmittfull, Marcel; Vlah, Zvonimir; McDonald, Patrick

2016-05-01

The usual fluid equations describing the large-scale evolution of mass density in the universe can be written as local in the density, velocity divergence, and velocity potential fields. As a result, the perturbative expansion in small density fluctuations, usually written in terms of convolutions in Fourier space, can be written as a series of products of these fields evaluated at the same location in configuration space. Based on this, we establish a new method to numerically evaluate the 1-loop power spectrum (i.e., Fourier transform of the 2-point correlation function) with one-dimensional fast Fourier transforms. This is exact and a fewmore » orders of magnitude faster than previously used numerical approaches. Numerical results of the new method are in excellent agreement with the standard quadrature integration method. This fast model evaluation can in principle be extended to higher loop order where existing codes become painfully slow. Our approach follows by writing higher order corrections to the 2-point correlation function as, e.g., the correlation between two second-order fields or the correlation between a linear and a third-order field. These are then decomposed into products of correlations of linear fields and derivatives of linear fields. In conclusion, the method can also be viewed as evaluating three-dimensional Fourier space convolutions using products in configuration space, which may also be useful in other contexts where similar integrals appear.« less

Structural control of nonlinear optical absorption and refraction in dense metal nanoparticle arrays.

PubMed

Kohlgraf-Owens, Dana C; Kik, Pieter G

2009-08-17

The linear and nonlinear optical properties of a composite containing interacting spherical silver nanoparticles embedded in a dielectric host are studied as a function of interparticle separation using three dimensional frequency domain simulations. It is shown that for a fixed amount of metal, the effective third-order nonlinear susceptibility of the composite chi((3))(omega) can be significantly enhanced with respect to the linear optical properties, due to a combination of resonant surface plasmon excitation and local field redistribution. It is shown that this geometry-dependent susceptibility enhancement can lead to an improved figure of merit for nonlinear absorption. Enhancement factors for the nonlinear susceptibility of the composite are calculated, and the complex nature of the enhancement factors is discussed.

Characterization of the Nonlinear Elastic Properties of Graphite/Epoxy Composites Using Ultrasound

NASA Technical Reports Server (NTRS)

Prosser, William H.; Green, Robert E., Jr.

1990-01-01

The normalized change in ultrasonic "natural" velocity as a function of stress and temperature was measured in a unidirectional laminate of T300/5208 graphite/epoxy composite using a pulsed phase locked loop ultrasonic interferometer. These measurements were used together with the linear (second order) elastic moduli to calculate some of the nonlinear (third order) moduli of this material.

A first principles study of the electronic structure, elastic and thermal properties of UB2

NASA Astrophysics Data System (ADS)

Jossou, Ericmoore; Malakkal, Linu; Szpunar, Barbara; Oladimeji, Dotun; Szpunar, Jerzy A.

2017-07-01

Uranium diboride (UB2) has been widely deployed for refractory use and is a proposed material for Accident Tolerant Fuel (ATF) due to its high thermal conductivity. However, the applicability of UB2 towards high temperature usage in a nuclear reactor requires the need to investigate the thermomechanical properties, and recent studies have failed in highlighting applicable properties. In this work, we present an in-depth theoretical outlook of the structural and thermophysical properties of UB2, including but not limited to elastic, electronic and thermal transport properties. These calculations were performed within the framework of Density Functional Theory (DFT) + U approach, using Quantum ESPRESSO (QE) code considering the addition of Coulomb correlations on the uranium atom. The phonon spectra and elastic constant analysis show the dynamic and mechanical stability of UB2 structure respectively. The electronic structure of UB2 was investigated using full potential linear augmented plane waves plus local orbitals method (FP-LAPW+lo) as implemented in WIEN2k code. The absence of a band gap in the total and partial density of states confirms the metallic nature while the valence electron density plot reveals the presence of covalent bond between adjacent B-B atoms. We predicted the lattice thermal conductivity (kL) by solving Boltzmann Transport Equation (BTE) using ShengBTE. The second order harmonic and third-order anharmonic interatomic force constants required as input to ShengBTE was calculated using the Density-functional perturbation theory (DFPT). However, we predicted the electronic thermal conductivity (kel) using Wiedemann-Franz law as implemented in Boltztrap code. We also show that the sound velocity along 'a' and 'c' axes exhibit high anisotropy, which accounts for the anisotropic thermal conductivity of UB2.

Comparing the Quality of Third, Fourth, and Fifth Graders' Social Interactions and Cognitive Strategy Use during Structured Online Inquiry

ERIC Educational Resources Information Center

Coiro, Julie; Sekeres, Diane Carver; Castek, Jill; Guzniczak, Lizabeth

2014-01-01

This study examined the social and cognitive interaction patterns of third, fourth, and fifth graders as they collaboratively read on the Internet and responded to an inquiry prompt. Data analysis revealed patterns of cognitive strategy use that intersected with social forms and functions of dialogue. Dyads that exhibited higher levels of…

Rough-pipe flows and the existence of fully developed turbulence

NASA Astrophysics Data System (ADS)

Gioia, G.; Chakraborty, Pinaki; Bombardelli, Fabián A.

2006-03-01

It is widely believed that at high Reynolds number (Re) all turbulent flows approach a limiting state of "fully developed turbulence" in which the statistics of the velocity fluctuations are independent of Re. Nevertheless, direct measurements of the velocity fluctuations have failed to yield firm empirical evidence that even the second-order structure function becomes independent of Re at high Re, let alone structure functions of higher order. Here we relate the friction coefficient (f) of rough-pipe flows to the second-order structure function. Then we show that in light of experimental measurements of f our results yield unequivocal evidence that the second-order structure function becomes independent of Re at high Re, compatible with the existence of fully developed turbulence.

Student Oriented Approaches in the Teaching of Thermodynamics at Universities--Developing an Effective Course Structure

ERIC Educational Resources Information Center

Partanen, Lauri

2016-01-01

The aim of this study was to apply current pedagogical research in order to develop an effective course and exercise structure for a physical chemistry thermodynamics course intended for second or third year university students of chemistry. A mixed-method approach was used to measure the impact the changes had on student learning. In its final…

Anomalous transport from holography: part II

NASA Astrophysics Data System (ADS)

Bu, Yanyan; Lublinsky, Michael; Sharon, Amir

2017-03-01

This is a second study of chiral anomaly-induced transport within a holographic model consisting of anomalous U(1)_V× U(1)_A Maxwell theory in Schwarzschild-AdS_5 spacetime. In the first part, chiral magnetic/separation effects (CME/CSE) are considered in the presence of a static spatially inhomogeneous external magnetic field. Gradient corrections to CME/CSE are analytically evaluated up to third order in the derivative expansion. Some of the third order gradient corrections lead to an anomaly-induced negative B^2-correction to the diffusion constant. We also find modifications to the chiral magnetic wave nonlinear in B. In the second part, we focus on the experimentally interesting case of the axial chemical potential being induced dynamically by a constant magnetic and time-dependent electric fields. Constitutive relations for the vector/axial currents are computed employing two different approximations: (a) derivative expansion (up to third order) but fully nonlinear in the external fields, and (b) weak electric field limit but resuming all orders in the derivative expansion. A non-vanishing nonlinear axial current (CSE) is found in the first case. The dependence on magnetic field and frequency of linear transport coefficient functions is explored in the second.

Frame-dependence of higher-order inflationary observables in scalar-tensor theories

NASA Astrophysics Data System (ADS)

Karam, Alexandros; Pappas, Thomas; Tamvakis, Kyriakos

2017-09-01

In the context of scalar-tensor theories of gravity we compute the third-order corrected spectral indices in the slow-roll approximation. The calculation is carried out by employing the Green's function method for scalar and tensor perturbations in both the Einstein and Jordan frames. Then, using the interrelations between the Hubble slow-roll parameters in the two frames we find that the frames are equivalent up to third order. Since the Hubble slow-roll parameters are related to the potential slow-roll parameters, we express the observables in terms of the latter which are manifestly invariant. Nevertheless, the same inflaton excursion leads to different predictions in the two frames since the definition of the number of e -folds differs. To illustrate this effect we consider a nonminimal inflationary model and find that the difference in the predictions grows with the nonminimal coupling, and it can actually be larger than the difference between the first and third order results for the observables. Finally, we demonstrate the effect of various end-of-inflation conditions on the observables. These effects will become important for the analyses of inflationary models in view of the improved sensitivity of future experiments.

Investigations on structural, optical, electrical, mechanical and third-order nonlinear behaviour of 3-aminopyridinium 2,4-dinitrophenolate single crystal

NASA Astrophysics Data System (ADS)

Mohanbabu, B.; Bharathikannan, R.; Siva, G.

2017-10-01

The single crystals of 3-aminopyridinium 2,4-dinitrophenolate (APDP) have been synthesized and grown by slow evaporation technique at room temperature. The crystal system was identified and lattice dimensions were measured from the single-crystal X-ray diffraction (SXRD) analysis. UV-visible absorption and transmittance spectra have been recorded in the region between 250 and 1100 nm. The different vibrational modes of the molecule were studied by Fourier transform infrared (FTIR) spectroscopic analysis. The decreasing tendency of dielectric constant with increasing frequency was analysed in dielectric study. The polarizability value calculated using Penn analysis well agrees with the value calculated using Clausius-Mossotti equation. The photoconductivity and photoluminescence behaviour were also studied on grown APDP crystal. The mechanical strength of the crystal has been studied using a Vickers' microhardness test. The stiffness constant and yield strength of the crystal were also calculated from the microhardness test. The third-order nonlinear optical parameters such as refractive index, absorption coefficient and third-order susceptibility were estimated by Z-scan studies.

Molecular structure and gas chromatographic retention behavior of the components of Ylang-Ylang oil.

PubMed

Olivero, J; Gracia, T; Payares, P; Vivas, R; Díaz, D; Daza, E; Geerlings, P

1997-05-01

Using quantitative structure-retention relationships (QSRR) methodologies the Kovats gas chromatographic retention indices for both apolar (DB-1) and polar (DB-Wax) columns for 48 compounds from Ylang-Ylang essential oil were empirically predicted from calculated and experimental data on molecular structure. Topological, geometric, and electronic descriptors were obtained for model generation. Relationships between descriptors and the retention data reported were established by linear multiple regression, giving equations that can be used to predict the Kovats indices for compounds present in essential oils, both in DB-1 and DB-Wax columns. Factor analysis was performed to interpret the meaning of the descriptors included in the models. The prediction model for the DB-1 column includes descriptors such as Randic's first-order connectivity index (1X), the molecular surface (MSA), the sum of the atomic charge on all the hydrogens (QH), Randic's third-order connectivity index (3X) and the molecular electronegativity (chi). The prediction model for the DB-Wax column includes the first three descriptors mentioned for the DB-1 column (1X, MSA and QH) and the most negative charge (MNC), the global softness (S), and the difference between Randic's and Kier and Hall's third-order connectivity indexes (3X-3XV).

Quasiparticle Properties of a Mobile Impurity in a Bose-Einstein Condensate.

PubMed

Christensen, Rasmus Søgaard; Levinsen, Jesper; Bruun, Georg M

2015-10-16

We develop a systematic perturbation theory for the quasiparticle properties of a single impurity immersed in a Bose-Einstein condensate. Analytical results are derived for the impurity energy, effective mass, and residue to third order in the impurity-boson scattering length. The energy is shown to depend logarithmically on the scattering length to third order, whereas the residue and the effective mass are given by analytical power series. When the boson-boson scattering length equals the boson-impurity scattering length, the energy has the same structure as that of a weakly interacting Bose gas, including terms of the Lee-Huang-Yang and fourth order logarithmic form. Our results, which cannot be obtained within the canonical Fröhlich model of an impurity interacting with phonons, provide valuable benchmarks for many-body theories and for experiments.

Perception of second- and third-order orientation signals and their interactions

PubMed Central

Victor, Jonathan D.; Thengone, Daniel J.; Conte, Mary M.

2013-01-01

Orientation signals, which are crucial to many aspects of visual function, are more complex and varied in the natural world than in the stimuli typically used for laboratory investigation. Gratings and lines have a single orientation, but in natural stimuli, local features have multiple orientations, and multiple orientations can occur even at the same location. Moreover, orientation cues can arise not only from pairwise spatial correlations, but from higher-order ones as well. To investigate these orientation cues and how they interact, we examined segmentation performance for visual textures in which the strengths of different kinds of orientation cues were varied independently, while controlling potential confounds such as differences in luminance statistics. Second-order cues (the kind present in gratings) at different orientations are largely processed independently: There is no cancellation of positive and negative signals at orientations that differ by 45°. Third-order orientation cues are readily detected and interact only minimally with second-order cues. However, they combine across orientations in a different way: Positive and negative signals largely cancel if the orientations differ by 90°. Two additional elements are superimposed on this picture. First, corners play a special role. When second-order orientation cues combine to produce corners, they provide a stronger signal for texture segregation than can be accounted for by their individual effects. Second, while the object versus background distinction does not influence processing of second-order orientation cues, this distinction influences the processing of third-order orientation cues. PMID:23532909

Functional and Structural Brain Changes Associated with Methamphetamine Abuse

PubMed Central

Jan, Reem K.; Kydd, Rob R.; Russell, Bruce R.

2012-01-01

Methamphetamine (MA) is a potent psychostimulant drug whose abuse has become a global epidemic in recent years. Firstly, this review article briefly discusses the epidemiology and clinical pharmacology of methamphetamine dependence. Secondly, the article reviews relevant animal literature modeling methamphetamine dependence and discusses possible mechanisms of methamphetamine-induced neurotoxicity. Thirdly, it provides a critical review of functional and structural neuroimaging studies in human MA abusers; including positron emission tomography (PET) and functional and structural magnetic resonance imaging (MRI). The effect of abstinence from methamphetamine, both short- and long-term within the context of these studies is also reviewed. PMID:24961256

MODY - calculation of ordered structures by symmetry-adapted functions

NASA Astrophysics Data System (ADS)

Białas, Franciszek; Pytlik, Lucjan; Sikora, Wiesława

2016-01-01

In this paper we focus on the new version of computer program MODY for calculations of symmetryadapted functions based on the theory of groups and representations. The choice of such a functional frame of coordinates for description of ordered structures leads to a minimal number of parameters which must be used for presentation of such structures and investigations of their properties. The aim of this work is to find those parameters, which are coefficients of a linear combination of calculated functions, leading to construction of different types of structure ordering with a given symmetry. A spreadsheet script for simplification of this work has been created and attached to the program.

Measurement of Shear Elastic Moduli in Quasi-Incompressible Soft Solids

NASA Astrophysics Data System (ADS)

Rénier, Mathieu; Gennisson, Jean-Luc; Barrière, Christophe; Catheline, Stefan; Tanter, Mickaël; Royer, Daniel; Fink, Mathias

2008-06-01

Recently a nonlinear equation describing the plane shear wave propagation in isotropic quasi-incompressible media has been developed using a new expression of the strain energy density, as a function of the second, third and fourth order shear elastic constants (respectively μ, A, D) [1]. In such a case, the shear nonlinearity parameter βs depends only from these last coefficients. To date, no measurement of the parameter D have been carried out in soft solids. Using a set of two experiments, acoustoelasticity and finite amplitude shear waves, the shear elastic moduli up to the fourth order of soft solids are measured. Firstly, this theoretical background is applied to the acoustoelasticity theory, giving the variations of the shear wave speed as a function of the stress applied to the medium. From such variations, both linear (μ) and third order shear modulus (A) are deduced in agar-gelatin phantoms. Experimentally the radiation force induced by a focused ultrasound beam is used to generate quasi-plane linear shear waves within the medium. Then the shear wave propagation is imaged with an ultrafast ultrasound scanner. Secondly, in order to give rise to finite amplitude plane shear waves, the radiation force generation technique is replaced by a vibrating plate applied at the surface of the phantoms. The propagation is also imaged using the same ultrafast scanner. From the assessment of the third harmonic amplitude, the nonlinearity parameter βS is deduced. Finally, combining these results with the acoustoelasticity experiment, the fourth order modulus (D) is deduced. This set of experiments provides the characterization, up to the fourth order, of the nonlinear shear elastic moduli in quasi-incompressible soft media. Measurements of the A moduli reveal that while the behaviors of both soft solids are close from a linear point of view, the corresponding nonlinear moduli A are quite different. In a 5% agar-gelatin phantom, the fourth order elastic constant D is found to be 30±10 kPa.

Growth curves for ostriches (Struthio camelus) in a Brazilian population.

PubMed

Ramos, S B; Caetano, S L; Savegnago, R P; Nunes, B N; Ramos, A A; Munari, D P

2013-01-01

The objective of this study was to fit growth curves using nonlinear and linear functions to describe the growth of ostriches in a Brazilian population. The data set consisted of 112 animals with BW measurements from hatching to 383 d of age. Two nonlinear growth functions (Gompertz and logistic) and a third-order polynomial function were applied. The parameters for the models were estimated using the least-squares method and Gauss-Newton algorithm. The goodness-of-fit of the models was assessed using R(2) and the Akaike information criterion. The R(2) calculated for the logistic growth model was 0.945 for hens and 0.928 for cockerels and for the Gompertz growth model, 0.938 for hens and 0.924 for cockerels. The third-order polynomial fit gave R(2) of 0.938 for hens and 0.924 for cockerels. Among the Akaike information criterion calculations, the logistic growth model presented the lowest values in this study, both for hens and for cockerels. Nonlinear models are more appropriate for describing the sigmoid nature of ostrich growth.

Numerically constructed internal-coordinate Hamiltonian with Eckart embedding and its application for the inversion tunneling of ammonia.

PubMed

Fábri, Csaba; Mátyus, Edit; Császár, Attila G

2014-02-05

It is shown that the use of an Eckart-frame embedding with a kinetic energy operator expressed in curvilinear internal coordinates becomes feasible and straightforward to implement for arbitrary molecular compositions and internal coordinates if the operator is defined numerically over a (discrete variable representation) grid. The algorithm proposed utilizes the transformation method of Dymarsky and Kudin to maintain the rotational Eckart condition. In order to demonstrate the applicability and flexibility of our approach the non-rigid ammonia molecule is considered and the corresponding rotational-vibrational energy levels and wave functions are computed using kinetic energy operators with three different embeddings. Two of them fulfill the Eckart conditions corresponding to a trigonal pyramidal (C3v) and a trigonal planar (D3h) reference structure and the third one is a non-Eckart frame. The computed energy levels are, of course, identical, and the structure of the three different wave-function representations are analyzed in terms of the rigid rotor functions for a symmetric top. The possible advantages of one frame representation over another are discussed concerning the interpretation of the rovibrational states in terms of the traditional rigid rotor labels. Copyright © 2013 Elsevier B.V. All rights reserved.

Order reduction, identification and localization studies of dynamical systems

NASA Astrophysics Data System (ADS)

Ma, Xianghong

In this thesis methods are developed for performing order reduction, system identification and induction of nonlinear localization in complex mechanical dynamic systems. General techniques are proposed for constructing low-order models of linear and nonlinear mechanical systems; in addition, novel mechanical designs are considered for inducing nonlinear localization phenomena for the purpose of enhancing their dynamical performance. The thesis is in three major parts. In the first part, the transient dynamics of an impulsively loaded multi-bay truss is numerically computed by employing the Direct Global Matrix (DGM) approach. The approach is applicable to large-scale flexible structures with periodicity. Karhunen-Loeve (K-L) decomposition is used to discretize the dynamics of the truss and to create the low-order models of the truss. The leading order K-L modes are recovered by an experiment, which shows the feasibility of K-L based order reduction technique. In the second part of the thesis, nonlinear localization in dynamical systems is studied through two applications. In the seismic base isolation study, it is shown that the dynamics are sensitive to the presence of nonlinear elements and that passive motion confinement can be induced under proper design. In the coupled rod system, numerical simulation of the transient dynamics shows that a nonlinear backlash spring can induce either nonlinear localization or delocalization in the form of beat phenomena. K-L decomposition and poincare maps are utilized to study the nonlinear effects. The study shows that nonlinear localization can be induced in complex structures through backlash. In the third and final part of the thesis, a new technique based on Green!s function method is proposed to identify the dynamics of practical bolted joints. By modeling the difference between the dynamics of the bolted structure and the corresponding unbolted one, one constructs a nonparametric model for the joint dynamics. Two applications are given with a bolted beam and a truss joint in order to show the applicability of the technique.

Development of the field of structural physiology

PubMed Central

FUJIYOSHI, Yoshinori

2015-01-01

Electron crystallography is especially useful for studying the structure and function of membrane proteins — key molecules with important functions in neural and other cells. Electron crystallography is now an established technique for analyzing the structures of membrane proteins in lipid bilayers that closely simulate their natural biological environment. Utilizing cryo-electron microscopes with helium-cooled specimen stages that were developed through a personal motivation to understand the functions of neural systems from a structural point of view, the structures of membrane proteins can be analyzed at a higher than 3 Å resolution. This review covers four objectives. First, I introduce the new research field of structural physiology. Second, I recount some of the struggles involved in developing cryo-electron microscopes. Third, I review the structural and functional analyses of membrane proteins mainly by electron crystallography using cryo-electron microscopes. Finally, I discuss multifunctional channels named “adhennels” based on structures analyzed using electron and X-ray crystallography. PMID:26560835

New stochastic approach for extreme response of slow drift motion of moored floating structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kato, Shunji; Okazaki, Takashi

1995-12-31

A new stochastic method for investigating the flow drift response statistics of moored floating structures is described. Assuming that wave drift excitation process can be driven by a Gaussian white noise process, an exact stochastic equation governing a time evolution of the response Probability Density Function (PDF) is derived on a basis of Projection operator technique in the field of statistical physics. In order to get an approximate solution of the GFP equation, the authors develop the renormalized perturbation technique which is a kind of singular perturbation methods and solve the GFP equation taken into account up to third ordermore » moments of a non-Gaussian excitation. As an example of the present method, a closed form of the joint PDF is derived for linear response in surge motion subjected to a non-Gaussian wave drift excitation and it is represented by the product of a form factor and the quasi-Cauchy PDFs. In this case, the motion displacement and velocity processes are not mutually independent if the excitation process has a significant third order moment. From a comparison between the response PDF by the present solution and the exact one derived by Naess, it is found that the present solution is effective for calculating both the response PDF and the joint PDF. Furthermore it is shown that the displacement-velocity independence is satisfied if the damping coefficient in equation of motion is not so large and that both the non-Gaussian property of excitation and the damping coefficient should be taken into account for estimating the probability exceedance of the response.« less

Expression, purification and crystallization of CTB-MPR, a candidate mucosal vaccine component against HIV-1

DOE PAGES

Lee, Ho-Hsien; Cherni, Irene; Yu, HongQi; ...

2014-08-20

CTB-MPR is a fusion protein between the B subunit of cholera toxin (CTB) and the membrane-proximal region of gp41 (MPR), the transmembrane envelope protein of Human immunodeficiency virus 1 (HIV-1), and has previously been shown to induce the production of anti-HIV-1 antibodies with antiviral functions. To further improve the design of this candidate vaccine, X-ray crystallography experiments were performed to obtain structural information about this fusion protein. Several variants of CTB-MPR were designed, constructed and recombinantly expressed in Escherichia coli . The first variant contained a flexible GPGP linker between CTB and MPR, and yielded crystals that diffracted to amore » resolution of 2.3 Å, but only the CTB region was detected in the electron-density map. A second variant, in which the CTB was directly attached to MPR, was shown to destabilize pentamer formation. A third construct containing a polyalanine linker between CTB and MPR proved to stabilize the pentameric form of the protein during purification. The purification procedure was shown to produce a homogeneously pure and monodisperse sample for crystallization. Initial crystallization experiments led to pseudo-crystals which were ordered in only two dimensions and were disordered in the third dimension. Nanocrystals obtained using the same precipitant showed promising X-ray diffraction to 5 Å resolution in femtosecond nanocrystallography experiments at the Linac Coherent Light Source at the SLAC National Accelerator Laboratory. The results demonstrate the utility of femtosecond X-ray crystallography to enable structural analysis based on nano/microcrystals of a protein for which no macroscopic crystals ordered in three dimensions have been observed before.« less

Expression, purification and crystallization of CTB-MPR, a candidate mucosal vaccine component against HIV-1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Ho-Hsien; Cherni, Irene; Yu, HongQi

CTB-MPR is a fusion protein between the B subunit of cholera toxin (CTB) and the membrane-proximal region of gp41 (MPR), the transmembrane envelope protein of Human immunodeficiency virus 1 (HIV-1), and has previously been shown to induce the production of anti-HIV-1 antibodies with antiviral functions. To further improve the design of this candidate vaccine, X-ray crystallography experiments were performed to obtain structural information about this fusion protein. Several variants of CTB-MPR were designed, constructed and recombinantly expressed in Escherichia coli . The first variant contained a flexible GPGP linker between CTB and MPR, and yielded crystals that diffracted to amore » resolution of 2.3 Å, but only the CTB region was detected in the electron-density map. A second variant, in which the CTB was directly attached to MPR, was shown to destabilize pentamer formation. A third construct containing a polyalanine linker between CTB and MPR proved to stabilize the pentameric form of the protein during purification. The purification procedure was shown to produce a homogeneously pure and monodisperse sample for crystallization. Initial crystallization experiments led to pseudo-crystals which were ordered in only two dimensions and were disordered in the third dimension. Nanocrystals obtained using the same precipitant showed promising X-ray diffraction to 5 Å resolution in femtosecond nanocrystallography experiments at the Linac Coherent Light Source at the SLAC National Accelerator Laboratory. The results demonstrate the utility of femtosecond X-ray crystallography to enable structural analysis based on nano/microcrystals of a protein for which no macroscopic crystals ordered in three dimensions have been observed before.« less

Factorial structure and psychometric properties of a brief version of the Reminiscence Functions Scale with Chinese older adults.

PubMed

Lou, Vivian W Q; Choy, Jacky C P

2014-05-01

The current study aims to examine the factorial structure and psychometric properties of a brief version of the Reminiscence Functions Scale (RFS), a 14-item assessment tool of reminiscence functions, with Chinese older adults. The scale, covering four reminiscence functions (boredom reduction, bitterness revival, problem solving, and identity) was translated from English into Chinese and administered to older adults (N=675). Confirmatory factor analysis and hierarchical confirmatory factor analysis were conducted to examine its factorial structure, and its psychometric properties and criterion validity were examined. Confirmatory factor analysis supports a second-order model comprising one second-order factor and four first-order factors of RFS. The Cronbach's alpha of the subscales ranged from 0.75 to 0.90. The brief RFS contains a second-order factorial structure. Its psychometric properties support it as a sound instrument for measuring reminiscence functions among Chinese older adults.

A third-order moving mesh cell-centered scheme for one-dimensional elastic-plastic flows

NASA Astrophysics Data System (ADS)

Cheng, Jun-Bo; Huang, Weizhang; Jiang, Song; Tian, Baolin

2017-11-01

A third-order moving mesh cell-centered scheme without the remapping of physical variables is developed for the numerical solution of one-dimensional elastic-plastic flows with the Mie-Grüneisen equation of state, the Wilkins constitutive model, and the von Mises yielding criterion. The scheme combines the Lagrangian method with the MMPDE moving mesh method and adaptively moves the mesh to better resolve shock and other types of waves while preventing the mesh from crossing and tangling. It can be viewed as a direct arbitrarily Lagrangian-Eulerian method but can also be degenerated to a purely Lagrangian scheme. It treats the relative velocity of the fluid with respect to the mesh as constant in time between time steps, which allows high-order approximation of free boundaries. A time dependent scaling is used in the monitor function to avoid possible sudden movement of the mesh points due to the creation or diminishing of shock and rarefaction waves or the steepening of those waves. A two-rarefaction Riemann solver with elastic waves is employed to compute the Godunov values of the density, pressure, velocity, and deviatoric stress at cell interfaces. Numerical results are presented for three examples. The third-order convergence of the scheme and its ability to concentrate mesh points around shock and elastic rarefaction waves are demonstrated. The obtained numerical results are in good agreement with those in literature. The new scheme is also shown to be more accurate in resolving shock and rarefaction waves than an existing third-order cell-centered Lagrangian scheme.

Towards a unifying theory for the first-, second-, and third-order molecular (non)linear optical response

NASA Astrophysics Data System (ADS)

Pérez-Moreno, Javier; Clays, Koen; Kuzyk, Mark G.

2010-05-01

We present a procedure for the modeling of the dispersion of the nonlinear optical response of complex molecular structures that is based strictly on the results from experimental characterization. We show how under some general conditions, the use of the Thomas-Kuhn sum-rules leads to a successful modeling of the nonlinear response of complex molecular structures.

Characterizing Atomistic Geometries and Potential Functions Using Strain Functionals

NASA Astrophysics Data System (ADS)

Kober, Edward; Mathew, Nithin; Rudin, Sven

2017-06-01

We demonstrate the use of strain tensor functionals for characterizing arbitrarily ordered atomistic structures. This approach defines a Gaussian-weighted neighborhood around each atom and characterizes that local geometry in terms of n-th order strain tensors, which are equivalent to the n-th order moments/derivatives of the neighborhood. Fourth order expansions can distinguish the cubic structures (and deformations thereof), but sixth order expansions are required to fully characterize hexagonal structures. These functions are continuous and smooth and much less sensitive to thermal fluctuations than other descriptors based on discrete neighborhoods. Reducing these metrics to rotational invariant descriptors allows a large number of defect structures to be readily identified and forms the basis of a classification scheme that allows molecular dynamics simulations to be readily analyzed. Applications to the analysis of shock waves impinging on samples of Cu, Ta and Ti will be presented. The method has been extended to vector fields as well, enabling the local stress to be cast in terms of rotationally invariant functions as well. The stress-strain correlations can then be used as the basis for developing and analyzing potential functions.

Synthesis, growth, structural modeling and physio-chemical properties of a charge transfer molecule: Guanidinium tosylate

NASA Astrophysics Data System (ADS)

Era, Paavai; Jauhar, RO. MU.; Vinitha, G.; Murugakoothan, P.

2018-05-01

An organic nonlinear optical material, guanidinium tosylate was synthesized adopting slow evaporation method and the crystals were harvested from aqueous methanolic medium with dimensions 13 × 9 × 3 mm3. Constitution of crystalline material was confirmed by single crystal X-ray diffraction study. The title compound crystallizes in the monoclinic crystal system with space group P21/c. The UV-vis-NIR spectral study of the grown crystal exhibits high transparency of 80% in the entire visible region with lower cut-off wavelength at 282 nm. Optimized molecular geometry of the grown crystal was obtained using density functional theory (DFT) and the frontier energy gaps calculated from the DFT aids to understand the charge transfer taking place in the molecule. The dielectric properties were studied as a function of temperature and frequency to find the charge distribution within the crystal. The titular compound is thermally stable up to 230 °C assessed by thermogravimetric and differential thermal analysis. Anisotropy in the mechanical behavior was observed while measuring for individual planes. The laser induced surface damage threshold of the grown crystal was measured to be 0.344 GW/cm2 for 1064 nm Nd:YAG laser radiation. Z-scan technique confirms the third-order nonlinear optical property with the ascertained nonlinear refractive index (n2), nonlinear absorption coefficient (β) and third order nonlinear susceptibility (χ(3)). Optical limiting study divulges that the transmitted output power step-up linearly with the increase of the input power at lower power realms and saturates from the threshold 24.95 mW/cm2 and amplitude 0.23 mW/cm2.

The Mass Function of Cosmic Structures

NASA Astrophysics Data System (ADS)

Audit, E.; Teyssier, R.; Alimi, J.-M.

We investigate some modifications to the Press and Schechter (1974) (PS) prescription resulting from shear and tidal effects. These modifications rely on more realistic treatments of the collapse process than the standard approach based on the spherical model. First, we show that the mass function resulting from a new approximate Lagrangian dynamic (Audit and Alimi, A&A 1996), contains more objects at high mass, than the classical PS mass function and is well fitted by a PS-like function with a threshold density of deltac ≍ 1.4. However, such a Lagrangian description can underestimate the epoch of structure formation since it defines it as the collapse of the first principal axis. We therefore suggest some analytical prescriptions, for computing the collapse time along the second and third principal axes, and we deduce the corresponding mass functions. The collapse along the third axis is delayed by the shear and the number of objects of high mass then decreases. Finally, we show that the shear also strongly affects the formation of low-mass halos. This dynamical effect implies a modification of the low-mass slope of the mass function and allows the reproduction of the observed luminosity function of field galaxies.

Coherent source interaction, third-order nonlinear response of synthesized PEG coated magnetite nanoparticles in polyethylene glycol and its application

NASA Astrophysics Data System (ADS)

Gopal, S. Veena; Chitrambalam, S.; Joe, I. Hubert

2018-01-01

Third-order nonlinear response of synthesized polyethylene glycol coated Fe3O4 nanoparticles dispersed in a suitable solvent, polyethylene glycol has been studied. The structural characterization of the synthesized magnetite nanoparticles were carried out. The linear optical property of the synthesized magnetite nanoparticles was investigated using UV-visible technique. Both closed and open aperture Z-scan techniques have been performed at 532 nm with pulse width 5 ns and repetition rate 10 Hz. It was found that polyethylene glycol coated magnetite exhibits reverse saturable absorption, with significant nonlinear absorption coefficient. Two-photon absorption intensity dependent positive nonlinear refraction coefficients indicate self focusing phenomena. Results show that higher concentration gives better nonlinear and optical limiting properties.

Ecosystem Food Web Lift-The-Flap Pages

ERIC Educational Resources Information Center

Atwood-Blaine, Dana; Rule, Audrey C.; Morgan, Hannah

2016-01-01

In the lesson on which this practical article is based, third grade students constructed a "lift-the-flap" page to explore food webs on the prairie. The moveable papercraft focused student attention on prairie animals' external structures and how the inferred functions of those structures could support further inferences about the…

Self-stress control of real civil engineering tensegrity structures

NASA Astrophysics Data System (ADS)

Kłosowska, Joanna; Obara, Paulina; Gilewski, Wojciech

2018-01-01

The paper introduces the impact of the self-stress level on the behaviour of the tensegrity truss structures. Displacements for real civil engineering tensegrity structures are analysed. Full-scale tensegrity tower Warnow Tower which consists of six Simplex trusses is considered in this paper. Three models consisting of one, two and six modules are analysed. The analysis is performed by the second and third order theory. Mathematica software and Sofistik programme is applied to the analysis.

Word order processing in the bilingual brain.

PubMed

Saur, Dorothee; Baumgaertner, Annette; Moehring, Anja; Büchel, Christian; Bonnesen, Matthias; Rose, Michael; Musso, Mariachristina; Meisel, Jürgen M

2009-01-01

One of the issues debated in the field of bilingualism is the question of a "critical period" for second language acquisition. Recent studies suggest an influence of age of onset of acquisition (AOA) particularly on syntactic processing; however, the processing of word order in a sentence context has not yet been examined specifically. We used functional MRI to examine word order processing in two groups of highly proficient German-French bilinguals who had either acquired French or German after the age of 10, and a third group which had acquired both languages before the age of three. Subjects listened to French and German sentences in which the order of subject and verb was systematically varied. In both groups of late bilinguals, processing of L2 compared to L1 resulted in higher levels of activation mainly of the left inferior frontal cortex while early bilinguals showed no activation difference in any of these areas. A selective increase in activation for late bilinguals only suggests that AOA contributes to modulating overall syntactic processing in L2. In addition, native speakers of French showed significantly higher activation for verb-subject-order than native German speakers. These data suggest that AOA effects may in particular affect those grammatical structures which are marked in the first language.

Molecular structure, second- and third-order nonlinear optical properties and DFT studies of a novel non-centrosymmetric chalcone derivative: (2E)-3-(4-fluorophenyl)-1-(4-{[(1E)-(4-fluorophenyl)methylene]amino}phenyl)prop-2-en-1-one

NASA Astrophysics Data System (ADS)

Maidur, Shivaraj R.; Patil, Parutagouda Shankaragouda; Ekbote, Anusha; Chia, Tze Shyang; Quah, Ching Kheng

2017-09-01

In the present work, the title chalcone, (2E)-3-(4-fluorophenyl)-1-(4-{[(1E)-(4-fluorophenyl) methylene]amino}phenyl)prop-2-en-1-one (abbreviated as FAMFC), was synthesized and structurally characterized by single-crystal X-ray diffraction. The compound is crystallized in the monoclinic system with non-centrosymmetric space group P21 and hence it satisfies the essential condition for materials to exhibit second-order nonlinear optical properties. The molecular structure was further confirmed by using FT-IR and 1H NMR spectroscopic techniques. The title crystal is transparent in the Vis-NIR region and has a direct band gap. The third-order nonlinear optical properties were investigated in solution (0.01 M) by Z-scan technique using a continuous wave (CW) DPSS laser at the wavelength of 532 nm. The title chalcone exhibited significant two-photon absorption (β = 35.8 × 10- 5 cm W- 1), negative nonlinear refraction (n2 = - 0.18 × 10- 8 cm2 W- 1) and optical limiting (OL threshold = 2.73 kJ cm- 2) under the CW regime. In support of the experimental results, a comprehensive theoretical study was carried out on the molecule of FAMFC using density functional theory (DFT). The optimized geometries and frontier molecular orbitals were calculated by employing B3LYP/6-31 + G level of theory. The optimized molecular structure was confirmed computationally by IR vibrational and 1H NMR spectral analysis. The experimental UV-Vis-NIR spectrum was interpreted using computational chemistry under time-dependent DFT. The static and dynamic NLO properties such as dipole moments (μ), polarizability (α), and first hyperpolarizabilities (β) were computed by using finite field method. The obtained dynamic first hyperpolarizability β(- 2ω;ω,ω) at input frequency ω = 0.04282 a.u. is predicted to be 161 times higher than urea standard. The electronic excitation energies and HOMO-LUMO band gap for FAMFC were also evaluated by DFT. The experimental and theoretical results are in good agreement, and the NLO study suggests that FAMFC molecule can be a potential candidate in the nonlinear optical applications.

Molecular structure, second- and third-order nonlinear optical properties and DFT studies of a novel non-centrosymmetric chalcone derivative: (2E)-3-(4-fluorophenyl)-1-(4-{[(1E)-(4-fluorophenyl)methylene]amino}phenyl)prop-2-en-1-one.

PubMed

Maidur, Shivaraj R; Patil, Parutagouda Shankaragouda; Ekbote, Anusha; Chia, Tze Shyang; Quah, Ching Kheng

2017-09-05

In the present work, the title chalcone, (2E)-3-(4-fluorophenyl)-1-(4-{[(1E)-(4-fluorophenyl) methylene]amino}phenyl)prop-2-en-1-one (abbreviated as FAMFC), was synthesized and structurally characterized by single-crystal X-ray diffraction. The compound is crystallized in the monoclinic system with non-centrosymmetric space group P2 1 and hence it satisfies the essential condition for materials to exhibit second-order nonlinear optical properties. The molecular structure was further confirmed by using FT-IR and 1 H NMR spectroscopic techniques. The title crystal is transparent in the Vis-NIR region and has a direct band gap. The third-order nonlinear optical properties were investigated in solution (0.01M) by Z-scan technique using a continuous wave (CW) DPSS laser at the wavelength of 532nm. The title chalcone exhibited significant two-photon absorption (β=35.8×10 -5 cmW -1 ), negative nonlinear refraction (n 2 =-0.18×10 -8 cm 2 W -1 ) and optical limiting (OL threshold=2.73kJcm -2 ) under the CW regime. In support of the experimental results, a comprehensive theoretical study was carried out on the molecule of FAMFC using density functional theory (DFT). The optimized geometries and frontier molecular orbitals were calculated by employing B3LYP/6-31+G level of theory. The optimized molecular structure was confirmed computationally by IR vibrational and 1 H NMR spectral analysis. The experimental UV-Vis-NIR spectrum was interpreted using computational chemistry under time-dependent DFT. The static and dynamic NLO properties such as dipole moments (μ), polarizability (α), and first hyperpolarizabilities (β) were computed by using finite field method. The obtained dynamic first hyperpolarizability β(-2ω;ω,ω) at input frequency ω=0.04282a.u. is predicted to be 161 times higher than urea standard. The electronic excitation energies and HOMO-LUMO band gap for FAMFC were also evaluated by DFT. The experimental and theoretical results are in good agreement, and the NLO study suggests that FAMFC molecule can be a potential candidate in the nonlinear optical applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Multistability of second-order competitive neural networks with nondecreasing saturated activation functions.

PubMed

Nie, Xiaobing; Cao, Jinde

2011-11-01

In this paper, second-order interactions are introduced into competitive neural networks (NNs) and the multistability is discussed for second-order competitive NNs (SOCNNs) with nondecreasing saturated activation functions. Firstly, based on decomposition of state space, Cauchy convergence principle, and inequality technique, some sufficient conditions ensuring the local exponential stability of 2N equilibrium points are derived. Secondly, some conditions are obtained for ascertaining equilibrium points to be locally exponentially stable and to be located in any designated region. Thirdly, the theory is extended to more general saturated activation functions with 2r corner points and a sufficient criterion is given under which the SOCNNs can have (r+1)N locally exponentially stable equilibrium points. Even if there is no second-order interactions, the obtained results are less restrictive than those in some recent works. Finally, three examples with their simulations are presented to verify the theoretical analysis.

Lennard-Jones fluids in two-dimensional nano-pores. Multi-phase coexistence and fluid structure

NASA Astrophysics Data System (ADS)

Yatsyshin, Petr; Savva, Nikos; Kalliadasis, Serafim

2014-03-01

We present a number of fundamental findings on the wetting behaviour of nano-pores. A popular model for fluid confinement is a one-dimensional (1D) slit pore formed by two parallel planar walls and it exhibits capillary condensation (CC): a first-order phase transition from vapour to capillary-liquid (Kelvin shift). Capping such a pore at one end by a third orthogonal wall forms a prototypical two-dimensional (2D) pore. We show that 2D pores possess a wetting temperature such that below this temperature CC remains of first order, above it becomes a continuous phase transition manifested by a slab of capillary-liquid filling the pore from the capping wall. Continuous CC exhibits hysteresis and can be preceded by a first-order capillary prewetting transition. Additionally, liquid drops can form in the corners of the 2D pore (remnant of 2D wedge prewetting). The three fluid phases, vapour, capillary-liquid slab and corner drops, can coexist at the pore triple point. Our model is based on the statistical mechanics of fluids in the density functional formulation. The fluid-fluid and fluid-substrate interactions are dispersive. We analyze in detail the microscopic fluid structure, isotherms and full phase diagrams. Our findings also suggest novel ways to control wetting of nano-pores. We are grateful to the European Research Council via Advanced Grant No. 247031 for support.

Meta-Symplectic Geometry of 3rd Order Monge-Ampère Equations and their Characteristics

NASA Astrophysics Data System (ADS)

Manno, Gianni; Moreno, Giovanni

2016-03-01

This paper is a natural companion of [Alekseevsky D.V., Alonso Blanco R., Manno G., Pugliese F., Ann. Inst. Fourier (Grenoble) 62 (2012), 497-524, arXiv:1003.5177], generalising its perspectives and results to the context of third-order (2D) Monge-Ampère equations, by using the so-called ''meta-symplectic structure'' associated with the 8D prolongation M^{(1)} of a 5D contact manifold M. We write down a geometric definition of a third-order Monge-Ampère equation in terms of a (class of) differential two-form on M^{(1)}. In particular, the equations corresponding to decomposable forms admit a simple description in terms of certain three-dimensional distributions, which are made from the characteristics of the original equations. We conclude the paper with a study of the intermediate integrals of these special Monge-Ampère equations, herewith called of Goursat type.

ISR corrections to associated HZ production at future Higgs factories

NASA Astrophysics Data System (ADS)

Greco, Mario; Montagna, Guido; Nicrosini, Oreste; Piccinini, Fulvio; Volpi, Gabriele

2018-02-01

We evaluate the QED corrections due to initial state radiation (ISR) to associated Higgs boson production in electron-positron (e+e-) annihilation at typical energies of interest for the measurement of the Higgs properties at future e+e- colliders, such as CEPC and FCC-ee. We apply the QED Structure Function approach to the four-fermion production process e+e- →μ+μ- b b bar , including both signal and background contributions. We emphasize the relevance of the ISR corrections particularly near threshold and show that finite third order collinear contributions are mandatory to meet the expected experimental accuracy. We analyze in turn the rôle played by a full four-fermion calculation and beam energy spread in precision calculations for Higgs physics at future e+e- colliders.

Fracture mechanics concepts in reliability analysis of monolithic ceramics

NASA Technical Reports Server (NTRS)

Manderscheid, Jane M.; Gyekenyesi, John P.

1987-01-01

Basic design concepts for high-performance, monolithic ceramic structural components are addressed. The design of brittle ceramics differs from that of ductile metals because of the inability of ceramic materials to redistribute high local stresses caused by inherent flaws. Random flaw size and orientation requires that a probabilistic analysis be performed in order to determine component reliability. The current trend in probabilistic analysis is to combine linear elastic fracture mechanics concepts with the two parameter Weibull distribution function to predict component reliability under multiaxial stress states. Nondestructive evaluation supports this analytical effort by supplying data during verification testing. It can also help to determine statistical parameters which describe the material strength variation, in particular the material threshold strength (the third Weibull parameter), which in the past was often taken as zero for simplicity.

AB INITIO Molecular Dynamics Simulations on Local Structure and Electronic Properties in Liquid MgxBi1-x Alloys

NASA Astrophysics Data System (ADS)

Hao, Qing-Hai; You, Yu-Wei; Kong, Xiang-Shan; Liu, C. S.

2013-03-01

The microscopic structure and dynamics of liquid MgxBi1-x(x = 0.5, 0.6, 0.7) alloys together with pure liquid Mg and Bi metals were investigated by means of ab initio molecular dynamics simulations. We present results of structure properties including pair correlation function, structural factor, bond-angle distribution function and bond order parameter, and their composition dependence. The dynamical and electronic properties have also been studied. The structure factor and pair correlation function are in agreement with the available experimental data. The calculated bond-angle distribution function and bond order parameter suggest that the stoichiometric composition Mg3Bi2 exhibits a different local structure order compared with other concentrations, which help us understand the appearance of the minimum electronic conductivity at this composition observed in previous experiments.

Evaluation of objective structured clinical examination for advanced orthodontic education 12 years after introduction.

PubMed

Fields, Henry W; Kim, Do-Gyoon; Jeon, Minjeong; Firestone, Allen R; Sun, Zongyang; Shanker, Shiva; Mercado, Ana M; Deguchi, Toru; Vig, Katherine W L

2017-05-01

Advanced education programs in orthodontics must ensure student competency in clinical skills. An objective structure clinical examination has been used in 1 program for over a decade. The results were analyzed cross-sectionally and longitudinally to provide insights regarding the achievement of competency, student growth, question difficulty, question discrimination, and question predictive ability. In this study, we analyzed 218 (82 first-year, 68 second-year, and 68 third-year classes) scores of each station from 85 orthodontic students. The grades originated from 13 stations and were collected anonymously for 12 consecutive years during the first 2 decades of the 2000s. The stations tested knowledge and skills regarding dental relationships, analyzing a cephalometric tracing, performing a diagnostic skill, identifying cephalometric points, bracket placement, placing first-order and second-order bends, forming a loop, placing accentuated third-order bends, identifying problems and planning mixed dentition treatment, identifying problems and planning adolescent dentition treatment, identifying problems and planning nongrowing skeletal treatment, superimposing cephalometric tracings, and interpreting cephalometric superimpositions. Results were evaluated using multivariate analysis of variance, chi-square tests, and latent growth analysis. The multivariate analysis of variance showed that all stations except 3 (analyzing a cephalometric tracing, forming a loop, and identifying cephalometric points) had significantly lower mean scores for the first-year student class than the second- and third-year classes (P <0.028); scores between the second- and third-year student classes were not significantly different (P >0.108). The chi-square analysis of the distribution of the number of noncompetent item responses decreased from the first to the second years (P <0.0003), from the second to the third years (P <0.0042), and from the first to the third years (P <0.00003). The latent growth analysis showed a wide range of difficulty and discrimination between questions. It also showed continuous growth for some areas and the ability of 6 questions to predict competency at greater than the 80% level. Objective structure clinical examinations can provide a method of evaluating student performance and curriculum impact over time, but cross-sectional and longitudinal analyses of the results may not be complementary. Significant learning appears to occur during all years of a 3-year program. Valuable questions were both easy and difficult, discriminating and not discriminating, and came from all domains: diagnostic, technical, and evaluation/synthesis. Copyright © 2017 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Making Brains run Faster: are they Becoming Smarter?

PubMed

Pahor, Anja; Jaušovec, Norbert

2016-12-05

A brief overview of structural and functional brain characteristics related to g is presented in the light of major neurobiological theories of intelligence: Neural Efficiency, P-FIT and Multiple-Demand system. These theories provide a framework to discuss the main objective of the paper: what is the relationship between individual alpha frequency (IAF) and g? Three studies were conducted in order to investigate this relationship: two correlational studies and a third study in which we experimentally induced changes in IAF by means of transcranial alternating current stimulation (tACS). (1) In a large scale study (n = 417), no significant correlations between IAF and IQ were observed. However, in males IAF positively correlated with mental rotation and shape manipulation and with an attentional focus on detail. (2) The second study showed sex-specific correlations between IAF (obtained during task performance) and scope of attention in males and between IAF and reaction time in females. (3) In the third study, individuals' IAF was increased with tACS. The induced changes in IAF had a disrupting effect on male performance on Raven's matrices, whereas a mild positive effect was observed for females. Neuro-electric activity after verum tACS showed increased desynchronization in the upper alpha band and dissociation between fronto-parietal and right temporal brain areas during performance on Raven's matrices. The results are discussed in the light of gender differences in brain structure and activity.

Synthesis, characterization and theoretical investigations of the structure, electronic properties and third-order nonlinearity optics (NLO) of M(DPIP)2

NASA Astrophysics Data System (ADS)

Li, Kang; Tang, Guodong; Kou, ShanShan; Culnane, Lance F.; Zhang, Yu; Song, Yinglin; Li, Rongqing; Wei, Changmei

2015-03-01

Three complexes of M(DPIP)2 (M = Cu, Co, Zn as 1, 2, 3) were synthesized and characterized by elemental analysis, IR, UV-Vis, thermogravimetry, and X-ray diffraction. Their nonlinear optical properties were measured by the Z-scan technique and yielded a normalized transmittance of about 70% for complex 1 (45 μJ pulse), and 93% for complex 3 (68 μJ pulse at the focus point). The nonlinear absorption coefficient, β, is 1.4 × 10-11 m/W for 1 and 5.6 × 10-13 m/W for 3, and the third-order nonlinear refraction index, n2, is 1.0 × 10-18 m2/W for 3. Complex 1 shows self-defocusing property, while complex 3 exhibits self-focusing property. The thermogravimetric results show that the frame structure of compounds 1-3 begin to collapse at 400, 250 and 280 °C, respectively, which suggests that they elicit excellent thermal stability. This research aims to provide better understanding of these compounds, and offer preliminary explanations for the significant differences between compounds 1-3, in order to potentially help in the designing of future novel materials with NLO properties.

Theory of Literature. Third Edition.

ERIC Educational Resources Information Center

Wellek, Rene; Warren, Austin

Methods of studying literature are defined and described. A section on definitions and distinctions investigates literature and literary study; the nature and function of literature; literary theory, criticism, and history; and general, comparative, and national literature. The ordering and establishing of evidence is described. The bulk of the…

Stochastic, real-space, imaginary-time evaluation of third-order Feynman-Goldstone diagrams

NASA Astrophysics Data System (ADS)

Willow, Soohaeng Yoo; Hirata, So

2014-01-01

A new, alternative set of interpretation rules of Feynman-Goldstone diagrams for many-body perturbation theory is proposed, which translates diagrams into algebraic expressions suitable for direct Monte Carlo integrations. A vertex of a diagram is associated with a Coulomb interaction (rather than a two-electron integral) and an edge with the trace of a Green's function in real space and imaginary time. With these, 12 diagrams of third-order many-body perturbation (MP3) theory are converted into 20-dimensional integrals, which are then evaluated by a Monte Carlo method. It uses redundant walkers for convergence acceleration and a weight function for importance sampling in conjunction with the Metropolis algorithm. The resulting Monte Carlo MP3 method has low-rank polynomial size dependence of the operation cost, a negligible memory cost, and a naturally parallel computational kernel, while reproducing the correct correlation energies of small molecules within a few mEh after 106 Monte Carlo steps.

Cardiac function, myocardial mechano-energetic efficiency, and ventricular-arterial coupling in normal pregnancy.

PubMed

Iacobaeus, Charlotte; Andolf, Ellika; Thorsell, Malin; Bremme, Katarina; Östlund, Eva; Kahan, Thomas

2018-04-01

To assess cardiac function, myocardial mechanoenergetic efficiency (MEE), and ventricular-arterial coupling (VAC) longitudinally during normal pregnancy, and to study if there was an association between cardiac structure and function, and fetal growth. Cardiac structure and function, MEE, and ventricular-arterial coupling was assessed longitudinally in 52 healthy nulliparous women at 14, 24, and 34 weeks' gestation and 9-month postpartum. Left atrial diameter increased during pregnancy (30.41 ± 3.59 mm in the nonpregnant state and 31.02 ± 3.91, 34.06 ± 3.58, and 33.9 ± 2.97 mm in the first, second, and third trimesters, P < 0.001). Left ventricular mass increased 117.12 ± 45.0 g in the nonpregnant state and 116.5 ± 33.0, 126.9 ± 34.5, 128.4 ± 36 g in the first, second, and third trimesters (P < 0.001). Cardiac output increased from 3.4 ± 1.2 l/min to 4.3 ± 0.7 l/min in the second and third trimesters (P < 0.001). Diastolic function decreased as both E/A and e'/a' decreased during pregnancy (P < 0.05 and P < 0.001, respectively). MEE and VAC were retained during pregnancy. Heart rate was associated with birth weight centile in the first (r = 0.41, P = 0.002) and second (r = 0.46, P = 0.002) trimester. The increase in cardiac output during normal pregnancy is obtained by an increase in heart rate, followed by structural cardiac changes. The impaired systolic function is accomplished by a deteriorated diastolic function. Despite these rapid changes, the myocardium manages to work efficient with a preserved MEE. Cardiac and arterial adaption to pregnancy seems to appear parallel as evidenced by a preserved VAC.

Quantitative evaluation of capillaroscopic microvascular changes in patients with established coronary heart disease.

PubMed

Sanchez-Garcia, M Esther; Ramirez-Lara, Irene; Gomez-Delgado, Francisco; Yubero-Serrano, Elena M; Leon-Acuña, Ana; Marin, Carmen; Alcala-Diaz, Juan F; Camargo, Antonio; Lopez-Moreno, Javier; Perez-Martinez, Pablo; Tinahones, Francisco José; Ordovas, Jose M; Caballero, Javier; Blanco-Molina, Angeles; Lopez-Miranda, Jose; Delgado-Lista, Javier

2018-02-23

Microcirculation disturbances have been associated to most of the cardiovascular risk factors as well as to multiple inflammatory diseases. However, whether these abnormalities are specifically augmented in patients with coronary heart disease is still unknown. We aimed to evaluate if there is a relationship between the presence of coronary heart disease and the existence of functional and structural capillary abnormalities evaluated in the cutaneous microcirculation by videocapillaroscopy. Two matched samples of 30 participants with and without coronary heart disease but with similar clinical and anthropometric characteristics were evaluated by videocapillaroscopy at the dorsal skin of the third finger of the non-dominant hand. We calculated basal capillary density as well as capillary density after a period of arterial and venous occlusion in order to evaluate functionality and maximum capillary density. We also measured capillary recruitment. Microvascular capillary density at rest was significantly lower in patients suffering from coronary heart disease than in controls. This fact was also found after dynamic tests (arterial and venous occlusion), suggesting functional impairments. Capillary recruitment of the samples was not different in our sample. In our study, patients with coronary heart disease exhibit functional and structural microvascular disturbances. Although this is a very preliminary study, these findings open the door for further studying the microvascular functionality in coronary patients and how it relates to the response to treatment and/or the prognosis of the disease. Copyright © 2017 Elsevier España, S.L.U. All rights reserved.

Norbornane: An investigation into its valence electronic structure using electron momentum spectroscopy, and density functional and Green's function theories

NASA Astrophysics Data System (ADS)

Knippenberg, S.; Nixon, K. L.; Brunger, M. J.; Maddern, T.; Campbell, L.; Trout, N.; Wang, F.; Newell, W. R.; Deleuze, M. S.; Francois, J.-P.; Winkler, D. A.

2004-12-01

We report on the results of an exhaustive study of the valence electronic structure of norbornane (C7H12), up to binding energies of 29 eV. Experimental electron momentum spectroscopy and theoretical Green's function and density functional theory approaches were all utilized in this investigation. A stringent comparison between the electron momentum spectroscopy and theoretical orbital momentum distributions found that, among all the tested models, the combination of the Becke-Perdew functional and a polarized valence basis set of triple-ζ quality provides the best representation of the electron momentum distributions for all of the 20 valence orbitals of norbornane. This experimentally validated quantum chemistry model was then used to extract some chemically important properties of norbornane. When these calculated properties are compared to corresponding results from other independent measurements, generally good agreement is found. Green's function calculations with the aid of the third-order algebraic diagrammatic construction scheme indicate that the orbital picture of ionization breaks down at binding energies larger than 22.5 eV. Despite this complication, they enable insights within 0.2 eV accuracy into the available ultraviolet photoemission and newly presented (e,2e) ionization spectra, except for the band associated with the 1a2-1 one-hole state, which is probably subject to rather significant vibronic coupling effects, and a band at ˜25 eV characterized by a momentum distribution of "s-type" symmetry, which Green's function calculations fail to reproduce. We note the vicinity of the vertical double ionization threshold at ˜26 eV.

A recursively formulated first-order semianalytic artificial satellite theory based on the generalized method of averaging. Volume 1: The generalized method of averaging applied to the artificial satellite problem

NASA Technical Reports Server (NTRS)

Mcclain, W. D.

1977-01-01

A recursively formulated, first-order, semianalytic artificial satellite theory, based on the generalized method of averaging is presented in two volumes. Volume I comprehensively discusses the theory of the generalized method of averaging applied to the artificial satellite problem. Volume II presents the explicit development in the nonsingular equinoctial elements of the first-order average equations of motion. The recursive algorithms used to evaluate the first-order averaged equations of motion are also presented in Volume II. This semianalytic theory is, in principle, valid for a term of arbitrary degree in the expansion of the third-body disturbing function (nonresonant cases only) and for a term of arbitrary degree and order in the expansion of the nonspherical gravitational potential function.

Third Structure Determination by Powder Diffractometery Round Robin (SDPDRR-3)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Le Bail, A.; Cranswick, L; Adil, K

2009-01-01

The results from a third structure determination by powder diffractometry (SDPD) round robin are discussed. From the 175 potential participants having downloaded the powder data, nine sent a total of 12 solutions (8 and 4 for samples 1 and 2, respectively, a tetrahydrated calcium tartrate and a lanthanum tungstate). Participants used seven different computer programs for structure solution (ESPOIR, EXPO, FOX, PSSP, SHELXS, SUPERFLIP, and TOPAS), applying Patterson, direct methods, direct space methods, and charge flipping approach. It is concluded that solving a structure from powder data remains a challenge, at least one order of magnitude more difficult than solvingmore » a problem with similar complexity from single-crystal data. Nevertheless, a few more steps in the direction of increasing the SDPD rate of success were accomplished since the two previous round robins: this time, not only the computer program developers were successful but also some users. No result was obtained from crystal structure prediction experts.« less

Fluctuating hydrodynamics, current fluctuations, and hyperuniformity in boundary-driven open quantum chains

NASA Astrophysics Data System (ADS)

Carollo, Federico; Garrahan, Juan P.; Lesanovsky, Igor; Pérez-Espigares, Carlos

2017-11-01

We consider a class of either fermionic or bosonic noninteracting open quantum chains driven by dissipative interactions at the boundaries and study the interplay of coherent transport and dissipative processes, such as bulk dephasing and diffusion. Starting from the microscopic formulation, we show that the dynamics on large scales can be described in terms of fluctuating hydrodynamics. This is an important simplification as it allows us to apply the methods of macroscopic fluctuation theory to compute the large deviation (LD) statistics of time-integrated currents. In particular, this permits us to show that fermionic open chains display a third-order dynamical phase transition in LD functions. We show that this transition is manifested in a singular change in the structure of trajectories: while typical trajectories are diffusive, rare trajectories associated with atypical currents are ballistic and hyperuniform in their spatial structure. We confirm these results by numerically simulating ensembles of rare trajectories via the cloning method, and by exact numerical diagonalization of the microscopic quantum generator.

Fluctuating hydrodynamics, current fluctuations, and hyperuniformity in boundary-driven open quantum chains.

PubMed

Carollo, Federico; Garrahan, Juan P; Lesanovsky, Igor; Pérez-Espigares, Carlos

2017-11-01

We consider a class of either fermionic or bosonic noninteracting open quantum chains driven by dissipative interactions at the boundaries and study the interplay of coherent transport and dissipative processes, such as bulk dephasing and diffusion. Starting from the microscopic formulation, we show that the dynamics on large scales can be described in terms of fluctuating hydrodynamics. This is an important simplification as it allows us to apply the methods of macroscopic fluctuation theory to compute the large deviation (LD) statistics of time-integrated currents. In particular, this permits us to show that fermionic open chains display a third-order dynamical phase transition in LD functions. We show that this transition is manifested in a singular change in the structure of trajectories: while typical trajectories are diffusive, rare trajectories associated with atypical currents are ballistic and hyperuniform in their spatial structure. We confirm these results by numerically simulating ensembles of rare trajectories via the cloning method, and by exact numerical diagonalization of the microscopic quantum generator.

Blind third-order dispersion estimation based on fractional Fourier transformation for coherent optical communication

NASA Astrophysics Data System (ADS)

Yang, Lin; Guo, Peng; Yang, Aiying; Qiao, Yaojun

2018-02-01

In this paper, we propose a blind third-order dispersion estimation method based on fractional Fourier transformation (FrFT) in optical fiber communication system. By measuring the chromatic dispersion (CD) at different wavelengths, this method can estimation dispersion slope and further calculate the third-order dispersion. The simulation results demonstrate that the estimation error is less than 2 % in 28GBaud dual polarization quadrature phase-shift keying (DP-QPSK) and 28GBaud dual polarization 16 quadrature amplitude modulation (DP-16QAM) system. Through simulations, the proposed third-order dispersion estimation method is shown to be robust against nonlinear and amplified spontaneous emission (ASE) noise. In addition, to reduce the computational complexity, searching step with coarse and fine granularity is chosen to search optimal order of FrFT. The third-order dispersion estimation method based on FrFT can be used to monitor the third-order dispersion in optical fiber system.

Third-Order Memristive Morris-Lecar Model of Barnacle Muscle Fiber

NASA Astrophysics Data System (ADS)

Rajamani, Vetriveeran; Sah, Maheshwar Pd.; Mannan, Zubaer Ibna; Kim, Hyongsuk; Chua, Leon

This paper presents a detailed analysis of various oscillatory behaviors observed in relation to the calcium and potassium ions in the third-order Morris-Lecar model of giant barnacle muscle fiber. Since, both the calcium and potassium ions exhibit all of the characteristics of memristor fingerprints, we claim that the time-varying calcium and potassium ions in the third-order Morris-Lecar model are actually time-invariant calcium and potassium memristors in the third-order memristive Morris-Lecar model. We confirmed the existence of a small unstable limit cycle oscillation in both the second-order and the third-order Morris-Lecar model by numerically calculating the basin of attraction of the asymptotically stable equilibrium point associated with two subcritical Hopf bifurcation points. We also describe a comprehensive analysis of the generation of oscillations in third-order memristive Morris-Lecar model via small-signal circuit analysis and a subcritical Hopf bifurcation phenomenon.

Nonlinear Optical Spectroscopy of Two-Dimensional Materials

NASA Astrophysics Data System (ADS)

Cui, Qiannan

Nonlinear optical properties of two-dimensional (2D) materials, such as transition metal dichalcogenides (TMDs), graphene, black phosphorus, and so on, play a key role of understanding nanoscale light-matter interactions, as well as developing nanophotonics applications from solar cells to quantum computation. With ultrafast lasers, we experimentally study nonlinear optical properties of 2D materials. Employing transient absorption microscopy, we study several members of 2D materials, such as WSe2, TiS3 and ReS2. The dynamical saturable absorption process of 2D excitons is spatiotemporally resolved. Intrinsic parameters of these 2D materials, such as exciton lifetime, exciton diffusion coefficient, and exciton mobility, are effectively measured. Especially, in-plane anisotropy of transient absorption and diffusive transport is observed for 2D excitons in monolayer ReS2, demonstrating the in-plane degree of freedom. Furthermore, with quantum interference and control nanoscopy, we all-optically inject, detect and manipulate nanoscale ballistic charge currents in a ReS2 thin film. By tuning the phase difference between one photon absorption and two photon absorption transition paths, sub-picosecond timescale of ballistic currents is coherently controlled for the first time in TMDs. In addition, the spatial resolution is two-order of magnitude smaller than optical diffraction limit. The second-order optical nonlinearity of 2D monolayers is resolved by second harmonic generation (SHG) microscopy. We measure the second-order susceptibility of monolayer MoS 2. The angular dependence of SHG in monolayer MoS2 shows strong symmetry dependence on its crystal lattice structure. Hence, second harmonic generation microscopy can serve as a powerful tool to noninvasively determine the crystalline directions of 2D monolayers. The real and imaginary parts of third-order optical nonlinearity of 2D monolayers are resolved by third harmonic generation (THG) microscopy and two-photon transient absorption microscopy, respectively. With third harmonic generation microscopy, we observe strong and anisotropic THG in monolayer and multilayer ReS2. Comparing with 2D materials with hexagonal lattice, such as MoS2, the third-order susceptibility is higher by one order of magnitude in ReS2 with a distorted 1T structure. The in-plane anisotropy of THG is attributed to the lattice distortion in ReS2 after comparing with a symmetry analysis. With two-photon transient absorption microscopy, we observe a giant two-photon absorption coefficient of monolayer WS2.

National perspective on in-hospital emergency units in Iraq

PubMed Central

Lafta, Riyadh K.; Al-Nuaimi, Maha A.

2013-01-01

Background: Hospitals play a crucial role in providing communities with essential medical care during times of disasters. The emergency department is the most vital component of hospitals' inpatient business. In Iraq, at present, there are many casualties that cause a burden of work and the need for structural assessment, equipment updating and evaluation of process. Objective: To examine the current pragmatic functioning of the existing set-up of services of in-hospital emergency departments within some general hospitals in Baghdad and Mosul in order to establish a mechanism for future evaluation for the health services in our community. Methods: A cross-sectional study was employed to evaluate the structure, process and function of six major hospitals with emergency units: four major hospitals in Baghdad and two in Mosul. Results: The six surveyed emergency units are distinct units within general hospitals that serve (collectively) one quarter of the total population. More than one third of these units feature observation unit beds, laboratory services, imaging facilities, pharmacies with safe storage, and ambulatory entrance. Operation room was found only in one hospital's reception and waiting area. Consultation/track area, cubicles for infection control, and discrete tutorial rooms were not available. Patient assessment was performed (although without adequate privacy). The emergency specialist, family medicine specialist and interested general practitioner exist in one-third of the surveyed units. Psychiatrist, physiotherapists, occupational therapists, and social work links are not available. The shortage in medication, urgent vaccines and vital facilities is an obvious problem. Conclusions: Our emergency unit's level and standards of care are underdeveloped. The inconsistent process and inappropriate environments need to be reconstructed. The lack of drugs, commodities, communication infrastructure, audit and training all require effective build up. PMID:25003053

Research in robust control for hypersonic aircraft

NASA Technical Reports Server (NTRS)

Calise, A. J.

1994-01-01

The research during the third reporting period focused on fixed order robust control design for hypersonic vehicles. A new technique was developed to synthesize fixed order H(sub infinity) controllers. A controller canonical form is imposed on the compensator structure and a homotopy algorithm is employed to perform the controller design. Various reduced order controllers are designed for a simplified version of the hypersonic vehicle model used in our previous studies to demonstrate the capabilities of the code. However, further work is needed to investigate the issue of numerical ill-conditioning for large order systems and to make the numerical approach more reliable.

Synthesis, crystal structure and third-order non-linear optical property of heterobimetallic cluster compound [MoOICu 3S 3(2,2'-bipy) 2

NASA Astrophysics Data System (ADS)

Li, Yong; Lu, Jing; Xu, Jiqing; Cui, Xiaobing; Sun, Yinghua; Yang, Qingxin; Pan, Lingyun

2004-03-01

Nest-shaped cluster [MoOICu 3S 3(2,2'-bipy) 2] ( 1) was synthesized by the treatment of (NH 4) 2MoS 4, CuI, ( n-Bu) 4NI, and 2,2'-bipyridine (2,2'-bipy) through a solid-state reaction. It crystallizes in monoclinic space group P2 1/ n, a=9.591(2) Å, b=14.820(3) Å, c=17.951(4) Å, β=91.98(2)°, V=2549.9(10) Å3, and Z=4. The nest-shaped cluster was obtained for the first time with a neutral skeleton containing 2,2'-bipy ligand. The non-linear optical (NLO) property of [MoOICu 3S 3(2,2'-bipy) 2] in DMF solution was measured by using a Z-scan technique with 15 ns and 532 nm laser pulses. The cluster has large third-order NLO absorption and the third-order NLO refraction, its α2 and n2 values were calculated as 6.2×10 -10 and -3.8×10 -17 m 2 W -1 in a 3.7×10 -4 M DMF solution.

Benchmarking density functional tight binding models for barrier heights and reaction energetics of organic molecules.

PubMed

Gruden, Maja; Andjeklović, Ljubica; Jissy, Akkarapattiakal Kuriappan; Stepanović, Stepan; Zlatar, Matija; Cui, Qiang; Elstner, Marcus

2017-09-30

Density Functional Tight Binding (DFTB) models are two to three orders of magnitude faster than ab initio and Density Functional Theory (DFT) methods and therefore are particularly attractive in applications to large molecules and condensed phase systems. To establish the applicability of DFTB models to general chemical reactions, we conduct benchmark calculations for barrier heights and reaction energetics of organic molecules using existing databases and several new ones compiled in this study. Structures for the transition states and stable species have been fully optimized at the DFTB level, making it possible to characterize the reliability of DFTB models in a more thorough fashion compared to conducting single point energy calculations as done in previous benchmark studies. The encouraging results for the diverse sets of reactions studied here suggest that DFTB models, especially the most recent third-order version (DFTB3/3OB augmented with dispersion correction), in most cases provide satisfactory description of organic chemical reactions with accuracy almost comparable to popular DFT methods with large basis sets, although larger errors are also seen for certain cases. Therefore, DFTB models can be effective for mechanistic analysis (e.g., transition state search) of large (bio)molecules, especially when coupled with single point energy calculations at higher levels of theory. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

A Cross-Dispersed Medium-Resolution Spectrograph for Appalachian State Univeristy's 32-inch Telescope

NASA Astrophysics Data System (ADS)

Kluttz, K. A.; Gray, R. O.

2003-12-01

We have designed and constructed an economical medium-resolution spectrograph to be used on the 32-inch telescope of Appalachian State University's Dark Sky Observatory (DSO). The primary function of this instrument will be to study shell and emission-line stars. However, we will also use this instrument for chemical abundance studies and radial velocities. The basic design is that of an Ebert spectrograph with a single 6-inch mirror acting as both the collimator and camera. The primary dispersion is accomplished by a reflection grating, and order separation is accomplished by a grism. The spectrograph has been designed so that three wavelength regions are simultaneously imaged on the CCD camera. When the Hα line is centered in the third order, Hβ and lines of Fe II multiplet 42 -- often enhanced in shell and emission-line stars -- appear in the fourth order and the fifth order contains both the Ca II K & H lines. To facilitate abundance measurements, a telluric-free region near 6400Å is available in the third order by tilting the main diffraction grating. Preliminary tests have shown that the resolution of the new spectrograph is 0.42Å in the third order (R ≈ 15,000). This relatively high resolution will allow studies to be conducted at DSO which have not previously been possible with the instrumentation currently in use. Several optical components for this spectrograph were purchased with grants from the Fund for Astrophysical Research and the University Research Council.

Motions about a fixed point by hypergeometric functions: new non-complex analytical solutions and integration of the herpolhode

NASA Astrophysics Data System (ADS)

Mingari Scarpello, Giovanni; Ritelli, Daniele

2018-06-01

The present study highlights the dynamics of a body moving about a fixed point and provides analytical closed form solutions. Firstly, for the symmetrical heavy body, that is the Lagrange-Poisson case, we compute the second (precession, ψ ) and third (spin, φ) Euler angles in explicit and real form by means of multiple hypergeometric (Lauricella) functions. Secondly, releasing the weight assumption but adding the complication of the asymmetry, by means of elliptic integrals of third kind, we provide the precession angle ψ completing the treatment of the Euler-Poinsot case. Thirdly, by integrating the relevant differential equation, we reach the finite polar equation of a special motion trajectory named the herpolhode. Finally, we keep the symmetry of the first problem, but without weight, and take into account a viscous dissipation. The use of motion first integrals—adopted for the first two problems—is no longer practicable in this situation; therefore, the Euler equations, faced directly, are driving to particular occurrences of Bessel functions of order - 1/2.

A cobalt (II) complex with 6-methylpicolinate: Synthesis, characterization, second- and third-order nonlinear optical properties, and DFT calculations

NASA Astrophysics Data System (ADS)

Altürk, Sümeyye; Avcı, Davut; Tamer, Ömer; Atalay, Yusuf; Şahin, Onur

2016-11-01

A cobalt(II) complex of 6-methylpicolinic acid, [Co(6-Mepic)2(H2O)2]·2H2O, was prepared and fully determined by single crystal X-ray crystal structure analysis as well as FT-IR, FT-Raman. UV-vis spectra were recorded within different solvents, to illustrate electronic transitions and molecular charge transfer within complex 1. The coordination sphere of complex 1 is a distorted octahedron according to single crystal X-ray results. Moreover, DFT (density functional theory) calculations with HSEH1PBE/6-311 G(d,p) level were carried out to back up the experimental results, and form base for future work in advanced level. Hyperconjugative interactions, intramolecular charge transfer (ICT), molecular stability and bond strength were researched by the using natural bond orbital (NBO) analysis. X-ray and NBO analysis results demonsrate that O-H···O hydrogen bonds between the water molecules and carboxylate oxygen atoms form a 2D supramolecular network, and also adjacent 2D networks connected by C-H···π and π···π interactions to form a 3D supramolecular network. Additionally, the second- and third-order nonlinear optical parameters of complex 1 were computed at DFT/HSEH1PBE/6-311 G(d,p) level. The refractive index (n) was calculated by using the Lorentz-Lorenz equation in order to investigate polarization behavior of complex 1 in different solvent polarities. The first-order static hyperpolarizability (β) value is found to be lower than pNA value because of the inversion symmetry around Co (II). But the second-order static hyperpolarizability (γ) value is 2.45 times greater than pNA value (15×10-30 esu). According to these results, Co(II) complex can be considered as a candidate to NLO material. Lastly molecular electrostatic potential (MEP), frontier molecular orbital energies and related molecular parameters for complex 1 were evaluated.

First-and Second-Order Displacement Transfer Functions for Structural Shape Calculations Using Analytically Predicted Surface Strains

NASA Technical Reports Server (NTRS)

Ko, William L.; Fleischer, Van Tran

2012-01-01

New first- and second-order displacement transfer functions have been developed for deformed shape calculations of nonuniform cross-sectional beam structures such as aircraft wings. The displacement transfer functions are expressed explicitly in terms of beam geometrical parameters and surface strains (uniaxial bending strains) obtained at equally spaced strain stations along the surface of the beam structure. By inputting the measured or analytically calculated surface strains into the displacement transfer functions, one could calculate local slopes, deflections, and cross-sectional twist angles of the nonuniform beam structure for mapping the overall structural deformed shapes for visual display. The accuracy of deformed shape calculations by the first- and second-order displacement transfer functions are determined by comparing these values to the analytically predicted values obtained from finite element analyses. This comparison shows that the new displacement transfer functions could quite accurately calculate the deformed shapes of tapered cantilever tubular beams with different tapered angles. The accuracy of the present displacement transfer functions also are compared to those of the previously developed displacement transfer functions.

A New High-Order Spectral Difference Method for Simulating Viscous Flows on Unstructured Grids with Mixed Elements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Mao; Qiu, Zihua; Liang, Chunlei

In the present study, a new spectral difference (SD) method is developed for viscous flows on meshes with a mixture of triangular and quadrilateral elements. The standard SD method for triangular elements, which employs Lagrangian interpolating functions for fluxes, is not stable when the designed accuracy of spatial discretization is third-order or higher. Unlike the standard SD method, the method examined here uses vector interpolating functions in the Raviart-Thomas (RT) spaces to construct continuous flux functions on reference elements. Studies have been performed for 2D wave equation and Euler equa- tions. Our present results demonstrated that the SDRT method ismore » stable and high-order accurate for a number of test problems by using triangular-, quadrilateral-, and mixed- element meshes.« less

Longitudinal structure function from logarithmic slopes of F2 at low x

NASA Astrophysics Data System (ADS)

Boroun, G. R.

2018-01-01

Using Laplace transform techniques, I calculate the longitudinal structure function FL(x ,Q2) from the scaling violations of the proton structure function F2(x ,Q2) and make a critical study of this relationship between the structure functions at leading order (LO) up to next-to-next-to leading order (NNLO) analysis at small x . Furthermore, I consider heavy quark contributions to the relation between the structure functions, which leads to compact formula for Nf=3 +Heavy . The nonlinear corrections to the longitudinal structure function at LO up to NNLO analysis are shown in the Nf=4 (light quark flavor) based on the nonlinear corrections at R =2 and R =4 GeV-1 . The results are compared with experimental data of the longitudinal proton structure function FL in the range of 6.5 ≤Q2≤800 GeV2 .

Thermodynamics of third-order Lovelock-AdS black holes in the presence of Born-Infeld type nonlinear electrodynamics

NASA Astrophysics Data System (ADS)

Hendi, S. H.; Dehghani, A.

2015-03-01

In this paper, we obtain topological black hole solutions of third-order Lovelock gravity coupled with two classes of Born-Infeld-type nonlinear electrodynamics with anti-de Sitter asymptotic structure. We investigate geometric and thermodynamics properties of the solutions and obtain conserved quantities of the black holes. We examine the first law of thermodynamics and find that the conserved and thermodynamic quantities of the black hole solutions satisfy the first law of thermodynamics. Finally, we calculate the heat capacity and determinant of the Hessian matrix to evaluate thermal stability in both canonical and grand canonical ensembles. Moreover, we consider the extended phase space thermodynamics to obtain a generalized first law of thermodynamics as well as the extended Smarr formula.

Traversable wormholes satisfying the weak energy condition in third-order Lovelock gravity

NASA Astrophysics Data System (ADS)

Zangeneh, Mahdi Kord; Lobo, Francisco S. N.; Dehghani, Mohammad Hossein

2015-12-01

In this paper, we consider third-order Lovelock gravity with a cosmological constant term in an n -dimensional spacetime M4×Kn -4, where Kn -4 is a constant curvature space. We decompose the equations of motion to four and higher dimensional ones and find wormhole solutions by considering a vacuum Kn -4 space. Applying the latter constraint, we determine the second- and third-order Lovelock coefficients and the cosmological constant in terms of specific parameters of the model, such as the size of the extra dimensions. Using the obtained Lovelock coefficients and Λ , we obtain the four-dimensional matter distribution threading the wormhole. Furthermore, by considering the zero tidal force case and a specific equation of state, given by ρ =(γ p -τ )/[ω (1 +γ )], we find the exact solution for the shape function which represents both asymptotically flat and nonflat wormhole solutions. We show explicitly that these wormhole solutions in addition to traversibility satisfy the energy conditions for suitable choices of parameters and that the existence of a limited spherically symmetric traversable wormhole with normal matter in a four-dimensional spacetime implies a negative effective cosmological constant.

Influence of second-order bracket-archwire misalignments on loads generated during third-order archwire rotation in orthodontic treatment.

PubMed

Romanyk, Dan L; George, Andrew; Li, Yin; Heo, Giseon; Carey, Jason P; Major, Paul W

2016-05-01

To investigate the influence of a rotational second-order bracket-archwire misalignment on the loads generated during third-order torque procedures. Specifically, torque in the second- and third-order directions was considered. An orthodontic torque simulator (OTS) was used to simulate the third-order torque between Damon Q brackets and 0.019 × 0.025-inch stainless steel archwires. Second-order misalignments were introduced in 0.5° increments from a neutral position, 0.0°, up to 3.0° of misalignment. A sample size of 30 brackets was used for each misalignment. The archwire was then rotated in the OTS from its neutral position up to 30° in 3° increments and then unloaded in the same increments. At each position, all forces and torques were recorded. Repeated-measures analysis of variance was used to determine if the second-order misalignments significantly affected torque values in the second- and third-order directions. From statistical analysis of the experimental data, it was found that the only statistically significant differences in third-order torque between a misaligned state and the neutral position occurred for 2.5° and 3.0° of misalignment, with mean differences of 2.54 Nmm and 2.33 Nmm, respectively. In addition, in pairwise comparisons of second-order torque for each misalignment increment, statistical differences were observed in all comparisons except for 0.0° vs 0.5° and 1.5° vs 2.0°. The introduction of a second-order misalignment during third-order torque simulation resulted in statistically significant differences in both second- and third-order torque response; however, the former is arguably clinically insignificant.

Spherical integral transforms of second-order gravitational tensor components onto third-order gravitational tensor components

NASA Astrophysics Data System (ADS)

Šprlák, Michal; Novák, Pavel

2017-02-01

New spherical integral formulas between components of the second- and third-order gravitational tensors are formulated in this article. First, we review the nomenclature and basic properties of the second- and third-order gravitational tensors. Initial points of mathematical derivations, i.e., the second- and third-order differential operators defined in the spherical local North-oriented reference frame and the analytical solutions of the gradiometric boundary-value problem, are also summarized. Secondly, we apply the third-order differential operators to the analytical solutions of the gradiometric boundary-value problem which gives 30 new integral formulas transforming (1) vertical-vertical, (2) vertical-horizontal and (3) horizontal-horizontal second-order gravitational tensor components onto their third-order counterparts. Using spherical polar coordinates related sub-integral kernels can efficiently be decomposed into azimuthal and isotropic parts. Both spectral and closed forms of the isotropic kernels are provided and their limits are investigated. Thirdly, numerical experiments are performed to test the consistency of the new integral transforms and to investigate properties of the sub-integral kernels. The new mathematical apparatus is valid for any harmonic potential field and may be exploited, e.g., when gravitational/magnetic second- and third-order tensor components become available in the future. The new integral formulas also extend the well-known Meissl diagram and enrich the theoretical apparatus of geodesy.

Optimization of digital designs

NASA Technical Reports Server (NTRS)

Miles, Lowell H. (Inventor); Whitaker, Sterling R. (Inventor)

2009-01-01

An application specific integrated circuit is optimized by translating a first representation of its digital design to a second representation. The second representation includes multiple syntactic expressions that admit a representation of a higher-order function of base Boolean values. The syntactic expressions are manipulated to form a third representation of the digital design.

Off-diagonal series expansion for quantum partition functions

NASA Astrophysics Data System (ADS)

Hen, Itay

2018-05-01

We derive an integral-free thermodynamic perturbation series expansion for quantum partition functions which enables an analytical term-by-term calculation of the series. The expansion is carried out around the partition function of the classical component of the Hamiltonian with the expansion parameter being the strength of the off-diagonal, or quantum, portion. To demonstrate the usefulness of the technique we analytically compute to third order the partition functions of the 1D Ising model with longitudinal and transverse fields, and the quantum 1D Heisenberg model.

General Flow-Solver Code for Turbomachinery Applications

NASA Technical Reports Server (NTRS)

Dorney, Daniel; Sondak, Douglas

2006-01-01

Phantom is a computer code intended primarily for real-fluid turbomachinery problems. It is based on Corsair, an ideal-gas turbomachinery code, developed by the same authors, which evolved from the ROTOR codes from NASA Ames. Phantom is applicable to real and ideal fluids, both compressible and incompressible, flowing at subsonic, transonic, and supersonic speeds. It utilizes structured, overset, O- and H-type zonal grids to discretize flow fields and represent relative motions of components. Values on grid boundaries are updated at each time step by bilinear interpolation from adjacent grids. Inviscid fluxes are calculated to third-order spatial accuracy using Roe s scheme. Viscous fluxes are calculated using second-order-accurate central differences. The code is second-order accurate in time. Turbulence is represented by a modified Baldwin-Lomax algebraic model. The code offers two options for determining properties of fluids: One is based on equations of state, thermodynamic departure functions, and corresponding state principles. The other, which is more efficient, is based on splines generated from tables of properties of real fluids. Phantom currently contains fluid-property routines for water, hydrogen, oxygen, nitrogen, kerosene, methane, and carbon monoxide as well as ideal gases.

Statistical scaling of pore-scale Lagrangian velocities in natural porous media.

PubMed

Siena, M; Guadagnini, A; Riva, M; Bijeljic, B; Pereira Nunes, J P; Blunt, M J

2014-08-01

We investigate the scaling behavior of sample statistics of pore-scale Lagrangian velocities in two different rock samples, Bentheimer sandstone and Estaillades limestone. The samples are imaged using x-ray computer tomography with micron-scale resolution. The scaling analysis relies on the study of the way qth-order sample structure functions (statistical moments of order q of absolute increments) of Lagrangian velocities depend on separation distances, or lags, traveled along the mean flow direction. In the sandstone block, sample structure functions of all orders exhibit a power-law scaling within a clearly identifiable intermediate range of lags. Sample structure functions associated with the limestone block display two diverse power-law regimes, which we infer to be related to two overlapping spatially correlated structures. In both rocks and for all orders q, we observe linear relationships between logarithmic structure functions of successive orders at all lags (a phenomenon that is typically known as extended power scaling, or extended self-similarity). The scaling behavior of Lagrangian velocities is compared with the one exhibited by porosity and specific surface area, which constitute two key pore-scale geometric observables. The statistical scaling of the local velocity field reflects the behavior of these geometric observables, with the occurrence of power-law-scaling regimes within the same range of lags for sample structure functions of Lagrangian velocity, porosity, and specific surface area.

Feasibility study of launch vehicle ground cloud neutralization

NASA Technical Reports Server (NTRS)

Vanderarend, P. C.; Stoy, S. T.; Kranyecz, T. E.

1976-01-01

The distribution of hydrogen chloride in the cloud was analyzed as a function of launch pad geometry and rate of rise of the vehicle during the first 24 sec of burn in order to define neutralization requirements. Delivery systems of various types were developed in order to bring the proposed chemical agents in close contact with the hydrogen chloride. Approximately one-third of the total neutralizing agent required can be delivered from a ground installed system at the launch pad; concentrated sodium carbonate solution is the preferred choice of agent for this launch pad system. Two-thirds of the neutralization requirement appears to need delivery by aircraft. Only one chemical agent (ammonia) may be reasonably considered for delivery by aircraft, because weight and bulk of all other agents are too large.

An exact solution of the van der Waals interaction between two ground-state hydrogen atoms

NASA Astrophysics Data System (ADS)

Koga, Toshikatsu; Matsumoto, Shinya

1985-06-01

A momentum space treatment shows that perturbation equations for the H(1s)-H(1s) van der Waals interaction can be exactly solved in their Schrödinger forms without invoking any variational methods. Using the Fock transformation, which projects the momentum vector of an electron from the three-dimensional hyperplane onto the four-dimensional hypersphere, we solve the third order integral-type perturbation equation with respect to the reciprocal of the internuclear distance R. An exact third order wave function is found as a linear combination of infinite number of four-dimensional spherical harmonics. The result allows us to evaluate the exact dispersion energy E6R-6, which is completely determined by the first three coefficients of the above linear combination.

Third molars and premolars extraction in conventional orthodontics and in treatments based on maxillary bone remodeling with temporary anchorage: indications and care.

PubMed

Consolaro, Alberto

2017-02-01

A bone is an anatomic structure in constant remodeling, with different, mutant and wonderfully inconstant designs. With every new and immediate functional demand, there are changes in cortical thickness, trabecular bone density and also in direction and size of trabeculae. Bones' non-stopping search is for adjusting to the functions induced by forces and movements required by a certain life style. Conventional orthodontic planning or with temporary anchorage based on bone remodeling takes into consideration the spaces that are - or may be - occupied by the teeth, in the formation of a functional and esthetic dental arch for the patient. In case it is necessary to extract a tooth and the options are the third molars, partially or totally unerupted, and teeth that belong to other dental groups, obviousness recommends - due to mouth anatomy and physiology, as well as pathologic reasons - extracting the third molars, due to of the several reasons described in the present study.

Third molars and premolars extraction in conventional orthodontics and in treatments based on maxillary bone remodeling with temporary anchorage: indications and care

PubMed Central

Consolaro, Alberto

2017-01-01

ABSTRACT A bone is an anatomic structure in constant remodeling, with different, mutant and wonderfully inconstant designs. With every new and immediate functional demand, there are changes in cortical thickness, trabecular bone density and also in direction and size of trabeculae. Bones' non-stopping search is for adjusting to the functions induced by forces and movements required by a certain life style. Conventional orthodontic planning or with temporary anchorage based on bone remodeling takes into consideration the spaces that are - or may be - occupied by the teeth, in the formation of a functional and esthetic dental arch for the patient. In case it is necessary to extract a tooth and the options are the third molars, partially or totally unerupted, and teeth that belong to other dental groups, obviousness recommends - due to mouth anatomy and physiology, as well as pathologic reasons - extracting the third molars, due to of the several reasons described in the present study. PMID:28444013

Study on Failure of Third-Party Damage for Urban Gas Pipeline Based on Fuzzy Comprehensive Evaluation.

PubMed

Li, Jun; Zhang, Hong; Han, Yinshan; Wang, Baodong

2016-01-01

Focusing on the diversity, complexity and uncertainty of the third-party damage accident, the failure probability of third-party damage to urban gas pipeline was evaluated on the theory of analytic hierarchy process and fuzzy mathematics. The fault tree of third-party damage containing 56 basic events was built by hazard identification of third-party damage. The fuzzy evaluation of basic event probabilities were conducted by the expert judgment method and using membership function of fuzzy set. The determination of the weight of each expert and the modification of the evaluation opinions were accomplished using the improved analytic hierarchy process, and the failure possibility of the third-party to urban gas pipeline was calculated. Taking gas pipelines of a certain large provincial capital city as an example, the risk assessment structure of the method was proved to conform to the actual situation, which provides the basis for the safety risk prevention.

Response spectrum method for extreme wave loading with higher order components of drag force

NASA Astrophysics Data System (ADS)

Reza, Tabeshpour Mohammad; Mani, Fatemi Dezfouli; Ali, Dastan Diznab Mohammad; Saied, Mohajernasab; Saied, Seif Mohammad

2017-03-01

Response spectra of fixed offshore structures impacted by extreme waves are investigated based on the higher order components of the nonlinear drag force. In this way, steel jacket platforms are simplified as a mass attached to a light cantilever cylinder and their corresponding deformation response spectra are estimated by utilizing a generalized single degree of freedom system. Based on the wave data recorded in the Persian Gulf region, extreme wave loading conditions corresponding to different return periods are exerted on the offshore structures. Accordingly, the effect of the higher order components of the drag force is considered and compared to the linearized state for different sea surface levels. When the fundamental period of the offshore structure is about one third of the main period of wave loading, the results indicate the linearized drag term is not capable of achieving a reliable deformation response spectrum.

Extinction order and altered community structure rapidly disrupt ecosystem functioning.

PubMed

Larsen, Trond H; Williams, Neal M; Kremen, Claire

2005-05-01

By causing extinctions and altering community structure, anthropogenic disturbances can disrupt processes that maintain ecosystem integrity. However, the relationship between community structure and ecosystem functioning in natural systems is poorly understood. Here we show that habitat loss appeared to disrupt ecosystem functioning by affecting extinction order, species richness and abundance. We studied pollination by bees in a mosaic of agricultural and natural habitats in California and dung burial by dung beetles on recently created islands in Venezuela. We found that large-bodied bee and beetle species tended to be both most extinction-prone and most functionally efficient, contributing to rapid functional loss. Simulations confirmed that extinction order led to greater disruption of function than predicted by random species loss. Total abundance declined with richness and also appeared to contribute to loss of function. We demonstrate conceptually and empirically how the non-random response of communities to disturbance can have unexpectedly large functional consequences.

Femtosecond laser nanosurgery of sub-cellular structures in HeLa cells by employing Third Harmonic Generation imaging modality as diagnostic tool.

PubMed

Tserevelakis, George J; Psycharakis, Stylianos; Resan, Bojan; Brunner, Felix; Gavgiotaki, Evagelia; Weingarten, Kurt; Filippidis, George

2012-02-01

Femtosecond laser assisted nanosurgery of microscopic biological specimens is a relatively new technique which allows the selective disruption of sub-cellular structures without causing any undesirable damage to the surrounding regions. The targeted structures have to be stained in order to be clearly visualized for the nanosurgery procedure. However, the validation of the final nanosurgery result is difficult, since the targeted structure could be simply photobleached rather than selectively destroyed. This fact comprises a main drawback of this technique. In our study we employed a multimodal system which integrates non-linear imaging modalities with nanosurgery capabilities, for the selective disruption of sub-cellular structures in HeLa cancer cells. Third Harmonic Generation (THG) imaging modality was used as a tool for the identification of structures that were subjected to nanosurgery experiments. No staining of the biological samples was required, since THG is an intrinsic property of matter. Furthermore, cells' viability after nanosurgery processing was verified via Two Photon Excitation Fluorescence (TPEF) measurements. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bond-orientational analysis of hard-disk and hard-sphere structures.

PubMed

Senthil Kumar, V; Kumaran, V

2006-05-28

We report the bond-orientational analysis results for the thermodynamic, random, and homogeneously sheared inelastic structures of hard-disks and hard-spheres. The thermodynamic structures show a sharp rise in the order across the freezing transition. The random structures show the absence of crystallization. The homogeneously sheared structures get ordered at a packing fraction higher than the thermodynamic freezing packing fraction, due to the suppression of crystal nucleation. On shear ordering, strings of close-packed hard-disks in two dimensions and close-packed layers of hard-spheres in three dimensions, oriented along the velocity direction, slide past each other. Such a flow creates a considerable amount of fourfold order in two dimensions and body-centered-tetragonal (bct) structure in three dimensions. These transitions are the flow analogs of the martensitic transformations occurring in metals due to the stresses induced by a rapid quench. In hard-disk structures, using the bond-orientational analysis we show the presence of fourfold order. In sheared inelastic hard-sphere structures, even though the global bond-orientational analysis shows that the system is highly ordered, a third-order rotational invariant analysis shows that only about 40% of the spheres have face-centered-cubic (fcc) order, even in the dense and near-elastic limits, clearly indicating the coexistence of multiple crystalline orders. When layers of close-packed spheres slide past each other, in addition to the bct structure, the hexagonal-close-packed (hcp) structure is formed due to the random stacking faults. Using the Honeycutt-Andersen pair analysis and an analysis based on the 14-faceted polyhedra having six quadrilateral and eight hexagonal faces, we show the presence of bct and hcp signatures in shear ordered inelastic hard-spheres. Thus, our analysis shows that the dense sheared inelastic hard-spheres have a mixture of fcc, bct, and hcp structures.

Home and health in the third age - methodological background and descriptive findings.

PubMed

Kylén, Maya; Ekström, Henrik; Haak, Maria; Elmståhl, Sölve; Iwarsson, Susanne

2014-07-11

The understanding of the complex relationship between the home environment, well-being and daily functioning in the third age is currently weak. The aim of this paper is to present the methodological background of the Home and Health in the Third Age Study, and describe a sample of men and women in relation to their home and health situation. The study sample included 371 people aged 67-70, living in ordinary housing in the south of Sweden. Structured interviews and observations were conducted to collect data about objective and perceived aspects of home and health. The majority of the participants were in good health and had few functional limitations. Women had more functional limitations and reported more symptoms than men. Environmental barriers were found in every home investigated; the most were found in the kitchen and hygiene area. Environmental barriers were more common in multi-family than in one-family dwellings. This study will increase our knowledge on home and health dynamics among people in the third age. The results have potential to contribute to societal planning related to housing provision, home care and social services for senior citizens.

Home and Health in the Third Age — Methodological Background and Descriptive Findings

PubMed Central

Kylén, Maya; Ekström, Henrik; Haak, Maria; Elmståhl, Sölve; Iwarsson, Susanne

2014-01-01

Background: The understanding of the complex relationship between the home environment, well-being and daily functioning in the third age is currently weak. The aim of this paper is to present the methodological background of the Home and Health in the Third Age Study, and describe a sample of men and women in relation to their home and health situation. Methods and Design: The study sample included 371 people aged 67–70, living in ordinary housing in the south of Sweden. Structured interviews and observations were conducted to collect data about objective and perceived aspects of home and health. Results: The majority of the participants were in good health and had few functional limitations. Women had more functional limitations and reported more symptoms than men. Environmental barriers were found in every home investigated; the most were found in the kitchen and hygiene area. Environmental barriers were more common in multi-family than in one-family dwellings. Discussion: This study will increase our knowledge on home and health dynamics among people in the third age. The results have potential to contribute to societal planning related to housing provision, home care and social services for senior citizens. PMID:25019267

Craniofacial structures' development in prenatal period: An MRI study.

PubMed

Begnoni, G; Serrao, G; Musto, F; Pellegrini, G; Triulzi, F M; Dellavia, C

2018-05-01

The development of skeletal structures (cranial base, upper and lower) and upper airways spaces (oropharyngeal and nasopharyngeal) of the skull has always been an issue of great interest in orthodontics. Foetal MRI images obtained as screening exam during pregnancy can help to understand the development of these structures using a sample cephalometric analysis. A total of 28 MRI images in sagittal section of foetuses from 20th to 32th weeks of gestation were obtained to dispel doubts about the presence of skeletal malformations. Cephalometric measurements were performed on MRI T2-dependent images acquired with a 1.5 T scanner. The Software Osirix 5 permits to study sagittal and vertical dimensions of the skull analysing linear measurements, angles and areas of the skeletal structures. Vertical and sagittal dimension of cranial base, maxilla and mandible grow significantly (P < .01) between the second and third trimester of gestational period as well as nasopharyngeal and oropharyngeal spaces (P < .05). High correlation between the development of anterior cranial base and functional areas devoted to speech and swallow is demonstrated (r: .97). The development of craniofacial structures during foetal period seems to show a close correlation between skeletal features and functional spaces with a peak between the second and third trimester of gestation. MRI images result helpful for the clinician to detect with a sample cephalometric analysis anomalies of skeletal and functional structures during prenatal period. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Structural insights into the evolution of a sexy protein: novel topology and restricted backbone flexibility in a hypervariable pheromone from the red-legged salamander, Plethodon shermani.

PubMed

Wilburn, Damien B; Bowen, Kathleen E; Doty, Kari A; Arumugam, Sengodagounder; Lane, Andrew N; Feldhoff, Pamela W; Feldhoff, Richard C

2014-01-01

In response to pervasive sexual selection, protein sex pheromones often display rapid mutation and accelerated evolution of corresponding gene sequences. For proteins, the general dogma is that structure is maintained even as sequence or function may rapidly change. This phenomenon is well exemplified by the three-finger protein (TFP) superfamily: a diverse class of vertebrate proteins co-opted for many biological functions - such as components of snake venoms, regulators of the complement system, and coordinators of amphibian limb regeneration. All of the >200 structurally characterized TFPs adopt the namesake "three-finger" topology. In male red-legged salamanders, the TFP pheromone Plethodontid Modulating Factor (PMF) is a hypervariable protein such that, through extensive gene duplication and pervasive sexual selection, individual male salamanders express more than 30 unique isoforms. However, it remained unclear how this accelerated evolution affected the protein structure of PMF. Using LC/MS-MS and multidimensional NMR, we report the 3D structure of the most abundant PMF isoform, PMF-G. The high resolution structural ensemble revealed a highly modified TFP structure, including a unique disulfide bonding pattern and loss of secondary structure, that define a novel protein topology with greater backbone flexibility in the third peptide finger. Sequence comparison, models of molecular evolution, and homology modeling together support that this flexible third finger is the most rapidly evolving segment of PMF. Combined with PMF sequence hypervariability, this structural flexibility may enhance the plasticity of PMF as a chemical signal by permitting potentially thousands of structural conformers. We propose that the flexible third finger plays a critical role in PMF:receptor interactions. As female receptors co-evolve, this flexibility may allow PMF to still bind its receptor(s) without the immediate need for complementary mutations. Consequently, this unique adaptation may establish new paradigms for how receptor:ligand pairs co-evolve, in particular with respect to sexual conflict.

Numerical Simulations of Strong MHD Turbulence

NASA Astrophysics Data System (ADS)

Mason, J.; Cattaneo, F.; Boldyrev, S.

2007-11-01

Magnetohydrodynamic turbulence plays an important role in many astrophysical phenomena, including the solar wind, angular momentum transport in accretion disks and interstellar scintillation. Despite more than 40 years of investigations much within the subject remains controversial. Recently a new theory has been developed [1, 2]. It predicts a scale-dependent dynamic alignment between the velocity and magnetic fluctuations and leads to the field-perpendicular energy spectrum E(k)k-3/2. Here we discuss this new theory and present the results of a series of numerical tests. Quantities measured include the alignment angle, the spectrum and the third order structure functions for which the exact relations due to Politano & Pouquet [3] hold. [1] Boldyrev, S. (2005) Astrophys. J. 626, L37. [2] Boldyrev, S. (2006) Phys. Rev. Lett. 96, 115002. [3] Politano, H. & Pouquet, A. (1998) Geophys. Res. Lett. 25, 273.

Ask and You Might Not Receive: How FERPA's Disclosure Provisions Can Affect Educational Research

ERIC Educational Resources Information Center

Tonsager, Lindsey; Skeath, Caleb W.

2017-01-01

The Family Educational Rights and Privacy Act (FERPA) regulates how schools collect, use, and disclose student information, including disclosures to third-party educational researchers. This article examines how educational researchers can structure their activities to reduce the risk of violating FERPA's disclosure restrictions. In order to do…

Synthesis, growth, crystal structure, optical and third order nonlinear optical properties of quinolinium derivative single crystal: PNQI

NASA Astrophysics Data System (ADS)

Karthigha, S.; Krishnamoorthi, C.

2018-03-01

An organic quinolinium derivative nonlinear optical (NLO) crystal, 1-ethyl-2-[2-(4-nitro-phenyl)-vinyl]-quinolinium iodide (PNQI) was synthesized and successfully grown by slow evaporation solution growth technique. Formation of a crystalline compound was confirmed by single crystal X-ray diffraction. The quinolinium compound PNQI crystallizes in the triclinic crystal system with a centrosymmetric space group of P-1 symmetry. The molecular structure of PNQI was confirmed by 1H NMR and 13C NMR spectral studies. The thermal properties of the crystal have been investigated by thermogravimetric (TG) and differential scanning calorimetry (DSC) studies. The optical characteristics obtained from UV-Vis-NIR spectral data were described and the cut-off wavelength observed at 506 nm. The etching study was performed to analyse the growth features of PNQI single crystal. The third order NLO properties such as nonlinear refractive index (n2), nonlinear absorption coefficient (β) and nonlinear susceptibility (χ (3)) of the crystal were investigated using Z-scan technique at 632.8 nm of Hesbnd Ne laser.

Application of manual control theory to the study of biological stress

NASA Technical Reports Server (NTRS)

Replogle, C. R.; Holden, F. M.; Iay, C. N.

1972-01-01

A study was run using both a stable, third-order task and an adaptive first-order unstable task singly and in combination to test the effects of 2 min hypoxia (22000 ft) on human operator. The results indicate that the RMS error in the stable task does not change as a function of hypoxic stress whereas the error in an unstable task changes significantly. Models involving human operator parameter changes and noise injection are discussed.

The actual scaling of a nominally third-order Reynolds stress

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krommes, J. A., E-mail: krommes@princeton.edu; Hammett, G. W., E-mail: hammett@princeton.edu

2014-05-15

It is shown that a particular higher-order Reynolds stress arising from a term in the third-order gyrokinetic Hamiltonian is smaller than it nominally appears to be. However, it does not follow that all third-order terms are unimportant. The discussion is relevant to the ongoing debate about the importance of higher-order terms in the gyrokinetic theory of momentum transport.

Nucleation, growth, and repair of a cobalt-based oxygen evolving catalyst.

PubMed

Surendranath, Yogesh; Lutterman, Daniel A; Liu, Yi; Nocera, Daniel G

2012-04-11

The mechanism of nucleation, steady-state growth, and repair is investigated for an oxygen evolving catalyst prepared by electrodeposition from Co(2+) solutions in weakly basic electrolytes (Co-OEC). Potential step chronoamperometry and atomic force microscopy reveal that nucleation of Co-OEC is progressive and reaches a saturation surface coverage of ca. 70% on highly oriented pyrolytic graphite substrates. Steady-state electrodeposition of Co-OEC exhibits a Tafel slope approximately equal to 2.3 × RT/F. The electrochemical rate law exhibits a first order dependence on Co(2+) and inverse orders on proton (third order) and proton acceptor, methylphosphonate (first order for 1.8 mM ≤ [MeP(i)] ≤ 18 mM and second order dependence for 32 mM ≤ [MeP(i)] ≤ 180 mM). These electrokinetic studies, combined with recent XAS studies of catalyst structure, suggest a mechanism for steady state growth at intermediate MeP(i) concentration (1.8-18 mM) involving a rapid solution equilibrium between aquo Co(II) and Co(III) hydroxo species accompanied with a rapid surface equilibrium involving electrolyte dissociation and deprotonation of surface bound water. These equilibria are followed by a chemical rate-limiting step for incorporation of Co(III) into the growing cobaltate clusters comprising Co-OEC. At higher concentrations of MeP(i) ([MeP(i)] ≥ 32 mM), MePO(3)(2-) equilibrium binding to Co(II) in solution is suggested by the kinetic data. Consistent with the disparate pH profiles for oxygen evolution electrocatalysis and catalyst formation, NMR-based quantification of catalyst dissolution as a function of pH demonstrates functional stability and repair at pH values >6 whereas catalyst corrosion prevails at lower pH values. These kinetic insights provide a basis for developing and operating functional water oxidation (photo)anodes under benign pH conditions. © 2012 American Chemical Society

Differential effects of genetically distinct mechanisms of elevating amylose on barley starch characteristics.

PubMed

Regina, Ahmed; Blazek, Jaroslav; Gilbert, Elliot; Flanagan, Bernadine M; Gidley, Michael J; Cavanagh, Colin; Ral, Jean-Philippe; Larroque, Oscar; Bird, Anthony R; Li, Zhongyi; Morell, Matthew K

2012-07-01

The relationships between starch structure and functionality are important in underpinning the industrial and nutritional utilisation of starches. In this work, the relationships between the biosynthesis, structure, molecular organisation and functionality have been examined using a series of defined genotypes in barley with low (<20%), standard (20-30%), elevated (30-50%) and high (>50%) amylose starches. A range of techniques have been employed to determine starch physical features, higher order structure and functionality. The two genetic mechanisms for generating high amylose contents (down-regulation of branching enzymes and starch synthases, respectively) yielded starches with very different amylopectin structures but similar gelatinisation and viscosity properties driven by reduced granular order and increased amylose content. Principal components analysis (PCA) was used to elucidate the relationships between genotypes and starch molecular structure and functionality. Parameters associated with granule order (PC1) accounted for a large percentage of the variance (57%) and were closely related to amylose content. Parameters associated with amylopectin fine structure accounted for 18% of the variance but were less closely aligned to functionality parameters. Copyright © 2012 Elsevier Ltd. All rights reserved.

Generalized Israel junction conditions for a fourth-order brane world

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balcerzak, Adam; Dabrowski, Mariusz P.

2008-01-15

We discuss a general fourth-order theory of gravity on the brane. In general, the formulation of the junction conditions (except for Euler characteristics such as Gauss-Bonnet term) leads to the higher powers of the delta function and requires regularization. We suggest the way to avoid such a problem by imposing the metric and its first derivative to be regular at the brane, while the second derivative to have a kink, the third derivative of the metric to have a step function discontinuity, and no sooner as the fourth derivative of the metric to give the delta function contribution to themore » field equations. Alternatively, we discuss the reduction of the fourth-order gravity to the second-order theory by introducing an extra tensor field. We formulate the appropriate junction conditions on the brane. We prove the equivalence of both theories. In particular, we prove the equivalence of the junction conditions with different assumptions related to the continuity of the metric along the brane.« less

Investigations on nucleation, HRXRD, optical, piezoelectric, polarizability and Z-scan analysis of L-arginine maleate dihydrate single crystals

NASA Astrophysics Data System (ADS)

Sakthy Priya, S.; Alexandar, A.; Surendran, P.; Lakshmanan, A.; Rameshkumar, P.; Sagayaraj, P.

2017-04-01

An efficient organic nonlinear optical single crystal of L-arginine maleate dihydrate (LAMD) has been grown by slow evaporation solution technique (SEST) and slow cooling technique (SCT). The crystalline perfection of the crystal was examined using high-resolution X-ray diffractometry (HRXRD) analysis. Photoluminescence study confirmed the optical properties and defects level in the crystal lattice. Electromechanical behaviour was observed using piezoelectric co-efficient (d33) analysis. The photoconductivity analysis confirmed the negative photoconducting nature of the material. The dielectric constant and loss were measured as a function of frequency with varying temperature and vice-versa. The laser damage threshold (LDT) measurement was carried out using Nd:YAG Laser with a wavelength of 1064 nm (Focal length is 35 cm) and the obtained results showed that LDT value of the crystal is high compared to KDP crystal. The high laser damage threshold of the grown crystal makes it a potential candidate for second and higher order nonlinear optical device application. The third order nonlinear optical parameters of LAMD crystal is determined by open-aperture and closed-aperture studies using Z-scan technique. The third order linear and nonlinear optical parameters such as the nonlinear refractive index (n2), two photon absorption coefficient (β), Real part (Reχ3) and imaginary part (Imχ3) of third-order nonlinear optical susceptibility are calculated.

Stokes waves revisited: Exact solutions in the asymptotic limit

NASA Astrophysics Data System (ADS)

Davies, Megan; Chattopadhyay, Amit K.

2016-03-01

The Stokes perturbative solution of the nonlinear (boundary value dependent) surface gravity wave problem is known to provide results of reasonable accuracy to engineers in estimating the phase speed and amplitudes of such nonlinear waves. The weakling in this structure though is the presence of aperiodic "secular variation" in the solution that does not agree with the known periodic propagation of surface waves. This has historically necessitated increasingly higher-ordered (perturbative) approximations in the representation of the velocity profile. The present article ameliorates this long-standing theoretical insufficiency by invoking a compact exact n -ordered solution in the asymptotic infinite depth limit, primarily based on a representation structured around the third-ordered perturbative solution, that leads to a seamless extension to higher-order (e.g., fifth-order) forms existing in the literature. The result from this study is expected to improve phenomenological engineering estimates, now that any desired higher-ordered expansion may be compacted within the same representation, but without any aperiodicity in the spectral pattern of the wave guides.

Synthesis, characterization and theoretical investigations of the structure, electronic properties and third-order nonlinearity optics (NLO) of M(DPIP)₂.

PubMed

Li, Kang; Tang, Guodong; Kou, ShanShan; Culnane, Lance F; Zhang, Yu; Song, Yinglin; Li, Rongqing; Wei, Changmei

2015-03-15

Three complexes of M(DPIP)2 (M=Cu, Co, Zn as 1, 2, 3) were synthesized and characterized by elemental analysis, IR, UV-Vis, thermogravimetry, and X-ray diffraction. Their nonlinear optical properties were measured by the Z-scan technique and yielded a normalized transmittance of about 70% for complex 1 (45 μJ pulse), and 93% for complex 3 (68 μJ pulse at the focus point). The nonlinear absorption coefficient, β, is 1.4×10(-11) m/W for 1 and 5.6×10(-13) m/W for 3, and the third-order nonlinear refraction index, n2, is 1.0×10(-18) m(2)/W for 3. Complex 1 shows self-defocusing property, while complex 3 exhibits self-focusing property. The thermogravimetric results show that the frame structure of compounds 1-3 begin to collapse at 400, 250 and 280°C, respectively, which suggests that they elicit excellent thermal stability. This research aims to provide better understanding of these compounds, and offer preliminary explanations for the significant differences between compounds 1-3, in order to potentially help in the designing of future novel materials with NLO properties. Copyright © 2014 Elsevier B.V. All rights reserved.

Phenotypic and genetic structure of traits delineating personality disorder.

PubMed

Livesley, W J; Jang, K L; Vernon, P A

1998-10-01

The evidence suggests that personality traits are hierarchically organized with more specific or lower-order traits combining to form more generalized higher-order traits. Agreement exists across studies regarding the lower-order traits that delineate personality disorder but not the higher-order traits. This study seeks to identify the higher-order structure of personality disorder by examining the phenotypic and genetic structures underlying lower-order traits. Eighteen lower-order traits were assessed using the Dimensional Assessment of Personality Disorder-Basic Questionnaire in samples of 656 personality disordered patients, 939 general population subjects, and a volunteer sample of 686 twin pairs. Principal components analysis yielded 4 components, labeled Emotional Dysregulation, Dissocial Behavior, Inhibitedness, and Compulsivity, that were similar across the 3 samples. Multivariate genetic analyses also yielded 4 genetic and environmental factors that were remarkably similar to the phenotypic factors. Analysis of the residual heritability of the lower-order traits when the effects of the higher-order factors were removed revealed a substantial residual heritable component for 12 of the 18 traits. The results support the following conclusions. First, the stable structure of traits across clinical and nonclinical samples is consistent with dimensional representations of personality disorders. Second, the higher-order traits of personality disorder strongly resemble dimensions of normal personality. This implies that a dimensional classification should be compatible with normative personality. Third, the residual heritability of the lower-order traits suggests that the personality phenotypes are based on a large number of specific genetic components.

Computer simulation results for bounds on the effective conductivity of composite media

NASA Astrophysics Data System (ADS)

Smith, P. A.; Torquato, S.

1989-02-01

This paper studies the determination of third- and fourth-order bounds on the effective conductivity σe of a composite material composed of aligned, infinitely long, identical, partially penetrable, circular cylinders of conductivity σ2 randomly distributed throughout a matrix of conductivity σ1. Both bounds involve the microstructural parameter ζ2 which is a multifold integral that depends upon S3, the three-point probability function of the composite. This key integral ζ2 is computed (for the possible range of cylinder volume fraction φ2) using a Monte Carlo simulation technique for the penetrable-concentric-shell model in which cylinders are distributed with an arbitrary degree of impenetrability λ, 0≤λ≤1. Results for the limiting cases λ=0 (``fully penetrable'' or randomly centered cylinders) and λ=1 (``totally impenetrable'' cylinders) compare very favorably with theoretical predictions made by Torquato and Beasley [Int. J. Eng. Sci. 24, 415 (1986)] and by Torquato and Lado [Proc. R. Soc. London Ser. A 417, 59 (1988)], respectively. Results are also reported for intermediate values of λ: cases which heretofore have not been examined. For a wide range of α=σ2/σ1 (conductivity ratio) and φ2, the third-order bounds on σe significantly improve upon second-order bounds which just depend upon φ2. The fourth-order bounds are, in turn, narrower than the third-order bounds. Moreover, when the cylinders are highly conducting (α≫1), the fourth-order lower bound provides an excellent estimate of the effective conductivity for a wide range of volume fractions.

Structural and functional analysis of the finished genome of the recently isolated toxic Anabaena sp. WA102.

PubMed

Brown, Nathan M; Mueller, Ryan S; Shepardson, Jonathan W; Landry, Zachary C; Morré, Jeffrey T; Maier, Claudia S; Hardy, F Joan; Dreher, Theo W

2016-06-13

Very few closed genomes of the cyanobacteria that commonly produce toxic blooms in lakes and reservoirs are available, limiting our understanding of the properties of these organisms. A new anatoxin-a-producing member of the Nostocaceae, Anabaena sp. WA102, was isolated from a freshwater lake in Washington State, USA, in 2013 and maintained in non-axenic culture. The Anabaena sp. WA102 5.7 Mbp genome assembly has been closed with long-read, single-molecule sequencing and separately a draft genome assembly has been produced with short-read sequencing technology. The closed and draft genome assemblies are compared, showing a correlation between long repeats in the genome and the many gaps in the short-read assembly. Anabaena sp. WA102 encodes anatoxin-a biosynthetic genes, as does its close relative Anabaena sp. AL93 (also introduced in this study). These strains are distinguished by differences in the genes for light-harvesting phycobilins, with Anabaena sp. AL93 possessing a phycoerythrocyanin operon. Biologically relevant structural variants in the Anabaena sp. WA102 genome were detected only by long-read sequencing: a tandem triplication of the anaBCD promoter region in the anatoxin-a synthase gene cluster (not triplicated in Anabaena sp. AL93) and a 5-kbp deletion variant present in two-thirds of the population. The genome has a large number of mobile elements (160). Strikingly, there was no synteny with the genome of its nearest fully assembled relative, Anabaena sp. 90. Structural and functional genome analyses indicate that Anabaena sp. WA102 has a flexible genome. Genome closure, which can be readily achieved with long-read sequencing, reveals large scale (e.g., gene order) and local structural features that should be considered in understanding genome evolution and function.

Third-order dissipative hydrodynamics from the entropy principle

NASA Astrophysics Data System (ADS)

El, Andrej; Xu, Zhe; Greiner, Carsten

2010-06-01

We review the entropy based derivation of third-order hydrodynamic equations and compare their solutions in one-dimensional boost-invariant geometry with calculations by the partonic cascade BAMPS. We demonstrate that Grad's approximation, which underlies the derivation of both Israel-Stewart and third-order equations, describes the transverse spectra from BAMPS with high accuracy. At the same time solutions of third-order equations are much closer to BAMPS results than solutions of Israel-Stewart equations. Introducing a resummation scheme for all higher-oder corrections to one-dimensional hydrodynamic equation we demonstrate the importance of higher-order terms if the Knudsen number is large.

Protein–DNA Interactions: The Story so Far and a New Method for Prediction

DOE PAGES

Jones, Susan; Thornton, Janet M.

2003-01-01

This review describes methods for the prediction of DNA binding function, and specifically summarizes a new method using 3D structural templates. The new method features the HTH motif that is found in approximately one-third of DNAbinding protein families. A library of 3D structural templates of HTH motifs was derived from proteins in the PDB. Templates were scanned against complete protein structures and the optimal superposition of a template on a structure calculated. Significance thresholds in terms of a minimum root mean squared deviation (rmsd) of an optimal superposition, and a minimum motif accessible surface area (ASA), have been calculated. Inmore » this way, it is possible to scan the template library against proteins of unknown function to make predictions about DNA-binding functionality.« less

Assembly of bicyclic or monocyclic clusters from [(η5-C5Me5)2Mo2(μ3-S)4(CuMeCN)2]2+ with tetraphosphine or N,P mixed ligands: syntheses, structures and enhanced third-order NLO performances.

PubMed

Ren, Zhi-Gang; Sun, Sha; Dai, Min; Wang, Hui-Fang; Lü, Chun-Ning; Lang, Jian-Ping; Sun, Zhen-Rong

2011-09-07

Reactions of the preformed cluster [(η(5)-C(5)Me(5))(2)Mo(2)(μ(3)-S)(4)Cu(2)(MeCN)(2)](ClO(4))(2) (1) with two tetraphosphine ligands, 1,4-N,N,N',N'-tetra(diphenylphosphanylmethyl)benzene diamine (dpppda) and N,N,N',N'-tetra(diphenylphosphanylmethyl)ethylene diamine (dppeda), produced two bicyclic clusters {[(η(5)-C(5)Me(5))(2)Mo(2)(μ(3)-S)(4)Cu(2)](2)(L)}(ClO(4))(4) (3: L = dpppda; 4: L = dppeda). Analogous reactions of 1 or [(η(5)-C(5)Me(5))(2)Mo(2)(μ(3)-S)(4)Cu(2)(MeCN)(2)](PF(6))(2) (2) with two N,P mixed ligands, N,N-bi(diphenylphosphanylmethyl)-2-aminopyridine (bdppmapy) and N-diphenylphosphanylmethyl-4-aminopyridine (dppmapy), afforded two monocyclic clusters {[(η(5)-C(5)Me(5))(2)Mo(2)(μ(3)-S)(4)Cu(2)](2)(L)(2)}X(4) (5: L = bdppmapy, X = ClO(4); 6: L = dppmapy, X = PF(6)). Compounds 3-6 were fully characterized by elemental analysis, IR spectra, UV-vis spectra, (1)H and (31)P{(1)H} NMR spectra, ESI-MS and single-crystal X-ray crystallography. In the tetracations of 3-6, two cubane-like [Mo(2)(μ(3)-S)(4)Cu(2)] cores are linked either by one dpppda or dppeda bridge to form a bicyclic structure or by a pair of bdppmapy or dppmapy bridges to afford a monocyclic structure. The third-order nonlinear optical (NLO) properties of 1 and 3-6 in MeCN were also investigated by femtosecond degenerate four-wave mixing (DFWM) technique with a 50 fs pulse width at 800 nm. Compounds 3-6 exhibited enhanced third-order NLO performances relative to that of 1. This journal is © The Royal Society of Chemistry 2011

Optical, structural and nonlinear optical properties of laser ablation synthesized Ag nanoparticles and photopolymer nanocomposites based on them

NASA Astrophysics Data System (ADS)

Zulina, Natalia A.; Pavlovetc, Ilia M.; Baranov, Mikhail A.; Denisyuk, Igor Yu.

2017-03-01

In this work Ag nanoparticles (NPs) stable colloid solution were prepared by laser ablation of chemically pure silver rod in liquid monomer isodecyl acrylate (IDA). Sizes of obtained nanoparticles were determined by scanning electron microscope and vary from 27 to 120 nm. Nanocomposites films were prepared from obtained stable colloid solution of AgNPs by photocuring. For aliphatic polymer IDA long molecules cross-linking Diurethane dimethacrylate, 1,6-Hexandiol diacrylate and Tetra (ethylene glycol) diacrylate were used. Prepared nanomaterials exhibit strong third-order nonlinear optical responses, which was estimated by using z-scan technique. The third-order nonlinear optical coefficients of the studied nanocomposites were found to be up to Reχ(3)=1.31×10-5 (esu) and Imχ(3)=7.64×10-5 (esu).

Can the second order multireference perturbation theory be considered a reliable tool to study mixed-valence compounds?

PubMed

Pastore, Mariachiara; Helal, Wissam; Evangelisti, Stefano; Leininger, Thierry; Malrieu, Jean-Paul; Maynau, Daniel; Angeli, Celestino; Cimiraglia, Renzo

2008-05-07

In this paper, the problem of the calculation of the electronic structure of mixed-valence compounds is addressed in the frame of multireference perturbation theory (MRPT). Using a simple mixed-valence compound (the 5,5(') (4H,4H('))-spirobi[ciclopenta[c]pyrrole] 2,2('),6,6(') tetrahydro cation), and the n-electron valence state perturbation theory (NEVPT2) and CASPT2 approaches, it is shown that the ground state (GS) energy curve presents an unphysical "well" for nuclear coordinates close to the symmetric case, where a maximum is expected. For NEVPT, the correct shape of the energy curve is retrieved by applying the MPRT at the (computationally expensive) third order. This behavior is rationalized using a simple model (the ionized GS of two weakly interacting identical systems, each neutral system being described by two electrons in two orbitals), showing that the unphysical well is due to the canonical orbital energies which at the symmetric (delocalized) conformation lead to a sudden modification of the denominators in the perturbation expansion. In this model, the bias introduced in the second order correction to the energy is almost entirely removed going to the third order. With the results of the model in mind, one can predict that all MRPT methods in which the zero order Hamiltonian is based on canonical orbital energies are prone to present unreasonable energy profiles close to the symmetric situation. However, the model allows a strategy to be devised which can give a correct behavior even at the second order, by simply averaging the orbital energies of the two charge-localized electronic states. Such a strategy is adopted in a NEVPT2 scheme obtaining a good agreement with the third order results based on the canonical orbital energies. The answer to the question reported in the title (is this theoretical approach a reliable tool for a correct description of these systems?) is therefore positive, but care must be exercised, either in defining the orbital energies or by resorting to the third order using for them the standard definition.

Azimuthal-angle dependence of charged-pion-interferometry measurements with respect to second- and third-order event planes in Au+Au collisions at √[S(NN)]=200  GeV.

PubMed

Adare, A; Afanasiev, S; Aidala, C; Ajitanand, N N; Akiba, Y; Al-Bataineh, H; Alexander, J; Aoki, K; Aramaki, Y; Atomssa, E T; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Bai, M; Baksay, G; Baksay, L; Barish, K N; Bassalleck, B; Basye, A T; Bathe, S; Baublis, V; Baumann, C; Bazilevsky, A; Belikov, S; Belmont, R; Bennett, R; Berdnikov, A; Berdnikov, Y; Bickley, A A; Bok, J S; Boyle, K; Brooks, M L; Buesching, H; Bumazhnov, V; Bunce, G; Butsyk, S; Camacho, C M; Campbell, S; Chen, C-H; Chi, C Y; Chiu, M; Choi, I J; Choudhury, R K; Christiansen, P; Chujo, T; Chung, P; Chvala, O; Cianciolo, V; Citron, Z; Cole, B A; Connors, M; Constantin, P; Csanád, M; Csörgő, T; Dahms, T; Dairaku, S; Danchev, I; Das, K; Datta, A; David, G; Denisov, A; Deshpande, A; Desmond, E J; Dietzsch, O; Dion, A; Donadelli, M; Drapier, O; Drees, A; Drees, K A; Durham, J M; Durum, A; Dutta, D; Edwards, S; Efremenko, Y V; Ellinghaus, F; Engelmore, T; Enokizono, A; En'yo, H; Esumi, S; Fadem, B; Fields, D E; Finger, M; Finger, M; Fleuret, F; Fokin, S L; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fujiwara, K; Fukao, Y; Fusayasu, T; Garishvili, I; Glenn, A; Gong, H; Gonin, M; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grosse Perdekamp, M; Gunji, T; Gustafsson, H-Å; Haggerty, J S; Hahn, K I; Hamagaki, H; Hamblen, J; Han, R; Hanks, J; Hartouni, E P; Haslum, E; Hayano, R; He, X; Heffner, M; Hemmick, T K; Hester, T; Hill, J C; Hohlmann, M; Holzmann, W; Homma, K; Hong, B; Horaguchi, T; Hornback, D; Huang, S; Ichihara, T; Ichimiya, R; Ide, J; Ikeda, Y; Imai, K; Inaba, M; Isenhower, D; Ishihara, M; Isobe, T; Issah, M; Isupov, A; Ivanischev, D; Jacak, B V; Jia, J; Jin, J; Johnson, B M; Joo, K S; Jouan, D; Jumper, D S; Kajihara, F; Kametani, S; Kamihara, N; Kamin, J; Kang, J H; Kapustinsky, J; Karatsu, K; Kawall, D; Kawashima, M; Kazantsev, A V; Kempel, T; Khanzadeev, A; Kijima, K M; Kim, B I; Kim, D H; Kim, D J; Kim, E; Kim, E-J; Kim, S H; Kim, Y-J; Kinney, E; Kiriluk, K; Kiss, A; Kistenev, E; Kochenda, L; Komkov, B; Konno, M; Koster, J; Kotchetkov, D; Kozlov, A; Král, A; Kravitz, A; Kunde, G J; Kurita, K; Kurosawa, M; Kwon, Y; Kyle, G S; Lacey, R; Lai, Y S; Lajoie, J G; Lebedev, A; Lee, D M; Lee, J; Lee, K; Lee, K B; Lee, K S; Leitch, M J; Leite, M A L; Leitner, E; Lenzi, B; Li, X; Liebing, P; Linden Levy, L A; Liška, T; Litvinenko, A; Liu, H; Liu, M X; Love, B; Luechtenborg, R; Lynch, D; Maguire, C F; Makdisi, Y I; Malakhov, A; Malik, M D; Manko, V I; Mannel, E; Mao, Y; Masui, H; Matathias, F; McCumber, M; McGaughey, P L; Means, N; Meredith, B; Miake, Y; Mignerey, A C; Mikeš, P; Miki, K; Milov, A; Mishra, M; Mitchell, J T; Mohanty, A K; Morino, Y; Morreale, A; Morrison, D P; Moukhanova, T V; Murata, J; Nagamiya, S; Nagle, J L; Naglis, M; Nagy, M I; Nakagawa, I; Nakamiya, Y; Nakamura, T; Nakano, K; Newby, J; Nguyen, M; Niida, T; Nouicer, R; Nyanin, A S; O'Brien, E; Oda, S X; Ogilvie, C A; Oka, M; Okada, K; Onuki, Y; Oskarsson, A; Ouchida, M; Ozawa, K; Pak, R; Pantuev, V; Papavassiliou, V; Park, I H; Park, J; Park, S K; Park, W J; Pate, S F; Pei, H; Peng, J-C; Pereira, H; Peresedov, V; Peressounko, D Yu; Pinkenburg, C; Pisani, R P; Proissl, M; Purschke, M L; Purwar, A K; Qu, H; Rak, J; Rakotozafindrabe, A; Ravinovich, I; Read, K F; Reygers, K; Riabov, V; Riabov, Y; Richardson, E; Roach, D; Roche, G; Rolnick, S D; Rosati, M; Rosen, C A; Rosendahl, S S E; Rosnet, P; Rukoyatkin, P; Ružička, P; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakashita, K; Samsonov, V; Sano, S; Sato, T; Sawada, S; Sedgwick, K; Seele, J; Seidl, R; Semenov, A Yu; Seto, R; Sharma, D; Shein, I; Shibata, T-A; Shigaki, K; Shimomura, M; Shoji, K; Shukla, P; Sickles, A; Silva, C L; Silvermyr, D; Silvestre, C; Sim, K S; Singh, B K; Singh, C P; Singh, V; Slunečka, M; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Sparks, N A; Stankus, P W; Stenlund, E; Stoll, S P; Sugitate, T; Sukhanov, A; Sziklai, J; Takagui, E M; Taketani, A; Tanabe, R; Tanaka, Y; Tanida, K; Tannenbaum, M J; Tarafdar, S; Taranenko, A; Tarján, P; Themann, H; Thomas, T L; Todoroki, T; Togawa, M; Toia, A; Tomášek, L; Torii, H; Towell, R S; Tserruya, I; Tsuchimoto, Y; Vale, C; Valle, H; van Hecke, H W; Vazquez-Zambrano, E; Veicht, A; Velkovska, J; Vértesi, R; Vinogradov, A A; Virius, M; Vrba, V; Vznuzdaev, E; Wang, X R; Watanabe, D; Watanabe, K; Watanabe, Y; Wei, F; Wei, R; Wessels, J; White, S N; Winter, D; Wood, J P; Woody, C L; Wright, R M; Wysocki, M; Xie, W; Yamaguchi, Y L; Yamaura, K; Yang, R; Yanovich, A; Ying, J; Yokkaichi, S; You, Z; Young, G R; Younus, I; Yushmanov, I E; Zajc, W A; Zhang, C; Zhou, S; Zolin, L

2014-06-06

Charged-pion-interferometry measurements were made with respect to the second- and third-order event plane for Au+Au collisions at sqrt[s_{NN}]=200  GeV. A strong azimuthal-angle dependence of the extracted Gaussian-source radii was observed with respect to both the second- and third-order event planes. The results for the second-order dependence indicate that the initial eccentricity is reduced during the medium evolution, which is consistent with previous results. In contrast, the results for the third-order dependence indicate that the initial triangular shape is significantly reduced and potentially reversed by the end of the medium evolution, and that the third-order oscillations are largely dominated by the dynamical effects from triangular flow.

Synthesis, growth, structure, mechanical and optical properties of a new semi-organic 2-methyl imidazolium dihydrogen phosphate single crystal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nagapandiselvi, P., E-mail: nagapandiselvip@ssn.edu.in; Baby, C.; Gopalakrishnan, R.

2016-09-15

Highlights: • 2MIDP crystals were grown by slow evaporation solution growth technique. • Single crystal XRD revealed self-assembled supramolecular framework. • Z scan technique is employed for third order nonlinear optical susceptibility. • Structure-property correlation is established. - Abstract: A new semi-organic compound, 2-methyl imidazolium dihydrogen phosphate (2MIDP), was prepared and good quality single crystals of 2MIDP were grown by slow evaporation solution growth technique. Crystal structure elucidated using Single crystal XRD showed that 2MIDP crystallizes in monoclinic system with P2{sub 1}/c space group. FT-IR, UV-Vis-NIR, Fluorescence and FT-NMR spectra confirm the molecular structure of 2MIDP. The UV-Vis-NIR spectra establishedmore » the suitability of the compound for NLO applications. TG-DSC showed that 2MIDP is thermally stable up to 200 °C. Mechanical characteristics like hardness number (H{sub v}), stiffness constant (C{sub 11}), yield strength (σ{sub v}), fracture toughness (K{sub c}) and brittleness index (B{sub i}) were assessed using Vicker’s microhardness tester. Third order nonlinear optical properties determined from Z-scan measurement using femto and picosecond lasers showed two photon reverse saturable absorption. The enhancement of nonlinear optical properties in femto second laser, revealed the suitability of 2MIDP for optical limiting applications.« less

A third-order gas-kinetic CPR method for the Euler and Navier-Stokes equations on triangular meshes

NASA Astrophysics Data System (ADS)

Zhang, Chao; Li, Qibing; Fu, Song; Wang, Z. J.

2018-06-01

A third-order accurate gas-kinetic scheme based on the correction procedure via reconstruction (CPR) framework is developed for the Euler and Navier-Stokes equations on triangular meshes. The scheme combines the accuracy and efficiency of the CPR formulation with the multidimensional characteristics and robustness of the gas-kinetic flux solver. Comparing with high-order finite volume gas-kinetic methods, the current scheme is more compact and efficient by avoiding wide stencils on unstructured meshes. Unlike the traditional CPR method where the inviscid and viscous terms are treated differently, the inviscid and viscous fluxes in the current scheme are coupled and computed uniformly through the kinetic evolution model. In addition, the present scheme adopts a fully coupled spatial and temporal gas distribution function for the flux evaluation, achieving high-order accuracy in both space and time within a single step. Numerical tests with a wide range of flow problems, from nearly incompressible to supersonic flows with strong shocks, for both inviscid and viscous problems, demonstrate the high accuracy and efficiency of the present scheme.

A knowledge representation view on biomedical structure and function.

PubMed Central

Schulz, Stefan; Hahn, Udo

2002-01-01

In biomedical ontologies, structural and functional considerations are of outstanding importance, and concepts which belong to these two categories are highly interdependent. At the representational level both axes must be clearly kept separate in order to support disciplined ontology engineering. Furthermore, the biaxial organization of physical structure (both by a taxonomic and partonomic order) entails intricate patterns of inference. We here propose a layered encoding of taxonomic, partonomic and functional aspects of biomedical concepts using description logics. PMID:12463912

Discretisation Schemes for Level Sets of Planar Gaussian Fields

NASA Astrophysics Data System (ADS)

Beliaev, D.; Muirhead, S.

2018-01-01

Smooth random Gaussian functions play an important role in mathematical physics, a main example being the random plane wave model conjectured by Berry to give a universal description of high-energy eigenfunctions of the Laplacian on generic compact manifolds. Our work is motivated by questions about the geometry of such random functions, in particular relating to the structure of their nodal and level sets. We study four discretisation schemes that extract information about level sets of planar Gaussian fields. Each scheme recovers information up to a different level of precision, and each requires a maximum mesh-size in order to be valid with high probability. The first two schemes are generalisations and enhancements of similar schemes that have appeared in the literature (Beffara and Gayet in Publ Math IHES, 2017. https://doi.org/10.1007/s10240-017-0093-0; Mischaikow and Wanner in Ann Appl Probab 17:980-1018, 2007); these give complete topological information about the level sets on either a local or global scale. As an application, we improve the results in Beffara and Gayet (2017) on Russo-Seymour-Welsh estimates for the nodal set of positively-correlated planar Gaussian fields. The third and fourth schemes are, to the best of our knowledge, completely new. The third scheme is specific to the nodal set of the random plane wave, and provides global topological information about the nodal set up to `visible ambiguities'. The fourth scheme gives a way to approximate the mean number of excursion domains of planar Gaussian fields.

Three-photon states in nonlinear crystal superlattices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Antonosyan, D. A.; Kryuchkyan, G. Yu.; Institute for Physical Researches, National Academy of Sciences Ashtarak-2, 0203 Ashtarak

2011-04-15

It has been a longstanding goal in quantum optics to realize controllable sources generating joint multiphoton states, particularly photon triplet with arbitrary spectral characteristics. We demonstrate that such sources can be realized via cascaded parametric down-conversion (PDC) in superlattice structures of nonlinear and linear segments. We consider a scheme that involves two parametric processes--{omega}{sub 0{yields}{omega}1}+{omega}{sub 2}, {omega}{sub 2{yields}{omega}1}+{omega}{sub 1} under pulsed pump--and investigate the spontaneous creation of a photon triplet as well as the generation of high-intensity mode in intracavity three-photon splitting. We show the preparation of Greenberger-Horne-Zeilinger polarization-entangled states in cascaded type-II and type-I PDC in the framework ofmore » considering the dual-grid structure that involves two periodically poled crystals. We demonstrate the method of compensation of the dispersive effects in nonlinear segments by appropriately chosen linear dispersive segments of superlattice for preparation of the heralded joint states of two polarized photons. In the case of intracavity three-photon splitting, we concentrate on the investigation of photon-number distributions, third-order photon-number correlation function, as well as the Wigner functions. These quantities are observed both for short interaction time intervals and the over-transient regime, when dissipative effects are essential.« less

High-Order Energy Stable WENO Schemes

NASA Technical Reports Server (NTRS)

Yamaleev, Nail K.; Carpenter, Mark H.

2009-01-01

A third-order Energy Stable Weighted Essentially Non-Oscillatory (ESWENO) finite difference scheme developed by Yamaleev and Carpenter was proven to be stable in the energy norm for both continuous and discontinuous solutions of systems of linear hyperbolic equations. Herein, a systematic approach is presented that enables 'energy stable' modifications for existing WENO schemes of any order. The technique is demonstrated by developing a one-parameter family of fifth-order upwind-biased ESWENO schemes; ESWENO schemes up to eighth order are presented in the appendix. New weight functions are also developed that provide (1) formal consistency, (2) much faster convergence for smooth solutions with an arbitrary number of vanishing derivatives, and (3) improved resolution near strong discontinuities.

Electronic structures and nonlinear optical properties of trinuclear transition metal clusters M-(mu-S)-M' (M = Mo, W; M' = Cu, Ag, Au).

PubMed

Chen, Xihua; Wu, Kechen; Snijders, Jaap G; Lin, Chensheng

2003-01-27

A series of trinuclear metal clusters MS4(M'PPh3)2(M'PPh3) (M = Mo, W; M' = Cu, Ag, Au) have been studied using the density functional theory (DFT) method. The static polarizabilities and hyperpolarizabilities of the model clusters have been calculated using the finite-field (F-F) method. The model clusters, divided into two groups, are alike in the structure of two fragments of rhombic units M-(mu-S)2-M' (M = Mo, W; M' = Cu, Ag, Au), perpendicular to each other, which are joined by sharing the bridge metal M. It is the charge transfer from one of these moieties to the other in these characteristic sulfido-transitional metal cores that is responsible for the polarizabilities and hyperpolarizabilities. This kind of electronic delocalization, different from that of the planar pi-system, is interesting and warrants further investigation. The structural effects on properties are important. In these models, considerable third-order nonlinearities are exhibited. The element substitution effect of Mo and W is weak, while that of Cu and Ag is relatively substantial. An overall order is gamma xxxx(Mo-Ag) > gamma xxxx(W-Ag) > gamma xxxx(Mo-Au) > gamma xxxx(W-Au) > gamma xxxx (Mo-Cu) > gamma xxxx(W-Cu) and gamma av(Mo-Ag) approximately gamma av(W-Ag) > gamma av(Mo-Au) approximately gamma av(W-Au) approximately gamma av (Mo-Cu) approximately gamma av(W-Cu).

In situ grazing incidence small-angle X-ray scattering investigation of polystyrene nanoparticle spray deposition onto silicon.

PubMed

Herzog, Gerd; Benecke, Gunthard; Buffet, Adeline; Heidmann, Berit; Perlich, Jan; Risch, Johannes F H; Santoro, Gonzalo; Schwartzkopf, Matthias; Yu, Shun; Wurth, Wilfried; Roth, Stephan V

2013-09-10

We investigated the spray deposition and subsequent self-assembly during drying of a polystyrene nanoparticle dispersion with in situ grazing incidence small-angle X-ray scattering at high time resolution. During the fast deposition of the dispersion and the subsequent evaporation of the solvent, different transient stages of nanoparticle assembly can be identified. In the first stage, the solvent starts to evaporate without ordering of the nanoparticles. During the second stage, large-scale structures imposed by the breakup of the liquid film are observable. In this stage, the solvent evaporates further and nanoparticle ordering starts. In the late third drying stage, the nanoparticles self-assemble into the final layer structure.

The structure of coping among older adults living with HIV/AIDS and depressive symptoms

PubMed Central

Hansen, Nathan B; Harrison, Blair; Fambro, Stacy; Bodnar, Sara; Heckman, Timothy G; Sikkema, Kathleen J

2013-01-01

One-third of adults living with HIV/AIDS are over the age of 50. This study evaluated the structure of coping among 307 older adults living with HIV/AIDS. Participants completed 61 coping items and measures of anxiety, depression, loneliness, and coping self-efficacy. Exploratory factor analyses retained 40 coping items loading on five specific first order factors (Distancing Avoidance, Social Support Seeking, Self-Destructive Avoidance, Spiritual Coping, and Solution-Focused Coping) and two general second order factors (Active and Avoidant Coping). Factors demonstrated good reliability and validity. Results suggest that general coping factors should be considered with specific factors when measuring coping among older adults. PMID:22453164

Effects of Air Drag and Lunar Third-Body Perturbations on Motion Near a Reference KAM Torus

DTIC Science & Technology

2011-03-01

body m 1) mass of satellite; 2) order of associated Legendre polynomial n 1) mean motion; 2) degree of associated Legendre polynomial n3 mean motion...physical momentum pi ith physical momentum Pmn associated Legendre polynomial of order m and degree n q̇ physical coordinate derivatives vector, [q̇1...are constants specifying the shape of the gravitational field; and Pmn are associated Legendre polynomials . When m = n = 0, the geopotential function

Influence of an externally modulated photonic link on a microwave communications system

NASA Technical Reports Server (NTRS)

Yao, X. S.; Maleki, L.

1994-01-01

We analyze the influence of an externally modulated photonic link on the performance of a microwave communications system. From the analysis, we deduce limitations on the photocurrent, magnitude of the relaxation oscillation noise of the laser, third-order intercept point of the preamplifier, and other parameters in order for the photonic link to function according to the system specifications. Based on this, we outline a procedure for designing a photonic link that can be integrated in a system with minimal performance degradation.

Metalloproteomics: Forward and Reverse Approaches in Metalloprotein Structural and Functional Characterization

PubMed Central

Shi, Wuxian; Chance, Mark R.

2010-01-01

About one-third of all proteins are associated with a metal. Metalloproteomics is defined as the structural and functional characterization of metalloproteins on a genome-wide scale. The methodologies utilized in metalloproteomics, including both forward (bottom-up) and reverse (top-down) technologies, to provide information on the identity, quantity and function of metalloproteins are discussed. Important techniques frequently employed in metalloproteomics include classical proteomics tools such as mass spectrometry and 2-D gels, immobilized-metal affinity chromatography, bioinformatics sequence analysis and homology modeling, X-ray absorption spectroscopy and other synchrotron radiation based tools. Combinative applications of these techniques provide a powerful approach to understand the function of metalloproteins. PMID:21130021

The singular values of the imbedding operators of some classes of analytic functions of several variables

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parfenov, O.G.

1994-12-25

We discuss three results. The first exhibits the order of decrease of the s-values as a function of the CR-dimension of a compact set on which we approximate the class of analytic functions being studied. The second is an asymptotic formula for the case when the domain of analyticity and the compact set are Reinhart domains. The third is the computation of the s-values of a special operator that is of interest for approximation theory on one-dimensional manifolds.

Multi-functional layered structure having structural and radiation shielding attributes

NASA Technical Reports Server (NTRS)

Kaul, Raj K. (Inventor); Barghouty, Abdulnasser Fakhri (Inventor); Penn, Benjamin G. (Inventor); Hulcher, Anthony Bruce (Inventor)

2010-01-01

A cosmic and solar radiation shielding structure that also has structural attributes is comprised of three layers. The first layer is 30-42 percent by volume of ultra-high molecular weight (UHMW) polyethylene fibers, 18-30 percent by volume of graphite fibers, and a remaining percent by volume of an epoxy resin matrix. The second layer is approximately 68 percent by volume of UHMW polyethylene fibers and a remaining percent by volume of a polyethylene matrix. The third layer is a ceramic material.

Breakdown of the single-exchange approximation in third-order symmetry-adapted perturbation theory.

PubMed

Lao, Ka Un; Herbert, John M

2012-03-22

We report third-order symmetry-adapted perturbation theory (SAPT) calculations for several dimers whose intermolecular interactions are dominated by induction. We demonstrate that the single-exchange approximation (SEA) employed to derive the third-order exchange-induction correction (E(exch-ind)((30))) fails to quench the attractive nature of the third-order induction (E(ind)((30))), leading to one-dimensional potential curves that become attractive rather than repulsive at short intermolecular separations. A scaling equation for (E(exch-ind)((30))), based on an exact formula for the first-order exchange correction, is introduced to approximate exchange effects beyond the SEA, and qualitatively correct potential energy curves that include third-order induction are thereby obtained. For induction-dominated systems, our results indicate that a "hybrid" SAPT approach, in which a dimer Hartree-Fock calculation is performed in order to obtain a correction for higher-order induction, is necessary not only to obtain quantitative binding energies but also to obtain qualitatively correct potential energy surfaces. These results underscore the need to develop higher-order exchange-induction formulas that go beyond the SEA. © 2012 American Chemical Society

Environmental constraints shaping constituent order in emerging communication systems: Structural iconicity, interactive alignment and conventionalization.

PubMed

Christensen, Peer; Fusaroli, Riccardo; Tylén, Kristian

2016-01-01

Where does linguistic structure come from? Recent gesture elicitation studies have indicated that constituent order (corresponding to for instance subject-verb-object, or SVO in English) may be heavily influenced by human cognitive biases constraining gesture production and transmission. Here we explore the alternative hypothesis that syntactic patterns are motivated by multiple environmental and social-interactional constraints that are external to the cognitive domain. In three experiments, we systematically investigate different motivations for structure in the gestural communication of simple transitive events. The first experiment indicates that, if participants communicate about different types of events, manipulation events (e.g. someone throwing a cake) and construction events (e.g. someone baking a cake), they spontaneously and systematically produce different constituent orders, SOV and SVO respectively, thus following the principle of structural iconicity. The second experiment shows that participants' choice of constituent order is also reliably influenced by social-interactional forces of interactive alignment, that is, the tendency to re-use an interlocutor's previous choice of constituent order, thus potentially overriding affordances for iconicity. Lastly, the third experiment finds that the relative frequency distribution of referent event types motivates the stabilization and conventionalization of a single constituent order for the communication of different types of events. Together, our results demonstrate that constituent order in emerging gestural communication systems is shaped and stabilized in response to multiple external environmental and social factors: structural iconicity, interactive alignment and distributional frequency. Copyright © 2015 Elsevier B.V. All rights reserved.

Granule-by-granule reconstruction of a sandpile from x-ray microtomography data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seidler, G. T.; Martinez, G.; Seeley, L. H.

2000-12-01

Mesoscale disordered materials are ubiquitous in industry and in the environment. Any fundamental understanding of the transport and mechanical properties of such materials must follow from a thorough understanding of their structure. However, in the overwhelming majority of cases, experimental characterization of such materials has been limited to first- and second-order structural correlation functions, i.e., the mean filling fraction and the structural autocorrelation function. We report here the successful combination of synchrotron x-ray microtomography and image processing to determine the full three-dimensional real-space structure of a model disordered material, a granular bed of relatively monodisperse glass spheres. Specifically, we determinemore » the center location and the local connectivity of each granule. This complete knowledge of structure can be used to calculate otherwise inaccessible high-order correlation functions. We analyze nematic order parameters for contact bonds to characterize the geometric anisotropy or fabric induced by the sample boundary conditions. Away from the boundaries we find short-range bond orientational order exhibiting characteristics of the underlying polytetrahedral structure.« less

A prototype of behavior selection mechanism based on emotion

NASA Astrophysics Data System (ADS)

Zhang, Guofeng; Li, Zushu

2007-12-01

In bionic methodology rather than in design methodology more familiar with, summarizing the psychological researches of emotion, we propose the biologic mechanism of emotion, emotion selection role in creature evolution and a anima framework including emotion similar to the classical control structure; and consulting Prospect Theory, build an Emotion Characteristic Functions(ECF) that computer emotion; two more emotion theories are added to them that higher emotion is preferred and middle emotion makes brain run more efficiently, emotional behavior mechanism comes into being. A simulation of proposed mechanism are designed and carried out on Alife Swarm software platform. In this simulation, a virtual grassland ecosystem is achieved where there are two kinds of artificial animals: herbivore and preyer. These artificial animals execute four types of behavior: wandering, escaping, finding food, finding sex partner in their lives. According the theories of animal ethnology, escaping from preyer is prior to other behaviors for its existence, finding food is secondly important behavior, rating is third one and wandering is last behavior. In keeping this behavior order, based on our behavior characteristic function theory, the specific functions of emotion computing are built of artificial autonomous animals. The result of simulation confirms the behavior selection mechanism.

Intraoral extraction of an ectopic mandibular third molar detected in the subcondylar region without a pathological cause: A case report and literature review.

PubMed

Okuyama, Kohei; Sakamoto, Yuki; Naruse, Tomofumi; Kawakita, Akiko; Yanamoto, Souichi; Furukawa, Kohei; Umeda, Masahiro

2017-09-01

To present a case report on the presence of an ectopic mandibular third molar (EMTM), the surgical treatment, and outcome. A 63-year-old woman presented with right preauricular facial swelling, limited jaw function, and pain. Radiographic assessment demonstrated an EMTM positioned in the superoposterior aspect of the ramus. Radiographically, there was a bony tunnel extending from the third molar to distal of the second molar. The patient was treated by an intraoral approach on the medial aspect of the ramus for removal of the ectopic third molar, as well as the tissue in the bony tunnel. The patient healed uneventfully. The soft tissue in the bony canal was granulation tissue, and nerve function was preserved. A literature search of EMTMs was conducted identifying 17 reported cases. Three-dimensional imaging in the management of EMTM can be beneficial in identifying position of the tooth, associated pathology, and identifying the position of neurovascular structures to aid in removal of the ectopic tooth.

The determination of third order linear models from a seventh order nonlinear jet engine model

NASA Technical Reports Server (NTRS)

Lalonde, Rick J.; Hartley, Tom T.; De Abreu-Garcia, J. Alex

1989-01-01

Results are presented that demonstrate how good reduced-order models can be obtained directly by recursive parameter identification using input/output (I/O) data of high-order nonlinear systems. Three different methods of obtaining a third-order linear model from a seventh-order nonlinear turbojet engine model are compared. The first method is to obtain a linear model from the original model and then reduce the linear model by standard reduction techniques such as residualization and balancing. The second method is to identify directly a third-order linear model by recursive least-squares parameter estimation using I/O data of the original model. The third method is to obtain a reduced-order model from the original model and then linearize the reduced model. Frequency responses are used as the performance measure to evaluate the reduced models. The reduced-order models along with their Bode plots are presented for comparison purposes.

Near- and far-field investigation of dark and bright higher order resonances in square loop elements at mid-infrared wavelengths.

PubMed

Tucker, Eric; D'Archangel, Jeffrey; Boreman, Glenn

2017-03-06

Three different size gold square loop structures were fabricated as arrays on ZnS over a ground plane and designed to have absorptive fundamental, second order, and third order resonances at a wavelength of 10.6 µm and 60° off-normal. The angular dependent far-field spectral absorptivity was investigated over the mid-infrared for each size loop array. It was found that the second order modes were dark at normal incidence, but became excited at off-normal incidence, which is consistent with previous work for similar geometry structures. Furthermore, near-field measurements and simulations at a wavelength of 10.6 µm and 60° off-normal showed that the second order mode (quadrupolar) of the medium size loop yielded a near-field response similar in magnitude to the fundamental mode (dipolar) of the small size loop, which can be important for sensing related applications where both strong near-field enhancement and more uniform or less localized field is beneficial.

Statistically generated weighted curve fit of residual functions for modal analysis of structures

NASA Technical Reports Server (NTRS)

Bookout, P. S.

1995-01-01

A statistically generated weighting function for a second-order polynomial curve fit of residual functions has been developed. The residual flexibility test method, from which a residual function is generated, is a procedure for modal testing large structures in an external constraint-free environment to measure the effects of higher order modes and interface stiffness. This test method is applicable to structures with distinct degree-of-freedom interfaces to other system components. A theoretical residual function in the displacement/force domain has the characteristics of a relatively flat line in the lower frequencies and a slight upward curvature in the higher frequency range. In the test residual function, the above-mentioned characteristics can be seen in the data, but due to the present limitations in the modal parameter evaluation (natural frequencies and mode shapes) of test data, the residual function has regions of ragged data. A second order polynomial curve fit is required to obtain the residual flexibility term. A weighting function of the data is generated by examining the variances between neighboring data points. From a weighted second-order polynomial curve fit, an accurate residual flexibility value can be obtained. The residual flexibility value and free-free modes from testing are used to improve a mathematical model of the structure. The residual flexibility modal test method is applied to a straight beam with a trunnion appendage and a space shuttle payload pallet simulator.

Local structure of dilute aqueous DMSO solutions, as seen from molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Idrissi, Abdenacer; Marekha, Bogdan A.; Barj, Mohammed; Miannay, François Alexandre; Takamuku, Toshiyuki; Raptis, Vasilios; Samios, Jannis; Jedlovszky, Pál

2017-06-01

The information about the structure of dimethyl sulfoxide (DMSO)-water mixtures at relatively low DMSO mole fractions is an important step in order to understand their cryoprotective properties as well as the solvation process of proteins and amino acids. Classical MD simulations, using the potential model combination that best reproduces the free energy of mixing of these compounds, are used to analyze the local structure of DMSO-water mixtures at DMSO mole fractions below 0.2. Significant changes in the local structure of DMSO are observed around the DMSO mole fraction of 0.1. The array of evidence, based on the cluster and the metric and topological parameters of the Voronoi polyhedra distributions, indicates that these changes are associated with the simultaneous increase of the number of DMSO-water and decrease of water-water hydrogen bonds with increasing DMSO concentration. The inversion between the dominance of these two types of H-bonds occurs around XDMSO = 0.1, above which the DMSO-DMSO interactions also start playing an important role. In other words, below the DMSO mole fraction of 0.1, DMSO molecules are mainly solvated by water molecules, while above it, their solvation shell consists of a mixture of water and DMSO. The trigonal, tetrahedral, and trigonal bipyramidal distributions of water shift to lower corresponding order parameter values indicating the loosening of these orientations. Adding DMSO does not affect the hydrogen bonding between a reference water molecule and its first neighbor hydrogen bonded water molecules, while it increases the bent hydrogen bond geometry involving the second ones. The close-packed local structure of the third, fourth, and fifth water neighbors also is reinforced. In accordance with previous theoretical and experimental data, the hydrogen bonding between water and the first, the second, and the third DMSO neighbors is stronger than that with its corresponding water neighbors. At a given DMSO mole fraction, the behavior of the intensity of the high orientational order parameter values indicates that water molecules are more ordered in the vicinity of the hydrophilic group while their structure is close-packed near the hydrophobic group of DMSO.

Design, Test, and Evaluation of a Transonic Axial Compressor Rotor with Splitter Blades

DTIC Science & Technology

2013-09-01

parameters .......................................................17 Figure 13. Third-order spline fit for blade camber line distribution...18 Figure 14. Third-order spline fit for blade thickness distribution .....................................19 Figure 15. Blade...leading edge: third-order spline fit for thickness distribution ...............20 Figure 16. Blade leading edge and trailing edge slope blending

Disappearance of Anisotropic Intermittency in Large-amplitude MHD Turbulence and Its Comparison with Small-amplitude MHD Turbulence

NASA Astrophysics Data System (ADS)

Yang, Liping; Zhang, Lei; He, Jiansen; Tu, Chuanyi; Li, Shengtai; Wang, Xin; Wang, Linghua

2018-03-01

Multi-order structure functions in the solar wind are reported to display a monofractal scaling when sampled parallel to the local magnetic field and a multifractal scaling when measured perpendicularly. Whether and to what extent will the scaling anisotropy be weakened by the enhancement of turbulence amplitude relative to the background magnetic strength? In this study, based on two runs of the magnetohydrodynamic (MHD) turbulence simulation with different relative levels of turbulence amplitude, we investigate and compare the scaling of multi-order magnetic structure functions and magnetic probability distribution functions (PDFs) as well as their dependence on the direction of the local field. The numerical results show that for the case of large-amplitude MHD turbulence, the multi-order structure functions display a multifractal scaling at all angles to the local magnetic field, with PDFs deviating significantly from the Gaussian distribution and a flatness larger than 3 at all angles. In contrast, for the case of small-amplitude MHD turbulence, the multi-order structure functions and PDFs have different features in the quasi-parallel and quasi-perpendicular directions: a monofractal scaling and Gaussian-like distribution in the former, and a conversion of a monofractal scaling and Gaussian-like distribution into a multifractal scaling and non-Gaussian tail distribution in the latter. These results hint that when intermittencies are abundant and intense, the multifractal scaling in the structure functions can appear even if it is in the quasi-parallel direction; otherwise, the monofractal scaling in the structure functions remains even if it is in the quasi-perpendicular direction.

Structural and functional characterization of Mycobacterium tuberculosis triosephosphate isomerase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Connor, Sean E.; Capodagli, Glenn C.; Deaton, Michelle K.

Tuberculosis (TB) is a major infectious disease that accounts for over 1.7 million deaths every year. Mycobacterium tuberculosis, the causative agent of tuberculosis, enters the human host by the inhalation of infectious aerosols. Additionally, one third of the world's population is likely to be infected with latent TB. The incidence of TB is on the rise owing in part to the emergence of multidrug-resistant strains. As a result, there is a growing need to focus on novel M. tuberculosis enzyme targets. M. tuberculosis triosephosphate isomerase (MtTPI) is an essential enzyme for gluconeogenetic pathways, making it a potential target for futuremore » therapeutics. In order to determine its structure, the X-ray crystal structure of MtTPI has been determined, as well as that of MtTPI bound with a reaction-intermediate analog. As a result, two forms of the active site were revealed. In conjunction with the kinetic parameters obtained for the MtTPI-facilitated conversion of dihydroxyacetone phosphate (DHAP) to D-glyceraldehyde-3-phosphate (D-GAP), this provides a greater structural and biochemical understanding of this enzyme. Additionally, isothermal titration calorimetry was used to determine the binding constant for a reaction-intermediate analog bound to the active site of MtTPI.« less

First cytoplasmic loop of glucagon-like peptide-1 receptor can function at the third cytoplasmic loop position of rhodopsin.

PubMed

Yamashita, Takahiro; Tose, Koji; Shichida, Yoshinori

2008-01-01

G protein-coupled receptors (GPCRs) are classified into several families based on their amino acid sequences. In family 1, GPCRs such as rhodopsin and adrenergic receptor, the structure-function relationship has been extensively investigated to demonstrate that exposure of the third cytoplasmic loop is essential for selective G protein activation. In contrast, much less is known about other families. Here we prepared chimeric mutants between Gt-coupled rhodopsin and Gi/Go- and Gs-coupled glucagon-like peptide-1 (GLP-1) receptor of family 2 and tried to identify the loop region that functions at the third cytoplasmic loop position of rhodopsin. We succeeded in expressing a mutant having the first cytoplasmic loop of GLP-1 receptor and found that this mutant activated Gi and Go efficiently but did not activate Gt. Moreover, the rhodopsin mutant having the first loop of Gs-coupled secretin receptor of family 2 decreased the Gi and Go activation efficiencies. Therefore, the first loop of GLP-1 receptor would share a similar role to the third loop of rhodopsin in G protein activation. This result strongly suggested that different families of GPCRs have maintained molecular architectures of their ancestral types to generate a common mechanism, namely exposure of the cytoplasmic loop, to activate peripheral G protein.

The SUNY Summer Internship: The First Twenty Years.

ERIC Educational Resources Information Center

Mozlin, Rochelle; Suchoff, Irwin B.

1987-01-01

The State University of New York's innovative summer internship program bringing together 18 students between their third and fourth years to study functional vision care and vision therapy is described. Its history, program structure, recruitment and selection, and evaluation are highlighted. (MSE)

Early Development of Functional Network Segregation Revealed by Connectomic Analysis of the Preterm Human Brain.

PubMed

Cao, Miao; He, Yong; Dai, Zhengjia; Liao, Xuhong; Jeon, Tina; Ouyang, Minhui; Chalak, Lina; Bi, Yanchao; Rollins, Nancy; Dong, Qi; Huang, Hao

2017-03-01

Human brain functional networks are topologically organized with nontrivial connectivity characteristics such as small-worldness and densely linked hubs to support highly segregated and integrated information processing. However, how they emerge and change at very early developmental phases remains poorly understood. Here, we used resting-state functional MRI and voxel-based graph theory analysis to systematically investigate the topological organization of whole-brain networks in 40 infants aged around 31 to 42 postmenstrual weeks. The functional connectivity strength and heterogeneity increased significantly in primary motor, somatosensory, visual, and auditory regions, but much less in high-order default-mode and executive-control regions. The hub and rich-club structures in primary regions were already present at around 31 postmenstrual weeks and exhibited remarkable expansions with age, accompanied by increased local clustering and shortest path length, indicating a transition from a relatively random to a more organized configuration. Moreover, multivariate pattern analysis using support vector regression revealed that individual brain maturity of preterm babies could be predicted by the network connectivity patterns. Collectively, we highlighted a gradually enhanced functional network segregation manner in the third trimester, which is primarily driven by the rapid increases of functional connectivity of the primary regions, providing crucial insights into the topological development patterns prior to birth. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Study on Failure of Third-Party Damage for Urban Gas Pipeline Based on Fuzzy Comprehensive Evaluation

PubMed Central

Li, Jun; Zhang, Hong; Han, Yinshan; Wang, Baodong

2016-01-01

Focusing on the diversity, complexity and uncertainty of the third-party damage accident, the failure probability of third-party damage to urban gas pipeline was evaluated on the theory of analytic hierarchy process and fuzzy mathematics. The fault tree of third-party damage containing 56 basic events was built by hazard identification of third-party damage. The fuzzy evaluation of basic event probabilities were conducted by the expert judgment method and using membership function of fuzzy set. The determination of the weight of each expert and the modification of the evaluation opinions were accomplished using the improved analytic hierarchy process, and the failure possibility of the third-party to urban gas pipeline was calculated. Taking gas pipelines of a certain large provincial capital city as an example, the risk assessment structure of the method was proved to conform to the actual situation, which provides the basis for the safety risk prevention. PMID:27875545

Stereomotion is processed by the third-order motion system: reply to comment on Three-systems theory of human visual motion perception: review and update

NASA Astrophysics Data System (ADS)

Lu, Zhong-Lin; Sperling, George

2002-10-01

Two theories are considered to account for the perception of motion of depth-defined objects in random-dot stereograms (stereomotion). In the LuSperling three-motion-systems theory J. Opt. Soc. Am. A 18 , 2331 (2001), stereomotion is perceived by the third-order motion system, which detects the motion of areas defined as figure (versus ground) in a salience map. Alternatively, in his comment J. Opt. Soc. Am. A 19 , 2142 (2002), Patterson proposes a low-level motion-energy system dedicated to stereo depth. The critical difference between these theories is the preprocessing (figureground based on depth and other cues versus simply stereo depth) rather than the motion-detection algorithm itself (because the motion-extraction algorithm for third-order motion is undetermined). Furthermore, the ability of observers to perceive motion in alternating feature displays in which stereo depth alternates with other features such as texture orientation indicates that the third-order motion system can perceive stereomotion. This reduces the stereomotion question to Is it third-order alone or third-order plus dedicated depth-motion processing? Two new experiments intended to support the dedicated depth-motion processing theory are shown here to be perfectly accounted for by third-order motion, as are many older experiments that have previously been shown to be consistent with third-order motion. Cyclopean and rivalry images are shown to be a likely confound in stereomotion studies, rivalry motion being as strong as stereomotion. The phase dependence of superimposed same-direction stereomotion stimuli, rivalry stimuli, and isoluminant color stimuli indicates that these stimuli are processed in the same (third-order) motion system. The phase-dependence paradigm Lu and Sperling, Vision Res. 35 , 2697 (1995) ultimately can resolve the question of which types of signals share a single motion detector. All the evidence accumulated so far is consistent with the three-motion-systems theory. 2002 Optical Society of America

Growth, structural, thermal, dielectric and nonlinear optical properties of potassium hexachloro cadmate (IV) a novel single crystal

NASA Astrophysics Data System (ADS)

Umarani, P.; Jagannathan, K.

2018-02-01

The Potassium hexachloro cadmate (IV) (PHC) single crystal was grown from the aqueous of the solution by a controlled evaporation method. Single crystal XRD solved the structure. FTIR is used to identify the functional groups of grown crystal. The UV-Vis-NIR spectrometer was used to find out the UV cut off region and to calculate the optical band gap of the Potassium hexachloro cadmate (IV) single crystal. The EDAX spectrum has been used to identify the compounds present in title compound. The TG-DTA profile shows the thermal stability of the grown crystal of Potassium hexachloro cadmate (IV). The Vicker's hardness measurement was used to calculate the material hardness of the title compound. The dielectric loss and constant varied with frequencies and activation energy is also calculated. The solid state parameters like plasma energy, Penn gap, Fermi energy, electronic polarizability using Penn analysis and Clausius-Mossotti equation were also calculated for the title compound. The Z-scan technique is used to calculate the third order nonlinear susceptibility of a real and imaginary part.

Third-order nonlinear optical property of a polyphenylene oligomer: poly(2,5-dialkozyphenylene)

NASA Astrophysics Data System (ADS)

Wu, Jianyao; Yan, Jun; Sun, Diechi; Li, Fuming; Zhou, Luwei; Sun, Meng

1997-02-01

The third-order nonlinear optical (NLO) property of a soluble, π-backbone conjugated polymer poly(2,5-dialkozyphenylene) (for abbreviation called dialkozy-PP) is studied at the picosecond time region. The near resonance third-order hyperpolarizability γxxxx at 532 nm is 8.2×10 -30 esu, and the corresponding macroscopic third-order susceptibility χ(3)(- ω, ω, ω, - ω) and nonlinear refractive index n2 are estimated to be 6.3×10 -10 esu and 1.4×10 -8 esu, respectively. The half-width of the laser pulse is 35 ps.

Improvements in deep-space tracking by use of third-order loops.

NASA Technical Reports Server (NTRS)

Tausworth, R. C.; Crow, R. B.

1972-01-01

Third-order phase-locked receivers have not yet found wide application in deep-space communications systems because the second-order systems now used have performed adequately on past spacecraft missions. However, a survey of the doppler profiles for future missions shows that an unaided second-order loop may be unable to perform within reasonable error bounds. This article discusses the characteristics of a simple third-order extension to present second-order systems that not only extends doppler-tracking capability, but widens the pull-in range and decreases pull-in time as well.

How well can ultracompact bodies imitate black hole ringdowns?

NASA Astrophysics Data System (ADS)

Glampedakis, Kostas; Pappas, George

2018-02-01

The ongoing observations of merging black holes by the instruments of the fledging gravitational wave astronomy has opened the way for testing the general-relativistic Kerr black hole metric and, at the same time, for probing the existence of more speculative horizonless ultracompact objects. In this paper we quantify the difference that these two classes of objects may exhibit in the post-merger ringdown signal. By considering rotating systems in general relativity and assuming an eikonal limit and a third-order Hartle-Thorne slow-rotation approximation, we provide the first calculation of the early ringdown frequency and damping time as a function of the body's multipolar structure. Using the example of a gravastar, we show that the main ringdown signal may differ by as much as a few percent with respect to that of a Kerr black hole, a deviation that could be probed by near-future Advanced LIGO/Virgo searches.

Ultrabroadband direct detection of nonclassical photon statistics at telecom wavelength

PubMed Central

Wakui, Kentaro; Eto, Yujiro; Benichi, Hugo; Izumi, Shuro; Yanagida, Tetsufumi; Ema, Kazuhiro; Numata, Takayuki; Fukuda, Daiji; Takeoka, Masahiro; Sasaki, Masahide

2014-01-01

Broadband light sources play essential roles in diverse fields, such as high-capacity optical communications, optical coherence tomography, optical spectroscopy, and spectrograph calibration. Although a nonclassical state from spontaneous parametric down-conversion may serve as a quantum counterpart, its detection and characterization have been a challenging task. Here we demonstrate the direct detection of photon numbers of an ultrabroadband (110 nm FWHM) squeezed state in the telecom band centred at 1535 nm wavelength, using a superconducting transition-edge sensor. The observed photon-number distributions violate Klyshko's criterion for the nonclassicality. From the observed photon-number distribution, we evaluate the second- and third-order correlation functions, and characterize a multimode structure, which implies that several tens of orthonormal modes of squeezing exist in the single optical pulse. Our results and techniques open up a new possibility to generate and characterize frequency-multiplexed nonclassical light sources for quantum info-communications technology. PMID:24694515

The development of neural correlates for memory formation

PubMed Central

Ofen, Noa

2012-01-01

A growing body of literature considers the development of episodic memory systems in the brain; the majority are neuroimaging studies conducted during memory encoding in order to explore developmental trajectories in memory formation. This review considers evidence from behavioral studies of memory development, neural correlates of memory formation in adults, and structural brain development, all of which form the foundation of a developmental cognitive neuroscience approach to memory development. I then aim to integrate the current evidence from developmental functional neuroimaging studies of memory formation with respect to three hypotheses. First, memory development reflects the development in the use of memory strategies, linked to prefrontal cortex. Second, developmental effects within the medial temporal lobes are more complex, and correspond to current notions about the nature in which the MTL support the formation of memory. Third, neurocognitive changes in content representation influence memory. Open issues and current directions are discussed. PMID:22414608

Ultrabroadband direct detection of nonclassical photon statistics at telecom wavelength.

PubMed

Wakui, Kentaro; Eto, Yujiro; Benichi, Hugo; Izumi, Shuro; Yanagida, Tetsufumi; Ema, Kazuhiro; Numata, Takayuki; Fukuda, Daiji; Takeoka, Masahiro; Sasaki, Masahide

2014-04-03

Broadband light sources play essential roles in diverse fields, such as high-capacity optical communications, optical coherence tomography, optical spectroscopy, and spectrograph calibration. Although a nonclassical state from spontaneous parametric down-conversion may serve as a quantum counterpart, its detection and characterization have been a challenging task. Here we demonstrate the direct detection of photon numbers of an ultrabroadband (110 nm FWHM) squeezed state in the telecom band centred at 1535 nm wavelength, using a superconducting transition-edge sensor. The observed photon-number distributions violate Klyshko's criterion for the nonclassicality. From the observed photon-number distribution, we evaluate the second- and third-order correlation functions, and characterize a multimode structure, which implies that several tens of orthonormal modes of squeezing exist in the single optical pulse. Our results and techniques open up a new possibility to generate and characterize frequency-multiplexed nonclassical light sources for quantum info-communications technology.

Adapting SAFT-γ perturbation theory to site-based molecular dynamics simulation. II. Confined fluids and vapor-liquid interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghobadi, Ahmadreza F.; Elliott, J. Richard, E-mail: elliot1@uakron.edu

2014-07-14

In this work, a new classical density functional theory is developed for group-contribution equations of state (EOS). Details of implementation are demonstrated for the recently-developed SAFT-γ WCA EOS and selective applications are studied for confined fluids and vapor-liquid interfaces. The acronym WCA (Weeks-Chandler-Andersen) refers to the characterization of the reference part of the third-order thermodynamic perturbation theory applied in formulating the EOS. SAFT-γ refers to the particular form of “statistical associating fluid theory” that is applied to the fused-sphere, heteronuclear, united-atom molecular models of interest. For the monomer term, the modified fundamental measure theory is extended to WCA-spheres. A newmore » chain functional is also introduced for fused and soft heteronuclear chains. The attractive interactions are taken into account by considering the structure of the fluid, thus elevating the theory beyond the mean field approximation. The fluctuations of energy are also included via a non-local third-order perturbation theory. The theory includes resolution of the density profiles of individual groups such as CH{sub 2} and CH{sub 3} and satisfies stoichiometric constraints for the density profiles. New molecular simulations are conducted to demonstrate the accuracy of each Helmholtz free energy contribution in reproducing the microstructure of inhomogeneous systems at the united-atom level of coarse graining. At each stage, comparisons are made to assess where the present theory stands relative to the current state of the art for studying inhomogeneous fluids. Overall, it is shown that the characteristic features of real molecular fluids are captured both qualitatively and quantitatively. For example, the average pore density deviates ∼2% from simulation data for attractive pentadecane in a 2-nm slit pore. Another example is the surface tension of ethane/heptane mixture, which deviates ∼1% from simulation data while the theory reproduces the excess accumulation of ethane at the interface.« less

Studies on 2-amino-5-nitropyridinium nitrate (2A5NPN): A semi-organic third order nonlinear optical single crystal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sivasubramani, V.; Pandian, Muthu Senthil, E-mail: senthilpandianm@ssn.edu.in; Ramasamy, P.

2016-05-23

2-amino-5-nitropyridinium nitrate (2A5NPN) is a semi-organic nonlinear optical crystal and optically good quality 2A5NPN single crystals were successfully grown by slow evaporation solution growth technique (SEST) at ambient temperature. The crystallographic structure of the grown crystal was determined by single crystal X-Ray diffraction analysis and it belongs to Monoclinic crystal system with centro symmetric crystalline nature. The crystallinity of the grown crystal was confirmed by powder X-ray diffraction analysis. The other physical properties of grown crystals are also characterized using TG-DTA, UV-Visible NIR, chemical etching, photoconductivity and Z-scan measurements. The Z-scan method reveals that the 2A5NPN crystal possesses multi photonmore » absorption behaviour and the significantly higher third order susceptibility and it is a promising potential NLO material.« less

Link predication based on matrix factorization by fusion of multi class organizations of the network.

PubMed

Jiao, Pengfei; Cai, Fei; Feng, Yiding; Wang, Wenjun

2017-08-21

Link predication aims at forecasting the latent or unobserved edges in the complex networks and has a wide range of applications in reality. Almost existing methods and models only take advantage of one class organization of the networks, which always lose important information hidden in other organizations of the network. In this paper, we propose a link predication framework which makes the best of the structure of networks in different level of organizations based on nonnegative matrix factorization, which is called NMF 3 here. We first map the observed network into another space by kernel functions, which could get the different order organizations. Then we combine the adjacency matrix of the network with one of other organizations, which makes us obtain the objective function of our framework for link predication based on the nonnegative matrix factorization. Third, we derive an iterative algorithm to optimize the objective function, which converges to a local optimum, and we propose a fast optimization strategy for large networks. Lastly, we test the proposed framework based on two kernel functions on a series of real world networks under different sizes of training set, and the experimental results show the feasibility, effectiveness, and competitiveness of the proposed framework.

Probing turbulence with infrared observations in OMC1

NASA Astrophysics Data System (ADS)

Gustafsson, M.; Field, D.; Lemaire, J. L.; Pijpers, F. P.

2006-01-01

A statistical analysis is presented of the turbulent velocity structure in the Orion Molecular Cloud at scales ranging from 70 AU to 3×104 AU. Results are based on IR Fabry-Perot interferometric observations of shock and photon-excited H2 in the K-band S(1) v=1{-}0 line at 2.121 μm and refer to the dynamical characteristics of warm perturbed gas. Data consist of a spatially resolved image with a measured velocity for each resolution limited region (70 AU× 70 AU) in the image. The effect of removal of apparent large scale velocity gradients is discussed and the conclusion drawn that these apparent gradients represent part of the turbulent cascade and should remain within the data. Using our full data set, observations establish that the Larson size-linewidth relation is obeyed to the smallest scales studied here extending the range of validity of this relationship by nearly 2 orders of magnitude. The velocity probability distribution function (PDF) is constructed showing extended exponential wings, providing evidence of intermittency, further supported by the skewness (third moment) and kurtosis (fourth moment) of the velocity distribution. Variance and kurtosis of the PDF of velocity differences are constructed as a function of lag. The variance shows an approximate power law dependence on lag, with exponent significantly lower than the Kolmogorov value, and with deviations below 2000 AU which are attributed to outflows and possibly disk structures associated with low mass star formation within OMC1. The kurtosis shows strong deviation from a Gaussian velocity field, providing evidence of velocity correlations at small lags. Results agree accurately with semi-empirical simulations in Eggers & Wang (1998). In addition, 170 individual H2 emitting clumps have been analysed with sizes between 500 and 2200 AU. These show considerable diversity with regard to PDFs and variance functions (related to second order structure functions) displaying a variety of shapes of the PDF and different values of the scaling exponent within a restricted spatial region. However, a region associated with an outflow from a deeply embedded O-star shows high values of the scaling exponent of the variance function, representing a strong segregation of high and low exponent clumps. Our analysis constitutes the first characterization of the turbulent velocity field at the scale of star formation and provide a dataset which models of star-forming regions should aim to reproduce.

Toward a better understanding of helicopter stability derivatives

NASA Technical Reports Server (NTRS)

Hansen, R. S.

1982-01-01

An amended six degree of freedom helicopter stability and control derivative model was developed in which body acceleration and control rate derivatives were included in the Taylor series expansion. These additional derivatives were derived from consideration of the effects of the higher order rotor flapping dynamics, which are known to be inadequately represented in the conventional six degree of freedom, quasistatic stability derivative model. The amended model was a substantial improvement over the conventional model, effectively doubling the unsable bandwidth and providing a more accurate representation of the short period and cross axis characteristics. Further investigations assessed the applicability of the two stability derivative model structures for flight test parameter identification. Parameters were identified using simulation data generated from a higher order base line model having sixth order rotor tip path plane dynamics. Three lower order models were identified: one using the conventional stability derivative model structure, a second using the amended six degree of freedom model structure, and a third model having eight degrees of freedom that included a simplified rotor tip path plane tilt representation.

Nonlinear guided wave propagation in prestressed plates.

PubMed

Pau, Annamaria; Lanza di Scalea, Francesco

2015-03-01

The measurement of stress in a structure presents considerable interest in many fields of engineering. In this paper, the diagnostic potential of nonlinear elastic guided waves in a prestressed plate is investigated. To do so, an analytical model is formulated accounting for different aspects involved in the phenomenon. The fact that the initial strains can be finite is considered using the Green Lagrange strain tensor, and initial and final configurations are not merged, as it would be assumed in the infinitesimal strain theory. Moreover, an appropriate third-order expression of the strain energy of the hyperelastic body is adopted to account for the material nonlinearities. The model obtained enables to investigate both the linearized case, which gives the variation of phase and group velocity as a function of the initial stress, and the nonlinear case, involving second-harmonic generation as a function of the initial state of stress. The analysis is limited to Rayleigh-Lamb waves propagating in a plate. Three cases of initial prestress are considered, including prestress in the direction of the wave propagation, prestress orthogonal to the direction of wave propagation, and plane isotropic stress.

Exact result in strong wave turbulence of thin elastic plates

NASA Astrophysics Data System (ADS)

Düring, Gustavo; Krstulovic, Giorgio

2018-02-01

An exact result concerning the energy transfers between nonlinear waves of a thin elastic plate is derived. Following Kolmogorov's original ideas in hydrodynamical turbulence, but applied to the Föppl-von Kármán equation for thin plates, the corresponding Kármán-Howarth-Monin relation and an equivalent of the 4/5 -Kolmogorov's law is derived. A third-order structure function involving increments of the amplitude, velocity, and the Airy stress function of a plate, is proven to be equal to -ɛ ℓ , where ℓ is a length scale in the inertial range at which the increments are evaluated and ɛ the energy dissipation rate. Numerical data confirm this law. In addition, a useful definition of the energy fluxes in Fourier space is introduced and proven numerically to be flat in the inertial range. The exact results derived in this Rapid Communication are valid for both weak and strong wave turbulence. They could be used as a theoretical benchmark of new wave-turbulence theories and to develop further analogies with hydrodynamical turbulence.

Nonlinear elastic response of strong solids: First-principles calculations of the third-order elastic constants of diamond

DOE PAGES

Hmiel, A.; Winey, J. M.; Gupta, Y. M.; ...

2016-05-23

Accurate theoretical calculations of the nonlinear elastic response of strong solids (e.g., diamond) constitute a fundamental and important scientific need for understanding the response of such materials and for exploring the potential synthesis and design of novel solids. However, without corresponding experimental data, it is difficult to select between predictions from different theoretical methods. Recently the complete set of third-order elastic constants (TOECs) for diamond was determined experimentally, and the validity of various theoretical approaches to calculate the same may now be assessed. We report on the use of density functional theory (DFT) methods to calculate the six third-order elasticmore » constants of diamond. Two different approaches based on homogeneous deformations were used: (1) an energy-strain fitting approach using a prescribed set of deformations, and (2) a longitudinal stress-strain fitting approach using uniaxial compressive strains along the [100], [110], and [111] directions, together with calculated pressure derivatives of the second-order elastic constants. The latter approach provides a direct comparison to the experimental results. The TOECs calculated using the energy-strain approach differ significantly from the measured TOECs. In contrast, calculations using the longitudinal stress-uniaxial strain approach show good agreement with the measured TOECs and match the experimental values significantly better than the TOECs reported in previous theoretical studies. Lastly, our results on diamond have demonstrated that, with proper analysis procedures, first-principles calculations can indeed be used to accurately calculate the TOECs of strong solids.« less

Symmetry analysis of strain, electric and magnetic fields in the Bi2Se3-class of topological insulators

NASA Astrophysics Data System (ADS)

Rosdahl Brems, Mathias; Paaske, Jens; Lunde, Anders Mathias; Willatzen, Morten

2018-05-01

Based on group theoretical arguments we derive the most general Hamiltonian for the Bi2Se3-class of materials including terms to third order in the wave vector, first order in electric and magnetic fields, first order in strain and first order in both strain and wave vector. We determine analytically the effects of strain on the electronic structure of Bi2Se3. For the most experimentally relevant surface termination we analytically derive the surface state (SS) spectrum, revealing an anisotropic Dirac cone with elliptical constant energy contours giving rise to a direction-dependent group velocity. The spin-momentum locking of strained Bi2Se3 is shown to be modified. Hence, strain control can be used to manipulate the spin degree of freedom via the spin–orbit coupling. We show that for a thin film of Bi2Se3 the SS band gap induced by coupling between the opposite surfaces changes opposite to the bulk band gap under strain. Tuning the SS band gap by strain, gives new possibilities for the experimental investigation of the thickness dependent gap and optimization of optical properties relevant for, e.g., photodetector and energy harvesting applications. We finally derive analytical expressions for the effective mass tensor of the Bi2Se3 class of materials as a function of strain and electric field.

Simulating functional magnetic materials on supercomputers.

PubMed

Gruner, Markus Ernst; Entel, Peter

2009-07-22

The recent passing of the petaflop per second landmark by the Roadrunner project at the Los Alamos National Laboratory marks a preliminary peak of an impressive world-wide development in the high-performance scientific computing sector. Also, purely academic state-of-the-art supercomputers such as the IBM Blue Gene/P at Forschungszentrum Jülich allow us nowadays to investigate large systems of the order of 10(3) spin polarized transition metal atoms by means of density functional theory. Three applications will be presented where large-scale ab initio calculations contribute to the understanding of key properties emerging from a close interrelation between structure and magnetism. The first two examples discuss the size dependent evolution of equilibrium structural motifs in elementary iron and binary Fe-Pt and Co-Pt transition metal nanoparticles, which are currently discussed as promising candidates for ultra-high-density magnetic data storage media. However, the preference for multiply twinned morphologies at smaller cluster sizes counteracts the formation of a single-crystalline L1(0) phase, which alone provides the required hard magnetic properties. The third application is concerned with the magnetic shape memory effect in the Ni-Mn-Ga Heusler alloy, which is a technologically relevant candidate for magnetomechanical actuators and sensors. In this material strains of up to 10% can be induced by external magnetic fields due to the field induced shifting of martensitic twin boundaries, requiring an extremely high mobility of the martensitic twin boundaries, but also the selection of the appropriate martensitic structure from the rich phase diagram.

Z-scan: A simple technique for determination of third-order optical nonlinearity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Vijender, E-mail: chahal-gju@rediffmail.com; Aghamkar, Praveen, E-mail: p-aghamkar@yahoo.co.in

Z-scan is a simple experimental technique to measure intensity dependent nonlinear susceptibilities of third-order nonlinear optical materials. This technique is used to measure the sign and magnitude of both real and imaginary part of the third order nonlinear susceptibility (χ{sup (3)}) of nonlinear optical materials. In this paper, we investigate third-order nonlinear optical properties of Ag-polymer composite film by using single beam z-scan technique with Q-switched, frequency doubled Nd: YAG laser (λ=532 nm) at 5 ns pulse. The values of nonlinear absorption coefficient (β), nonlinear refractive index (n{sub 2}) and third-order nonlinear optical susceptibility (χ{sup (3)}) of permethylazine were found to bemore » 9.64 × 10{sup −7} cm/W, 8.55 × 10{sup −12} cm{sup 2}/W and 5.48 × 10{sup −10} esu, respectively.« less

Embedded-atom-method interatomic potentials from lattice inversion.

PubMed

Yuan, Xiao-Jian; Chen, Nan-Xian; Shen, Jiang; Hu, Wangyu

2010-09-22

The present work develops a physically reliable procedure for building the embedded-atom-method (EAM) interatomic potentials for the metals with fcc, bcc and hcp structures. This is mainly based on Chen-Möbius lattice inversion (Chen et al 1997 Phys. Rev. E 55 R5) and first-principles calculations. Following Baskes (Baskes et al 2007 Phys. Rev. B 75 094113), this new version of the EAM eliminates all of the prior arbitrary choices in the determination of the atomic electron density and pair potential functions. Parameterizing the universal form deduced from the calculations within the density-functional scheme for homogeneous electron gas as the embedding function, the new-type EAM potentials for Cu, Fe and Ti metals have successfully been constructed by considering interatomic interactions up to the fifth neighbor, the third neighbor and the seventh neighbor, respectively. The predictions of elastic constants, structural energy difference, vacancy formation energy and migration energy, activation energy of vacancy diffusion, latent heat of melting and relative volume change on melting all satisfactorily agree with the experimental results available or first-principles calculations. The predicted surface energies for low-index crystal faces and the melting point are in agreement with the experimental data to the same extent as those calculated by other EAM-type potentials such as the FBD-EAM, 2NN MEAM and MS-EAM. In addition, the order among the predicted low-index surface energies is also consistent with the experimental information.

A Systematic Methodology for Constructing High-Order Energy-Stable WENO Schemes

NASA Technical Reports Server (NTRS)

Yamaleev, Nail K.; Carpenter, Mark H.

2008-01-01

A third-order Energy Stable Weighted Essentially Non-Oscillatory (ESWENO) finite difference scheme developed by Yamaleev and Carpenter (AIAA 2008-2876, 2008) was proven to be stable in the energy norm for both continuous and discontinuous solutions of systems of linear hyperbolic equations. Herein, a systematic approach is presented that enables \\energy stable" modifications for existing WENO schemes of any order. The technique is demonstrated by developing a one-parameter family of fifth-order upwind-biased ESWENO schemes; ESWENO schemes up to eighth order are presented in the appendix. New weight functions are also developed that provide (1) formal consistency, (2) much faster convergence for smooth solutions with an arbitrary number of vanishing derivatives, and (3) improved resolution near strong discontinuities.

A Systematic Methodology for Constructing High-Order Energy Stable WENO Schemes

NASA Technical Reports Server (NTRS)

Yamaleev, Nail K.; Carpenter, Mark H.

2009-01-01

A third-order Energy Stable Weighted Essentially Non{Oscillatory (ESWENO) finite difference scheme developed by Yamaleev and Carpenter [1] was proven to be stable in the energy norm for both continuous and discontinuous solutions of systems of linear hyperbolic equations. Herein, a systematic approach is presented that enables "energy stable" modifications for existing WENO schemes of any order. The technique is demonstrated by developing a one-parameter family of fifth-order upwind-biased ESWENO schemes; ESWENO schemes up to eighth order are presented in the appendix. New weight functions are also developed that provide (1) formal consistency, (2) much faster convergence for smooth solutions with an arbitrary number of vanishing derivatives, and (3) improved resolution near strong discontinuities.

Effective quadrature formula in solving linear integro-differential equations of order two

NASA Astrophysics Data System (ADS)

Eshkuvatov, Z. K.; Kammuji, M.; Long, N. M. A. Nik; Yunus, Arif A. M.

2017-08-01

In this note, we solve general form of Fredholm-Volterra integro-differential equations (IDEs) of order 2 with boundary condition approximately and show that proposed method is effective and reliable. Initially, IDEs is reduced into integral equation of the third kind by using standard integration techniques and identity between multiple and single integrals then truncated Legendre series are used to estimate the unknown function. For the kernel integrals, we have applied Gauss-Legendre quadrature formula and collocation points are chosen as the roots of the Legendre polynomials. Finally, reduce the integral equations of the third kind into the system of algebraic equations and Gaussian elimination method is applied to get approximate solutions. Numerical examples and comparisons with other methods reveal that the proposed method is very effective and dominated others in many cases. General theory of existence of the solution is also discussed.

Efficient Third-Order Distributed Feedback Laser with Enhanced Beam Pattern

NASA Technical Reports Server (NTRS)

Hu, Qing (Inventor); Lee, Alan Wei Min (Inventor); Kao, Tsung-Yu (Inventor)

2015-01-01

A third-order distributed feedback laser has an active medium disposed on a substrate as a linear array of segments having a series of periodically spaced interstices therebetween and a first conductive layer disposed on a surface of the active medium on each of the segments and along a strip from each of the segments to a conductive electrical contact pad for application of current along a path including the active medium. Upon application of a current through the active medium, the active medium functions as an optical waveguide, and there is established an alternating electric field, at a THz frequency, both in the active medium and emerging from the interstices. Spacing of adjacent segments is approximately half of a wavelength of the THz frequency in free space or an odd integral multiple thereof, so that the linear array has a coherence length greater than the length of the linear array.

Structural and Functional Evaluations for the Early Detection of Glaucoma.

PubMed

Lucy, Katie A; Wollstein, Gadi

2016-01-01

The early detection of glaucoma is imperative in order to preserve functional vision. Structural and functional methods are utilized to detect and monitor glaucomatous damage and the vision loss it causes. The relationship between these detection measures is complex and differs between individuals, especially in early glaucoma. Using both measures together is advised in order to ensure the highest probability of glaucoma detection, and new testing methods are continuously developed with the goals of earlier disease detection and improvement of disease monitoring. The purpose of this review is to explore the relationship between structural and functional glaucoma detection and discuss important technological advances for early glaucoma detection.

Structural and Functional Evaluations for the Early Detection of Glaucoma

PubMed Central

Lucy, Katie A.; Wollstein, Gadi

2016-01-01

The early detection of glaucoma is imperative in order to preserve functional vision. Structural and functional methods are utilized to detect and monitor glaucomatous damage and the vision loss it causes. The relationship between these detection measures is complex and differs between individuals, especially in early glaucoma. Using both measures together is advised in order to ensure the highest probability of glaucoma detection, and new testing methods are continuously developed with the goals of earlier disease detection and improvement of disease monitoring. The purpose of this review is to explore the relationship between structural and functional glaucoma detection and discuss important technological advances for early glaucoma detection. PMID:28603546

Effects of molecular size and structure on self-diffusion coefficient and viscosity for saturated hydrocarbons having six carbon atoms.

PubMed

Iwahashi, Makio; Kasahara, Yasutoshi

2007-01-01

Self-diffusion coefficients and viscosities for the saturated hydrocarbons having six carbon atoms such as hexane, 2-methylpentane (2MP), 3-methylpentane (3MP), 2,2-dimethylbutane (22DMB), 2,3-dimethylbutane (23DMB), methylcyclopentane (McP) and cyclohexane (cH) were measured at various constant temperatures; obtained results were discussed in connection with their molar volumes, molecular structures and thermodynamic properties. The values of self-diffusion coefficients as the microscopic property were inversely proportional to those of viscosities as the macroscopic property. The order of their viscosities was almost same to those of their melting temperatures and enthalpies of fusion, which reflect the attractive interactions among their molecules. On the other hand, the order of the self-diffusion coefficients inversely related to the order of the melting temperatures and the enthalpies of the fusion. Namely, the compound having the larger attractive interaction mostly shows the less mobility in its liquid state, e.g., cyclohexane (cH), having the largest attractive interaction and the smallest molar volume exhibits an extremely large viscosity and small self-diffusion coefficient comparing with other hydrocarbons. However, a significant exception was 22DMB, being most close to a sphere: In spite of the smallest attractive interaction and the largest molar volume of 22DMB in the all samples, it has the thirdly larger viscosity and the thirdly smaller self-diffusion coefficient. Consequently, the dynamical properties such as self-diffusion and viscosity for the saturated hydrocarbons are determined not only by their attractive interactions but also by their molecular structures.

Ionization of pyridine: Interplay of orbital relaxation and electron correlation.

PubMed

Trofimov, A B; Holland, D M P; Powis, I; Menzies, R C; Potts, A W; Karlsson, L; Gromov, E V; Badsyuk, I L; Schirmer, J

2017-06-28

The valence shell ionization spectrum of pyridine was studied using the third-order algebraic-diagrammatic construction approximation scheme for the one-particle Green's function and the outer-valence Green's function method. The results were used to interpret angle resolved photoelectron spectra recorded with synchrotron radiation in the photon energy range of 17-120 eV. The lowest four states of the pyridine radical cation, namely, 2 A 2 (1a 2 -1 ), 2 A 1 (7a 1 -1 ), 2 B 1 (2b 1 -1 ), and 2 B 2 (5b 2 -1 ), were studied in detail using various high-level electronic structure calculation methods. The vertical ionization energies were established using the equation-of-motion coupled-cluster approach with single, double, and triple excitations (EOM-IP-CCSDT) and the complete basis set extrapolation technique. Further interpretation of the electronic structure results was accomplished using Dyson orbitals, electron density difference plots, and a second-order perturbation theory treatment for the relaxation energy. Strong orbital relaxation and electron correlation effects were shown to accompany ionization of the 7a 1 orbital, which formally represents the nonbonding σ-type nitrogen lone-pair (nσ) orbital. The theoretical work establishes the important roles of the π-system (π-π* excitations) in the screening of the nσ-hole and of the relaxation of the molecular orbitals in the formation of the 7a 1 (nσ) -1 state. Equilibrium geometric parameters were computed using the MP2 (second-order Møller-Plesset perturbation theory) and CCSD methods, and the harmonic vibrational frequencies were obtained at the MP2 level of theory for the lowest three cation states. The results were used to estimate the adiabatic 0-0 ionization energies, which were then compared to the available experimental and theoretical data. Photoelectron anisotropy parameters and photoionization partial cross sections, derived from the experimental spectra, were compared to predictions obtained with the continuum multiple scattering approach.

Parabolic quantitative structure-activity relationships and photodynamic therapy: application of a three-compartment model with clearance to the in vivo quantitative structure-activity relationships of a congeneric series of pyropheophorbide derivatives used as photosensitizers for photodynamic therapy.

PubMed

Potter, W R; Henderson, B W; Bellnier, D A; Pandey, R K; Vaughan, L A; Weishaupt, K R; Dougherty, T J

1999-11-01

An open three-compartment pharmacokinetic model was applied to the in vivo quantitative structure-activity relationship (QSAR) data of a homologous series of pyropheophorbide photosensitizers for photodynamic therapy (PDT). The physical model was a lipid compartment sandwiched between two identical aqueous compartments. The first compartment was assumed to clear irreversibly at a rate K0. The measured octanol-water partition coefficients, P(i) (where i is the number of carbons in the alkyl chain) and the clearance rate K0 determined the clearance kinetics of the drugs. Solving the coupled differential equations of the three-compartment model produced clearance kinetics for each of the sensitizers in each of the compartments. The third compartment was found to contain the target of PDT. This series of compounds is quite lipophilic. Therefore these drugs are found mainly in the second compartment. The drug level in the third compartment represents a small fraction of the tissue level and is thus not accessible to direct measurement by extraction. The second compartment of the model accurately predicted the clearance from the serum of mice of the hexyl ether of pyropheophorbide a, one member of this series of compounds. The diffusion and clearance rate constants were those found by fitting the pharmacokinetics of the third compartment to the QSAR data. This result validated the magnitude and mechanistic significance of the rate constants used to model the QSAR data. The PDT response to dose theory was applied to the kinetic behavior of the target compartment drug concentration. This produced a pharmacokinetic-based function connecting PDT response to dose as a function of time postinjection. This mechanistic dose-response function was fitted to published, single time point QSAR data for the pheophorbides. As a result, the PDT target threshold dose together with the predicted QSAR as a function of time postinjection was found.

Omnipresence of the polyproline II helix in fibrous and globular proteins.

PubMed

Esipova, Natalia G; Tumanyan, Vladimir G

2017-02-01

Left-handed helical conformation of a polypeptide chain (PPII) is the third type of the protein backbone structure. This conformation universally exists in fibrous, globular proteins, and biologically active peptides. It has unique physical and chemical properties determining a wide range of biological functions, from the protein folding to the tissue differentiation. New examples of the structure have been appearing in spite of difficulties in their detection and investigation. The annotation and prediction of the PPII was also a challenging task. Recently, many PPII motifs with new and/or unexpected functions are being accumulated in databases. In this review we describe the major structural and dynamic forms of PPII, the diversity of its functions, and the role in different biological processes. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Formula: see text]Executive functions and social information processing in adolescents with severe behavior problems.

PubMed

Van Nieuwenhuijzen, M; Van Rest, M M; Embregts, P J C M; Vriens, A; Oostermeijer, S; Van Bokhoven, I; Matthys, W

2017-02-01

One tradition in research for explaining aggression and antisocial behavior has focused on social information processing (SIP). Aggression and antisocial behavior have also been studied from the perspective of executive functions (EFs), the higher-order cognitive abilities that affect other cognitive processes, such as social cognitive processes. The main goal of the present study is to provide insight into the relation between EFs and SIP in adolescents with severe behavior problems. Because of the hierarchical relation between EFs and SIP, we examined EFs as predictors of SIP. We hypothesized that, first, focused attention predicts encoding and interpretation, second, inhibition predicts interpretation, response generation, evaluation, and selection, and third, working memory predicts response generation and selection. The participants consisted of 94 respondents living in residential facilities aged 12-20 years, all showing behavior problems in the clinical range according to care staff. EFs were assessed using subtests from the Amsterdam Neuropsychological Test battery. Focused attention was measured by the Flanker task, inhibition by the GoNoGo task, and working memory by the Visual Spatial Sequencing task. SIP was measured by video vignettes and a structured interview. The results indicate that positive evaluation of aggressive responses is predicted by impaired inhibition and selection of aggressive responses by a combination of impaired focused attention and inhibition. It is concluded that different components of EFs as higher-order cognitive abilities affect SIP.

On the Mathematical Modeling of Single and Multiple Scattering of Ultrasonic Guided Waves by Small Scatterers: A Structural Health Monitoring Measurement Model

NASA Astrophysics Data System (ADS)

Strom, Brandon William

In an effort to assist in the paradigm shift from schedule based maintenance to conditioned based maintenance, we derive measurement models to be used within structural health monitoring algorithms. Our models are physics based, and use scattered Lamb waves to detect and quantify pitting corrosion. After covering the basics of Lamb waves and the reciprocity theorem, we develop a technique for the scattered wave solution. The first application is two-dimensional, and is employed in two different ways. The first approach integrates a traction distribution and replaces it by an equivalent force. The second approach is higher order and uses the actual traction distribution. We find that the equivalent force version of the solution technique holds well for small pits at low frequencies. The second application is three-dimensional. The equivalent force caused by the scattered wave of an arbitrary equivalent force is calculated. We obtain functions for the scattered wave displacements as a function of equivalent forces, equivalent forces as a function of incident wave, and scattered wave amplitudes as a function of incident amplitude. The third application uses self-consistency to derive governing equations for the scattered waves due to multiple corrosion pits. We decouple the implicit set of equations and solve explicitly by using a recursive series solution. Alternatively, we solve via an undetermined coefficient method which results in an interaction operator and solution via matrix inversion. The general solution is given for N pits including mode conversion. We show that the two approaches are equivalent, and give a solution for three pits. Various approximations are advanced to simplify the problem while retaining the leading order physics. As a final application, we use the multiple scattering model to investigate resonance of Lamb waves. We begin with a one-dimensional problem and progress to a three-dimensional problem. A directed graph enables interpretation of the interaction operator, and we show that a series solution converges due to loss of energy in the system. We see that there are four causes of resonance and plot the modulation depth as a function of spacing between the pits.

Structural and Histone Binding Ability Characterizations of Human PWWP Domains

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Hong; Zeng, Hong; Lam, Robert

2013-09-25

The PWWP domain was first identified as a structural motif of 100-130 amino acids in the WHSC1 protein and predicted to be a protein-protein interaction domain. It belongs to the Tudor domain 'Royal Family', which consists of Tudor, chromodomain, MBT and PWWP domains. While Tudor, chromodomain and MBT domains have long been known to bind methylated histones, PWWP was shown to exhibit histone binding ability only until recently. The PWWP domain has been shown to be a DNA binding domain, but sequence analysis and previous structural studies show that the PWWP domain exhibits significant similarity to other 'Royal Family' members,more » implying that the PWWP domain has the potential to bind histones. In order to further explore the function of the PWWP domain, we used the protein family approach to determine the crystal structures of the PWWP domains from seven different human proteins. Our fluorescence polarization binding studies show that PWWP domains have weak histone binding ability, which is also confirmed by our NMR titration experiments. Furthermore, we determined the crystal structures of the BRPF1 PWWP domain in complex with H3K36me3, and HDGF2 PWWP domain in complex with H3K79me3 and H4K20me3. PWWP proteins constitute a new family of methyl lysine histone binders. The PWWP domain consists of three motifs: a canonical {beta}-barrel core, an insertion motif between the second and third {beta}-strands and a C-terminal {alpha}-helix bundle. Both the canonical {beta}-barrel core and the insertion motif are directly involved in histone binding. The PWWP domain has been previously shown to be a DNA binding domain. Therefore, the PWWP domain exhibits dual functions: binding both DNA and methyllysine histones.« less

37 CFR 1.948 - Limitations on submission of prior art by third party requester following the order for inter...

Code of Federal Regulations, 2011 CFR

2011-07-01

... prior art by third party requester following the order for inter partes reexamination. 1.948 Section 1... Responses (before the Examiner) in Inter Partes Reexamination § 1.948 Limitations on submission of prior art... partes reexamination order, the third party requester may only cite additional prior art as defined under...

37 CFR 1.948 - Limitations on submission of prior art by third party requester following the order for inter...

Code of Federal Regulations, 2010 CFR

2010-07-01

... prior art by third party requester following the order for inter partes reexamination. 1.948 Section 1... Responses (before the Examiner) in Inter Partes Reexamination § 1.948 Limitations on submission of prior art... partes reexamination order, the third party requester may only cite additional prior art as defined under...

76 FR 45513 - Fresh and Chilled Atlantic Salmon From Norway: Preliminary Results of Full Third Sunset Review of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-29

... Salmon From Norway: Preliminary Results of Full Third Sunset Review of Antidumping Duty Order AGENCY...) order on fresh and chilled Atlantic salmon from Norway pursuant to section 751(c) of the Tariff Act of..., the Department initiated the third sunset review of the AD order on fresh and chilled Atlantic salmon...

High order methods for the integration of the Bateman equations and other problems of the form of y‧ = F(y,t)y

NASA Astrophysics Data System (ADS)

Josey, C.; Forget, B.; Smith, K.

2017-12-01

This paper introduces two families of A-stable algorithms for the integration of y‧ = F (y , t) y: the extended predictor-corrector (EPC) and the exponential-linear (EL) methods. The structure of the algorithm families are described, and the method of derivation of the coefficients presented. The new algorithms are then tested on a simple deterministic problem and a Monte Carlo isotopic evolution problem. The EPC family is shown to be only second order for systems of ODEs. However, the EPC-RK45 algorithm had the highest accuracy on the Monte Carlo test, requiring at least a factor of 2 fewer function evaluations to achieve a given accuracy than a second order predictor-corrector method (center extrapolation / center midpoint method) with regards to Gd-157 concentration. Members of the EL family can be derived to at least fourth order. The EL3 and the EL4 algorithms presented are shown to be third and fourth order respectively on the systems of ODE test. In the Monte Carlo test, these methods did not overtake the accuracy of EPC methods before statistical uncertainty dominated the error. The statistical properties of the algorithms were also analyzed during the Monte Carlo problem. The new methods are shown to yield smaller standard deviations on final quantities as compared to the reference predictor-corrector method, by up to a factor of 1.4.

X-ray Diffraction Study of Aluminum Carbide Powder to 50 GPa

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ji, C.; Ma, Y; Chyu, M

2009-01-01

The crystal structure and equation of state (EOS) of aluminum carbide (Al{sub 4}C{sub 3}) have been determined directly up to 50.1 GPa at room temperature by the synchrotron x-ray diffraction techniques. The results indicate that Al{sub 4}C{sub 3} remained in rhombohedral structure under all tested pressure-temperature conditions and exhibited anisotropic compressibility, with the c-axis more compressible than the a-axis. Fitting the experimental data to third order Birch-Murnaghan EOS yields a bulk modulus of K{sub OT} = 233 {+-} 6 GPa with its pressure derivative K{sub OT}{prime} = 3.4 {+-} 0.4, while the second-order EOS yields K{sub OT} = 223 {+-}more » 2 GPa.« less

Structure of Lie point and variational symmetry algebras for a class of odes

NASA Astrophysics Data System (ADS)

Ndogmo, J. C.

2018-04-01

It is known for scalar ordinary differential equations, and for systems of ordinary differential equations of order not higher than the third, that their Lie point symmetry algebras is of maximal dimension if and only if they can be reduced by a point transformation to the trivial equation y(n)=0. For arbitrary systems of ordinary differential equations of order n ≥ 3 reducible by point transformations to the trivial equation, we determine the complete structure of their Lie point symmetry algebras as well as that for their variational, and their divergence symmetry algebras. As a corollary, we obtain the maximal dimension of the Lie point symmetry algebra for any system of linear or nonlinear ordinary differential equations.

The analysis of harmonic generation coefficients in the ablative Rayleigh-Taylor instability

NASA Astrophysics Data System (ADS)

Lu, Yan; Fan, Zhengfeng; Lu, Xinpei; Ye, Wenhua; Zou, Changlin; Zhang, Ziyun; Zhang, Wen

2017-10-01

In this research, we use the numerical simulation method to investigate the generation coefficients of the first three harmonics and the zeroth harmonic in the Ablative Rayleigh-Taylor Instability. It is shown that the interface shifts to the low temperature side during the ablation process. In consideration of the third-order perturbation theory, the first three harmonic amplitudes of the weakly nonlinear regime are calculated and then the harmonic generation coefficients are obtained by curve fitting. The simulation results show that the harmonic generation coefficients changed with time and wavelength. Using the higher-order perturbation theory, we find that more and more harmonics are generated in the later weakly nonlinear stage, which is caused by the negative feedback of the later higher harmonics. Furthermore, extending the third-order theory to the fifth-order theory, we find that the second and the third harmonics coefficients linearly depend on the wavelength, while the feedback coefficients are almost constant. Further analysis also shows that when the fifth-order theory is considered, the normalized effective amplitudes of second and third harmonics can reach about 25%-40%, which are only 15%-25% in the frame of the previous third-order theory. Therefore, the third order perturbation theory is needed to be modified by the higher-order theory when ηL reaches about 20% of the perturbation wavelength.

Potential Energy Surface of the Chromium Dimer Re-re-revisited with Multiconfigurational Perturbation Theory.

PubMed

Vancoillie, Steven; Malmqvist, Per Åke; Veryazov, Valera

2016-04-12

The chromium dimer has long been a benchmark molecule to evaluate the performance of different computational methods ranging from density functional theory to wave function methods. Among the latter, multiconfigurational perturbation theory was shown to be able to reproduce the potential energy surface of the chromium dimer accurately. However, for modest active space sizes, it was later shown that different definitions of the zeroth-order Hamiltonian have a large impact on the results. In this work, we revisit the system for the third time with multiconfigurational perturbation theory, now in order to increase the active space of the reference wave function. This reduces the impact of the choice of zeroth-order Hamiltonian and improves the shape of the potential energy surface significantly. We conclude by comparing our results of the dissocation energy and vibrational spectrum to those obtained from several highly accurate multiconfigurational methods and experiment. For a meaningful comparison, we used the extrapolation to the complete basis set for all methods involved.

Is intramedullary nailing more effective than non-operative treatment in adults with displaced middle-third clavicle fractures?

PubMed

Hill, Christopher Edward

2014-09-01

Clavicle fractures are common, accounting for 5-12 % of all fractures. Traditionally, displaced middle-third clavicle fractures have been managed non-operatively but the associated displacement often leads to mal-union with shortening, cosmetic deformity and occasionally non-union, with clinicians looking towards alternative operative methods such as intramedullary nailing (IMN). However, such methods have their own complications. In order to ascertain the effectiveness of IMN in the management of middle-third clavicle fractures compared with non-operative treatment, analysis of recent evidence is required and this review aims to achieve that, focusing on relevant, contemporary randomised-control trials. Essential search-terms identified from the research question were used to formulate a search strategy. A systematic search of multiple databases was then performed from 1966 until present and appropriate papers for appraisal identified. Thirteen papers were identified, with 10 excluded using appropriate eligibility criteria. The remaining papers were then critically appraised. With regards shoulder function, all papers demonstrated an association between IMN and a significantly (P < 0.05) superior shoulder function score, but no consensus with regards to complication rates. However, all have identified limitations; therefore, their overall findings must be considered conservatively. Further, high-quality research, ideally in the form of well-designed, multi-centre RCTs is required to allow acceptable implementation of IMN of middle-third clavicle fractures into widespread practice. However, early results demonstrate that in young patients with displaced middle-third clavicle fractures, who are motivated to return to work, IMN provides superior functional results and should be considered. However, the importance of considering each patient individually as to their suitability for each management option, before coming to an informed decision with the patient rather than having a blanket approach to MTCF is essential. Level 1.

Probing the self-assembled nanostructures of functional polymers with synchrotron grazing incidence X-ray scattering.

PubMed

Ree, Moonhor

2014-05-01

For advanced functional polymers such as biopolymers, biomimic polymers, brush polymers, star polymers, dendritic polymers, and block copolymers, information about their surface structures, morphologies, and atomic structures is essential for understanding their properties and investigating their potential applications. Grazing incidence X-ray scattering (GIXS) is established for the last 15 years as the most powerful, versatile, and nondestructive tool for determining these structural details when performed with the aid of an advanced third-generation synchrotron radiation source with high flux, high energy resolution, energy tunability, and small beam size. One particular merit of this technique is that GIXS data can be obtained facilely for material specimens of any size, type, or shape. However, GIXS data analysis requires an understanding of GIXS theory and of refraction and reflection effects, and for any given material specimen, the best methods for extracting the form factor and the structure factor from the data need to be established. GIXS theory is reviewed here from the perspective of practical GIXS measurements and quantitative data analysis. In addition, schemes are discussed for the detailed analysis of GIXS data for the various self-assembled nanostructures of functional homopolymers, brush, star, and dendritic polymers, and block copolymers. Moreover, enhancements to the GIXS technique are discussed that can significantly improve its structure analysis by using the new synchrotron radiation sources such as third-generation X-ray sources with picosecond pulses and partial coherence and fourth-generation X-ray laser sources with femtosecond pulses and full coherence. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Theoretical and experimental evaluation of a new organic proton transfer crystal aminoguanidinium p-nitrobenzoate monohydrate for optical limiting applications

NASA Astrophysics Data System (ADS)

Shanmugavadivu, T.; Senthilkumar, K.; Dhandapani, M.; Muthuraja, P.; Balachandar, S.; Sethu Raman, M.

2017-12-01

Aminoguanidinium p-nitrobenzoate monohydrate (AGPNB), an organic third order nonlinear crystal, was successfully grown by the slow evaporation technique. Single crystal XRD analysis reveals that the grown crystal belongs to monoclinic system with P21/n space group. FT-IR, 1H and 13C NMR spectroscopic studies were carried out to confirm the proton transfer. Optical and thermal suitability were assessed by UV-NIR and TG-DTA studies. Hirshfeld surface analysis predicts that the O⋯H/H⋯O interactions dominated over the crystal structure. Third order nonlinearity was studied by Z-scan analysis and it is found that AGPNB can be used as a reverse satuarble absorption (RSA) based optical limiter at 632.8 nm. Computational studies, such as geometry optimization, Natural bond orbital (NBO) analysis, Mulliken population analysis and Molecular electrostatic potential (MEP) were performed at B3LYP/6-311G(d,p) level of theory. The calculated first order hyperpolarizability of AGPNB is found to be 35 times that of urea.

DFTB3: Extension of the self-consistent-charge density-functional tight-binding method (SCC-DFTB).

PubMed

Gaus, Michael; Cui, Qiang; Elstner, Marcus

2012-04-10

The self-consistent-charge density-functional tight-binding method (SCC-DFTB) is an approximate quantum chemical method derived from density functional theory (DFT) based on a second-order expansion of the DFT total energy around a reference density. In the present study we combine earlier extensions and improve them consistently with, first, an improved Coulomb interaction between atomic partial charges, and second, the complete third-order expansion of the DFT total energy. These modifications lead us to the next generation of the DFTB methodology called DFTB3, which substantially improves the description of charged systems containing elements C, H, N, O, and P, especially regarding hydrogen binding energies and proton affinities. As a result, DFTB3 is particularly applicable to biomolecular systems. Remaining challenges and possible solutions are also briefly discussed.

Quasiparticle interference in multiband superconductors with strong coupling

NASA Astrophysics Data System (ADS)

Dutt, A.; Golubov, A. A.; Dolgov, O. V.; Efremov, D. V.

2017-08-01

We develop a theory of the quasiparticle interference (QPI) in multiband superconductors based on the strong-coupling Eliashberg approach within the Born approximation. In the framework of this theory, we study dependencies of the QPI response function in the multiband superconductors with the nodeless s -wave superconductive order parameter. We pay special attention to the difference in the quasiparticle scattering between the bands having the same and opposite signs of the order parameter. We show that at the momentum values close to the momentum transfer between two bands, the energy dependence of the quasiparticle interference response function has three singularities. Two of these correspond to the values of the gap functions and the third one depends on both the gaps and the transfer momentum. We argue that only the singularity near the smallest band gap may be used as a universal tool to distinguish between the s++ and s± order parameters. The robustness of the sign of the response function peak near the smaller gap value, irrespective of the change in parameters, in both the symmetry cases is a promising feature that can be harnessed experimentally.

Effects of specific surface area of metallic nickel particles on carbon deposition kinetics

NASA Astrophysics Data System (ADS)

Chen, Zhi-yuan; Bian, Liu-zhen; Yu, Zi-you; Wang, Li-jun; Li, Fu-shen; Chou, Kuo-Chih

2018-02-01

Carbon deposition on nickel powders in methane involves three stages in different reaction temperature ranges. Temperature programing oxidation test and Raman spectrum results indicated the formation of complex and ordered carbon structures at high deposition temperatures. The values of I(D)/ I(G) of the deposited carbon reached 1.86, 1.30, and 1.22 in the first, second, and third stages, respectively. The structure of carbon in the second stage was similar to that in the third stage. Carbon deposited in the first stage rarely contained homogeneous pyrolytic deposit layers. A kinetic model was developed to analyze the carbon deposition behavior in the first stage. The rate-determining step of the first stage is supposed to be interfacial reaction. Based on the investigation of carbon deposition kinetics on nickel powders from different resources, carbon deposition rate is suggested to have a linear relation with the square of specific surface area of nickel particles.

Flow through very porous screens

NASA Technical Reports Server (NTRS)

Durbin, P. A.; Muramoto, K. K.

1985-01-01

Flow through and around screens with small resistance coefficient were analyzed. Both steady and oscillatory flows are considered, however, the case of a screen normal to the flow is treated. At second order in the asymptotic expansion the steady flow normal to the screen is nonuniform along the screen, due to components induced by the wake and by tangential drag. The third order pressure drop is nonuniform and the wake contains distributed vorticity, in addition to the vortex sheet along its boundary. The unsteady drag coefficient is found as a function of frequency.

Numerical method based on the lattice Boltzmann model for the Fisher equation.

PubMed

Yan, Guangwu; Zhang, Jianying; Dong, Yinfeng

2008-06-01

In this paper, a lattice Boltzmann model for the Fisher equation is proposed. First, the Chapman-Enskog expansion and the multiscale time expansion are used to describe higher-order moment of equilibrium distribution functions and a series of partial differential equations in different time scales. Second, the modified partial differential equation of the Fisher equation with the higher-order truncation error is obtained. Third, comparison between numerical results of the lattice Boltzmann models and exact solution is given. The numerical results agree well with the classical ones.

Nonlinear Viscoelastic Analysis of Orthotropic Beams Using a General Third-Order Theory

DTIC Science & Technology

2012-06-20

Kirchhoff stress tensor, denoted by r and reduced strain tensor E e is given by rxx rzz rxz 8><>: 9>=>;¼ Q11ð0Þ Q13ð0Þ 0 Q13ð0Þ Q33ð0Þ 0 0 0 Q55ð0Þ...0.5 1 −0.5 0 0.5 1 (a) (b) Fig. 1. Graphs of (a) equi-spaced and (b) spectral lagrange interpolation functions for polynomial order of p = 11. 3762 V

Weakly nonlinear incompressible Rayleigh-Taylor instability in spherical geometry

NASA Astrophysics Data System (ADS)

Zhang, J.; Wang, L. F.; Ye, W. H.; Wu, J. F.; Guo, H. Y.; Zhang, W. Y.; He, X. T.

2017-06-01

In this research, a weakly nonlinear (WN) model for the incompressible Rayleigh-Taylor instability in cylindrical geometry [Wang et al., Phys. Plasmas 20, 042708 (2013)] is generalized to spherical geometry. The evolution of the interface with an initial small-amplitude single-mode perturbation in the form of Legendre mode (Pn) is analysed with the third-order WN solutions. The transition of the small-amplitude perturbed spherical interface to the bubble-and-spike structure can be observed by our model. For single-mode perturbation Pn, besides the generation of P 2 n and P 3 n , which are similar to the second and third harmonics in planar and cylindrical geometries, many other modes in the range of P0- P 3 n are generated by mode-coupling effects up to the third order. With the same initial amplitude, the bubbles at the pole grow faster than those at the equator in the WN regime. Furthermore, it is found that the behavior of the bubbles at the pole is similar to that of three-dimensional axisymmetric bubbles, while the behavior of the bubbles at the equator is similar to that of two-dimensional bubbles.

Higher order alchemical derivatives from coupled perturbed self-consistent field theory.

PubMed

Lesiuk, Michał; Balawender, Robert; Zachara, Janusz

2012-01-21

We present an analytical approach to treat higher order derivatives of Hartree-Fock (HF) and Kohn-Sham (KS) density functional theory energy in the Born-Oppenheimer approximation with respect to the nuclear charge distribution (so-called alchemical derivatives). Modified coupled perturbed self-consistent field theory is used to calculate molecular systems response to the applied perturbation. Working equations for the second and the third derivatives of HF/KS energy are derived. Similarly, analytical forms of the first and second derivatives of orbital energies are reported. The second derivative of Kohn-Sham energy and up to the third derivative of Hartree-Fock energy with respect to the nuclear charge distribution were calculated. Some issues of practical calculations, in particular the dependence of the basis set and Becke weighting functions on the perturbation, are considered. For selected series of isoelectronic molecules values of available alchemical derivatives were computed and Taylor series expansion was used to predict energies of the "surrounding" molecules. Predicted values of energies are in unexpectedly good agreement with the ones computed using HF/KS methods. Presented method allows one to predict orbital energies with the error less than 1% or even smaller for valence orbitals. © 2012 American Institute of Physics

Crystal growth, spectroscopic, DFT computational and third harmonic generation studies of nicotinic acid

NASA Astrophysics Data System (ADS)

Thaya Kumari, C. Rathika; Nageshwari, M.; Raman, R. Ganapathi; Caroline, M. Lydia

2018-07-01

An organic centrosymmetric nicotinic acid (NA) single crystal has been grown employing slow evaporation method in water. NA crystallizes in monoclinic system with centric space group P21/C. The experimental and theoretical investigation includes vibrational spectra based on Hartree - Fock (HF) and density functional theory (DFT) has been applied using different function at B3LYP level of theory using 6-311G++(d,p) basis set. The optical transparency of the title molecule was examined by TD- DFT analysis and for comparison basis experimental UV-Vis spectrum was recorded. The interaction of charge within the molecule was analyzed and the HOMO - LUMO energy gap was evaluated. The value of dipole moment, Mulliken charge and molecular electrostatic potential were estimated at the same level of theory. Also the first order hyper polarizability for NA was calculated. The dielectric behavior of the grown crystal was determined for few selected temperatures. The third order nonlinear response of NA has been examined using Z-scan technique and nonlinear susceptibility (χ3), nonlinear refraction (n2) and nonlinear absorption coefficient (β) has been calculated. The current results clearly indicate that the title compound is an excellent applicant in the domain of opto - electronic applications.

A new third-order sequence stratigraphic framework applied to the Triassic of the Paraná Basin, Rio Grande do Sul, Brazil, based on structural, stratigraphic and paleontological data

NASA Astrophysics Data System (ADS)

Horn, B. L. D.; Melo, T. M.; Schultz, C. L.; Philipp, R. P.; Kloss, H. P.; Goldberg, K.

2014-11-01

The Santacruzodon assemblage zone was originally defined as a vertebrate fossil assemblage composed basically of non-mammalian cynodonts found in Santa Cruz do Sul and Venâncio Aires municipalities in Southern Brazil. This assemblage zone was positioned at the top of the Sequence I, in the Triassic Santa Maria Supersequence, Paraná Basin. However, the Santacruzodon assemblage zone does not occur across the entire area of the Santa Maria Supersequence. Based on new paleontological, structural and sedimentological data, we propose the existence of a new third-order sequence (Santa Cruz Sequence) between Sequences I and II in the Santa Maria Supersequence. Satellite image analysis was used to identify regional, NW- and NE-oriented lineaments that limit the occurrence zone. Outcrop data allowed the identification of a regional, angular unconformity that bounds the new sequence. The faunal content allowed the correlation of the new Santa Cruz Sequence with Madagascar's Isalo II fauna, corresponding to the Ladinian (Middle Triassic). New names were suggested for the sequences in the Santa Maria Supersequence, since the Santa Cruz Sequence was deposited between the former Sequences I and II. This unit was deposited or preserved exclusively on the hanging wall of normal faults, being absent from the adjacent structural blocks.

Endodontic management of mandibular third molar with three mesial roots using spiral computed tomography scan as a diagnostic aid: a case report.

PubMed

Tomar, Deepak; Dhingra, Anil; Tomer, Anil; Sharma, Shalini; Sharma, Vivek; Miglani, Anjali

2013-05-01

Aberrant root canal anatomy is diagnostically and clinically challenging for clinicians. The most common root canal configuration of human molars is 2 roots and 3 canals, but various combinations may still exist. Third molars are known to have the most unusual anatomy among human teeth. Restorative, prosthetic, and orthodontic considerations often require endodontic treatment of third molars in order for them to be retained as functional components of the dental arch. The present case report demonstrates unusual root canal morphology of the mandibular third molar. Roentgenographic examination, which included spiral CT scan, revealed 3 separate mesial roots in tooth #48 with 3 independent canals and 3 canal orifices, indicating an endodontic rarity. The present case report puts impetus on exploration of additional canals using advanced diagnostic aids, such as spiral computed tomography, which can have a huge impact on the successful outcome of endodontic therapy. Copyright © 2013 Elsevier Inc. All rights reserved.

An approach to multiscale modelling with graph grammars.

PubMed

Ong, Yongzhi; Streit, Katarína; Henke, Michael; Kurth, Winfried

2014-09-01

Functional-structural plant models (FSPMs) simulate biological processes at different spatial scales. Methods exist for multiscale data representation and modification, but the advantages of using multiple scales in the dynamic aspects of FSPMs remain unclear. Results from multiscale models in various other areas of science that share fundamental modelling issues with FSPMs suggest that potential advantages do exist, and this study therefore aims to introduce an approach to multiscale modelling in FSPMs. A three-part graph data structure and grammar is revisited, and presented with a conceptual framework for multiscale modelling. The framework is used for identifying roles, categorizing and describing scale-to-scale interactions, thus allowing alternative approaches to model development as opposed to correlation-based modelling at a single scale. Reverse information flow (from macro- to micro-scale) is catered for in the framework. The methods are implemented within the programming language XL. Three example models are implemented using the proposed multiscale graph model and framework. The first illustrates the fundamental usage of the graph data structure and grammar, the second uses probabilistic modelling for organs at the fine scale in order to derive crown growth, and the third combines multiscale plant topology with ozone trends and metabolic network simulations in order to model juvenile beech stands under exposure to a toxic trace gas. The graph data structure supports data representation and grammar operations at multiple scales. The results demonstrate that multiscale modelling is a viable method in FSPM and an alternative to correlation-based modelling. Advantages and disadvantages of multiscale modelling are illustrated by comparisons with single-scale implementations, leading to motivations for further research in sensitivity analysis and run-time efficiency for these models.

Analysis of nodal aberration properties in off-axis freeform system design.

PubMed

Shi, Haodong; Jiang, Huilin; Zhang, Xin; Wang, Chao; Liu, Tao

2016-08-20

Freeform surfaces have the advantage of balancing off-axis aberration. In this paper, based on the framework of nodal aberration theory (NAT) applied to the coaxial system, the third-order astigmatism and coma wave aberration expressions of an off-axis system with Zernike polynomial surfaces are derived. The relationship between the off-axis and surface shape acting on the nodal distributions is revealed. The nodal aberration properties of the off-axis freeform system are analyzed and validated by using full-field displays (FFDs). It has been demonstrated that adding Zernike terms, up to nine, to the off-axis system modifies the nodal locations, but the field dependence of the third-order aberration does not change. On this basis, an off-axis two-mirror freeform system with 500 mm effective focal length (EFL) and 300 mm entrance pupil diameter (EPD) working in long-wave infrared is designed. The field constant aberrations induced by surface tilting are corrected by selecting specific Zernike terms. The design results show that the nodes of third-order astigmatism and coma move back into the field of view (FOV). The modulation transfer function (MTF) curves are above 0.4 at 20 line pairs per millimeter (lp/mm) which meets the infrared reconnaissance requirement. This work provides essential insight and guidance for aberration correction in off-axis freeform system design.

Bulk crystal growth and their effective third order nonlinear optical properties of 2-(4-fluorobenzylidene) malononitrile (FBM) single crystal

NASA Astrophysics Data System (ADS)

Priyadharshini, A.; Kalainathan, S.

2018-04-01

2-(4-fluorobenzylidene) malononitrile (FBM), an organic third order nonlinear (TONLO) single crystal with the dimensions of 32 × 7 × 11 mm3, has been successfully grown in acetone solution by slow evaporation technique at 35 °C. The crystal system (triclinic), space group (P-1) and crystalline purity of the titular crystal were measured by single crystal and powder X-ray diffraction, respectively. The molecular weight and the multiple functional groups of the FBM material were confirmed through the mass and FT-IR spectral analysis. UV-Vis-NIR spectral study enroles that the FBM crystal exhibits excellent transparency (83%) in the entire visible and near infra-red region with a wide bandgap 2.90 eV. The low dielectric constant (εr) value of FBM crystal is appreciable for microelectronics industry applications. Thermal stability and melting point (130.09 °C) were ascertained by TGA-DSC analysis. The laser-induced surface damage threshold (LDT) value of FBM specimen is found to be 2.14 GW/cm2, it is fairly good compared to other reported NLO crystals. The third - order nonlinear optical character of the FBM crystal was confirmed through the typical single beam Z-scan technique. All these finding authorized that the organic crystal of FBM is favorably suitable for NLO applications.

Growth and characterization of a third order nonlinear optical single crystal: Ethylenediamine-4-nitrophenolate monohydrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dhanalakshmi, B.; Ponnusamy, S., E-mail: suruponnus@gmail.com; Muthamizhchelvan, C.

2015-10-15

Highlights: • EDA4NPH crystal possesses negative nonlinear refractive index. • The crystal exhibits high third-order NLO susceptibility. • Wide transparency of the crystal makes it suitable for NLO applications. • Dielectric studies substantiate the suitability for electro-optic applications. • The crystal possesses suitable mechanical strength for device fabrication. - Abstract: Bulk crystals of the charge-transfer complex, ethylenediamine-4-nitrophenolate monohydrate, were grown by slow solvent evaporation method from aqueous solution at room temperature. The X-ray diffraction measurements showed that the crystal belongs to centrosymmetric space group C2/c of monoclinic system. The functional groups in the complex were identified using FTIR, FTRaman andmore » FTNMR analyses. The Z-scan measurements revealed the negative nonlinear refractive index of the crystal. The nonlinear absorption coefficient and third order nonlinear optical susceptibility calculated from the measurements were −3.5823 × 10{sup −3} cm/W and 2.3762 × 10{sup −6} esu respectively. The crystal was shown to be highly transparent above 366 nm by UV–vis spectroscopy and a yellow fluorescence was observed from PL spectrum. The TG–DTA and DSC analyses showed that the crystal is thermally stable up to 117.4 °C. The crystals were characterized by dielectric, etching and microhardness studies.« less

Visualizing water molecules in transmembrane proteins using radiolytic labeling methods†

PubMed Central

Orban, Tivadar; Gupta, Sayan; Palczewski, Krzysztof; Chance, Mark R.

2010-01-01

Essential to cells and their organelles, water is both shuttled to where it is needed and trapped within cellular compartments and structures. Moreover, ordered waters within protein structures often co-localize with strategically placed polar or charged groups critical for protein function. Yet it is unclear if these ordered water molecules provide structural stabilization, mediate conformational changes in signaling, neutralize charged residues, or carry out a combination of all these functions. Structures of many integral membrane proteins, including G protein-coupled receptors (GPCRs), reveal the presence of ordered water molecules that may act like prosthetic groups in a manner quite unlike bulk water. Identification of ‘ordered’ waters within a crystalline protein structure requires sufficient occupancy of water to enable its detection in the protein's X-ray diffraction pattern and thus the observed waters likely represent a subset of tightly-bound functional waters. In this review, we highlight recent studies that suggest the structures of ordered waters within GPCRs are as conserved (and thus as important) as conserved side chains. In addition, methods of radiolysis, coupled to structural mass spectrometry (protein footprinting), reveal dynamic changes in water structure that mediate transmembrane signaling. The idea of water as a prosthetic group mediating chemical reaction dynamics is not new in fields such as catalysis. However, the concept of water as a mediator of conformational dynamics in signaling is just emerging, owing to advances in both crystallographic structure determination and new methods of protein footprinting. Although oil and water do not mix, understanding the roles of water is essential to understanding the function of membrane proteins. PMID:20047303

Structure, functional characterization, and evolution of the dihydroorotase domain of human CAD.

PubMed

Grande-García, Araceli; Lallous, Nada; Díaz-Tejada, Celsa; Ramón-Maiques, Santiago

2014-02-04

Upregulation of CAD, the multifunctional protein that initiates and controls the de novo biosynthesis of pyrimidines in animals, is essential for cell proliferation. Deciphering the architecture and functioning of CAD is of interest for its potential usage as an antitumoral target. However, there is no detailed structural information about CAD other than that it self-assembles into hexamers of ∼1.5 MDa. Here we report the crystal structure and functional characterization of the dihydroorotase domain of human CAD. Contradicting all assumptions, the structure reveals an active site enclosed by a flexible loop with two Zn²⁺ ions bridged by a carboxylated lysine and a third Zn coordinating a rare histidinate ion. Site-directed mutagenesis and functional assays prove the involvement of the Zn and flexible loop in catalysis. Comparison with homologous bacterial enzymes supports a reclassification of the DHOase family and provides strong evidence against current models of the architecture of CAD. Copyright © 2014 Elsevier Ltd. All rights reserved.

The second– and third– order nonlinear optical properties and electronic transition of a NLO chromophore: A DFT study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Altürk, Sümeyye, E-mail: sumeyye-alturk@hotmail.com; Avci, Davut, E-mail: davci@sakarya.edu.tr; Tamer, Ömer, E-mail: omertamer@sakarya.edu.tr

2016-03-25

It is well known that the practical applications of second-order and third-order nonlinear optical (NLO) materials have been reported in modern technology, such as optical data processing, transmission and storage, etc. In this respect, the linear and nonlinear optical parameters (the molecular static polarizability (α), and the first–order static hyperpolarizability (β{sub 0}), the second–order static hyperpolarizability (γ)), UV-vis spectra and HOMO and LUMO energies of 2-(1′-(4’’’-Methoxyphenyl)-5′-(thien-2″-yl)pyrrol-2′-yl)-1,3-benzothiazole were investigated by using the HSEh1PBE/6–311G(d,p) level of density functional theory. The UV–vis spectra were simulated using TD/HSEh1PBE/6– 311G(d,p) level, and the major contributions to the electronic transitions were obtained. The molecular hardness (η)more » and electronegativity (χ) parameters were also obtained by using molecular frontier orbital energies. The NLO parameters of the title compound were calculated, and obtained data were compared with that of para-Nitroaniline (pNA) which is a typical NLO material and the corresponding experimental data. Obtained data of the chromosphere display significant molecular second-and third-nonlinearity.« less

Hybrid-exchange density-functional theory study of the electronic structure of MnV2O4 : Exotic orbital ordering in the cubic structure

NASA Astrophysics Data System (ADS)

Wu, Wei

2015-05-01

The electronic structures of cubic and tetragonal MnV2O4 have been studied using hybrid-exchange density-functional theory. The computed electronic structure of the tetragonal phase shows an antiferro-orbital ordering on V sites and a ferrimagnetic ground state (the spins on V and Mn are antialigned). These results are in good agreement with the previous theoretical result obtained from the local-density approximation + U methods [S. Sarkar et al., Phys. Rev. Lett. 102, 216405 (2009), 10.1103/PhysRevLett.102.216405]. Moreover, the electronic structure, especially the projected density of states of the cubic phase, has been predicted with good agreement with the recent soft x-ray spectroscopy experiment. Similar to the tetragonal phase, the spins on V and Mn in the cubic structure favor a ferrimagnetic configuration. Most interesting is that the computed charge densities of the spin-carrying orbitals on V in the cubic phase show an exotic orbital ordering, i.e., a ferro-orbital ordering along [110] but an antiferro-orbital ordering along [1 ¯10 ] .

Higher order moments, structure functions and spectral ratios in near- and far-wakes of a wind turbine array

NASA Astrophysics Data System (ADS)

Ali, Naseem; Aseyev, A.; McCraney, J.; Vuppuluri, V.; Abbass, O.; Al Jubaree, T.; Melius, M.; Cal, R. B.

2014-11-01

Hot-wire measurements obtained in a 3 × 3 wind turbine array boundary layer are utilized to analyze higher order statistics which include skewness, kurtosis as well as the ratios of structure functions and spectra. The ratios consist of wall-normal to streamwise components for both quantities. The aim is to understand the degree of anisotropy in the flow for the near- and far-wakes of the flow field where profiles at one diameter and five diameters are considered, respectively. The skewness at top tip for both wakes show a negative skewness while below the turbine canopy, this terms are positive. The kurtosis shows a Gaussian behavior in the near-wake immediately at hub-height. In addition, the effect due to the passage of the rotor in tandem with the shear layer at the top tip renders relatively high differences in the fourth order moment. The second order structure function and spectral ratios are found to exhibit anisotropic behavior at the top and bottom-tips for the large scales. Mixed structure functions and co-spectra are also considered in the context of isotropy.

Third molar development by measurements of open apices in an Italian sample of living subjects.

PubMed

De Luca, Stefano; Pacifici, Andrea; Pacifici, Luciano; Polimeni, Antonella; Fischetto, Sara Giulia; Velandia Palacio, Luz Andrea; Vanin, Stefano; Cameriere, Roberto

2016-02-01

The aim of this study is to analyse the age-predicting performance of third molar index (I3M) in dental age estimation. A multiple regression analysis was developed with chronological age as the independent variable. In order to investigate the relationship between the I3M and chronological age, the standard deviation and relative error were examined. Digitalized orthopantomographs (OPTs) of 975 Italian healthy subjects (531 female and 444 male), aged between 9 and 22 years, were studied. Third molar development was determined according to Cameriere et al. (2008). Analysis of covariance (ANCOVA) was applied to study the interaction between I3M and the gender. The difference between age and third molar index (I3M) was tested with Pearson's correlation coefficient. The I3M, the age and the gender of the subjects were used as predictive variable for age estimation. The small F-value for the gender (F = 0.042, p = 0.837) reveals that this factor does not affect the growth of the third molar. Adjusted R(2) (AdjR(2)) was used as parameter to define the best fitting function. All the regression models (linear, exponential, and polynomial) showed a similar AdjR(2). The polynomial (2nd order) fitting explains about the 78% of the total variance and do not add any relevant clinical information to the age estimation process from the third molar. The standard deviation and relative error increase with the age. The I3M has its minimum in the younger group of studied individuals and its maximum in the oldest ones, indicating that its precision and reliability decrease with the age. Copyright © 2015 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

Mathematical Methods for Physics and Engineering Third Edition Paperback Set

NASA Astrophysics Data System (ADS)

Riley, Ken F.; Hobson, Mike P.; Bence, Stephen J.

2006-06-01

Prefaces; 1. Preliminary algebra; 2. Preliminary calculus; 3. Complex numbers and hyperbolic functions; 4. Series and limits; 5. Partial differentiation; 6. Multiple integrals; 7. Vector algebra; 8. Matrices and vector spaces; 9. Normal modes; 10. Vector calculus; 11. Line, surface and volume integrals; 12. Fourier series; 13. Integral transforms; 14. First-order ordinary differential equations; 15. Higher-order ordinary differential equations; 16. Series solutions of ordinary differential equations; 17. Eigenfunction methods for differential equations; 18. Special functions; 19. Quantum operators; 20. Partial differential equations: general and particular; 21. Partial differential equations: separation of variables; 22. Calculus of variations; 23. Integral equations; 24. Complex variables; 25. Application of complex variables; 26. Tensors; 27. Numerical methods; 28. Group theory; 29. Representation theory; 30. Probability; 31. Statistics; Index.

Third-order nonlinear optical properties of thin sputtered gold films

NASA Astrophysics Data System (ADS)

Xenogiannopoulou, E.; Aloukos, P.; Couris, S.; Kaminska, E.; Piotrowska, A.; Dynowska, E.

2007-07-01

Au films of thickness ranging between 5 and 52 nm were prepared by sputtering on quartz substrates and their third-order nonlinear optical response was investigated by Optical Kerr effect (OKE) and Z-scan techniques using 532 nm, 35 ps laser pulses. All prepared films were characterized by XRD, AFM and UV-VIS-NIR spectrophotometry while their third-order susceptibility χ(3) was measured and found to be of the order of 10 -9 esu. The real and imaginary parts of the third-order susceptibility were found in very good agreement with experimental results and theoretical predictions reported by Smith et al. [D.D. Smith, Y. Yoon, R.W. Boyd, Y.K. Cambell, L.A. Baker, R.M. Crooks, M. George, J. Appl. Phys. 86 (1999) 6200].

Silicon optical modulators for optical digital and analog communications (Conference Presentation)

NASA Astrophysics Data System (ADS)

Yang, Lin; Ding, Jianfeng; Zhang, Lei; Shao, Sizu

2017-02-01

Silicon photonics is considered as a promising technology to overcome the difficulties of the existing digital and analog optical communication systems, such as low integration, high cost, and high power consumption. Silicon optical modulator, as a component to transfer data from electronic domain to optical one, has attracted extensive attentions in the past decade. In this paper, we review the statuses of the silicon optical modulators for digital and analog optical communications and introduce our efforts on these topics. We analyze the relationship between the performance and the structural parameters of the silicon optical modulator and present how to optimize its performance including electro-optical bandwidth, modulation efficiency, optical bandwidth and insertion loss. The fabricated silicon optical modulator has an electro-optical bandwidth of 30 GHz. Its extinction ratios are 14.0 dB, 11.2 dB and 9.0 dB at the speeds of 40 Gbps, 50 Gbps and 64 Gbps for OOK modulation. The high extinction ratio of the silicon optical modulator at the high speed makes it very appropriate for the application of optical coherent modulation, such as QPSK and 16-QAM. The fabricated silicon optical modulator also can be utilized for analog optical communication. With respect to a noise floor of -165 dBc, the dynamic ranges for the second-order harmonic and the third-order intermodulation distortion are 90.8 dB and 110.5 dB respectively. By adopting a differential driving structure, the dynamic range for the second-order harmonic can be further improved to 100.0 dB while the third-order intermodulation distortion remains the same level.

Body representation disorders predict left right orientation impairments after stroke: A voxel-based lesion symptom mapping study.

PubMed

van Stralen, Haike E; Dijkerman, H Chris; Biesbroek, J Matthijs; Kuijf, Hugo J; van Gemert, H Maarten A; Sluiter, David; Kappelle, L Jaap; van Zandvoort, Martine J E

2017-06-07

Deficits in the ability to distinguish between the left and right side of the body can severely impair daily life functioning. The current study examined the relation between left right orientation (LRO) impairments and somatosensory related deficits, ranging from primary somatosensory impairments to body representation impairments, in patients who suffered a recent stroke. We also examined which areas in the brain are associated with LRO impairments using a Voxel-based Lesion Symptom Mapping (VLSM) analysis. We tested 47 first-ever stroke patients and 48 age-matched healthy controls. LRO was assessed with the Bergen Right Left Discrimination Test (BRLD). Impairments on primary somatosensory function (touch perception, proprioception), higher order somatosensory function (finger gnosis, subjective sense of body ownership) and other cognitive functions (language, attention & working memory, visuospatial neglect) were entered as predictors in a logistic regression analyses. Outcome measures consisted of the BRLD-total performance which was further subdivided in performance for 1) first person perspective stimuli, 2) third person perspective stimuli, 3) alternating between first- and third person perspective. Impairments on BRLD-total performance was predicted by impairments in finger gnosis and visuospatial neglect. For items placed in third person perspective, performance was predicted by body representation impairments; finger agnosia and the subjective sense of body ownership. VLSM analysis showed a significant association between LRO impairments and damage to the right insula. The current study suggests that the somatosensory system is important for LRO. Furthermore, the results indicate that an affected body representation may hinder adopting a third person perspective that may subsequently also lead to LRO impairments. The right insular cortex appeared crucially involved in these processes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Multi-octave analog photonic link with improved second- and third-order SFDRs

NASA Astrophysics Data System (ADS)

Tan, Qinggui; Gao, Yongsheng; Fan, Yangyu; He, You

2018-03-01

The second- and third-order spurious free dynamic ranges (SFDRs) are two key performance indicators for a multi-octave analogy photonic link (APL). The linearization methods for either second- or third-order intermodulation distortion (IMD2 or IMD3) have been intensively studied, but the simultaneous suppression for the both were merely reported. In this paper, we propose an APL with improved second- and third-order SFDRs for multi-octave applications based on two parallel DPMZM-based sub-APLs. The IMD3 in each sub-APL is suppressed by properly biasing the DPMZM, and the IMD2 is suppressed by balanced detecting the two sub-APLs. The experiment demonstrates significant suppression ratios for both the IMD2 and IMD3 after linearization in the proposed link, and the measured second- and third-order SFDRs with the operating frequency from 6 to 40 GHz are above 91 dB ṡHz 1 / 2 and 116 dB ṡHz 2 / 3, respectively.

Higher-order corrections to the effective potential close to the jamming transition in the perceptron model

NASA Astrophysics Data System (ADS)

Altieri, Ada

2018-01-01

In view of the results achieved in a previously related work [A. Altieri, S. Franz, and G. Parisi, J. Stat. Mech. (2016) 093301], 10.1088/1742-5468/2016/09/093301, regarding a Plefka-like expansion of the free energy up to the second order in the perceptron model, we improve the computation here focusing on the role of third-order corrections. The perceptron model is a simple example of constraint satisfaction problem, falling in the same universality class as hard spheres near jamming and hence allowing us to get exact results in high dimensions for more complex settings. Our method enables to define an effective potential (or Thouless-Anderson-Palmer free energy), namely a coarse-grained functional, which depends on the generalized forces and the effective gaps between particles. The analysis of the third-order corrections to the effective potential reveals that, albeit irrelevant in a mean-field framework in the thermodynamic limit, they might instead play a fundamental role in considering finite-size effects. We also study the typical behavior of generalized forces and we show that two kinds of corrections can occur. The first contribution arises since the system is analyzed at a finite distance from jamming, while the second one is due to finite-size corrections. We nevertheless show that third-order corrections in the perturbative expansion vanish in the jamming limit both for the potential and the generalized forces, in agreement with the isostaticity argument proposed by Wyart and coworkers. Finally, we analyze the relevant scaling solutions emerging close to the jamming line, which define a crossover regime connecting the control parameters of the model to an effective temperature.

Higher-order corrections to the effective potential close to the jamming transition in the perceptron model.

PubMed

Altieri, Ada

2018-01-01

In view of the results achieved in a previously related work [A. Altieri, S. Franz, and G. Parisi, J. Stat. Mech. (2016) 093301]10.1088/1742-5468/2016/09/093301, regarding a Plefka-like expansion of the free energy up to the second order in the perceptron model, we improve the computation here focusing on the role of third-order corrections. The perceptron model is a simple example of constraint satisfaction problem, falling in the same universality class as hard spheres near jamming and hence allowing us to get exact results in high dimensions for more complex settings. Our method enables to define an effective potential (or Thouless-Anderson-Palmer free energy), namely a coarse-grained functional, which depends on the generalized forces and the effective gaps between particles. The analysis of the third-order corrections to the effective potential reveals that, albeit irrelevant in a mean-field framework in the thermodynamic limit, they might instead play a fundamental role in considering finite-size effects. We also study the typical behavior of generalized forces and we show that two kinds of corrections can occur. The first contribution arises since the system is analyzed at a finite distance from jamming, while the second one is due to finite-size corrections. We nevertheless show that third-order corrections in the perturbative expansion vanish in the jamming limit both for the potential and the generalized forces, in agreement with the isostaticity argument proposed by Wyart and coworkers. Finally, we analyze the relevant scaling solutions emerging close to the jamming line, which define a crossover regime connecting the control parameters of the model to an effective temperature.

Bright, dark and W-shaped solitons with extended nonlinear Schrödinger's equation for odd and even higher-order terms

NASA Astrophysics Data System (ADS)

Bendahmane, Issam; Triki, Houria; Biswas, Anjan; Saleh Alshomrani, Ali; Zhou, Qin; Moshokoa, Seithuti P.; Belic, Milivoj

2018-02-01

We present solitary wave solutions of an extended nonlinear Schrödinger equation with higher-order odd (third-order) and even (fourth-order) terms by using an ansatz method. The including high-order dispersion terms have significant physical applications in fiber optics, the Heisenberg spin chain, and ocean waves. Exact envelope solutions comprise bright, dark and W-shaped solitary waves, illustrating the potentially rich set of solitary wave solutions of the extended model. Furthermore, we investigate the properties of these solitary waves in nonlinear and dispersive media. Moreover, specific constraints on the system parameters for the existence of these structures are discussed exactly. The results show that the higher-order dispersion and nonlinear effects play a crucial role for the formation and properties of propagating waves.

Variations of cosmic large-scale structure covariance matrices across parameter space

NASA Astrophysics Data System (ADS)

Reischke, Robert; Kiessling, Alina; Schäfer, Björn Malte

2017-03-01

The likelihood function for cosmological parameters, given by e.g. weak lensing shear measurements, depends on contributions to the covariance induced by the non-linear evolution of the cosmic web. As highly non-linear clustering to date has only been described by numerical N-body simulations in a reliable and sufficiently precise way, the necessary computational costs for estimating those covariances at different points in parameter space are tremendous. In this work, we describe the change of the matter covariance and the weak lensing covariance matrix as a function of cosmological parameters by constructing a suitable basis, where we model the contribution to the covariance from non-linear structure formation using Eulerian perturbation theory at third order. We show that our formalism is capable of dealing with large matrices and reproduces expected degeneracies and scaling with cosmological parameters in a reliable way. Comparing our analytical results to numerical simulations, we find that the method describes the variation of the covariance matrix found in the SUNGLASS weak lensing simulation pipeline within the errors at one-loop and tree-level for the spectrum and the trispectrum, respectively, for multipoles up to ℓ ≤ 1300. We show that it is possible to optimize the sampling of parameter space where numerical simulations should be carried out by minimizing interpolation errors and propose a corresponding method to distribute points in parameter space in an economical way.

What can we learn about dispersion from the conformer surface of n-pentane?

PubMed

Martin, Jan M L

2013-04-11

In earlier work [Gruzman, D. ; Karton, A.; Martin, J. M. L. J. Phys. Chem. A 2009, 113, 11974], we showed that conformer energies in alkanes (and other systems) are highly dispersion-driven and that uncorrected DFT functionals fail badly at reproducing them, while simple empirical dispersion corrections tend to overcorrect. To gain greater insight into the nature of the phenomenon, we have mapped the torsional surface of n-pentane to 10-degree resolution at the CCSD(T)-F12 level near the basis set limit. The data obtained have been decomposed by order of perturbation theory, excitation level, and same-spin vs opposite-spin character. A large number of approximate electronic structure methods have been considered, as well as several empirical dispersion corrections. Our chief conclusions are as follows: (a) the effect of dispersion is dominated by same-spin correlation (or triplet-pair correlation, from a different perspective); (b) singlet-pair correlation is important for the surface, but qualitatively very dissimilar to the dispersion component; (c) single and double excitations beyond third order are essentially unimportant for this surface; (d) connected triple excitations do play a role but are statistically very similar to the MP2 singlet-pair correlation; (e) the form of the damping function is crucial for good performance of empirical dispersion corrections; (f) at least in the lower-energy regions, SCS-MP2 and especially MP2.5 perform very well; (g) novel spin-component scaled double hybrid functionals such as DSD-PBEP86-D2 acquit themselves very well for this problem.

Particle–hole ring diagrams for fermions in two dimensions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaiser, N., E-mail: nkaiser@ph.tum.de

2014-11-15

The set of particle–hole ring diagrams for a many-fermion system in two dimensions is studied. The complex-valued polarization function is derived in detail and shown to be expressible in terms of square-root functions. For a contact-interaction the perturbative contributions to the energy per particle Ē(k{sub f}) are calculated in a closed analytical form from third up to twelfth order. The resummation of the particle–hole ring diagrams to all orders is studied and a pronounced dependence on the dimensionless coupling parameter α is found. There is a substantial difference between the complete ring-sum with all exchange-type diagrams included and the standardmore » resummation of the leading n-ring diagrams only. The spin factor S{sub n}(g) associated to the nth order ring diagrams is derived for arbitrary spin-degeneracy g.« less

Classification of endoscopic capsule images by using color wavelet features, higher order statistics and radial basis functions.

PubMed

Lima, C S; Barbosa, D; Ramos, J; Tavares, A; Monteiro, L; Carvalho, L

2008-01-01

This paper presents a system to support medical diagnosis and detection of abnormal lesions by processing capsule endoscopic images. Endoscopic images possess rich information expressed by texture. Texture information can be efficiently extracted from medium scales of the wavelet transform. The set of features proposed in this paper to code textural information is named color wavelet covariance (CWC). CWC coefficients are based on the covariances of second order textural measures, an optimum subset of them is proposed. Third and forth order moments are added to cope with distributions that tend to become non-Gaussian, especially in some pathological cases. The proposed approach is supported by a classifier based on radial basis functions procedure for the characterization of the image regions along the video frames. The whole methodology has been applied on real data containing 6 full endoscopic exams and reached 95% specificity and 93% sensitivity.

Columnar organization of orientation domains in V1

NASA Astrophysics Data System (ADS)

Liedtke, Joscha; Wolf, Fred

In the primary visual cortex (V1) of primates and carnivores, the functional architecture of basic stimulus selectivities appears similar across cortical layers (Hubel & Wiesel, 1962) justifying the use of two-dimensional cortical models and disregarding organization in the third dimension. Here we show theoretically that already small deviations from an exact columnar organization lead to non-trivial three-dimensional functional structures. We extend two-dimensional random field models (Schnabel et al., 2007) to a three-dimensional cortex by keeping a typical scale in each layer and introducing a correlation length in the third, columnar dimension. We examine in detail the three-dimensional functional architecture for different cortical geometries with different columnar correlation lengths. We find that (i) topological defect lines are generally curved and (ii) for large cortical curvatures closed loops and reconnecting topological defect lines appear. This theory extends the class of random field models by introducing a columnar dimension and provides a systematic statistical assessment of the three-dimensional functional architecture of V1 (see also (Tanaka et al., 2011)).

Kinetics of Polydomain Ordering at Second-Order Phase Transitions (by the Example of the AuCu3 Alloy)

NASA Astrophysics Data System (ADS)

Feldman, E. P.; Stefanovich, L. I.; Gumennyk, K. V.

2008-08-01

Kinetics of polydomain spinodal ordering is studied in alloys of AuCu3 type. We introduce four non-conserved long-range order parameters whose sum, however, is conserved and, using the statistical approach, follow the temporal evolution of their random spatial distribution after a rapid temperature quench. A system of nonlinear differential equations for correlators of second and third order is derived. Asymptotical analysis of this system allows to investigate the scaling regime, which develops on the late stages of evolution and to extract additional information concerning the rate of decrease of the specific volume of disordered regions and the rate of decrease of the average thickness of antiphase boundaries. Comparison of these results to experimental data is given. The quench below the spinodal and the onset of long-range order may be separated by the incubation time, whose origin is different from that in first-order phase transitions. Numerical integration of equations for correlators shows also, that it is possible to prepare a sample in such a way that its further evolution will go with formation of transient kinetically slowed polydomain structures different from the final L12 structure.

The Gaussian streaming model and convolution Lagrangian effective field theory

DOE PAGES

Vlah, Zvonimir; Castorina, Emanuele; White, Martin

2016-12-05

We update the ingredients of the Gaussian streaming model (GSM) for the redshift-space clustering of biased tracers using the techniques of Lagrangian perturbation theory, effective field theory (EFT) and a generalized Lagrangian bias expansion. After relating the GSM to the cumulant expansion, we present new results for the real-space correlation function, mean pairwise velocity and pairwise velocity dispersion including counter terms from EFT and bias terms through third order in the linear density, its leading derivatives and its shear up to second order. We discuss the connection to the Gaussian peaks formalism. We compare the ingredients of the GSM tomore » a suite of large N-body simulations, and show the performance of the theory on the low order multipoles of the redshift-space correlation function and power spectrum. We highlight the importance of a general biasing scheme, which we find to be as important as higher-order corrections due to non-linear evolution for the halos we consider on the scales of interest to us.« less

The Gaussian streaming model and convolution Lagrangian effective field theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vlah, Zvonimir; Castorina, Emanuele; White, Martin, E-mail: zvlah@stanford.edu, E-mail: ecastorina@berkeley.edu, E-mail: mwhite@berkeley.edu

We update the ingredients of the Gaussian streaming model (GSM) for the redshift-space clustering of biased tracers using the techniques of Lagrangian perturbation theory, effective field theory (EFT) and a generalized Lagrangian bias expansion. After relating the GSM to the cumulant expansion, we present new results for the real-space correlation function, mean pairwise velocity and pairwise velocity dispersion including counter terms from EFT and bias terms through third order in the linear density, its leading derivatives and its shear up to second order. We discuss the connection to the Gaussian peaks formalism. We compare the ingredients of the GSM tomore » a suite of large N-body simulations, and show the performance of the theory on the low order multipoles of the redshift-space correlation function and power spectrum. We highlight the importance of a general biasing scheme, which we find to be as important as higher-order corrections due to non-linear evolution for the halos we consider on the scales of interest to us.« less

Dancing Protein Clouds: The Strange Biology and Chaotic Physics of Intrinsically Disordered Proteins*

PubMed Central

2016-01-01

Biologically active but floppy proteins represent a new reality of modern protein science. These intrinsically disordered proteins (IDPs) and hybrid proteins containing ordered and intrinsically disordered protein regions (IDPRs) constitute a noticeable part of any given proteome. Functionally, they complement ordered proteins, and their conformational flexibility and structural plasticity allow them to perform impossible tricks and be engaged in biological activities that are inaccessible to well folded proteins with their unique structures. The major goals of this minireview are to show that, despite their simplified amino acid sequences, IDPs/IDPRs are complex entities often resembling chaotic systems, are structurally and functionally heterogeneous, and can be considered an important part of the structure-function continuum. Furthermore, IDPs/IDPRs are everywhere, and are ubiquitously engaged in various interactions characterized by a wide spectrum of binding scenarios and an even wider spectrum of structural and functional outputs. PMID:26851286

Effect of halogenation on the nonlinear optical properties of porthyrin and substituted porphyrins

NASA Technical Reports Server (NTRS)

Cardelino, Beatriz H.; Moore, Craig E.; Benloss, Angela; Thompson, Albert N., Jr.; Richards, Rosalie A.; Roney, Celeste A.; Sanghadasa, Mohan

1998-01-01

The effect that fluorine and chlorine substitution has on the nonlinear optical properties of porphyrin, tetramethylporphyrin and tetraphenylporphyrin has been theoretically studied. The calculations of nonlinear optical properties have been obtained by performing finite-field calculations on structures determined by semiempirical methods. In addition, tetra(p-chlorophenyl)porphyrin and tetra(p-bromophenyl)porphyrin were synthesized by the condensation of pyrrol and the appropriate aldehyde. Thin films of polymethylmethacrylate were obtained containing these materials, by spin coating onto glass substrates. The films were characterized by third-harmonic generation. It was determined that the experimental conditions enhance the third-order polarizability of the tetraphenylporphyrins by a factor of about 1.6.

An Immersed-Boundary Method for Fluid-Structure Interaction in the Human Larynx

NASA Astrophysics Data System (ADS)

Luo, Haoxiang; Zheng, Xudong; Mittal, Rajat; Bielamowicz, Steven

2006-11-01

We describe a novel and accurate computational methodology for modeling the airflow and vocal fold dynamics in human larynx. The model is useful in helping us gain deeper insight into the complicated bio-physics of phonation, and may have potential clinical application in design and placement of synthetic implant in vocal fold surgery. The numerical solution of the airflow employs a previously developed immersed-boundary solver. However, in order to incorporate the vocal fold into the model, we have developed a new immersed-boundary method that can simulate the dynamics of the multi-layered, viscoelastic solids. In this method, a finite-difference scheme is used to approximate the derivatives and ghost cells are defined near the boundary. To impose the traction boundary condition, a third-order polynomial is obtained using the weighted least squares fitting to approximate the function locally. Like its analogue for the flow solver, this immersed-boundary method for the solids has the advantage of simple grid generation, and may be easily implemented on parallel computers. In the talk, we will present the simulation results on both the specified vocal fold motion and the flow-induced vocal fold vibration. Supported by NIDCD Grant R01 DC007125-01A1.

Quasilinear parabolic variational inequalities with multi-valued lower-order terms

NASA Astrophysics Data System (ADS)

Carl, Siegfried; Le, Vy K.

2014-10-01

In this paper, we provide an analytical frame work for the following multi-valued parabolic variational inequality in a cylindrical domain : Find and an such that where is some closed and convex subset, A is a time-dependent quasilinear elliptic operator, and the multi-valued function is assumed to be upper semicontinuous only, so that Clarke's generalized gradient is included as a special case. Thus, parabolic variational-hemivariational inequalities are special cases of the problem considered here. The extension of parabolic variational-hemivariational inequalities to the general class of multi-valued problems considered in this paper is not only of disciplinary interest, but is motivated by the need in applications. The main goals are as follows. First, we provide an existence theory for the above-stated problem under coercivity assumptions. Second, in the noncoercive case, we establish an appropriate sub-supersolution method that allows us to get existence, comparison, and enclosure results. Third, the order structure of the solution set enclosed by sub-supersolutions is revealed. In particular, it is shown that the solution set within the sector of sub-supersolutions is a directed set. As an application, a multi-valued parabolic obstacle problem is treated.

Closed-loop transfer recovery with observer-based controllers. I - Analysis. II - Design

NASA Technical Reports Server (NTRS)

Chen, Ben M.; Saberi, Ali; Ly, Uy-Loi

1992-01-01

A detailed study is presented of three fundamental issues related to the problem of closed-loop transfer (CLT) recovery. The first issues concerns what can and cannot be achieved for a given system and for an arbitrary target CLT function (TCLTF). The second issue involves developing necessary and/or sufficient conditions for a TCLTF to be recoverable either exactly or approximately. The third issue involves the necessary and/or sufficient conditions on a given system such that it has at least one recoverable TCLTF. The results of the analysis identify some fundamental limitations of the given system as a consequence of its structural properties which enables designers to appreciate at the outset different design limitations incurred in the synthesis of output-feedback controllers. Then, the actual design of full-order or reduced-order observer-based controllers is addressed which will achieve as close as possibly the desired TCLTF. Three design methods are considered: (1) the ATEA method, (2) a method that minimizes the H2-norm of a recovery matrix, and (3) a method that minimizes the respective H(infinity) norm. The relative merits of the methods are discussed.

Six-band terahertz metamaterial absorber based on the combination of multiple-order responses of metallic patches in a dual-layer stacked resonance structure.

PubMed

Wang, Ben-Xin; Wang, Gui-Zhen; Sang, Tian; Wang, Ling-Ling

2017-01-25

This paper reports on a numerical study of the six-band metamaterial absorber composed of two alternating stack of metallic-dielectric layers on top of a continuous metallic plane. Six obvious resonance peaks with high absorption performance (average larger than 99.37%) are realized. The first, third, fifth, and the second, fourth, sixth resonance absorption bands are attributed to the multiple-order responses (i.e., the 1-, 3- and 5-order responses) of the bottom- and top-layer of the structure, respectively, and thus the absorption mechanism of six-band absorber is due to the combination of two sets of the multiple-order resonances of these two layers. Besides, the size changes of the metallic layers have the ability to tune the frequencies of the six-band absorber. Employing the results, we also present a six-band polarization tunable absorber through varying the sizes of the structure in two orthogonal polarization directions. Moreover, nine-band terahertz absorber can be achieved by using a three-layer stacked structure. Simulation results indicate that the absorber possesses nine distinct resonance bands, and average absorptivities of them are larger than 94.03%. The six-band or nine-band absorbers obtained here have potential applications in many optoelectronic and engineering technology areas.

Statistical assessment of optical phase fluctuations through turbulent mixing layers

NASA Astrophysics Data System (ADS)

Gardner, Patrick J.; Roggemann, Michael C.; Welsh, Byron M.; Bowersox, Rodney D.

1995-09-01

A lateral shearing interferometer is used to measure the slope of perturbed wavefronts after propagating through turbulent shear flows. This provides a two-dimensional flow visualization technique which is nonintrusive. The slope measurements are used to reconstruct the phase of the turbulence-corrupted wave front. Experiments were performed on a plane shear mixing layer of helium and nitrogen gas at fixed velocities, for five locations in the flow development. The two gases, having a density ratio of approximately seven, provide an effective means of simulating compressible shear layers. Statistical autocorrelation functions and structure functions are computed on the reconstructed phase maps. The autocorrelation function results indicate that the turbulence-induced phase fluctuations are not wide-sense stationary. The structure functions exhibit statistical homogeneity, indicating the phase fluctuation are stationary in first increments. However, the turbulence-corrupted phase is not isotropic. A five-thirds power law is shown to fit one-dimensional, orthogonal slices of the structure function, with scaling coefficients related to the location in the flow.

High-Order Automatic Differentiation of Unmodified Linear Algebra Routines via Nilpotent Matrices

NASA Astrophysics Data System (ADS)

Dunham, Benjamin Z.

This work presents a new automatic differentiation method, Nilpotent Matrix Differentiation (NMD), capable of propagating any order of mixed or univariate derivative through common linear algebra functions--most notably third-party sparse solvers and decomposition routines, in addition to basic matrix arithmetic operations and power series--without changing data-type or modifying code line by line; this allows differentiation across sequences of arbitrarily many such functions with minimal implementation effort. NMD works by enlarging the matrices and vectors passed to the routines, replacing each original scalar with a matrix block augmented by derivative data; these blocks are constructed with special sparsity structures, termed "stencils," each designed to be isomorphic to a particular multidimensional hypercomplex algebra. The algebras are in turn designed such that Taylor expansions of hypercomplex function evaluations are finite in length and thus exactly track derivatives without approximation error. Although this use of the method in the "forward mode" is unique in its own right, it is also possible to apply it to existing implementations of the (first-order) discrete adjoint method to find high-order derivatives with lowered cost complexity; for example, for a problem with N inputs and an adjoint solver whose cost is independent of N--i.e., O(1)--the N x N Hessian can be found in O(N) time, which is comparable to existing second-order adjoint methods that require far more problem-specific implementation effort. Higher derivatives are likewise less expensive--e.g., a N x N x N rank-three tensor can be found in O(N2). Alternatively, a Hessian-vector product can be found in O(1) time, which may open up many matrix-based simulations to a range of existing optimization or surrogate modeling approaches. As a final corollary in parallel to the NMD-adjoint hybrid method, the existing complex-step differentiation (CD) technique is also shown to be capable of finding the Hessian-vector product. All variants are implemented on a stochastic diffusion problem and compared in-depth with various cost and accuracy metrics.

Fecal incontinence, sexual complaints, and anorectal function after third-degree obstetric anal sphincter injury (OASI): 5-year follow-up.

PubMed

Visscher, A P; Lam, T J; Hart, N; Felt-Bersma, R J F

2014-05-01

Our aim was to evaluate alterations in anorectal function after anal sphincteroplasty for third-degree obstetric anal sphincter injury (OASI) in relation to clinical outcome. In this retrospective, descriptive, cross-sectional study conducted between 1998 and 2008, women with persisting fecal incontinence (FI) after 3a OASI and all women with grade 3b or 3c OASI were sent for anorectal function evaluation (AFE) consisting of anal manometry and endosonography 3 months after sphincteroplasty. In 2011, questionnaires regarding FI (Vaizey/Wexner), urinary incontinence (UI) [International Consultation on Incontinence Questionnaire Short Form (ICIQ-SF)], sexual function [Female Sexual Function Index (FSFI)], and quality of life (QOL) (Rand-36) were sent and women were asked to undergo additional AFE. Sixty-six women underwent AFE. Mean follow-up was 5.0 years. Forty (61%) patients returned questionnaires regarding FI and UI. Prevalence of FI was 63% flatus, 50% liquid stool, and 20% solid stool. Thirty-two of 40 also reported on QOL and SF. Sexual dysfunction was present in the majority of women (cutoff value 26.55) and more pronounced in larger OASI. Sixteen of 40 women underwent additional AFE. Women with combined internal (IAS) and external (EAS) anal sphincter injury (n = 6) had worse FI (P < 0.050) and lower anal pressures (P = 0.040) than women with isolated EAS injury (n = 10). Follow-up after third-degree OASI suggests poor anorectal and sexual function. Women with combined external and internal OASI show more deterioration in anorectal function and experience worse FI. Therefore, special attention should be paid to these women in order to mitigate these symptoms later in life.

A second-order closure analysis of turbulent diffusion flames. [combustion physics

NASA Technical Reports Server (NTRS)

Varma, A. K.; Fishburne, E. S.; Beddini, R. A.

1977-01-01

A complete second-order closure computer program for the investigation of compressible, turbulent, reacting shear layers was developed. The equations for the means and the second order correlations were derived from the time-averaged Navier-Stokes equations and contain third order and higher order correlations, which have to be modeled in terms of the lower-order correlations to close the system of equations. In addition to fluid mechanical turbulence models and parameters used in previous studies of a variety of incompressible and compressible shear flows, a number of additional scalar correlations were modeled for chemically reacting flows, and a typical eddy model developed for the joint probability density function for all the scalars. The program which is capable of handling multi-species, multistep chemical reactions, was used to calculate nonreacting and reacting flows in a hydrogen-air diffusion flame.

Density functional calculations on structural materials for nuclear energy applications and functional materials for photovoltaic energy applications (abstract only).

PubMed

Domain, C; Olsson, P; Becquart, C S; Legris, A; Guillemoles, J F

2008-02-13

Ab initio density functional theory calculations are carried out in order to predict the evolution of structural materials under aggressive working conditions such as cases with exposure to corrosion and irradiation, as well as to predict and investigate the properties of functional materials for photovoltaic energy applications. Structural metallic materials used in nuclear facilities are subjected to irradiation which induces the creation of large amounts of point defects. These defects interact with each other as well as with the different elements constituting the alloys, which leads to modifications of the microstructure and the mechanical properties. VASP (Vienna Ab initio Simulation Package) has been used to determine the properties of point defect clusters and also those of extended defects such as dislocations. The resulting quantities, such as interaction energies and migration energies, are used in larger scale simulation methods in order to build predictive tools. For photovoltaic energy applications, ab initio calculations are used in order to search for new semiconductors and possible element substitutions for existing ones in order to improve their efficiency.

Extension of relativistic dissipative hydrodynamics to third order

NASA Astrophysics Data System (ADS)

El, Andrej; Xu, Zhe; Greiner, Carsten

2010-04-01

Following the procedure introduced by Israel and Stewart, we expand the entropy current up to the third order in the shear stress tensor παβ and derive a novel third-order evolution equation for παβ. This equation is solved for the one-dimensional Bjorken boost-invariant expansion. The scaling solutions for various values of the shear viscosity to the entropy density ratio η/s are shown to be in very good agreement with those obtained from kinetic transport calculations. For the pressure isotropy starting with 1 at τ0=0.4 fm/c, the third-order corrections to Israel-Stewart theory are approximately 10% for η/s=0.2 and more than a factor of 2 for η/s=3. We also estimate all higher-order corrections to Israel-Stewart theory and demonstrate their importance in describing highly viscous matters.

Modified two-photon absorption and dispersion of ultrafast third-order polarization beats via twin noisy driving fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang Yanpeng; Department of Electronic Science and Technology, Xi'an Jiaotong University, Xi'an 710049; Gan Chenli

2006-05-15

We investigate the color-locked twin-noisy-field correlation effects in third-order nonlinear absorption and dispersion of ultrafast polarization beats. We demonstrate a phase-sensitive method for studying the two-photon nondegenerate four-wave mixing (NDFWM) due to atomic coherence in a multilevel system. The reference signal is another one-photon degenerate four-wave-mixing signal, which propagates along the same optical path as the NDFWM signal. This method is used for studying the phase dispersion of the third-order susceptibility and for the optical heterodyne detection of the NDFWM signal. The third-order nonlinear response can be controlled and modified through the color-locked correlation of twin noisy fields.

Dynamics of a bistable Miura-origami structure

NASA Astrophysics Data System (ADS)

Fang, Hongbin; Li, Suyi; Ji, Huimin; Wang, K. W.

2017-05-01

Origami-inspired structures and materials have shown extraordinary properties and performances originating from the intricate geometries of folding. However, current state of the art studies have mostly focused on static and quasistatic characteristics. This research performs a comprehensive experimental and analytical study on the dynamics of origami folding through investigating a stacked Miura-Ori (SMO) structure with intrinsic bistability. We fabricate and experimentally investigated a bistable SMO prototype with rigid facets and flexible crease lines. Under harmonic base excitation, the SMO exhibits both intrawell and interwell oscillations. Spectrum analyses reveal that the dominant nonlinearities of SMO are quadratic and cubic, which generate rich dynamics including subharmonic and chaotic oscillations. The identified nonlinearities indicate that a third-order polynomial can be employed to approximate the measured force-displacement relationship. Such an approximation is validated via numerical study by qualitatively reproducing the phenomena observed in the experiments. The dynamic characteristics of the bistable SMO resemble those of a Helmholtz-Duffing oscillator (HDO); this suggests the possibility of applying the established tools and insights of HDO to predict origami dynamics. We also show that the bistability of SMO can be programmed within a large design space via tailoring the crease stiffness and initial stress-free configurations. The results of this research offer a wealth of fundamental insights into the dynamics of origami folding, and provide a solid foundation for developing foldable and deployable structures and materials with embedded dynamic functionalities.

Preparation, linear and NLO properties of DNA-CTMA-SBE complexes

NASA Astrophysics Data System (ADS)

Manea, Ana-Maria; Rau, Ileana; Kajzar, Francois; Meghea, Aurelia

2013-10-01

Synthesis of deoxyribonucleic acid (DNA) - was cetyltrimethylammonium (CTMA) - sea buckthorn extract (SBE) at different concentrations is decribed. The complexes were processed into good optical quality thin films by spin coating on different substrates such as: glass, silica and ITO covered glass substrates. SBE contains many bioactive substances that can be used in the treatment of several diseases, such as cardiovascular disease, cancer, and acute mountain sickness. The obtained thin films were characterized for their spectroscopic, fluorescent, linear and nonlinear optical properties as function of SBE concentration. The third-order nonlinear optical (NLO) properties of thin films were determined by the optical third-harmonic generation technique at 1 064.2 nm fundamental wavelength.

Human rights, health, and capital accumulation in the Third World.

PubMed

Chossudovsky, M

1979-01-01

This article examines the relationship between human rights and the pattern of capital accumulation in the Third World. The repressive authoritarian State increasingly constitutes the means for enforcing the intensive exploitation of labor in Third World industrial enclaves and commercial agriculture. While the development of center capitalism has evolved toward "the Welfare State" and a framework of liberal sociodemocracy, the "peripheral State" is generally characterized by nondemocratic forms of government. This bipolarity in the state structure between center and periphery is functionally related to the international division of labor and the unity of production and circulation on a world level. The programs and policies of the center Welfare State (health, education, social security, etc.) constitute an input of "human capital" into the high-technology center labor process. Moreover, welfare programs in center countries activate the process of circulation by sustaining high levels of consumer demand. In underdeveloped countries, the underlying vacuum in the social sectors and the important allocations to military expenditure support the requirements of the peripheral labor process. Programs in health in the center and periphery are related to the bipolarity (qualification/dequalification) in the international division of labor. The social and economic functions of health programs are intimately related to the organic structure of the State and the mechanics whereby the State allocates its financial surplus in support of both capitalist production and circulation.

Psychometric Properties of the Theory of Mind Assessment Scale in a Sample of Adolescents and Adults.

PubMed

Bosco, Francesca M; Gabbatore, Ilaria; Tirassa, Maurizio; Testa, Silvia

2016-01-01

This research aimed at the evaluation of the psychometric properties of the Theory of Mind Assessment Scale (Th.o.m.a.s.). Th.o.m.a.s. is a semi-structured interview meant to evaluate a person's Theory of Mind (ToM). It is composed of several questions organized in four scales, each focusing on one of the areas of knowledge in which such faculty may manifest itself: Scale A (I-Me) investigates first-order first-person ToM; Scale B (Other-Self) investigates third-person ToM from an allocentric perspective; Scale C (I-Other) again investigates third-person ToM, but from an egocentric perspective; and Scale D (Other-Me) investigates second-order ToM. The psychometric proprieties of Th.o.m.a.s. were evaluated in a sample of 156 healthy persons: 80 preadolescent and adolescent (aged 11-17 years, 42 females) and 76 adults (aged from 20 to 67 years, 35 females). Th.o.m.a.s. scores show good inter-rater agreement and internal consistency; the scores increase with age. Evidence of criterion validity was found as Scale B scores were correlated with those of an independent instrument for the evaluation of ToM, the Strange Stories task. Confirmatory factor analysis (CFA) showed good fit of the four-factors theoretical model to the data, although the four factors were highly correlated. For each of the four scales, Rasch analyses showed that, with few exceptions, items fitted the Partial credit model and their functioning was invariant for gender and age. The results of this study, along with those of previous researches with clinical samples, show that Th.o.m.a.s. is a promising instrument to assess ToM in different populations.

Psychometric Properties of the Theory of Mind Assessment Scale in a Sample of Adolescents and Adults

PubMed Central

Bosco, Francesca M.; Gabbatore, Ilaria; Tirassa, Maurizio; Testa, Silvia

2016-01-01

This research aimed at the evaluation of the psychometric properties of the Theory of Mind Assessment Scale (Th.o.m.a.s.). Th.o.m.a.s. is a semi-structured interview meant to evaluate a person's Theory of Mind (ToM). It is composed of several questions organized in four scales, each focusing on one of the areas of knowledge in which such faculty may manifest itself: Scale A (I-Me) investigates first-order first-person ToM; Scale B (Other-Self) investigates third-person ToM from an allocentric perspective; Scale C (I-Other) again investigates third-person ToM, but from an egocentric perspective; and Scale D (Other-Me) investigates second-order ToM. The psychometric proprieties of Th.o.m.a.s. were evaluated in a sample of 156 healthy persons: 80 preadolescent and adolescent (aged 11–17 years, 42 females) and 76 adults (aged from 20 to 67 years, 35 females). Th.o.m.a.s. scores show good inter-rater agreement and internal consistency; the scores increase with age. Evidence of criterion validity was found as Scale B scores were correlated with those of an independent instrument for the evaluation of ToM, the Strange Stories task. Confirmatory factor analysis (CFA) showed good fit of the four-factors theoretical model to the data, although the four factors were highly correlated. For each of the four scales, Rasch analyses showed that, with few exceptions, items fitted the Partial credit model and their functioning was invariant for gender and age. The results of this study, along with those of previous researches with clinical samples, show that Th.o.m.a.s. is a promising instrument to assess ToM in different populations. PMID:27242563

Influence of bis-thiourea nickel nitrate on the structural, optical, electrical, thermal and mechanical behavior of a KDP single crystal for NLO applications

NASA Astrophysics Data System (ADS)

Rasal, Y. B.; Shaikh, R. N.; Shirsat, M. D.; Kalainathan, S.; Hussaini, S. S.

2017-03-01

A single crystal of bis-thiourea nickel nitrate (BTNN) doped potassium dihydrogen phosphate (KDP) has been grown from solution at room temperature by a slow evaporation technique. The cell parameters of the grown crystals were determined using single crystal x-ray diffraction analysis. The different functional groups of the grown crystal were confirmed using Fourier transform infrared analysis. The improved optical parameters of the grown crystal have been evaluated in the range of 200-900 nm using UV-visible spectral analysis. The grown crystal was transparent in the entire visible region and the band gap value was found to be 4.96 eV. The influence of BTNN on the third order nonlinear optical properties of KDP crystal has been investigated by means of the Z-scan technique. The second harmonic generation (SHG) efficiency of grown crystal measured using a Nd-YAG laser is 1.98 times higher than that of pure KDP. The third order nonlinear optical susceptibility (χ 3) and nonlinear absorption coefficient (β) of BTNN doped KDP crystal is found to be 1.77  ×  10-5 esu and 5.57  ×  10-6 cm W-1 respectively. The laser damage threshold (LDT) energy for the grown crystal has been measured by using a Q-switched Nd:YAG laser source. The bis-thiourea nickel nitrate shows authoritative impact on the dielectric properties of doped crystal. The influence of bis-thiourea nickel nitrate on the mechanical behavior of KDP crystal has been investigated using Vickers microhardness intender. The thermal behavior of BTNN doped KDP crystal has been analyzed by TGA/DTA analysis.

77 FR 31849 - Information Collections Being Submitted for Review and Approval to the Office of Management and...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-30

... Broadcast Translator Stations, Fourth Report and Order and Third Order on Reconsideration (``Fourth Report... than 4 pending translator applications) to request the dismissal of applications to comply with these... Eligibility Rules for FM Broadcast Translator Stations, Fourth Report and Order and Third Order on...

Plasmon-enhanced versatile optical nonlinearities in a Au-Ag-Au multi-segmental hybrid structure.

PubMed

Yao, Lin-Hua; Zhang, Jun-Pei; Dai, Hong-Wei; Wang, Ming-Shan; Zhang, Lu-Man; Wang, Xia; Han, Jun-Bo

2018-06-27

A Au-Ag-Au multi-segmental hybrid structure has been synthesized by using an electrodeposition method based on an anodic aluminum oxide (AAO) membrane. The third-order optical nonlinearities, second harmonic generation (SHG) and photoluminescence (PL) properties containing ultrafast supercontinuum generation and plasmon mediated thermal emission have been investigated. Significant optical enhancements have been obtained near surface plasmon resonance wavelength in all the abovementioned nonlinear processes. Comparative studies between the Au-Ag-Au multi-segmental hybrid structure and the corresponding single-component Au and Ag hybrid structures demonstrate that the Au-Ag-Au multi-segmental hybrid structure has much larger optical nonlinearities than its counterparts. These results demonstrate that the Au-Ag-Au hybrid structure is a promising candidate for applications in plasmonic devices and enhancement substrates.

Structure Function Scaling Exponent and Intermittency in the Wake of a Wind Turbine Array

NASA Astrophysics Data System (ADS)

Aseyev, Aleksandr; Ali, Naseem; Cal, Raul

2015-11-01

Hot-wire measurements obtained in a 3 × 3 wind turbine array boundary layer are utilized to analyze high order structure functions, intermittency effects as well as the probability density functions of velocity increments at different scales within the energy cascade. The intermittency exponent is found to be greater in the far wake region in comparison to the near wake. At hub height, the intermittency exponent is found to be null. ESS scaling exponents of the second, fourth, and fifth order structure functions remain relatively constant as a function of height in the far-wake whereas in the near-wake these highly affected by the passage of the rotor thus showing a dependence on physical location. When comparing with proposed models, these generally over predict the structure functions in the far wake region. The pdf distributions in the far wake region display wider tails compared to the near wake region, and constant skewness hypothesis based on the local isotropy is verified in the wake. CBET-1034581.

Leaf litter breakdown, microbial respiration and shredder production in metal-polluted streams

USGS Publications Warehouse

Carlisle, D.M.; Clements, W.H.

2005-01-01

1. If species disproportionately influence ecosystem functioning and also differ in their sensitivities to environmental conditions, the selective removal of species by anthropogenic stressors may lead to strong effects on ecosystem processes. We evaluated whether these circumstances held for several Colorado, U.S.A. streams stressed by Zn. 2. Benthic invertebrates and chemistry were sampled in five second-third order streams for 1 year. Study streams differed in dissolved metal concentrations, but were otherwise similar in chemical and physical characteristics. Secondary production of leaf-shredding insects was estimated using the increment summation and size-frequency methods. Leaf litter breakdown rates were estimated by retrieving litter-bags over a 171 day period. Microbial activity on leaf litter was measured in the laboratory using changes in oxygen concentration over a 48 h incubation period. 3. Dissolved Zn concentrations varied eightfold among two reference and three polluted streams. Total secondary production of shredders was negatively associated with metal contamination. Secondary production in reference streams was dominated by Taenionema pallidum. Results of previous studies and the current investigation demonstrate that this shredder is highly sensitive to metals in Colorado headwater streams. Leaf litter breakdown rates were similar between reference streams and declined significantly in the polluted streams. Microbial respiration at the most contaminated site was significantly lower than at reference sites. 4. Our results supported the hypothesis that some shredder species contribute disproportionately to leaf litter breakdown. Furthermore, the functionally dominant taxon was also the most sensitive to metal contamination. We conclude that leaf litter breakdown in our study streams lacked functional redundancy and was therefore highly sensitive to contaminant-induced alterations in community structure. We argue for the necessity of simultaneously measuring community structure and ecosystem function in anthropogenically stressed ecosystems.

Dependence of the correlated-momentum patterns in double ionization on the carrier-envelope phase and intensity of a few-cycle laser pulse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xin, G. G.; Ye, D. F.; Graduate School, China Academy of Engineering Physics, Beijing 100088

2010-12-15

In the present paper, we investigate the correlated electron emission of atoms irradiated by a few-cycle laser pulse, with emphasis on the correlated longitudinal momentum spectra. We find that the spectra show clear v-shaped structures, in analogy to what was observed recently in long-pulse experiments. Moreover, the patterns of the spectra depend sensitively on the carrier-envelope phase as well as the laser intensity. The v-shaped structure is more pronounced at lower and higher intensities and becomes obscure at medium intensity. At a lower intensity, upon change of the phase from 0 to {pi}/2, the v-shaped structure shifts from the firstmore » quadrant to the third quadrant and the ratios between the double ionization yields in the first and third quadrants are found to increase by a few orders of magnitude. The semiclassical rescattering model is exploited in the preceding calculations and the underlying mechanisms are uncovered by analyzing the subcycle dynamics of classical trajectories.« less

76 FR 78613 - Furfuryl Alcohol From the People's Republic of China: Final Results of Expedited Third Sunset...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-19

... People's Republic of China: Final Results of Expedited Third Sunset Review of the Antidumping Duty Order... September 1, 2011, the Department of Commerce (``Department'') initiated the third five-year (``sunset'') review of the antidumping duty order on furfuryl alcohol from the People's Republic of China (``PRC...

Galilean-invariant preconditioned central-moment lattice Boltzmann method without cubic velocity errors for efficient steady flow simulations

NASA Astrophysics Data System (ADS)

Hajabdollahi, Farzaneh; Premnath, Kannan N.

2018-05-01

Lattice Boltzmann (LB) models used for the computation of fluid flows represented by the Navier-Stokes (NS) equations on standard lattices can lead to non-Galilean-invariant (GI) viscous stress involving cubic velocity errors. This arises from the dependence of their third-order diagonal moments on the first-order moments for standard lattices, and strategies have recently been introduced to restore Galilean invariance without such errors using a modified collision operator involving corrections to either the relaxation times or the moment equilibria. Convergence acceleration in the simulation of steady flows can be achieved by solving the preconditioned NS equations, which contain a preconditioning parameter that can be used to tune the effective sound speed, and thereby alleviating the numerical stiffness. In the present paper, we present a GI formulation of the preconditioned cascaded central-moment LB method used to solve the preconditioned NS equations, which is free of cubic velocity errors on a standard lattice, for steady flows. A Chapman-Enskog analysis reveals the structure of the spurious non-GI defect terms and it is demonstrated that the anisotropy of the resulting viscous stress is dependent on the preconditioning parameter, in addition to the fluid velocity. It is shown that partial correction to eliminate the cubic velocity defects is achieved by scaling the cubic velocity terms in the off-diagonal third-order moment equilibria with the square of the preconditioning parameter. Furthermore, we develop additional corrections based on the extended moment equilibria involving gradient terms with coefficients dependent locally on the fluid velocity and the preconditioning parameter. Such parameter dependent corrections eliminate the remaining truncation errors arising from the degeneracy of the diagonal third-order moments and fully restore Galilean invariance without cubic defects for the preconditioned LB scheme on a standard lattice. Several conclusions are drawn from the analysis of the structure of the non-GI errors and the associated corrections, with particular emphasis on their dependence on the preconditioning parameter. The GI preconditioned central-moment LB method is validated for a number of complex flow benchmark problems and its effectiveness to achieve convergence acceleration and improvement in accuracy is demonstrated.

Soliton structure versus singularity analysis: Third-order completely intergrable nonlinear differential equations in 1 + 1-dimensions

NASA Astrophysics Data System (ADS)

Fuchssteiner, Benno; Carillo, Sandra

1989-01-01

Bäcklund transformations between all known completely integrable third-order differential equations in (1 + 1)-dimensions are established and the corresponding transformations formulas for their hereditary operators and Hamiltonian formulations are exhibited. Some of these Bäcklund transformations are not injective; therefore additional non-commutative symmetry groups are found for some equations. These non-commutative symmetry groups are classified as having a semisimple part isomorphic to the affine algebra A(1)1. New completely integrable third-order integro-differential equations, some depending explicitly on x, are given. These new equations give rise to nonin equation. Connections between the singularity equations (from the Painlevé analysis) and the nonlinear equations for interacting solitons are established. A common approach to singularity analysis and soliton structure is introduced. The Painlevé analysis is modified in such a sense that it carries over directly and without difficulty to the time evolution of singularity manifolds of equations like the sine-Gordon and nonlinear Schrödinger equation. A method to recover the Painlevé series from its constant level term is exhibit. The soliton-singularity transform is recognized to be connected to the Möbius group. This gives rise to a Darboux-like result for the spectral properties of the recursion operator. These connections are used in order to explain why poles of soliton equations move like trajectories of interacting solitons. Furthermore it is explicitly computed how solitons of singularity equations behave under the effect of this soliton-singularity transform. This then leads to the result that only for scaling degrees α = -1 and α = -2 the usual Painlevé analysis can be carried out. A new invariance principle, connected to kernels of differential operators is discovered. This new invariance, for example, connects the explicit solutions of the Liouville equation with the Miura transform. Simple methods are exhibited which allow to compute out of N-soliton solutions of the KdV (Bargman potentials) explicit solutions of equations like the Harry Dym equation. Certain solutions are plotted.

Electronic resonances in broadband stimulated Raman spectroscopy

NASA Astrophysics Data System (ADS)

Batignani, G.; Pontecorvo, E.; Giovannetti, G.; Ferrante, C.; Fumero, G.; Scopigno, T.

2016-01-01

Spontaneous Raman spectroscopy is a formidable tool to probe molecular vibrations. Under electronic resonance conditions, the cross section can be selectively enhanced enabling structural sensitivity to specific chromophores and reaction centers. The addition of an ultrashort, broadband femtosecond pulse to the excitation field allows for coherent stimulation of diverse molecular vibrations. Within such a scheme, vibrational spectra are engraved onto a highly directional field, and can be heterodyne detected overwhelming fluorescence and other incoherent signals. At variance with spontaneous resonance Raman, however, interpreting the spectral information is not straightforward, due to the manifold of field interactions concurring to the third order nonlinear response. Taking as an example vibrational spectra of heme proteins excited in the Soret band, we introduce a general approach to extract the stimulated Raman excitation profiles from complex spectral lineshapes. Specifically, by a quantum treatment of the matter through density matrix description of the third order nonlinear polarization, we identify the contributions which generate the Raman bands, by taking into account for the cross section of each process.

Localised Nonlinear Waves in the Three-Component Coupled Hirota Equations

NASA Astrophysics Data System (ADS)

Xu, Tao; Chen, Yong

2017-10-01

We construct the Lax pair and Darboux transformation for the three-component coupled Hirota equations including higher-order effects such as third-order dispersion, self-steepening, and stimulated Raman scattering. A special vector solution of the Lax pair with 4×4 matrices for the three-component Hirota system is elaborately generated, based on this vector solution, various types of mixed higher-order localised waves are derived through the generalised Darboux transformation. Instead of considering various arrangements of the three potential functions q1, q2, and q3, here, the same combination is considered as the same type solution. The first- and second-order localised waves are mainly discussed in six mixed types: (1) the hybrid solutions degenerate to the rational ones and three components are all rogue waves; (2) two components are hybrid solutions between rogue wave (RW) and breather (RW+breather), and one component is interactional solution between RW and dark soliton (RW+dark soliton); (3) two components are RW+dark soliton, and one component is RW+bright soliton; (4) two components are RW+breather, and one component is RW+bright soliton; (5) two components are RW+dark soliton, and one component is RW+bright soliton; (6) three components are all RW+breather. Moreover, these nonlinear localised waves merge with each other by increasing the absolute values of two free parameters α, β. These results further uncover some striking dynamic structures in the multicomponent coupled system.

Allosteric control in a metalloprotein dramatically alters function

PubMed Central

Baxter, Elizabeth Leigh; Zuris, John A.; Wang, Charles; Vo, Phu Luong T.; Axelrod, Herbert L.; Cohen, Aina E.; Paddock, Mark L.; Nechushtai, Rachel; Onuchic, Jose N.; Jennings, Patricia A.

2013-01-01

Metalloproteins (MPs) comprise one-third of all known protein structures. This diverse set of proteins contain a plethora of unique inorganic moieties capable of performing chemistry that would otherwise be impossible using only the amino acids found in nature. Most of the well-studied MPs are generally viewed as being very rigid in structure, and it is widely thought that the properties of the metal centers are primarily determined by the small fraction of amino acids that make up the local environment. Here we examine both theoretically and experimentally whether distal regions can influence the metal center in the diabetes drug target mitoNEET. We demonstrate that a loop (L2) 20 Å away from the metal center exerts allosteric control over the cluster binding domain and regulates multiple properties of the metal center. Mutagenesis of L2 results in significant shifts in the redox potential of the [2Fe-2S] cluster and orders of magnitude effects on the rate of [2Fe-2S] cluster transfer to an apo-acceptor protein. These surprising effects occur in the absence of any structural changes. An examination of the native basin dynamics of the protein using all-atom simulations shows that twisting in L2 controls scissoring in the cluster binding domain and results in perturbations to one of the cluster-coordinating histidines. These allosteric effects are in agreement with previous folding simulations that predicted L2 could communicate with residues surrounding the metal center. Our findings suggest that long-range dynamical changes in the protein backbone can have a significant effect on the functional properties of MPs. PMID:23271805

Spatial and successional dynamics of microbial biofilm communities in a grassland stream ecosystem

DOE PAGES

Veach, Allison M.; Stegen, James C.; Brown, Shawn P.; ...

2016-09-06

Biofilms represent a metabolically active and structurally complex component of freshwater ecosystems. Ephemeral prairie streams are hydrologically harsh and prone to frequent perturbation. Elucidating both functional and structural community changes over time within prairie streams provides a general understanding of microbial responses to environmental disturbance. In this study, we examined microbial succession of biofilm communities at three sites in a third-order stream at Konza Prairie over a 2- to 64-day period. Microbial abundance (bacterial abundance, chlorophyll a concentrations) increased and never plateaued during the experiment. Net primary productivity (net balance of oxygen consumption and production) of the developing biofilms didmore » not differ statistically from zero until 64 days suggesting a balance of the use of autochthonous and allochthonous energy sources until late succession. Bacterial communities (MiSeq analyses of the V4 region of 16S rRNA) established quickly. Bacterial richness, diversity and evenness were high after 2 days and increased over time. Several dominant bacterial phyla (Beta-, Alphaproteobacteria, Bacteroidetes, Gemmatimonadetes, Acidobacteria, Chloroflexi) and genera ( Luteolibacter, Flavobacterium, Gemmatimonas, Hydrogenophaga) differed in relative abundance over space and time. Bacterial community composition differed across both space and successional time. Pairwise comparisons of phylogenetic turnover in bacterial community composition indicated that early-stage succession (≤16 days) was driven by stochastic processes, whereas later stages were driven by deterministic selection regardless of site. Finally, our data suggest that microbial biofilms predictably develop both functionally and structurally indicating distinct successional trajectories of bacterial communities in this ecosystem.« less

Spatial and successional dynamics of microbial biofilm communities in a grassland stream ecosystem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Veach, Allison M.; Stegen, James C.; Brown, Shawn P.

Biofilms represent a metabolically active and structurally complex component of freshwater ecosystems. Ephemeral prairie streams are hydrologically harsh and prone to frequent perturbation. Elucidating both functional and structural community changes over time within prairie streams provides a general understanding of microbial responses to environmental disturbance. In this study, we examined microbial succession of biofilm communities at three sites in a third-order stream at Konza Prairie over a 2- to 64-day period. Microbial abundance (bacterial abundance, chlorophyll a concentrations) increased and never plateaued during the experiment. Net primary productivity (net balance of oxygen consumption and production) of the developing biofilms didmore » not differ statistically from zero until 64 days suggesting a balance of the use of autochthonous and allochthonous energy sources until late succession. Bacterial communities (MiSeq analyses of the V4 region of 16S rRNA) established quickly. Bacterial richness, diversity and evenness were high after 2 days and increased over time. Several dominant bacterial phyla (Beta-, Alphaproteobacteria, Bacteroidetes, Gemmatimonadetes, Acidobacteria, Chloroflexi) and genera ( Luteolibacter, Flavobacterium, Gemmatimonas, Hydrogenophaga) differed in relative abundance over space and time. Bacterial community composition differed across both space and successional time. Pairwise comparisons of phylogenetic turnover in bacterial community composition indicated that early-stage succession (≤16 days) was driven by stochastic processes, whereas later stages were driven by deterministic selection regardless of site. Finally, our data suggest that microbial biofilms predictably develop both functionally and structurally indicating distinct successional trajectories of bacterial communities in this ecosystem.« less

Synthesis, crystal structure and growth of a new inorganic- organic hybrid compound for nonlinear optical applications: Aquadiiodo (3-aminopropanoic acid) cadmium (II)

NASA Astrophysics Data System (ADS)

Boopathi, K.; Babu, S. Moorthy; Jagan, R.; Ramasamy, P.

2017-12-01

The new inorganic-organic hybrid material aquadiiodo (3-aminopropanoic acid) cadmium (II) [ADI (3-AP) Cd] has been successfully synthesized and good quality crystals have been grown by slow evaporation solution technique. The structure was determined by single crystal X-ray diffraction at room temperature. The compound crystallizes in monoclinic crystal system with centro symmetric space group P21/c and four molecules in the unit cell. The structure of the title compound was further confirmed by 1H and 13C nuclear magnetic resonance spectral analysis. FT-IR spectroscopy was used to confirm the presence of various functional groups in the compound. The transmittance and optical parameters of the crystal were studied by UV- Visible-NIR spectroscopy. The thermal stability of the grown crystal was evaluated using thermogravimetric and differential thermal analyses. Mechanical hardness has been identified by Vickers micro hardness study and work hardening coefficient was calculated. Dielectric measurement was carried out as a function of frequency and results are discussed. The growth mechanism of the crystal was assessed by chemical etching studies. The third-order nonlinear optical susceptibility of [ADI (3-AP) Cd] was derived using the Z-scan technique, and it was 3.24955 × 10-8 esu. The positive nonlinear refractive index 2.48505 × 10-11 m2/W, is an indication of self-defocusing optical nonlinearity of the sample. It is believed that the [ADI (3-AP) Cd] is a promising new candidate for developing efficient nonlinear optical and optical power limiting devices.

Transcriptional Signatures in Response to Wheat Germ Agglutinin and Starvation in Drosophila melanogaster Larval Midgut

USDA-ARS?s Scientific Manuscript database

One function of plant lectins such as wheat germ agglutinin (WGA) is to serve as defenses against herbivorous insects. The midgut is one critical site affected by dietary lectins. We observed marked cellular, structural, and gene expression changes in the midguts of Drosophila melanogaster third-i...

Thermodynamic properties of diamond and wurtzite model fluids from computer simulation and thermodynamic perturbation theory

NASA Astrophysics Data System (ADS)

Zhou, S.; Solana, J. R.

2018-03-01

Monte Carlo NVT simulations have been performed to obtain the thermodynamic and structural properties and perturbation coefficients up to third order in the inverse temperature expansion of the Helmholtz free energy of fluids with potential models proposed in the literature for diamond and wurtzite lattices. These data are used to analyze performance of a coupling parameter series expansion (CPSE). The main findings are summarized as follows, (1) The CPSE provides accurate predictions of the first three coefficient in the inverse temperature expansion of Helmholtz free energy for the potential models considered and the thermodynamic properties of these fluids are predicted more accurately when the CPSE is truncated at second or third order. (2) The Barker-Henderson (BH) recipe is appropriate for determining the effective hard sphere diameter for strongly repulsive potential cores, but its performance worsens with increasing the softness of the potential core. (3) For some thermodynamic properties the first-order CPSE works better for the diamond potential, whose tail is dominated by repulsive interactions, than for the potential, whose tail is dominated by attractive interactions. However, the first-order CPSE provides unsatisfactory results for the excess internal energy and constant-volume excess heat capacity for the two potential models.

Efficient optical nonlinear Langmuir-Blodgett films: roles of matrix molecules

NASA Astrophysics Data System (ADS)

Ma, Shihong; Lu, Xingze; Liu, Liying; Han, Kui; Wang, Wencheng; Zhang, Zhi-Ming

1996-10-01

A novel bifat-chain amphiphilic molecule nitrogencrown (NC) was adopted as an inert material for fabrication of optical nonlinear Langmuir-Blodgett (LB) multilayers. Structural improvement in the Z-type mixed fullerene derivative (C60-Be)/NC LB multilayers samples was realized by insertion of the C60-Be molecules between two hydrophobic chains of the NC molecules. The relatively large third-order susceptibility (chi) (3)xxxx(- 3(omega) ;(omega) ,(omega) ,(omega) ) equals 2.9 multiplied by 10-19 M2V-2 (or 2.1 multiplied by 10-11 esu) was deduced by measuring third harmonic generation (THG) from the C60-Be samples. The second harmonic generation (SHG) intensity increased quadratically with the bilayer number (up to 116 bilayers) in Y-type hemicyanine (HEM)/NC interleaving LB multilayers due to improvement of the structural properties by insertion of the long hydrophobic tail of HEM molecules between two chains of NC molecules. The second-order susceptibility (chi) (2)zxx(-2(omega) ;(omega) ,(omega) ) equals 18 pM V-1 (or 4.35 multiplied by 10-8 esu) was obtained by measuring SHG from the HEM samples. The NC molecule has attractive features as a matrix material in fabrications of LB multilayers made from optically nonlinear materials with hydrophobic long tails or ball-like molecules.

Zn doped CdO thin films with enhanced linear and third order nonlinear optical properties for optoelectronic applications

NASA Astrophysics Data System (ADS)

Bairy, Raghavendra; Jayarama, A.; Shivakumar, G. K.; Patil, P. S.; Bhat, K. Udaya

2018-04-01

Thin films of undoped and zinc doped CdO have been deposited on glass substrate using spray pyrolysis technique with various dopant concentrations of Zn such as 1, 5 and 10%. Influence of Zn doping on CdO thin films for the structural, morphological, optical and nonlinear optical properties are reported. XRD analysis reveals that as prepared pure and Zn doped CdO films show polycrystalline nature with face centered cubic structure. Also, Zn doping does not significantly modify the crystallinity and not much increase in the crystallite size of the film. SEM images shows grains which are uniform and grain size with increase in dopant concentration. The transmittance of the prepared CdO films recorded in the UV visible spectra and it shows 50 to 60% in the visible region. The estimated optical band gap increases from 2.60 to 2.70 eV for various dopant concentrations. The nonlinear optical absorption of Zn-doped CdO films have been measured used the Z-scan technique at a wavelength 532 nm. The nonlinear optical absorption coefficient (β), nonlinear refractive index (n2) and the third order nonlinear optical susceptibility (χ(3)) of the pure and Zn doped films were determined.

Extension of relativistic dissipative hydrodynamics to third order

DOE Office of Scientific and Technical Information (OSTI.GOV)

El, Andrej; Xu Zhe; Greiner, Carsten

2010-04-15

Following the procedure introduced by Israel and Stewart, we expand the entropy current up to the third order in the shear stress tensor pi{sup a}lpha{sup b}eta and derive a novel third-order evolution equation for pi{sup a}lpha{sup b}eta. This equation is solved for the one-dimensional Bjorken boost-invariant expansion. The scaling solutions for various values of the shear viscosity to the entropy density ratio eta/s are shown to be in very good agreement with those obtained from kinetic transport calculations. For the pressure isotropy starting with 1 at tau{sub 0}=0.4 fm/c, the third-order corrections to Israel-Stewart theory are approximately 10% for eta/s=0.2more » and more than a factor of 2 for eta/s=3. We also estimate all higher-order corrections to Israel-Stewart theory and demonstrate their importance in describing highly viscous matters.« less

Estimation of Supersonic Stage Separation Aerodynamics of Winged-Body Launch Vehicles Using Response Surface Methods

NASA Technical Reports Server (NTRS)

Erickson, Gary E.

2010-01-01

Response surface methodology was used to estimate the longitudinal stage separation aerodynamic characteristics of a generic, bimese, winged multi-stage launch vehicle configuration at supersonic speeds in the NASA LaRC Unitary Plan Wind Tunnel. The Mach 3 staging was dominated by shock wave interactions between the orbiter and booster vehicles throughout the relative spatial locations of interest. The inference space was partitioned into several contiguous regions within which the separation aerodynamics were presumed to be well-behaved and estimable using central composite designs capable of fitting full second-order response functions. The underlying aerodynamic response surfaces of the booster vehicle in belly-to-belly proximity to the orbiter vehicle were estimated using piecewise-continuous lower-order polynomial functions. The quality of fit and prediction capabilities of the empirical models were assessed in detail, and the issue of subspace boundary discontinuities was addressed. Augmenting the central composite designs to full third-order using computer-generated D-optimality criteria was evaluated. The usefulness of central composite designs, the subspace sizing, and the practicality of fitting lower-order response functions over a partitioned inference space dominated by highly nonlinear and possibly discontinuous shock-induced aerodynamics are discussed.

Student Solution Manual for Mathematical Methods for Physics and Engineering Third Edition

NASA Astrophysics Data System (ADS)

Riley, K. F.; Hobson, M. P.

2006-03-01

Preface; 1. Preliminary algebra; 2. Preliminary calculus; 3. Complex numbers and hyperbolic functions; 4. Series and limits; 5. Partial differentiation; 6. Multiple integrals; 7. Vector algebra; 8. Matrices and vector spaces; 9. Normal modes; 10. Vector calculus; 11. Line, surface and volume integrals; 12. Fourier series; 13. Integral transforms; 14. First-order ordinary differential equations; 15. Higher-order ordinary differential equations; 16. Series solutions of ordinary differential equations; 17. Eigenfunction methods for differential equations; 18. Special functions; 19. Quantum operators; 20. Partial differential equations: general and particular; 21. Partial differential equations: separation of variables; 22. Calculus of variations; 23. Integral equations; 24. Complex variables; 25. Application of complex variables; 26. Tensors; 27. Numerical methods; 28. Group theory; 29. Representation theory; 30. Probability; 31. Statistics.

Structural habitat predicts functional dispersal habitat of a large carnivore: how leopards change spots.

PubMed

Fattebert, Julien; Robinson, Hugh S; Balme, Guy; Slotow, Rob; Hunter, Luke

2015-10-01

Natal dispersal promotes inter-population linkage, and is key to spatial distribution of populations. Degradation of suitable landscape structures beyond the specific threshold of an individual's ability to disperse can therefore lead to disruption of functional landscape connectivity and impact metapopulation function. Because it ignores behavioral responses of individuals, structural connectivity is easier to assess than functional connectivity and is often used as a surrogate for landscape connectivity modeling. However using structural resource selection models as surrogate for modeling functional connectivity through dispersal could be erroneous. We tested how well a second-order resource selection function (RSF) models (structural connectivity), based on GPS telemetry data from resident adult leopard (Panthera pardus L.), could predict subadult habitat use during dispersal (functional connectivity). We created eight non-exclusive subsets of the subadult data based on differing definitions of dispersal to assess the predictive ability of our adult-based RSF model extrapolated over a broader landscape. Dispersing leopards used habitats in accordance with adult selection patterns, regardless of the definition of dispersal considered. We demonstrate that, for a wide-ranging apex carnivore, functional connectivity through natal dispersal corresponds to structural connectivity as modeled by a second-order RSF. Mapping of the adult-based habitat classes provides direct visualization of the potential linkages between populations, without the need to model paths between a priori starting and destination points. The use of such landscape scale RSFs may provide insight into predicting suitable dispersal habitat peninsulas in human-dominated landscapes where mitigation of human-wildlife conflict should be focused. We recommend the use of second-order RSFs for landscape conservation planning and propose a similar approach to the conservation of other wide-ranging large carnivore species where landscape-scale resource selection data already exist.

Cost-effective accurate coarse-grid method for highly convective multidimensional unsteady flows

NASA Technical Reports Server (NTRS)

Leonard, B. P.; Niknafs, H. S.

1991-01-01

A fundamentally multidimensional convection scheme is described based on vector transient interpolation modeling rewritten in conservative control-volume form. Vector third-order upwinding is used as the basis of the algorithm; this automatically introduces important cross-difference terms that are absent from schemes using component-wise one-dimensional formulas. Third-order phase accuracy is good; this is important for coarse-grid large-eddy or full simulation. Potential overshoots or undershoots are avoided by using a recently developed universal limiter. Higher order accuracy is obtained locally, where needed, by the cost-effective strategy of adaptive stencil expansion in a direction normal to each control-volume face; this is controlled by monitoring the absolute normal gradient and curvature across the face. Higher (than third) order cross-terms do not appear to be needed. Since the wider stencil is used only in isolated narrow regions (near discontinuities), extremely high (in this case, seventh) order accuracy can be achieved for little more than the cost of a globally third-order scheme.

Decrease and enhancement of third-order optical nonlinearity in metal-dielectric composite films

NASA Astrophysics Data System (ADS)

Ning, Tingyin; Lu, Heng; Zhou, Yueliang; Man, Baoyuan

2018-04-01

We investigate third-order optical nonlinearity in gold nanoparticles embedded in CaCu3Ti4O12 (CCTO) films using the Z-scan method. We observe that the effective third-order nonlinear optical susceptibilities in such composite films can not only be enhanced, in line with the conventional behavior, but also be decreased, depending on the volume concentration of gold. In particular, the nonlinear absorption behavior can be changed from saturable absorption in pure CCTO films to reversed saturable absorption in composite films, and theoretically, even zero nonlinear absorption could be obtained. These results indicate that it should be possible to tune the third-order optical nonlinearity in Au:CCTO composite films by altering the gold concentration, thus making them suitable for applications in photonic devices.

An adaptive learning control system for large flexible structures

NASA Technical Reports Server (NTRS)

Thau, F. E.

1985-01-01

The objective of the research has been to study the design of adaptive/learning control systems for the control of large flexible structures. In the first activity an adaptive/learning control methodology for flexible space structures was investigated. The approach was based on using a modal model of the flexible structure dynamics and an output-error identification scheme to identify modal parameters. In the second activity, a least-squares identification scheme was proposed for estimating both modal parameters and modal-to-actuator and modal-to-sensor shape functions. The technique was applied to experimental data obtained from the NASA Langley beam experiment. In the third activity, a separable nonlinear least-squares approach was developed for estimating the number of excited modes, shape functions, modal parameters, and modal amplitude and velocity time functions for a flexible structure. In the final research activity, a dual-adaptive control strategy was developed for regulating the modal dynamics and identifying modal parameters of a flexible structure. A min-max approach was used for finding an input to provide modal parameter identification while not exceeding reasonable bounds on modal displacement.

Comparison of measured and computed Strehl ratios for light propagated through a channel flow of a He N 2 mixing layer at high Reynolds numbers

NASA Astrophysics Data System (ADS)

Gardner, Patrick J.; Roggemann, Michael C.; Welsh, Byron M.; Bowersox, Rodney D.; Luke, Theodore E.

1997-04-01

A lateral shearing interferometer was used to measure the slope of perturbed wave fronts after they propagated through a He N 2 mixing layer in a rectangular channel. Slope measurements were used to reconstruct the phase of the turbulence-corrupted wave front. The random phase fluctuations induced by the mixing layer were captured in a large ensemble of wave-front measurements. Phase structure functions, computed from the reconstructed phase surfaces, were stationary in first increments. A five-thirds power law is shown to fit streamwise and cross-stream slices of the structure function, analogous to the Kolmogorov model for isotropic turbulence, which describes the structure function with a single parameter. Strehl ratios were computed from the phase structure functions and compared with a measured experiment obtained from simultaneous point-spread function measurements. Two additional Strehl ratios were calculated by using classical estimates that assume statistical isotropy throughout the flow. The isotropic models are a reasonable estimate of the optical degradation only within a few centimeters of the initial mixing, where the Reynolds number is low. At higher Reynolds numbers, Strehl ratios calculated from the structure functions match the experiment much better than Strehl ratio calculations that assume isotropic flow.

Random regression models using Legendre polynomials or linear splines for test-day milk yield of dairy Gyr (Bos indicus) cattle.

PubMed

Pereira, R J; Bignardi, A B; El Faro, L; Verneque, R S; Vercesi Filho, A E; Albuquerque, L G

2013-01-01

Studies investigating the use of random regression models for genetic evaluation of milk production in Zebu cattle are scarce. In this study, 59,744 test-day milk yield records from 7,810 first lactations of purebred dairy Gyr (Bos indicus) and crossbred (dairy Gyr × Holstein) cows were used to compare random regression models in which additive genetic and permanent environmental effects were modeled using orthogonal Legendre polynomials or linear spline functions. Residual variances were modeled considering 1, 5, or 10 classes of days in milk. Five classes fitted the changes in residual variances over the lactation adequately and were used for model comparison. The model that fitted linear spline functions with 6 knots provided the lowest sum of residual variances across lactation. On the other hand, according to the deviance information criterion (DIC) and bayesian information criterion (BIC), a model using third-order and fourth-order Legendre polynomials for additive genetic and permanent environmental effects, respectively, provided the best fit. However, the high rank correlation (0.998) between this model and that applying third-order Legendre polynomials for additive genetic and permanent environmental effects, indicates that, in practice, the same bulls would be selected by both models. The last model, which is less parameterized, is a parsimonious option for fitting dairy Gyr breed test-day milk yield records. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Further efforts in optimizing nonlinear optical molecules

NASA Astrophysics Data System (ADS)

Dirk, Carl W.; Caballero, Noel; Tan, Alarice; Kuzyk, Mark G.; Cheng, Lap-Tak A.; Katz, Howard E.; Shilling, Marcia; King, Lori A.

1993-02-01

We summarize some of our past work in the field on optimizing molecules for second order and third order nonlinear optical applications. We also present some previously unpublished results suggesting a particular optimization of the popular cyano- and nitrovinyl acceptor groups. In addition we provide some new quadratic electro-optic results which serve to further verify our choice of a restricted three-level model suitable for optimizing third order nonlinearities in molecules. Finally we present a new squarylium dye with a large third order optical nonlinearity (-9.5 X 10-34 cm7/esu2; EFISH (gamma) at 1906 nm).

Exploration of Uncharted Regions of the Protein Universe

PubMed Central

Jaroszewski, Lukasz; Li, Zhanwen; Krishna, S. Sri; Bakolitsa, Constantina; Wooley, John; Deacon, Ashley M.; Wilson, Ian A.; Godzik, Adam

2009-01-01

The genome projects have unearthed an enormous diversity of genes of unknown function that are still awaiting biological and biochemical characterization. These genes, as most others, can be grouped into families based on sequence similarity. The PFAM database currently contains over 2,200 such families, referred to as domains of unknown function (DUF). In a coordinated effort, the four large-scale centers of the NIH Protein Structure Initiative have determined the first three-dimensional structures for more than 250 of these DUF families. Analysis of the first 248 reveals that about two thirds of the DUF families likely represent very divergent branches of already known and well-characterized families, which allows hypotheses to be formulated about their biological function. The remainder can be formally categorized as new folds, although about one third of these show significant substructure similarity to previously characterized folds. These results infer that, despite the enormous increase in the number and the diversity of new genes being uncovered, the fold space of the proteins they encode is gradually becoming saturated. The previously unexplored sectors of the protein universe appear to be primarily shaped by extreme diversification of known protein families, which then enables organisms to evolve new functions and adapt to particular niches and habitats. Notwithstanding, these DUF families still constitute the richest source for discovery of the remaining protein folds and topologies. PMID:19787035

A degree scale anisotropy measurement of the cosmic microwave background near the star Gamma Ursae Minoris

NASA Technical Reports Server (NTRS)

Gundersen, J. O.; Clapp, A. C.; Devlin, M.; Holmes, W.; Fischer, M. L.; Meinhold, P. R.; Lange, A. E.; Lubin, P. M.; Richards, P. L.; Smoot, G. F.

1993-01-01

Results from a search for anisotropy in the cosmic microwave background (CMB) are presented from the third flight of the Millimeter-wave Anisotropy experiment. The CMB observation occurred over 1.37 hours and covered a 6.24 sq deg area of the sky where very little foreground emission is expected. Significant correlated structure is observed at 6 and 9/cm. At 12/cm we place an upper limit on the structure. The relative amplitudes at 6, 9, and 12/cm are consistent with a CMB spectrum. The spectrum of the structure is inconsistent with thermal emission from known forms of interstellar dust. Synchrotron and free-free emission would both require unusually flat spectral indices at cm wavelengths in order to account for the amplitude of the observed structure. Although known systematic errors are not expected to contribute significantly to any of the three optical channels, excess sidelobe contamination cannot be definitively ruled out. If all the structure is attributed to CMB anisotropy, a value of the weighted rms of the 6 and 9/cm channels of Delta T/T(CMB) = 4.7 +/- 0.8 x 10 exp -5 (+/- 1 sigma) was measured. If the CMB anisotropy is assumed to have a Gaussian autocorrelation function with a coherence angle of 25 arcmin, then the most probable value is Delta T/T(CMB) = 4.2 +1.7 or -1.1 x 10 exp -5, where the +/- refers to the 95 percent confidence limits.

Optical nonclassicality test based on third-order intensity correlations

NASA Astrophysics Data System (ADS)

Rigovacca, L.; Kolthammer, W. S.; Di Franco, C.; Kim, M. S.

2018-03-01

We develop a nonclassicality criterion for the interference of three delayed, but otherwise identical, light fields in a three-mode Bell interferometer. We do so by comparing the prediction of quantum mechanics with those of a classical framework in which independent sources emit electric fields with random phases. In particular, we evaluate third-order correlations among output intensities as a function of the delays, and show how the presence of a correlation revival for small delays cannot be explained by the classical model of light. The observation of a revival is thus a nonclassicality signature, which can be achieved only by sources with a photon-number statistics that is highly sub-Poissonian. Our analysis provides strong evidence for the nonclassicality of the experiment discussed by Menssen et al. [Phys. Rev. Lett. 118, 153603 (2017), 10.1103/PhysRevLett.118.153603], and shows how a collective "triad" phase affects the interference of any three or more light fields, irrespective of their quantum or classical character.

Raman Microscopy: A Noninvasive Method to Visualize the Localizations of Biomolecules in the Cornea.

PubMed

Kaji, Yuichi; Akiyama, Toshihiro; Segawa, Hiroki; Oshika, Tetsuro; Kano, Hideaki

2017-11-01

In vivo and in situ visualization of biomolecules without pretreatment will be important for diagnosis and treatment of ocular disorders in the future. Recently, multiphoton microscopy, based on the nonlinear interactions between molecules and photons, has been applied to reveal the localizations of various molecules in tissues. We aimed to use multimodal multiphoton microscopy to visualize the localizations of specific biomolecules in rat corneas. Multiphoton images of the corneas were obtained from nonlinear signals of coherent anti-Stokes Raman scattering, third-order sum frequency generation, and second-harmonic generation. The localizations of the adhesion complex-containing basement membrane and Bowman layer were clearly visible in the third-order sum frequency generation images. The fine structure of type I collagen was observed in the corneal stroma in the second-harmonic generation images. The localizations of lipids, proteins, and nucleic acids (DNA/RNA) was obtained in the coherent anti-Stokes Raman scattering images. Imaging technologies have progressed significantly and been applied in medical fields. Optical coherence tomography and confocal microscopy are widely used but do not provide information on the molecular structure of the cornea. By contrast, multiphoton microscopy provides information on the molecular structure of living tissues. Using this technique, we successfully visualized the localizations of various biomolecules including lipids, proteins, and nucleic acids in the cornea. We speculate that multiphoton microscopy will provide essential information on the physiological and pathological conditions of the cornea, as well as molecular localizations in tissues without pretreatment.

Direct Observation of Quark-Hadron Duality in the Free Neutron {ital F}{sub 2} Structure Function

DOE PAGES

Niculescu, I.; Niculescu, G.; Melnitchouk, W.; ...

2015-05-21

Using the recently published data from the BONuS(Barely Off-shell Nucleon Structure) experiment at Jefferson Lab, which utilized a spectator tagging technique to extract the inclusive electron-free neutron scattering cross section, we obtain the first direct observation of quark-hadron duality in the neutron F-2 structure function. The data are used to reconstruct the lowest few (N = 2, 4, and 6) moments of F-2 in the three prominent nucleon resonance regions, as well as the moments integrated over the entire resonance region. Comparison with moments computed from global parametrizations of parton distribution functions suggest that quark-hadron duality holds locally for themore » neutron in the second and third resonance regions down to Q(2) approximate to 1 GeV2, with violations possibly up to 20% observed in the first resonance region.« less

Hydrogeomorphic connectivity on roads crossing in rural headwaters and its effect on stream dynamics.

PubMed

Thomaz, Edivaldo L; Peretto, Gustavo T

2016-04-15

Unpaved roads are ubiquitous features that have been transforming the landscape through human history. Unpaved roads affect the water and sediment pathways through a catchment and impacts the aquatic ecosystem. In this study, we describe the effect of unpaved road on the hydrogeomorphic connectivity at the rural headwater scale. Measurement was based on the stream crossing approach, i.e., road superimposing the drainage system. We installed a Parshall flume coupled with single-stage suspended sediment sampler at each stream crossing. In addition, we displayed our monitoring scheme with an upscaling perspective from second-order to third-order stream. We concluded that the road-stream coupling dramatically changed the stream dynamic. The increase of discharge caused by roads at the headwater was 50% larger compared to unaffected streams. Additionally, suspended sediment concentration enhancement at stream crossings ranged from to 413% at second-order streams to 145% at third-order streams. The landform characteristics associated with the road network produced an important hydrogeomorphic disruption in the landscape. As a result, the sediment filter function of the riparian zone was reduced dramatically. Therefore, we recommend that projects for aquatic system restoration or conservation in rural landscape consider the role of the road network on stream dynamics. Copyright © 2016 Elsevier B.V. All rights reserved.

Ion and impurity transport in turbulent, anisotropic magnetic fields

NASA Astrophysics Data System (ADS)

Negrea, M.; Petrisor, I.; Isliker, H.; Vogiannou, A.; Vlahos, L.; Weyssow, B.

2011-08-01

We investigate ion and impurity transport in turbulent, possibly anisotropic, magnetic fields. The turbulent magnetic field is modeled as a correlated stochastic field, with Gaussian distribution function and prescribed spatial auto-correlation function, superimposed onto a strong background field. The (running) diffusion coefficients of ions are determined in the three-dimensional environment, using two alternative methods, the semi-analytical decorrelation trajectory (DCT) method, and test-particle simulations. In a first step, the results of the test-particle simulations are compared with and used to validate the results obtained from the DCT method. For this purpose, a drift approximation was made in slab geometry, and relatively good qualitative agreement between the DCT method and the test-particle simulations was found. In a second step, the ion species He, Be, Ne and W, all assumed to be fully ionized, are considered under ITER-like conditions, and the scaling of their diffusivities is determined with respect to varying levels of turbulence (varying Kubo number), varying degrees of anisotropy of the turbulent structures and atomic number. In a third step, the test-particle simulations are repeated without drift approximation, directly using the Lorentz force, first in slab geometry, in order to assess the finite Larmor radius effects, and second in toroidal geometry, to account for the geometric effects. It is found that both effects are important, most prominently the effects due to toroidal geometry and the diffusivities are overestimated in slab geometry by an order of magnitude.

An analytical method for free vibration analysis of functionally graded beams with edge cracks

NASA Astrophysics Data System (ADS)

Wei, Dong; Liu, Yinghua; Xiang, Zhihai

2012-03-01

In this paper, an analytical method is proposed for solving the free vibration of cracked functionally graded material (FGM) beams with axial loading, rotary inertia and shear deformation. The governing differential equations of motion for an FGM beam are established and the corresponding solutions are found first. The discontinuity of rotation caused by the cracks is simulated by means of the rotational spring model. Based on the transfer matrix method, then the recurrence formula is developed to get the eigenvalue equations of free vibration of FGM beams. The main advantage of the proposed method is that the eigenvalue equation for vibrating beams with an arbitrary number of cracks can be conveniently determined from a third-order determinant. Due to the decrease in the determinant order as compared with previous methods, the developed method is simpler and more convenient to analytically solve the free vibration problem of cracked FGM beams. Moreover, free vibration analyses of the Euler-Bernoulli and Timoshenko beams with any number of cracks can be conducted using the unified procedure based on the developed method. These advantages of the proposed procedure would be more remarkable as the increase of the number of cracks. A comprehensive analysis is conducted to investigate the influences of the location and total number of cracks, material properties, axial load, inertia and end supports on the natural frequencies and vibration mode shapes of FGM beams. The present work may be useful for the design and control of damaged structures.

De Novo Proteins with Life-Sustaining Functions Are Structurally Dynamic.

PubMed

Murphy, Grant S; Greisman, Jack B; Hecht, Michael H

2016-01-29

Designing and producing novel proteins that fold into stable structures and provide essential biological functions are key goals in synthetic biology. In initial steps toward achieving these goals, we constructed a combinatorial library of de novo proteins designed to fold into 4-helix bundles. As described previously, screening this library for sequences that function in vivo to rescue conditionally lethal mutants of Escherichia coli (auxotrophs) yielded several de novo sequences, termed SynRescue proteins, which rescued four different E. coli auxotrophs. In an effort to understand the structural requirements necessary for auxotroph rescue, we investigated the biophysical properties of the SynRescue proteins, using both computational and experimental approaches. Results from circular dichroism, size-exclusion chromatography, and NMR demonstrate that the SynRescue proteins are α-helical and relatively stable. Surprisingly, however, they do not form well-ordered structures. Instead, they form dynamic structures that fluctuate between monomeric and dimeric states. These findings show that a well-ordered structure is not a prerequisite for life-sustaining functions, and suggests that dynamic structures may have been important in the early evolution of protein function. Copyright © 2015 Elsevier Ltd. All rights reserved.

Algorithms for Efficient Computation of Transfer Functions for Large Order Flexible Systems

NASA Technical Reports Server (NTRS)

Maghami, Peiman G.; Giesy, Daniel P.

1998-01-01

An efficient and robust computational scheme is given for the calculation of the frequency response function of a large order, flexible system implemented with a linear, time invariant control system. Advantage is taken of the highly structured sparsity of the system matrix of the plant based on a model of the structure using normal mode coordinates. The computational time per frequency point of the new computational scheme is a linear function of system size, a significant improvement over traditional, still-matrix techniques whose computational times per frequency point range from quadratic to cubic functions of system size. This permits the practical frequency domain analysis of systems of much larger order than by traditional, full-matrix techniques. Formulations are given for both open- and closed-loop systems. Numerical examples are presented showing the advantages of the present formulation over traditional approaches, both in speed and in accuracy. Using a model with 703 structural modes, the present method was up to two orders of magnitude faster than a traditional method. The present method generally showed good to excellent accuracy throughout the range of test frequencies, while traditional methods gave adequate accuracy for lower frequencies, but generally deteriorated in performance at higher frequencies with worst case errors being many orders of magnitude times the correct values.

Microstructure and phase behavior in colloids and liquid crystals

NASA Astrophysics Data System (ADS)

Lohr, Matthew Alan

This thesis describes our investigation of microstructure and phase behavior in colloids and liquid crystals. The first set of experiments explores the phase behavior of helical packings of thermoresponsive microspheres inside glass capillaries as a function of volume fraction. Stable helical packings are observed with long-range orientational order. Some of these packings evolve abruptly to disordered states as the volume fraction is reduced. We quantify these transitions using correlation functions and susceptibilities of an orientational order parameter. The emergence of coexisting metastable packings, as well as coexisting ordered and disordered states, is also observed. These findings support the notion of phase-transition-like behavior in quasi-one-dimensional systems. The second set of experiments investigates cross-over behavior from glasses with attractive interactions to sparse gel-like states. In particular, the vibrational modes of quasi-two-dimensional disordered colloidal packings of hard colloidal spheres with short-range attractions are measured as a function of packing fraction. A crossover from glassy to sparse gel-like states is indicated by an excess of low-frequency phonon modes. This change in vibrational mode distribution appears to arise from highly localized vibrations that tend to involve individual and/or small clusters of particles with few local bonds. These mode behaviors and corresponding structural insights may serve as a useful signature for glass-gel transitions in wider classes of attractive packings. A third set of experiments explores the director structures of aqueous lyotropic chromonic liquid crystal (LCLC) films created on square lattice cylindrical-micropost substrates. The structures are manipulated by modulating of the concentration-dependent elastic properties of LCLC s via drying. Nematic LCLC films exhibit preferred bistable alignment along the diagonals of the micropost lattice. Columnar LCLC films form two distinct director and defect configurations: a diagonally aligned director pattern with local squares of defects, and an off-diagonal configuration with zig-zag defects. The formation of these patterns appears to be tied to the relative free energy costs of splay and bend deformations in the precursor nematic films. The observed nematic and columnar configurations are understood numerically using a Landau-de Gennes free energy model. This work provides first examples of quasi-2D micropatterning of LC films in the columnar phase and the first micropatterning of lyotropic LC films in general, as well as demonstrating alignment and configuration switching of typically difficult-to-align LCLC films via bulk elastic properties.

High School Science Teachers' Interpretations and Perceptions of Reform and Literacy in the Discipline of Science

NASA Astrophysics Data System (ADS)

Lesinski-Roscoe, Rachel A.

This qualitative study sought to gain an understanding of science teachers' perceptions of reform and their role in implementing reform and science-based literacy practices in the classroom, as well as gain an understanding of science teachers' knowledge of disciplinary literacy as the implied framework of reform (i.e., the Next Generation Science Standards). Four focal participants from a suburban, middle-class high school district comprised of two high schools participated in semi-structured interviews, observations, and a stimulated recall task and interview. Data analysis revealed some of the Discourse memberships in which participants claimed membership and the tensions that resulted from those memberships. From this data, a theory emerged of the role of third space in navigating these tensions, and a model for developing a third space is presented, which literacy professionals can reference when working to develop collaborative relationships with science teachers in order to scaffold science-specific literacy practices for student engagement. The information in this study prompts future research regarding the ability of science teachers and literacy professionals to navigate Discourses in a Field Code Changed third space using a disciplinary literacy approach to developing curriculum in order to apprentice students into the discipline of science and develop a citizenry of scientifically literate individuals.

Experimental vibration damping characteristics of the third-stage rotor of a three-stage transonic axial-flow compressor

NASA Technical Reports Server (NTRS)

Newman, Frederick A.

1988-01-01

Rotor blade aerodynamic damping is experimentally determined in a three-stage transonic axial flow compressor having design aerodynamic performance goals of 4.5:1 pressure ratio and 65.5 lbm/sec weight flow. The combined damping associated with each mode is determined by a least squares fit of a single degree of freedom system transfer function to the nonsynchronous portion of the rotor blade strain gage output power spectra. The combined damping consists of the aerodynanmic damping and the structural and mechanical damping. The aerodynamic damping varies linearly with the inlet total pressure for a given corrected speed, weight flow, and pressure ratio while the structural and mechanical damping is assumed to remain constant. The combined damping is determined at three inlet total pressure levels to obtain the aerodynamic damping. The third-stage rotor blade aerodynamic damping is presented and discussed for the design equivalent speed with the stator blades reset for maximum efficiency. The compressor overall performance and experimental Campbell diagrams for the third-stage rotor blade row are also presented.

Experimental Vibration Damping Characteristics of the Third-stage Rotor of a Three-stage Transonic Axial-flow Compressor

NASA Technical Reports Server (NTRS)

Newman, Frederick A.

1988-01-01

Rotor blade aerodynamic damping is experimentally determined in a three-stage transonic axial flow compressor having design aerodynamic performance goals of 4.5:1 pressure ratio and 65.5 lbm/sec weight flow. The combined damping associated with each mode is determined by a least squares fit of a single degree of freedom system transfer function to the nonsynchronous portion of the rotor blade strain gage output power spectra. The combined damping consists of the aerodynamic damping and the structural and mechanical damping. The aerodynamic damping varies linearly with the inlet total pressure for a given corrected speed, weight flow, and pressure ratio while the structural and mechanical damping is assumed to remain constant. The combined damping is determined at three inlet total pressure levels to obtain the aerodynamic damping. The third-stage rotor blade aerodynamic damping is presented and discussed for the design equivalent speed with the stator blades reset for maximum efficiency. The compressor overall preformance and experimental Campbell diagrams for the third-stage rotor blade row are also presented.

Characterization of second and third order optical nonlinearities of ZnO sputtered films

NASA Astrophysics Data System (ADS)

Larciprete, M. C.; Haertle, D.; Belardini, A.; Bertolotti, M.; Sarto, F.; Günter, P.

2006-03-01

We measured the second and third order optical nonlinearity of zinc oxide, grown on glass substrates by the ion beam sputtering technique. Second and third harmonic generation measurements were performed by means of the rotational Maker fringes technique for different polarization configurations, thus allowing the determination of all non-zero components of the second order susceptibility at three different fundamental beam wavelengths, i.e., 1064 nm, 1542 nm and 1907 nm. The dispersion of the nonlinear optical coefficients has been evaluated, while the nonlinear optical coefficients were found to range between 0.9 pm/V and 0.16 pm/V for d33, 0.53 pm/V and 0.08 pm/V for |d15|, 0.31 and 0.08 pm/V for |d31|, with increasing wavelength. Finally, one third order susceptibility, χijkl (3), has been determined by third harmonic generation measurements at a fundamental wavelength λ=1907 nm and a value for χ3333 (3) of 185×10-20 m2/V2 has been found.

Highly sensitive quantitation of pesticides in fruit juice samples by modeling four-way data gathered with high-performance liquid chromatography with fluorescence excitation-emission detection.

PubMed

Montemurro, Milagros; Pinto, Licarion; Véras, Germano; de Araújo Gomes, Adriano; Culzoni, María J; Ugulino de Araújo, Mário C; Goicoechea, Héctor C

2016-07-01

A study regarding the acquisition and analytical utilization of four-way data acquired by monitoring excitation-emission fluorescence matrices at different elution time points in a fast HPLC procedure is presented. The data were modeled with three well-known algorithms: PARAFAC, U-PLS/RTL and MCR-ALS, the latter conveniently adapted to model third-order data. The second-order advantage was exploited when analyzing samples containing uncalibrated components. The best results were furnished with the algorithm U-PLS/RTL. This fact is indicative of both no peak time shifts occurrence among samples and high colinearity among spectra. Besides, this latent-variable structured algorithm is capable of better handle the need of achieving high sensitivity for the analysis of one of the analytes. In addition, a significant enhancement in both predictions and analytical figures of merit was observed for carbendazim, thiabendazole, fuberidazole, carbofuran, carbaryl and 1-naphtol, when going from second- to third-order data. LODs obtained were ranged between 0.02 and 2.4μgL(-1). Copyright © 2016 Elsevier B.V. All rights reserved.

New Formulae for the High-Order Derivatives of Some Jacobi Polynomials: An Application to Some High-Order Boundary Value Problems

PubMed Central

Abd-Elhameed, W. M.

2014-01-01

This paper is concerned with deriving some new formulae expressing explicitly the high-order derivatives of Jacobi polynomials whose parameters difference is one or two of any degree and of any order in terms of their corresponding Jacobi polynomials. The derivatives formulae for Chebyshev polynomials of third and fourth kinds of any degree and of any order in terms of their corresponding Chebyshev polynomials are deduced as special cases. Some new reduction formulae for summing some terminating hypergeometric functions of unit argument are also deduced. As an application, and with the aid of the new introduced derivatives formulae, an algorithm for solving special sixth-order boundary value problems are implemented with the aid of applying Galerkin method. A numerical example is presented hoping to ascertain the validity and the applicability of the proposed algorithms. PMID:25386599

Higher Order Analysis of Turbulent Changes Found in the ELF Range Electric Field Plasma Before Major Earthquakes

NASA Astrophysics Data System (ADS)

Kosciesza, M.; Blecki, J. S.; Parrot, M.

2014-12-01

We report the structure function analysis of changes found in electric field in the ELF range plasma turbulence registered in the ionosphere over epicenter region of major earthquakes with depth less than 40 km that took place during 6.5 years of the scientific mission of the DEMETER satellite. We compare the data for the earthquakes for which we found turbulence with events without any turbulent changes. The structure functions were calculated also for the Polar CUSP region and equatorial spread F region. Basic studies of the turbulent processes were conducted with use of higher order spectra and higher order statistics. The structure function analysis was performed to locate and check if there are intermittent behaviors in the ionospheres plasma over epicenter region of the earthquakes. These registrations are correlated with the plasma parameters measured onboard DEMETER satellite and with geomagnetic indices.

Self-consistent linear response for the spin-orbit interaction related properties

NASA Astrophysics Data System (ADS)

Solovyev, I. V.

2014-07-01

In many cases, the relativistic spin-orbit (SO) interaction can be regarded as a small perturbation to the electronic structure of solids and treated using regular perturbation theory. The major obstacle on this route comes from the fact that the SO interaction can also polarize the electron system and produce some additional contributions to the perturbation theory expansion, which arise from the electron-electron interactions in the same order of the SO coupling. In electronic structure calculations, it may even lead to the necessity of abandoning the perturbation theory and returning to the original self-consistent solution of Kohn-Sham-like equations with the effective potential v̂, incorporating simultaneously the effects of the electron-electron interactions and the SO coupling, even though the latter is small. In this work, we present the theory of self-consistent linear response (SCLR), which allows us to get rid of numerical self-consistency and formulate the last step fully analytically in the first order of the SO coupling. This strategy is applied to the unrestricted Hartree-Fock solution of an effective Hubbard-type model, derived from the first-principles electronic structure calculations in the basis of Wannier functions for the magnetically active states. We show that by using v̂, obtained in SCLR, one can successfully reproduce results of ordinary self-consistent calculations for the orbital magnetization and other properties, which emerge in the first order of the SO coupling. Particularly, SCLR appears to be an extremely useful approach for calculations of antisymmetric Dzyaloshinskii-Moriya (DM) interactions based on the magnetic force theorem, where only by using the total perturbation one can make a reliable estimate for the DM parameters. Furthermore, due to the powerful 2n+1 theorem, the SCLR theory allows us to obtain the total energy change up to the third order of the SO coupling, which can be used in calculations of magnetic anisotropy of compounds with low crystal symmetry. The fruitfulness of this approach for the analysis of complex magnetic structures is illustrated in a number of examples, including the quantitative description of the spin canting in YTiO3 and LaMnO3, formation of the spin-spiral order in BiFeO3, and the magnetic inversion symmetry breaking in BiMnO3, which gives rise to both ferroelectric activity and DM interactions, responsible for the ferromagnetism. In all these cases, the use of SCLR tremendously reduces the computational efforts related to the search for noncollinear magnetic structures in the ground state.

Structural characterization of Co-Re superlattices

NASA Astrophysics Data System (ADS)

Melo, L. V.; Trindade, I.; From, M.; Freitas, P. P.; Teixeira, N.; da Silva, M. F.; Soares, J. C.

1991-12-01

Co-Re superlattices were prepared with nominal periodicities of 65-67 Å and varying bilayer composition. The structural characterization was made by x-ray diffraction and Rutherford backscattering spectrometry (RBS). First, second, and third order satellites are observed in the x-ray diffractogram at 2θ values and with intensities close to those predicted by simulation. This confirms the coherence of the superlattice. RBS measurements combined with RUMP simulations give information on interface sharpness and the absolute thicknesses of the Co and Re layers. Discrepancies between the experimental and simulated diffractograms are found for Co thicknesses below 18 Å.

A non-local structural derivative model for characterization of ultraslow diffusion in dense colloids

NASA Astrophysics Data System (ADS)

Liang, Yingjie; Chen, Wen

2018-03-01

Ultraslow diffusion has been observed in numerous complicated systems. Its mean squared displacement (MSD) is not a power law function of time, but instead a logarithmic function, and in some cases grows even more slowly than the logarithmic rate. The distributed-order fractional diffusion equation model simply does not work for the general ultraslow diffusion. Recent study has used the local structural derivative to describe ultraslow diffusion dynamics by using the inverse Mittag-Leffler function as the structural function, in which the MSD is a function of inverse Mittag-Leffler function. In this study, a new stretched logarithmic diffusion law and its underlying non-local structural derivative diffusion model are proposed to characterize the ultraslow diffusion in aging dense colloidal glass at both the short and long waiting times. It is observed that the aging dynamics of dense colloids is a class of the stretched logarithmic ultraslow diffusion processes. Compared with the power, the logarithmic, and the inverse Mittag-Leffler diffusion laws, the stretched logarithmic diffusion law has better precision in fitting the MSD of the colloidal particles at high densities. The corresponding non-local structural derivative diffusion equation manifests clear physical mechanism, and its structural function is equivalent to the first-order derivative of the MSD.

Alternative bi-Hamiltonian structures for WDVV equations of associativity

NASA Astrophysics Data System (ADS)

Kalayci, J.; Nutku, Y.

1998-01-01

The WDVV equations of associativity in two-dimensional topological field theory are completely integrable third-order Monge-Ampère equations which admit bi-Hamiltonian structure. The time variable plays a distinguished role in the discussion of Hamiltonian structure, whereas in the theory of WDVV equations none of the independent variables merits such a distinction. WDVV equations admit very different alternative Hamiltonian structures under different possible choices of the time variable, but all these various Hamiltonian formulations can be brought together in the framework of the covariant theory of symplectic structure. They can be identified as different components of the covariant Witten-Zuckerman symplectic 2-form current density where a variational formulation of the WDVV equation that leads to the Hamiltonian operator through the Dirac bracket is available.

Toward large-area roll-to-roll printed nanophotonic sensors

NASA Astrophysics Data System (ADS)

Karioja, Pentti; Hiltunen, Jussi; Aikio, Sanna M.; Alajoki, Teemu; Tuominen, Jarkko; Hiltunen, Marianne; Siitonen, Samuli; Kontturi, Ville; Böhlen, Karl; Hauser, Rene; Charlton, Martin; Boersma, Arjen; Lieberzeit, Peter; Felder, Thorsten; Eustace, David; Haskal, Eliav

2014-05-01

Polymers have become an important material group in fabricating discrete photonic components and integrated optical devices. This is due to their good properties: high optical transmittance, versatile processability at relative low temperatures and potential for low-cost production. Recently, nanoimprinting or nanoimprint lithography (NIL) has obtained a plenty of research interest. In NIL, a mould is pressed against a substrate coated with a moldable material. After deformation of the material, the mold is separated and a replica of the mold is formed. Compared with conventional lithographic methods, imprinting is simple to carry out, requires less-complicated equipment and can provide high-resolution with high throughput. Nanoimprint lithography has shown potential to become a method for low-cost and high-throughput fabrication of nanostructures. We show the development process of nano-structured, large-area multi-parameter sensors using Photonic Crystal (PC) and Surface Enhanced Raman Scattering (SERS) methodologies for environmental and pharmaceutical applications. We address these challenges by developing roll-to-roll (R2R) UV-nanoimprint fabrication methods. Our development steps are the following: Firstly, the proof of concept structures are fabricated by the use of wafer-level processes in Si-based materials. Secondly, the master molds of successful designs are fabricated, and they are used to transfer the nanophotonic structures into polymer materials using sheet-level UV-nanoimprinting. Thirdly, the sheet-level nanoimprinting processes are transferred to roll-to-roll fabrication. In order to enhance roll-to-roll manufacturing capabilities, silicone-based polymer material development was carried out. In the different development phases, Photonic Crystal and SERS sensor structures with increasing complexities were fabricated using polymer materials in order to enhance sheet-level and roll-to-roll manufacturing processes. In addition, chemical and molecular imprint (MIP) functionalization methods were applied in the sensor demonstrators. In this paper, the process flow in fabricating large-area nanophotonic structures by the use of sheet-level and roll-to-roll UV- nanoimprinting is reported.

Unsymmetric Lanczos model reduction and linear state function observer for flexible structures

NASA Technical Reports Server (NTRS)

Su, Tzu-Jeng; Craig, Roy R., Jr.

1991-01-01

This report summarizes part of the research work accomplished during the second year of a two-year grant. The research, entitled 'Application of Lanczos Vectors to Control Design of Flexible Structures' concerns various ways to use Lanczos vectors and Krylov vectors to obtain reduced-order mathematical models for use in the dynamic response analyses and in control design studies. This report presents a one-sided, unsymmetric block Lanczos algorithm for model reduction of structural dynamics systems with unsymmetric damping matrix, and a control design procedure based on the theory of linear state function observers to design low-order controllers for flexible structures.

Dancing Protein Clouds: The Strange Biology and Chaotic Physics of Intrinsically Disordered Proteins.

PubMed

Uversky, Vladimir N

2016-03-25

Biologically active but floppy proteins represent a new reality of modern protein science. These intrinsically disordered proteins (IDPs) and hybrid proteins containing ordered and intrinsically disordered protein regions (IDPRs) constitute a noticeable part of any given proteome. Functionally, they complement ordered proteins, and their conformational flexibility and structural plasticity allow them to perform impossible tricks and be engaged in biological activities that are inaccessible to well folded proteins with their unique structures. The major goals of this minireview are to show that, despite their simplified amino acid sequences, IDPs/IDPRs are complex entities often resembling chaotic systems, are structurally and functionally heterogeneous, and can be considered an important part of the structure-function continuum. Furthermore, IDPs/IDPRs are everywhere, and are ubiquitously engaged in various interactions characterized by a wide spectrum of binding scenarios and an even wider spectrum of structural and functional outputs. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

["... mein Recht muss mir werden!" Hermann Bahr's tragicomedy Der Querulant (1914)].

PubMed

Gaderer, Rupert

2014-12-01

At the end of the eighteenth century, people who became notorious for their excessive engagement in legal proceedings started being labeled as "querulents" or "paranoid litigants". The term "querulents" first appeared in the General Order of the Court for the Prussian States (Allgemeine Gerichtsardnung für die Preussischen Staaten) from July 6, 1793. From there on, the spectrum of juridical measures undertaken against the so-labeled litigators included classifying these persons as ineligible for legal action and psychiatric hospitalization. The paper discusses to what extent Hermann Bahr rearranges psychiatric and legal knowledge about this special type of the complainer in his tragi- comedy Der Querulant, premiered in 1914. This concerns, first, the theatricality of the body and speech, secondly, the use of cultural techniques of writing and, thirdly, conflict- ing notions of justice. Therefore, the paper analyzes the aesthetic function of querulous behavior in the dramatic structure of the play from the point of view of both media theory and literary theory.

Preeclampsia, prematurity and cardiovascular health in adult life.

PubMed

Lewandowski, Adam J; Leeson, Paul

2014-11-01

Investigations into how perinatal growth and intrauterine environment may 'programme' risk of later cardiovascular disease have been ongoing for over two decades. One of the more recent outcomes of these studies is the observation that certain pregnancy-related conditions, such as preterm birth, have an unusually large impact on the long-term cardiovascular health of the offspring. In the present paper, we review the current literature of how preterm birth affects the long-term cardiovascular structure and function of the offspring, considering three major areas of investigation: firstly, outlining the long-term cardiovascular phenotypic changes in preterm-born individuals; secondly, investigating factors related to preterm birth that may be modifying cardiovascular phenotype, such as preeclampsia, perinatal interventions, and physiological disturbances; and thirdly, the expected clinical relevance of these cardiovascular changes. This review discusses the importance of continued research focused on the mechanistic understanding of these cardiovascular alterations in order to develop specific primary prevention strategies. Copyright © 2014 Elsevier Ltd. All rights reserved.

Aquatic ecotoxicology: from the ecosystem to the cellular and molecular levels.

PubMed Central

Boudou, A; Ribeyre, F

1997-01-01

This review of aquatic ecotoxicology is presented in three parts. First, we discuss the fundamental concepts and stress the importance of its ecological basis and the complexity and diversity of the field of investigation, which result from actions and interactions between the physicochemical characteristics of the biotopes, the structural and functional properties of the living organisms, and the contamination modalities. Ecotoxicological mechanisms, regardless of the level of biological complexity, primarily depend on the bioavailability of the toxic products. Numerous processes control the chemical fate of contaminants in the water column and/or sediment compartments; accessibility to the biological barriers that separate the organisms from their surrounding medium depends directly on bioavailability. Second, we review the principal methodologies of the field, from in situ studies at the ecosystem/ecocomplex level to bioassays or single species tests. Third, we focus on mercury, selected as a reference contaminant, in order to illustrate the main ecotoxicological concepts, the complementarity between field and laboratory studies, and the indispensable multidisciplinarity of the approaches. PMID:9114275

Beyond the schools of psychology 2: a digital analysis of psychological review, 1904-1923.

PubMed

Green, Christopher D; Feinerer, Ingo; Burman, Jeremy T

2014-01-01

In order to better understand the broader trends and points of contention in early American psychology, it is conventional to organize the relevant material in terms of "schools" of psychology-structuralism, functionalism, etc. Although not without value, this scheme marginalizes many otherwise significant figures, and tends to exclude a large number of secondary, but interesting, individuals. In an effort to address these problems, we grouped all the articles that appeared in the second and third decades of Psychological Review into five-year blocks, and then cluster analyzed each block by the articles' verbal similarity to each other. This resulted in a number of significant intellectual "genres" of psychology that are ignored by the usual "schools" taxonomy. It also made "visible" a number of figures who are typically downplayed or ignored in conventional histories of the discipline, and it provide us with an intellectual context in which to understand their contributions. © 2014 Wiley Periodicals, Inc.

Evolving application of biomimetic nanostructured hydroxyapatite

PubMed Central

Roveri, Norberto; Iafisco, Michele

2010-01-01

By mimicking Nature, we can design and synthesize inorganic smart materials that are reactive to biological tissues. These smart materials can be utilized to design innovative third-generation biomaterials, which are able to not only optimize their interaction with biological tissues and environment, but also mimic biogenic materials in their functionalities. The biomedical applications involve increasing the biomimetic levels from chemical composition, structural organization, morphology, mechanical behavior, nanostructure, and bulk and surface chemical–physical properties until the surface becomes bioreactive and stimulates cellular materials. The chemical–physical characteristics of biogenic hydroxyapatites from bone and tooth have been described, in order to point out the elective sides, which are important to reproduce the design of a new biomimetic synthetic hydroxyapatite. This review outlines the evolving applications of biomimetic synthetic calcium phosphates, details the main characteristics of bone and tooth, where the calcium phosphates are present, and discusses the chemical–physical characteristics of biomimetic calcium phosphates, methods of synthesizing them, and some of their biomedical applications. PMID:24198477

77 FR 17476 - Information Collections Being Reviewed by the Federal Communications Commission

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-26

... Rules for FM Broadcast Translator Stations, Fourth Report and Order and Third Order on Reconsideration... more than 4 pending translator applications) to request the dismissal of applications to comply with... Service and Eligibility Rules for FM Broadcast Translator Stations, Fourth Report and Order and Third...

Toward more realistic projections of soil carbon dynamics by Earth system models

USGS Publications Warehouse

Luo, Y.; Ahlström, Anders; Allison, Steven D.; Batjes, Niels H.; Brovkin, V.; Carvalhais, Nuno; Chappell, Adrian; Ciais, Philippe; Davidson, Eric A.; Finzi, Adien; Georgiou, Katerina; Guenet, Bertrand; Hararuk, Oleksandra; Harden, Jennifer; He, Yujie; Hopkins, Francesca; Jiang, L.; Koven, Charles; Jackson, Robert B.; Jones, Chris D.; Lara, M.; Liang, J.; McGuire, A. David; Parton, William; Peng, Changhui; Randerson, J.; Salazar, Alejandro; Sierra, Carlos A.; Smith, Matthew J.; Tian, Hanqin; Todd-Brown, Katherine E. O; Torn, Margaret S.; van Groenigen, Kees Jan; Wang, Ying; West, Tristram O.; Wei, Yaxing; Wieder, William R.; Xia, Jianyang; Xu, Xia; Xu, Xiaofeng; Zhou, T.

2016-01-01

Soil carbon (C) is a critical component of Earth system models (ESMs), and its diverse representations are a major source of the large spread across models in the terrestrial C sink from the third to fifth assessment reports of the Intergovernmental Panel on Climate Change (IPCC). Improving soil C projections is of a high priority for Earth system modeling in the future IPCC and other assessments. To achieve this goal, we suggest that (1) model structures should reflect real-world processes, (2) parameters should be calibrated to match model outputs with observations, and (3) external forcing variables should accurately prescribe the environmental conditions that soils experience. First, most soil C cycle models simulate C input from litter production and C release through decomposition. The latter process has traditionally been represented by first-order decay functions, regulated primarily by temperature, moisture, litter quality, and soil texture. While this formulation well captures macroscopic soil organic C (SOC) dynamics, better understanding is needed of their underlying mechanisms as related to microbial processes, depth-dependent environmental controls, and other processes that strongly affect soil C dynamics. Second, incomplete use of observations in model parameterization is a major cause of bias in soil C projections from ESMs. Optimal parameter calibration with both pool- and flux-based data sets through data assimilation is among the highest priorities for near-term research to reduce biases among ESMs. Third, external variables are represented inconsistently among ESMs, leading to differences in modeled soil C dynamics. We recommend the implementation of traceability analyses to identify how external variables and model parameterizations influence SOC dynamics in different ESMs. Overall, projections of the terrestrial C sink can be substantially improved when reliable data sets are available to select the most representative model structure, constrain parameters, and prescribe forcing fields.

A decade and a half of protein intrinsic disorder: Biology still waits for physics

PubMed Central

Uversky, Vladimir N

2013-01-01

The abundant existence of proteins and regions that possess specific functions without being uniquely folded into unique 3D structures has become accepted by a significant number of protein scientists. Sequences of these intrinsically disordered proteins (IDPs) and IDP regions (IDPRs) are characterized by a number of specific features, such as low overall hydrophobicity and high net charge which makes these proteins predictable. IDPs/IDPRs possess large hydrodynamic volumes, low contents of ordered secondary structure, and are characterized by high structural heterogeneity. They are very flexible, but some may undergo disorder to order transitions in the presence of natural ligands. The degree of these structural rearrangements varies over a very wide range. IDPs/IDPRs are tightly controlled under the normal conditions and have numerous specific functions that complement functions of ordered proteins and domains. When lacking proper control, they have multiple roles in pathogenesis of various human diseases. Gaining structural and functional information about these proteins is a challenge, since they do not typically “freeze” while their “pictures are taken.” However, despite or perhaps because of the experimental challenges, these fuzzy objects with fuzzy structures and fuzzy functions are among the most interesting targets for modern protein research. This review briefly summarizes some of the recent advances in this exciting field and considers some of the basic lessons learned from the analysis of physics, chemistry, and biology of IDPs. PMID:23553817

Protein domain organisation: adding order.

PubMed

Kummerfeld, Sarah K; Teichmann, Sarah A

2009-01-29

Domains are the building blocks of proteins. During evolution, they have been duplicated, fused and recombined, to produce proteins with novel structures and functions. Structural and genome-scale studies have shown that pairs or groups of domains observed together in a protein are almost always found in only one N to C terminal order and are the result of a single recombination event that has been propagated by duplication of the multi-domain unit. Previous studies of domain organisation have used graph theory to represent the co-occurrence of domains within proteins. We build on this approach by adding directionality to the graphs and connecting nodes based on their relative order in the protein. Most of the time, the linear order of domains is conserved. However, using the directed graph representation we have identified non-linear features of domain organization that are over-represented in genomes. Recognising these patterns and unravelling how they have arisen may allow us to understand the functional relationships between domains and understand how the protein repertoire has evolved. We identify groups of domains that are not linearly conserved, but instead have been shuffled during evolution so that they occur in multiple different orders. We consider 192 genomes across all three kingdoms of life and use domain and protein annotation to understand their functional significance. To identify these features and assess their statistical significance, we represent the linear order of domains in proteins as a directed graph and apply graph theoretical methods. We describe two higher-order patterns of domain organisation: clusters and bi-directionally associated domain pairs and explore their functional importance and phylogenetic conservation. Taking into account the order of domains, we have derived a novel picture of global protein organization. We found that all genomes have a higher than expected degree of clustering and more domain pairs in forward and reverse orientation in different proteins relative to random graphs with identical degree distributions. While these features were statistically over-represented, they are still fairly rare. Looking in detail at the proteins involved, we found strong functional relationships within each cluster. In addition, the domains tended to be involved in protein-protein interaction and are able to function as independent structural units. A particularly striking example was the human Jak-STAT signalling pathway which makes use of a set of domains in a range of orders and orientations to provide nuanced signaling functionality. This illustrated the importance of functional and structural constraints (or lack thereof) on domain organisation.

Testing higher-order Lagrangian perturbation theory against numerical simulation. 1: Pancake models

NASA Technical Reports Server (NTRS)

Buchert, T.; Melott, A. L.; Weiss, A. G.

1993-01-01

We present results showing an improvement of the accuracy of perturbation theory as applied to cosmological structure formation for a useful range of quasi-linear scales. The Lagrangian theory of gravitational instability of an Einstein-de Sitter dust cosmogony investigated and solved up to the third order is compared with numerical simulations. In this paper we study the dynamics of pancake models as a first step. In previous work the accuracy of several analytical approximations for the modeling of large-scale structure in the mildly non-linear regime was analyzed in the same way, allowing for direct comparison of the accuracy of various approximations. In particular, the Zel'dovich approximation (hereafter ZA) as a subclass of the first-order Lagrangian perturbation solutions was found to provide an excellent approximation to the density field in the mildly non-linear regime (i.e. up to a linear r.m.s. density contrast of sigma is approximately 2). The performance of ZA in hierarchical clustering models can be greatly improved by truncating the initial power spectrum (smoothing the initial data). We here explore whether this approximation can be further improved with higher-order corrections in the displacement mapping from homogeneity. We study a single pancake model (truncated power-spectrum with power-spectrum with power-index n = -1) using cross-correlation statistics employed in previous work. We found that for all statistical methods used the higher-order corrections improve the results obtained for the first-order solution up to the stage when sigma (linear theory) is approximately 1. While this improvement can be seen for all spatial scales, later stages retain this feature only above a certain scale which is increasing with time. However, third-order is not much improvement over second-order at any stage. The total breakdown of the perturbation approach is observed at the stage, where sigma (linear theory) is approximately 2, which corresponds to the onset of hierarchical clustering. This success is found at a considerable higher non-linearity than is usual for perturbation theory. Whether a truncation of the initial power-spectrum in hierarchical models retains this improvement will be analyzed in a forthcoming work.

Bio-medicolegal scientific research in Europe. A country-based analysis.

PubMed

Viel, Guido; Boscolo-Berto, Rafael; Cecchi, Rossana; Bajanowski, Thomas; Vieira, Nuno Duarte; Ferrara, Santo Davide

2011-09-01

The European mosaic of socio-cultural, economic and legal realities is reflected in forensic and legal medicine, in which a great variety of operational modes of forensic medical services, organisational systems, structures, functional competences and scientific research strategies can be observed. The present work analyses the European bio-medicolegal scientific output of the last 5.5 years (exact time window, January 1, 2005-June 1, 2010), categorising papers by nationality of the corresponding author and forensic sub-discipline in question, in order to identify the peculiarities of national sub-specialised competences and to build up international research projects. This country-based bibliometric analysis, based on the number of articles and the impact factor produced by each European country, also considering its economic profile (gross domestic product and per capita gross domestic product), highlights the prevailing productive role of Western and Southern Europe (Germany, Great Britain, Italy, Switzerland, Spain and France). Categorising scientific output by forensic sub-discipline and branch, significant in terms of impact factor are contributions from Germany (coming first in Pathology, Toxicology, Genetics, Anthropology and Biological Criminalistics), Great Britain (first in Clinical Forensic Medicine, Malpractice and Invalidity-Social Insurance), Switzerland (first in Criminology), Italy (second in Toxicology, Anthropology and Invalidity-Social Insurance), The Netherlands (third in Clinical Forensic Medicine and Medical Law and Ethics), Spain (third in Genetics, Criminalistics and Invalidity-Social Insurance) and France (third in Toxicology and Malpractice). Interestingly, several countries with low gross domestic product, such as Poland, Turkey and other Eastern European nations, show notable scientific production in specific sub-disciplines such as Pathology, Toxicology and Forensic Genetics, suggesting that fruitful international cooperation could be planned and be of interest to funding sources within the European Community, also taking into account funds reserved for depressed areas undergoing development.

Comparing nutrient export from first, second and third order watersheds in the South Carolina Atlantic coastal plain

Treesearch

Augustine Muwamba; Devendra M. Amatya; Carl C. Trettin; James B. Glover

2016-01-01

Monitoring of stream water chemistry in forested watersheds provides information to environmental scientists that relate management operations to hydrologic and biogeochemical processes. We used data for the first order watershed, WS80, and second order watershed, WS79, at Santee Experimental Forest. We also used data from a third order watershed, WS78, to...

Third-order optical conductivity of an electron fluid

NASA Astrophysics Data System (ADS)

Sun, Zhiyuan; Basov, D. N.; Fogler, M. M.

2018-02-01

We derive the nonlinear optical conductivity of an isotropic electron fluid at frequencies below the interparticle collision rate. In this regime, governed by hydrodynamics, the conductivity acquires a universal form at any temperature, chemical potential, and spatial dimension. We show that the nonlinear response of the fluid to a uniform field is dominated by the third-order conductivity tensor σ(3 ) whose magnitude and temperature dependence differ qualitatively from those in the conventional kinetic regime of higher frequencies. We obtain explicit formulas for σ(3 ) for Dirac materials such as graphene and Weyl semimetals. We make predictions for the third-harmonic generation, renormalization of the collective-mode spectrum, and the third-order circular magnetic birefringence experiments.

The Paris-Sud yeast structural genomics pilot-project: from structure to function.

PubMed

Quevillon-Cheruel, Sophie; Liger, Dominique; Leulliot, Nicolas; Graille, Marc; Poupon, Anne; Li de La Sierra-Gallay, Inès; Zhou, Cong-Zhao; Collinet, Bruno; Janin, Joël; Van Tilbeurgh, Herman

2004-01-01

We present here the outlines and results from our yeast structural genomics (YSG) pilot-project. A lab-scale platform for the systematic production and structure determination is presented. In order to validate this approach, 250 non-membrane proteins of unknown structure were targeted. Strategies and final statistics are evaluated. We finally discuss the opportunity of structural genomics programs to contribute to functional biochemical annotation.

A Theoretical Analysis of the Effect of the Hydrogenation of Graphene to Graphane on Its Mechanical Properties

NASA Astrophysics Data System (ADS)

Peng, Q.; Liang, Chao; Ji, Wei; de, Suvranu

2013-03-01

We investigated the mechanical properties of graphene and graphane using first-principles calculations based on density-functional theory. A conventional unitcell containing a hexagonal ring made of carbon atoms was chosen to capture the finite wave vector ``soft modes'', which affect the the fourth and fifth elastic constants considerably. Graphane has about 2/3 ultimate strengths in all three tested deformation modes - armchair, zigzag, and biaxial- compared to graphene. However, graphane has larger ultimate strains in zigzag deformation, and smaller in armchair deformation. We obtained the second, third, fourth, and fifth order elastic constants for a rigorous continuum description of the elastic response. Graphane has a relatively low in-plane stiffness of 240 N/m which is about 2/3 of that of graphene, and a very small Poisson ratio of 0.078, 44% of that of graphene. The pressure dependence of the second order elastic constants were predicted from the third order elastic constants. The Poisson's ratio monotonically decreases with increasing pressure. Acknowledge the financial support from DTRA Grant # BRBAA08-C-2-0130, the U.S. NRCFDP # NRC-38-08-950, and U.S. DOE NEUP Grant #DE-NE0000325.

31P NMR study of discrete time-crystalline signatures in an ordered crystal of ammonium dihydrogen phosphate

NASA Astrophysics Data System (ADS)

Rovny, Jared; Blum, Robert L.; Barrett, Sean E.

2018-05-01

The rich dynamics and phase structure of driven systems include the recently described phenomenon of the "discrete time crystal" (DTC), a robust phase which spontaneously breaks the discrete time translation symmetry of its driving Hamiltonian. Experiments in trapped ions and diamond nitrogen vacancy centers have recently shown evidence for this DTC order. Here, we show nuclear magnetic resonance (NMR) data of DTC behavior in a third, strikingly different, system: a highly ordered spatial crystal in three dimensions. We devise a DTC echo experiment to probe the coherence of the driven system. We examine potential decay mechanisms for the DTC oscillations, and demonstrate the important effect of the internal Hamiltonian during nonzero duration pulses.

Third-party disability in carers of people with dysphagia following non-surgical management for head and neck cancer.

PubMed

Nund, Rebecca L; Scarinci, Nerina A; Cartmill, Bena; Ward, Elizabeth C; Kuipers, Pim; Porceddu, Sandro V

2016-01-01

Third-party disability pertains to the consequences of a person's impairment which impacts on the functioning and ability of their family members or significant others. With the emergence of research demonstrating the pervasive effects of dysphagia following head and neck cancer (HNC) on the carer, the aim of this study was to identify the International Classification of Functioning, Disability and Health (ICF) domains and categories that describe the third-party disability of carers of people with dysphagia following HNC. Twelve carers of people with dysphagia following HNC participated in individual semi-structured, in-depth interviews. Categories and sub-categories identified from the qualitative analysis were mapped to the ICF using the established linking rules. The majority of the categories and sub-categories from the qualitative analysis were successfully linked to the ICF with most linking to the Activities and Participation component. A number of contextual factors were also identified as impacting on the functioning of carers. The ICF can be successfully used to describe the third-party disability in carers of people with dysphagia following HNC management. This information could be used by clinicians, researchers and policy makers to help establish evidence-based guidelines that include carers in the assessment and management of dysphagia associated with HNC. Clinical levels of distress and reduced quality of life have been associated with caring for a person with dysphagia following head and neck cancer. The flow-on effects of dysphagia experienced by a carer or close family member can be understood as a third-party disability, which impacts on their functioning, activities and participation in the context of the environment and personal factors. Using the ICF to describe the indirect effects of dysphagia on the carer may help to guide the assessment and support of this population, and advocate for the inclusion of the concerns of the carer in dysphagia management.

An evaluation of applicability of seismic refraction method in identifying shallow archaeological features A case study at archaeological site

NASA Astrophysics Data System (ADS)

Jahangardi, Morteza; Hafezi Moghaddas, Naser; Keivan Hosseini, Sayyed; Garazhian, Omran

2015-04-01

We applied the seismic refraction method at archaeological site, Tepe Damghani located in Sabzevar, NE of Iran, in order to determine the structures of archaeological interests. This pre-historical site has special conditions with respect to geographical location and geomorphological setting, so it is an urban archaeological site, and in recent years it has been used as an agricultural field. In spring and summer of 2012, the third season of archaeological excavation was carried out. Test trenches of excavations in this site revealed that cultural layers were often disturbed adversely due to human activities such as farming and road construction in recent years. Conditions of archaeological cultural layers in southern and eastern parts of Tepe are slightly better, for instance, in test trench 3×3 m²1S03, third test trench excavated in the southern part of Tepe, an adobe in situ architectural structure was discovered that likely belongs to cultural features of a complex with 5 graves. After conclusion of the third season of archaeological excavation, all of the test trenches were filled with the same soil of excavated test trenches. Seismic refraction method was applied with12 channels of P geophones in three lines with a geophone interval of 0.5 meter and a 1.5 meter distance between profiles on test trench 1S03. The goal of this operation was evaluation of applicability of seismic method in identification of archaeological features, especially adobe wall structures. Processing of seismic data was done with the seismic software, SiesImager. Results were presented in the form of seismic section for every profile, so that identification of adobe wall structures was achieved hardly. This could be due to that adobe wall had been built with the same materials of the natural surrounding earth. Thus, there is a low contrast and it has an inappropriate effect on seismic processing and identifying of archaeological features. Hence the result could be that application of the seismic method in order to determine the archaeological features, having the same conditions, is not affordable and efficient in comparison to GPR or magnetic methods which yield more desirable results.

Ferromagnetic quantum criticality: New aspects from the phase diagram of LaCrGe3

NASA Astrophysics Data System (ADS)

Taufour, Valentin; Kaluarachchi, Udhara S.; Bud'ko, Sergey L.; Canfield, Paul C.

2018-05-01

Recent theoretical and experimental studies have shown that ferromagnetic quantum criticality is always avoided in clean systems. Two possibilities have been identified. In the first scenario, the ferromagnetic transition becomes of the first order at a tricritical point before being suppressed. A wing structure phase diagram is observed indicating the possibility of a new type of quantum critical point under magnetic field. In a second scenario, a transition to a modulated magnetic phase occurs. Our recent studies on the compound LaCrGe3 illustrate a third scenario where not only a new magnetic phase occurs, but also a change of order of the transition at a tricritical point leading to a wing-structure phase diagram. Careful experimental study of the phase diagram near the tricritical point also illustrates new rules near this type of point.

Joining of polymer composite materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Magness, F.H.

1990-11-01

Under ideal conditions load bearing structures would be designed without joints, thus eliminating a source of added weight, complexity and weakness. In reality the need for accessibility, repair, and inspectability, added to the size limitations imposed by the manufacturing process and transportation/assembly requirements mean that some minimum number of joints will be required in most structures. The designer generally has two methods for joining fiber composite materials, adhesive bonding and mechanical fastening. As the use of thermoplastic materials increases, a third joining technique -- welding -- will become more common. It is the purpose of this document to provide amore » review of the available sources pertinent to the design of joints in fiber composites. The primary emphasis is given to adhesive bonding and mechanical fastening with information coming from documentary sources as old as 1961 and as recent as 1989. A third, shorter section on composite welding is included in order to provide a relatively comprehensive treatment of the subject.« less

An integrated fuzzy approach for strategic alliance partner selection in third-party logistics.

PubMed

Erkayman, Burak; Gundogar, Emin; Yilmaz, Aysegul

2012-01-01

Outsourcing some of the logistic activities is a useful strategy for companies in recent years. This makes it possible for firms to concentrate on their main issues and processes and presents facility to improve logistics performance, to reduce costs, and to improve quality. Therefore provider selection and evaluation in third-party logistics become important activities for companies. Making a strategic decision like this is significantly hard and crucial. In this study we proposed a fuzzy multicriteria decision making (MCDM) approach to effectively select the most appropriate provider. First we identify the provider selection criteria and build the hierarchical structure of decision model. After building the hierarchical structure we determined the selection criteria weights by using fuzzy analytical hierarchy process (AHP) technique. Then we applied fuzzy technique for order preference by similarity to ideal solution (TOPSIS) to obtain final rankings for providers. And finally an illustrative example is also given to demonstrate the effectiveness of the proposed model.

An Integrated Fuzzy Approach for Strategic Alliance Partner Selection in Third-Party Logistics

PubMed Central

Gundogar, Emin; Yılmaz, Aysegul

2012-01-01

Outsourcing some of the logistic activities is a useful strategy for companies in recent years. This makes it possible for firms to concentrate on their main issues and processes and presents facility to improve logistics performance, to reduce costs, and to improve quality. Therefore provider selection and evaluation in third-party logistics become important activities for companies. Making a strategic decision like this is significantly hard and crucial. In this study we proposed a fuzzy multicriteria decision making (MCDM) approach to effectively select the most appropriate provider. First we identify the provider selection criteria and build the hierarchical structure of decision model. After building the hierarchical structure we determined the selection criteria weights by using fuzzy analytical hierarchy process (AHP) technique. Then we applied fuzzy technique for order preference by similarity to ideal solution (TOPSIS) to obtain final rankings for providers. And finally an illustrative example is also given to demonstrate the effectiveness of the proposed model. PMID:23365520

Quantification of the impact of PSI:Biology according to the annotations of the determined structures.

PubMed

DePietro, Paul J; Julfayev, Elchin S; McLaughlin, William A

2013-10-21

Protein Structure Initiative:Biology (PSI:Biology) is the third phase of PSI where protein structures are determined in high-throughput to characterize their biological functions. The transition to the third phase entailed the formation of PSI:Biology Partnerships which are composed of structural genomics centers and biomedical science laboratories. We present a method to examine the impact of protein structures determined under the auspices of PSI:Biology by measuring their rates of annotations. The mean numbers of annotations per structure and per residue are examined. These are designed to provide measures of the amount of structure to function connections that can be leveraged from each structure. One result is that PSI:Biology structures are found to have a higher rate of annotations than structures determined during the first two phases of PSI. A second result is that the subset of PSI:Biology structures determined through PSI:Biology Partnerships have a higher rate of annotations than those determined exclusive of those partnerships. Both results hold when the annotation rates are examined either at the level of the entire protein or for annotations that are known to fall at specific residues within the portion of the protein that has a determined structure. We conclude that PSI:Biology determines structures that are estimated to have a higher degree of biomedical interest than those determined during the first two phases of PSI based on a broad array of biomedical annotations. For the PSI:Biology Partnerships, we see that there is an associated added value that represents part of the progress toward the goals of PSI:Biology. We interpret the added value to mean that team-based structural biology projects that utilize the expertise and technologies of structural genomics centers together with biological laboratories in the community are conducted in a synergistic manner. We show that the annotation rates can be used in conjunction with established metrics, i.e. the numbers of structures and impact of publication records, to monitor the progress of PSI:Biology towards its goals of examining structure to function connections of high biomedical relevance. The metric provides an objective means to quantify the overall impact of PSI:Biology as it uses biomedical annotations from external sources.

Quantification of the impact of PSI:Biology according to the annotations of the determined structures

PubMed Central

2013-01-01

Background Protein Structure Initiative:Biology (PSI:Biology) is the third phase of PSI where protein structures are determined in high-throughput to characterize their biological functions. The transition to the third phase entailed the formation of PSI:Biology Partnerships which are composed of structural genomics centers and biomedical science laboratories. We present a method to examine the impact of protein structures determined under the auspices of PSI:Biology by measuring their rates of annotations. The mean numbers of annotations per structure and per residue are examined. These are designed to provide measures of the amount of structure to function connections that can be leveraged from each structure. Results One result is that PSI:Biology structures are found to have a higher rate of annotations than structures determined during the first two phases of PSI. A second result is that the subset of PSI:Biology structures determined through PSI:Biology Partnerships have a higher rate of annotations than those determined exclusive of those partnerships. Both results hold when the annotation rates are examined either at the level of the entire protein or for annotations that are known to fall at specific residues within the portion of the protein that has a determined structure. Conclusions We conclude that PSI:Biology determines structures that are estimated to have a higher degree of biomedical interest than those determined during the first two phases of PSI based on a broad array of biomedical annotations. For the PSI:Biology Partnerships, we see that there is an associated added value that represents part of the progress toward the goals of PSI:Biology. We interpret the added value to mean that team-based structural biology projects that utilize the expertise and technologies of structural genomics centers together with biological laboratories in the community are conducted in a synergistic manner. We show that the annotation rates can be used in conjunction with established metrics, i.e. the numbers of structures and impact of publication records, to monitor the progress of PSI:Biology towards its goals of examining structure to function connections of high biomedical relevance. The metric provides an objective means to quantify the overall impact of PSI:Biology as it uses biomedical annotations from external sources. PMID:24139526

Element enrichment factor calculation using grain-size distribution and functional data regression.

PubMed

Sierra, C; Ordóñez, C; Saavedra, A; Gallego, J R

2015-01-01

In environmental geochemistry studies it is common practice to normalize element concentrations in order to remove the effect of grain size. Linear regression with respect to a particular grain size or conservative element is a widely used method of normalization. In this paper, the utility of functional linear regression, in which the grain-size curve is the independent variable and the concentration of pollutant the dependent variable, is analyzed and applied to detrital sediment. After implementing functional linear regression and classical linear regression models to normalize and calculate enrichment factors, we concluded that the former regression technique has some advantages over the latter. First, functional linear regression directly considers the grain-size distribution of the samples as the explanatory variable. Second, as the regression coefficients are not constant values but functions depending on the grain size, it is easier to comprehend the relationship between grain size and pollutant concentration. Third, regularization can be introduced into the model in order to establish equilibrium between reliability of the data and smoothness of the solutions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Fragile-to-strong transition in liquid silica

NASA Astrophysics Data System (ADS)

Geske, Julian; Drossel, Barbara; Vogel, Michael

2016-03-01

We investigate anomalies in liquid silica with molecular dynamics simulations and present evidence for a fragile-to-strong transition at around 3100 K-3300 K. To this purpose, we studied the structure and dynamical properties of silica over a wide temperature range, finding four indicators of a fragile-to-strong transition. First, there is a density minimum at around 3000 K and a density maximum at 4700 K. The turning point is at 3400 K. Second, the local structure characterized by the tetrahedral order parameter changes dramatically around 3000 K from a higher-ordered, lower-density phase to a less ordered, higher-density phase. Third, the correlation time τ changes from an Arrhenius behavior below 3300 K to a Vogel-Fulcher-Tammann behavior at higher temperatures. Fourth, the Stokes-Einstein relation holds for temperatures below 3000 K, but is replaced by a fractional relation above this temperature. Furthermore, our data indicate that dynamics become again simple above 5000 K, with Arrhenius behavior and a classical Stokes-Einstein relation.

Study of third order nonlinearity of chalcogenide thin films using third harmonic generation measurements

NASA Astrophysics Data System (ADS)

Rani, Sunita; Mohan, Devendra; Kumar, Manish; Sanjay

2018-05-01

Third order nonlinear susceptibility of (GeSe3.5)100-xBix (x = 0, 10, 14) and ZnxSySe100-x-y (x = 2, y = 28; x = 4, y = 20; x = 6, y = 12; x = 8, y = 4) amorphous chalcogenide thin films prepared using thermal evaporation technique is estimated. The dielectric constant at incident and third harmonic wavelength is calculated using "PARAV" computer program. 1064 nm wavelength of Nd: YAG laser is incident on thin film and third harmonic signal at 355 nm wavelength alongwith fundamental light is obtained in reflection that is separated from 1064 nm using suitable optical filter. Reflected third harmonic signal is measured to trace the influence of Bi and Zn on third order nonlinear susceptibility and is found to increase with increase in Bi and Zn content in (GeSe3.5)100-xBix, and ZnxSySe100-x-y chalcogenide thin films respectively. The excellent optical nonlinear property shows the use of chalcogenide thin films in photonics for wavelength conversion and optical data processing.

76 FR 70409 - Fresh and Chilled Atlantic Salmon From Norway: Final Results of Full Third Sunset Review of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-11-14

... Salmon From Norway: Final Results of Full Third Sunset Review of Antidumping Duty Order AGENCY: Import... and chilled Atlantic salmon from Norway pursuant to section 751(c) of the Tariff Act of 1930, as... Department initiated the third sunset review of the AD order on fresh and chilled Atlantic salmon from Norway...

Decoupling of the Leading Order DGLAP Evolution Equation with Spin Dependent Structure Functions

NASA Astrophysics Data System (ADS)

Azadbakht, F. Teimoury; Boroun, G. R.

2018-02-01

We propose an analytical solution for DGLAP evolution equations with polarized splitting functions at the Leading Order (LO) approximation based on the Laplace transform method. It is shown that the DGLAP evolution equations can be decoupled completely into two second order differential equations which then are solved analytically by using the initial conditions δ FS(x,Q2)=F[partial δ FS0(x), δ FS0(x)] and {δ G}(x,Q2)=G[partial δ G0(x), δ G0(x)]. We used this method to obtain the polarized structure function of the proton as well as the polarized gluon distribution function inside the proton and compared the numerical results with experimental data of COMPASS, HERMES, and AAC'08 Collaborations. It was found that there is a good agreement between our predictions and the experiments.

Sum Frequency Generation Vibrational Spectroscopy Studies on ModelPeptide Adsorption at the Hydrophobic Solid-Water and HydrophilicSolid-Water Interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

York, Roger L.

2007-01-01

Sum frequency generation (SFG) vibrational spectroscopy has been used to study the interfacial structure of several polypeptides and amino acids adsorbed to hydrophobic and hydrophilic surfaces under a variety of experimental conditions. Peptide sequence, peptide chain length, peptide hydrophobicity, peptide side-chain type, surface hydrophobicity, and solution ionic strength all affect an adsorbed peptide's interfacial structure. Herein, it is demonstrated that with the choice of simple, model peptides and amino acids, surface specific SFG vibrational spectroscopy can be a powerful tool to elucidate the interfacial structure of these adsorbates. Herein, four experiments are described. In one, a series of isosequential amphiphilicmore » peptides are synthesized and studied when adsorbed to both hydrophobic and hydrophilic surfaces. On hydrophobic surfaces of deuterated polystyrene, it was determined that the hydrophobic part of the peptide is ordered at the solid-liquid interface, while the hydrophilic part of the peptide appears to have a random orientation at this interface. On a hydrophilic surface of silica, it was determined that an ordered peptide was only observed if a peptide had stable secondary structure in solution. In another experiment, the interfacial structure of a model amphiphilic peptide was studied as a function of the ionic strength of the solution, a parameter that could change the peptide's secondary structure in solution. It was determined that on a hydrophobic surface, the peptide's interfacial structure was independent of its structure in solution. This was in contrast to the adsorbed structure on a hydrophilic surface, where the peptide's interfacial structure showed a strong dependence on its solution secondary structure. In a third experiment, the SFG spectra of lysine and proline amino acids on both hydrophobic and hydrophilic surfaces were obtained by using a different experimental geometry that increases the SFG signal. Upon comparison of these spectra to the SFG spectra of interfacial polylysine and polyproline it was determined that the interfacial structure of a peptide is strongly dependent on its chain length. Lastly, SFG spectroscopy has been extended to the Amide I vibrational mode of a peptide (which is sensitive to peptide secondary structure) by building a new optical parametric amplifier based on lithium thioindate. Evidence is presented that suggests that the interfacial secondary structure of a peptide can be perturbed by a surface.« less

Nonlinear identification of the total baroreflex arc: higher-order nonlinearity

PubMed Central

Moslehpour, Mohsen; Kawada, Toru; Sunagawa, Kenji; Sugimachi, Masaru

2016-01-01

The total baroreflex arc is the open-loop system relating carotid sinus pressure (CSP) to arterial pressure (AP). The nonlinear dynamics of this system were recently characterized. First, Gaussian white noise CSP stimulation was employed in open-loop conditions in normotensive and hypertensive rats with sectioned vagal and aortic depressor nerves. Nonparametric system identification was then applied to measured CSP and AP to establish a second-order nonlinear Uryson model. The aim in this study was to assess the importance of higher-order nonlinear dynamics via development and evaluation of a third-order nonlinear model of the total arc using the same experimental data. Third-order Volterra and Uryson models were developed by employing nonparametric and parametric identification methods. The R2 values between the AP predicted by the best third-order Volterra model and measured AP in response to Gaussian white noise CSP not utilized in developing the model were 0.69 ± 0.03 and 0.70 ± 0.03 for normotensive and hypertensive rats, respectively. The analogous R2 values for the best third-order Uryson model were 0.71 ± 0.03 and 0.73 ± 0.03. These R2 values were not statistically different from the corresponding values for the previously established second-order Uryson model, which were both 0.71 ± 0.03 (P > 0.1). Furthermore, none of the third-order models predicted well-known nonlinear behaviors including thresholding and saturation better than the second-order Uryson model. Additional experiments suggested that the unexplained AP variance was partly due to higher brain center activity. In conclusion, the second-order Uryson model sufficed to represent the sympathetically mediated total arc under the employed experimental conditions. PMID:27629885

On the Energy of the Minimizers of the Ginzburg-Landau Functional for Exterior Magnetic Fields Between HC2 and HC3

NASA Astrophysics Data System (ADS)

Helffer, Bernard

2011-04-01

Superconductivity for Type II superconductors in external magnetic fields of magnitude between the second and third critical fields is known to be restricted to a narrow boundary region. The profile of the superconducting order parameter in the Ginzburg-Landau model is expected to be governed by an effective one-dimensional model. This is known to be the case for external magnetic fields sufficiently close to the third critical field. In this text we announce such a result on a larger interval of validity. These results have been obtained in collaboration with Soeren Fournais and Mikael Persson and the complete proofs will appear elsewhere.

Interval-Valued Rank in Finite Ordered Sets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joslyn, Cliff; Pogel, Alex; Purvine, Emilie

We consider the concept of rank as a measure of the vertical levels and positions of elements of partially ordered sets (posets). We are motivated by the need for algorithmic measures on large, real-world hierarchically-structured data objects like the semantic hierarchies of ontolog- ical databases. These rarely satisfy the strong property of gradedness, which is required for traditional rank functions to exist. Representing such semantic hierarchies as finite, bounded posets, we recognize the duality of ordered structures to motivate rank functions which respect verticality both from the bottom and from the top. Our rank functions are thus interval-valued, and alwaysmore » exist, even for non-graded posets, providing order homomorphisms to an interval order on the interval-valued ranks. The concept of rank width arises naturally, allowing us to identify the poset region with point-valued width as its longest graded portion (which we call the “spindle”). A standard interval rank function is naturally motivated both in terms of its extremality and on pragmatic grounds. Its properties are examined, including the relation- ship to traditional grading and rank functions, and methods to assess comparisons of standard interval-valued ranks.« less

Non-linear non-local molecular electrodynamics with nano-optical fields.

PubMed

Chernyak, Vladimir Y; Saurabh, Prasoon; Mukamel, Shaul

2015-10-28

The interaction of optical fields sculpted on the nano-scale with matter may not be described by the dipole approximation since the fields may vary appreciably across the molecular length scale. Rather than incrementally adding higher multipoles, it is advantageous and more physically transparent to describe the optical process using non-local response functions that intrinsically include all multipoles. We present a semi-classical approach for calculating non-local response functions based on the minimal coupling Hamiltonian. The first, second, and third order response functions are expressed in terms of correlation functions of the charge and the current densities. This approach is based on the gauge invariant current rather than the polarization, and on the vector potential rather than the electric and magnetic fields.