A method of segment protection based on p-cycle for dynamic multicast with limited-range wavelength converter in WDM network

In the optical multicast network, node and link failures have very important influence on the network survivability which may lead to multiple destinations cannot receive data. Based on the wavelength layered-graph method, a method of efficiency-score based on heuristic algorithm of pre-configured cycle (p-Cycle) based-segment protection (ESHS) for dynamic multicast with limited-range wavelength conversion was presented in this paper. By finding the multicast tree segment protection, the total available p-Cycles are constructed for the multicast. Then we calculate each p-Cycle efficiency-score, the highest efficient-score p-Cycle is selected as the multicast route protection p-Cycle. The simulation results show that the ESHS can get higher performance than the existing ESHT algorithm, in terms of multicast request blocking probability and wavelength utilization.     

Adjoint-based h–p adaptive discontinuous Galerkin methods for the 2D compressible Euler equations

In this paper, we investigate and present an adaptive Discontinuous Galerkin algorithm driven by an adjoint-based error estimation technique for the inviscid compressible Euler equations. This approach requires the numerical approximations for the flow (i.e. primal) problem and the adjoint (i.e. dual) problem which corresponds to a particular simulation objective output of interest. The convergence of these two problems is accelerated by an hp-multigrid solver which makes use of an element Gauss–Seidel smoother on each level of the multigrid sequence. The error estimation of the output functional results in a spatial error distribution, which is used to drive an adaptive refinement strategy, which may include local mesh subdivision (h-refinement), local modification of discretization orders (p-enrichment) and the combination of both approaches known as hp-refinement. The selection between h- and p-refinement in the hp-adaptation approach is made based on a smoothness indicator applied to the most recently available flow solution values. Numerical results for the inviscid compressible flow over an idealized four-element airfoil geometry demonstrate that both pure h-refinement and pure p-enrichment algorithms achieve equivalent error reductions at each adaptation cycle compared to a uniform refinement approach, but requiring fewer degrees of freedom. The proposed hp-adaptive refinement strategy is capable of obtaining exponential error convergence in terms of degrees of freedom, and results in significant savings in computational cost. A high-speed flow test case is used to demonstrate the ability of the hp-refinement approach for capturing strong shocks or discontinuities while improving functional accuracy.     

Theoretical study of optical and electronic properties of p-terphenyls containing cyano substituents as promising light-emitting materials

Recently, p-terphenyls containing alkoxylated backbones with or without CN groups on either the central phenyl ring or peripheral rings were synthesized and their photo-luminescent properties were studied. Herein, semi-empirical AM1 and density functional theory (DFT) B3LYP calculations with the 6-31G* basis set have been performed to optimize structure for the ground state and the semi-empirical ZINDO calculations have been used to determine the maximum absorption (λ_abs^max) and emission wavelengths (λ_emi) for 19 p-terphenyls. The steric effect is assigned to be responsible for the calculated λ_abs^max and λ_emi shifts and the CN group at the central phenyl with ortho-substitution and at peripheral phenyl rings with para-substitution can also significantly influence these spectra. According to experimental results, the p-terphenyls with CN groups may have a lower energy of LUMO, and thus, we investigated the influence of the substitution position and the number of CN groups on the p-terphenyl moiety. The calculated optical and electronic properties provide important information on the behavior of the corresponding Organic light-emitting diode device (OLED). The suggested theoretical calculation protocol can be employed to predict electro-luminescent characteristics of other materials, and further, to design novel materials for OLED.     

Effect of Pt and Ti on Ni/Ag/(Pt or Ti)/Au p-ohmic contacts of GaN based flip-chip LEDs

In this paper, we report the dependence of Ni/Ag/diffusion barrier (D.B)/Au p-ohmic contact on Pt^D.B and Ti^D.B for GaN based flip-chip light emitting diodes (FC LEDs). It is shown that D.B metals have strongly influenced on the reflectance and contact resistivity of contacts. We present these results are caused by the variation of the morphology and atomic distribution due to D.Bs. The roles of Pt^D.B and Ti^D.B on Ni/Ag/D.B/Au p-GaN ohmic contacts are analyzed using the confocal laser scanning microscopy (CLSM) measurement and the secondary ion mass spectroscopy (SIMS) profiles in details.     

P-n codoping induced enhancement of ferromagnetism in Mn-doped In2O3: A first-principles study

We have performed first-principles density functional theory calculation in order to investigate the feasibility of “p-n codoping method” in improving magnetic property of In₂O₃ based diluted magnetic semiconductors. We find that the ferromagnetic state is favored in Mn-doped In₂O₃, and Sn doping can increase magnetic moment in Mn-doped In₂O₃. These findings are in line with our earlier experimental observation. Along with previous works, we now have enough evidences to support that p-n codoping is a valid method to improve magnetism of oxides based diluted magnetic semiconductors.     

Renormalization group approach to a p-wave superconducting model

We present in this work an exact renormalization group (RG) treatment of a one-dimensional p-wave superconductor. The model proposed by Kitaev consists of a chain of spinless fermions with a p-wave gap. It is a paradigmatic model of great actual interest since it presents a weak pairing superconducting phase that has Majorana fermions at the ends of the chain. Those are predicted to be useful for quantum computation. The RG allows to obtain the phase diagram of the model and to study the quantum phase transition from the weak to the strong pairing phase. It yields the attractors of these phases and the critical exponents of the weak to strong pairing transition. We show that the weak pairing phase of the model is governed by a chaotic attractor being non-trivial from both its topological and RG properties. In the strong pairing phase the RG flow is towards a conventional strong coupling fixed point. Finally, we propose an alternative way for obtaining p-wave superconductivity in a one-dimensional system without spin–orbit interaction.     

Determination of electrical types in the P-doped ZnO thin films by the control of ambient gas flow

Phosphorus (P)-doped ZnO thin films with amphoteric doping behavior were grown on c-sapphire substrates by radio frequency magnetron sputtering with various argon/oxygen gas ratios. Control of the electrical types in the P-doped ZnO films was achieved by varying the gas ratio without post-annealing. The P-doped ZnO films grown at a argon/oxygen ratio of 3/1 showed p-type conductivity with a hole concentration and hole mobility of 1.5 × 10¹⁷ cm⁻³ and 2.5 cm²/V s, respectively. X-ray diffraction showed that the ZnO (0 0 0 2) peak shifted to lower angle due to the positioning of P³⁻ ions with a larger ionic radius in the O²⁻ sites. This indicates that a p-type mechanism was due to the substitutional P_O. The low-temperature photoluminescence of the p-type ZnO films showed p-type related neutral acceptor-bound exciton emission. The p-ZnO/n-Si heterojunction light emitting diode showed typical rectification behavior, which confirmed the p-type characteristics of the ZnO films in the as-deposited status, despite the deep-level related electroluminescence emission.     

Measurement of regional cerebral glucose uptake by magnetic resonance spin-lock imaging

Purpose

The regional uptake of glucose in rat brain in vivo was measured at high resolution using spin-lock magnetic resonance imaging after infusion of the glucose analogue 2-deoxy-d-glucose (2DG). Previous studies of glucose metabolism have used ¹³C-labeled 2DG and NMR spectroscopy, ¹⁸F-labeled fluorodeoxyglucose (FDG) and PET, or chemical exchange saturation transfer (CEST) MRI, all of which have practical limitations. Our goal was to explore the ability of spin-lock sequences to detect specific chemically-exchanging species in vivo and to compare the effects of 2DG in brain tissue on CEST images.

Methods

Numerical simulations of R_1p and CEST contrasts for a variety of sample parameters were performed to evaluate the potential specificity of each method for detecting the exchange contributions of 2DG. Experimental measurements were made in tissue phantoms and in rat brain in vivo which demonstrated the ability of spin-lock sequences for detecting 2DG.

Results

R_1p contrast acquired with appropriate spin-lock sequences can isolate the contribution of exchanging protons in 2DG in vivo and appears to have better sensitivity and more specificity to 2DG–water exchange effects than CEST.

Conclusion

Spin-lock imaging provides a novel approach to the detection and measurement of glucose uptake in brain in vivo.     

The binding of 3-(p-bromophenyl)-5-methyl-thiohydantoin with human serum albumin: Investigation by fluorescence spectroscopy and molecular model

The binding of 3-(p-bromophenyl)-5-methyl-thiohydantoin (BPMT) with human serum albumin (HSA) was investigated by fluorescence spectroscopy in combination with UV absorption spectrum under physiological conditions. The intrinsic fluorescence of HSA was quenched by BPMT through static quenching mechanism and the fluorescence emission spectrum of HSA exhibited appreciable hypsochromic shift with increasing concentration of BPMT. The binding constants (K) of HSA with BPMT and the number binding sites (n) at different temperatures, thermodynamic parameter enthalpy changes (ΔH) and entropy changes (ΔS) of HSA-BPMT have been calculated according to the relevant fluorescence data, indicating that the hydrophobic interaction played a major role, which was consistent with the result of molecular modeling study.     

Non-linear realizations,Goldstone bosons of broken Lorentz rotations and effective actions for p-branes

We consider the non-linear realizations of the Poincare group for p  -branes with local subgroup SO(1,p)×SO(D−(p+1))$\mathit{SO}(1,p)\times \mathit{SO}(D-(p+1))$. The Nambu–Goto p-brane action is constructed using the Maurer–Cartan forms of the unbroken translations. We perform a throughout phase space analysis of the action and show that it leads to the canonical action of a p-brane. We also construct some higher order derivative terms of the effective p-brane action using the MC forms of the broken Lorentz transformations.     

Deposition and properties of B-N codoped p-type ZnO thin films by RF magnetron sputtering

B-N codoped p-type ZnO thin films have been realized by radio frequency (rf) magnetron sputtering using a mixture of argon and oxygen as sputtering gas. Types of conduction and electrical properties in codoped ZnO films were found to be dependent on oxygen partial pressure ratios in the sputtering gas mixture. When oxygen partial pressure ratio was 70%, the codoped ZnO film showed p-type conduction and had the best electrical properties. Additionally, the p-ZnO/n-Si heterojunction showed a clear p-n diode characteristic. XRD results indicate that the B-N codoped ZnO film prepared in 70% oxygen partial pressure ratio has high crystal quality with (0 0 2) preferential orientation. Meanwhile, the B-N codoped ZnO film has high optical quality and displays the stronger near band edge (NBE) emission in the temperature-dependent photoluminescence spectrum, the acceptor energy level was estimated to be located at 125 meV above the valence band.     

An algorithm for sparse MRI reconstruction by Schatten p-norm minimization

In recent years, there has been a concerted effort to reduce the MR scan time. Signal processing research aims at reducing the scan time by acquiring less K-space data. The image is reconstructed from the subsampled K-space data by employing compressed sensing (CS)-based reconstruction techniques. In this article, we propose an alternative approach to CS-based reconstruction. The proposed approach exploits the rank deficiency of the MR images to reconstruct the image. This requires minimizing the rank of the image matrix subject to data constraints, which is unfortunately a nondeterministic polynomial time (NP) hard problem. Therefore we propose to replace the NP hard rank minimization problem by its nonconvex surrogate — Schatten p-norm minimization. The same approach can be used for denoising MR images as well.Since there is no algorithm to solve the Schatten p-norm minimization problem, we derive an efficient first-order algorithm. Experiments on MR brain scans show that the reconstruction and denoising accuracy from our method is at par with that of CS-based methods. Our proposed method is considerably faster than CS-based methods.     

Joint L1/Lp-regularized minimization in video recovery of remote sensing based on compressed sensing

L₁ regularization and L_p regularization are proposed for processing recovered images based on compressed sensing (CS). L₁ regularization can be solved as a convex optimization problem but is less sparse than L_p (0 < p < 1). L_p regularization is sparser than L₁ regularization but is more difficult to solve. This paper proposes joint L₁/L_p (0 < p < 1) regularization, which combines L_p regularization and L₁ regularization. This joint regularization is applied to recover video of remote sensing based on CS. Joint regularization is sparser than L₁ regularization but is as easy to solve as L₁ regularization. A linearized Bregman reweighted iteration algorithm is proposed to solve the joint L₁/L_p regularization problem. The performance and capabilities of the linearized Bregman algorithm and linearized Bregman reweighted algorithm for solving the joint L₁/L_p regularization model are analyzed and compared through numerical simulations.     

Explicit one-step time discretizations for discontinuous Galerkin and finite volume schemes based on local predictors

We consider a family of explicit one-step time discretizations for finite volume and discontinuous Galerkin schemes, which is based on a predictor-corrector formulation. The predictor remains local taking into account the time evolution of the data only within the grid cell. Based on a space–time Taylor expansion, this idea is already inherent in the MUSCL finite volume scheme to get second order accuracy in time and was generalized in the context of higher order ENO finite volume schemes. We interpret the space–time Taylor expansion used in this approach as a local predictor and conclude that other space–time approximate solutions of the local Cauchy problem in the grid cell may be applied. Three possibilities are considered in this paper: (1) the classical space–time Taylor expansion, in which time derivatives are obtained from known space-derivatives by the Cauchy–Kovalewsky procedure; (2) a local continuous extension Runge–Kutta scheme and (3) a local space–time Galerkin predictor with a version suitable for stiff source terms. The advantage of the predictor–corrector formulation is that the time evolution is done in one step which establishes optimal locality during the whole time step. This time discretization scheme can be used within all schemes which are based on a piecewise continuous approximation as finite volume schemes, discontinuous Galerkin schemes or the recently proposed reconstructed discontinuous Galerkin or P_NP_M schemes. The implementation of these approaches is described, advantages and disadvantages of different predictors are discussed and numerical results are shown.     

Observation of the 5pΠu Rydberg state of Li2

Some weak, collisionally induced transitions in ⁷Li₂ have been recorded by Fourier transform spectrometry in the near infrared, following excitation of the 5d¹Π_g state by optical-optical double resonance. They have been assigned as transitions to the 1 ¹Δ_g state from levels v=0 and 1 of a new ungerade Rydberg state, 5p¹Π_u. Quantum defect considerations indicate that the principal quantum number for this new state is 5, and that the assignment to 5p is compatible with a Rydberg series of which the lowest members would be the B¹Π_u and C¹Π_u states.     

9,10-Anthracene-centered oligo(p-phenyleneethynylene)s with end-capping didecylamines exhibiting enhanced two-photon fluorescence action cross-section

This study reports the synthesis and the two-photon absorption (TPA) properties of a series of 9,10-anthracene-centred oligo(p-phenyleneethynylene)s with end-capping didecylamine. The results show that both the maximal TPA cross-sections (δ_max) and the fluorescence quantum yields (Φ) of the oligomers increase with the extension of phenylethynyl bridges. Interestingly, the Φδ_max per repeating unit to is obviously enhanced by extending linearly conjugation size of the oligomers. Moreover, these oligomers all show the maximal two-photon absorption cross-sections at 800 nm and emit strong green to yellowish-green two-photon excited fluorescence. These materials may find applications in which two-photon excited fluorescence and photo-induced electron transfer are utilized.     

Realization of p-ZnO thin films by GaP codoping

An attempt has been made to realize p-ZnO by directly doping (codoping) GaP into ZnO thin films. GaP codoped ZnO thin films of different concentrations (1, 2 and 4 mol%) have been grown by RF magnetron sputtering. The grown films on sapphire substrate have been characterized by X-ray diffraction (XRD), Hall measurement, Photoluminescence (PL) and Energy dispersive spectroscopy (EDS) to validate the p-type conduction. XRD result shows that all the films have been preferentially oriented along (0 0 2) orientation. The decrease of full-width at half maximum (FWHM) with increase in GaP doping depicts the decrease in native donor defects. Hall measurement shows that among the three films, 2 and 4 mol% GaP doped ZnO shows p-conductivity due to the sufficient amount of phosphorous incorporation. It has been found that low resistivity (2.17 Ωcm) and high hole concentration (1.8×10¹⁸ cm⁻³) for 2% GaP codoped ZnO films due to best codoping. The red shift in near-band-edge (NBE) emission and donar-acceptor-pair (DAP) and neutral acceptor bound recombination (A°X) observed by room temperature and low temperature (10 K) PL, respectively, well acknowledged the formation of p-ZnO. The incorporated phosphorous in the film has been also confirmed by EDS analysis.     

Cu-codoping inducing the room-temperature magnetism and p-type conductivity of ZnCoO diluted magnetic semiconductor

Successful synthesis of room-temperature ferromagnetic semiconductors, Cu-codoped ZnCoO films are obtained by sol-gel method. It is found that the essential ingredient in achieving room-temperature ferromagnetism is Cu-codoping. By Hall-effect measurement a p-type conductivity was observed for the Cu-codoped films, the hole concentration increases with the increase in Cu concentration. XPS result confirmed Cu ions are univalent in the films, which induced the room-temperature ferromagnetism.     

Dielectric and piezoelectric properties of non-stoichiometric (K0.5Na0.5)(Nb0.9+xTa0.1)O3 ceramics

In the study, in order to develop the lead-free piezoelectric ceramics for actuator, transformer and other electronic-devices application, (K_0.5Na_0.5)(Nb_0.9+xTa_0.1)O₃ + 0.5 mol% CuO + 0.2 mol% MnO₂ ceramics were prepared by conventional mixed oxide method. The effects of B-site non-stoichiometry in [(K_0.5Na_0.5)] [(Nb_0.9+xTa_0.1)O₃] ceramics on microstructure and piezoelectric properties were investigated. The density, electromechanical coupling factor (k_p), mechanical quality factor (Q_m), piezoelectric constant (d₃₃), T_C and T_O-T of NKNT ceramics with x = 0.0065 showed the optimum values of 4.58 g/cm³, 0.427, 1554, 109 pC/N, 373 °C and 226 °C, respectively, suitable for piezoelectric motor, and transformer applications.     

Optimal Runge–Kutta smoothers for the p-multigrid discontinuous Galerkin solution of the 1D Euler equations

This work presents a family of original Runge–Kutta methods specifically designed to be effective relaxation schemes in the numerical solution of the steady state solution of purely advective problems with a high-order accurate discontinuous Galerkin space discretization and a p-multigrid solution algorithm. The design criterion for the construction of the Runge–Kutta methods here developed is different form the one traditionally used to derive optimal Runge–Kutta smoothers for the h-multigrid algorithm, which are designed in order to provide a uniform damping of the error modes in the high-frequency range only. The method here proposed is instead designed in order to provide a variable amount of damping of the error modes over the entire frequency spectrum. The performance of the proposed schemes is assessed in the solution of the steady state quasi one-dimensional Euler equations for two test cases of increasing difficulty. Some preliminary results showing the performance for multidimensional applications are also presented.