Complex wavelets and shift invariance

Recently we have developed a new form of discrete wavelet transform, which generates complex coefficients by using a dual tree of wavelet filters to obtain their real and imaginary parts. This introduces limited redundancy (2 m:1 for m-dimensional signals) and allows the transform to provide approximate shift invariance and directionally selective filters (properties lacking in the traditional wavelet transform) while preserving the usual properties of perfect reconstruction and computational efficiency with good well-balanced frequency responses. In this paper we analyse why the new transform can be designed to be shift invariant, and describe how to estimate the accuracy of this approximation and design suitable filters to achieve this.

Density of photon states in dye-doped chiral nematic liquid crystal cells in the presence of losses and gain

We calculate the density of photon states (DOS) of the normal modes in dye-doped chiral nematic liquid crystal (LC) cells in the presence of various loss mechanisms. Losses and gain are incorporated into the transmission characteristics through the introduction of a small imaginary part in the dielectric constant perpendicular and along the director, for which we assume no frequency dispersion. Theoretical results are presented on the DOS in the region of the photonic band gap for a range of values of the loss coefficient and different values of the optical anisotropy. The obtained values of the DOS at the photonic band gap edges predict a reversal of the dominant modes in the structure. Our results are found to be in good agreement with the experimentally obtained excitation thresholds in chiral nematic LC lasers. The behavior of the DOS is also discussed for amplifying LC cells providing additional insight to the lasing mechanism of these structures. © 2012 American Physical Society.

Density of photon states in dye-doped chiral nematic liquid crystal cells in the presence of losses and gain.

We calculate the density of photon states (DOS) of the normal modes in dye-doped chiral nematic liquid crystal (LC) cells in the presence of various loss mechanisms. Losses and gain are incorporated into the transmission characteristics through the introduction of a small imaginary part in the dielectric constant perpendicular and along the director, for which we assume no frequency dispersion. Theoretical results are presented on the DOS in the region of the photonic band gap for a range of values of the loss coefficient and different values of the optical anisotropy. The obtained values of the DOS at the photonic band gap edges predict a reversal of the dominant modes in the structure. Our results are found to be in good agreement with the experimentally obtained excitation thresholds in chiral nematic LC lasers. The behavior of the DOS is also discussed for amplifying LC cells providing additional insight to the lasing mechanism of these structures.

Spin glass behaviour and spin-dependent scattering in la 0.7Ca 0.3Mn 0.9Cr 0.1O 3 perovskites

The magnetic, electrical and thermal transport properties of the perovskite La 0.7Ca 0.3Mn 0.9Cr 0.1O 3 have been investigated by measuring dc magnetization, ac susceptibility, the magnetoresistance and thermal conductivity in the temperature range of 5-300K. The spin glass behaviour with a spin freezing temperature of 70 K has been well confirmed for this compound, which demonstrates the coexistence and competition between ferromagnetic and antiferromagnetic clusters by the introduction of Cr. Colossal magnetoresistance has been observed over the temperature range investigated. The introduction of Cr causes the "double-bump" feature in electrical resistivity ρ(T). Anomalies on the susceptibility and the thermal conductivity associated with the double-bumps in ρ(T) are observed simultaneously. The imaginary part of ac susceptibility shows a sharp peak at the temperature of insulating-metallic transition where the first resistivity bump was observed, but it is a deep-set valley near the temperature where the second bump in ρ(T) emerges. The thermal conductivity shows an increase below the temperature of the insulating-metallic transition, but the phonon scattering is enhanced accompanying the appearance of the second peak of double-bumps in ρ(T). We relate those observed in magnetic and transport properties of La 0.7Ca 0.3Mn 0.9Cr 0.1O 3 to the spin-dependent scattering. The results reveal that the spin-phonon interaction may be of more significance than the electron (charge)-phonon interaction in the mixed perovskite system. © 2005 Chinese Physical Society and IOP Publishing Ltd.

Quantum Confinement and Electronic Properties of Rutile TiO2 Nanowires

The quantum confinement effect, electronic properties, and optical properties of TiO2 nanowires in rutile structure are investigated via first-principles calculations. We calculate the size- and shape-dependent band gap of the nanowires and fit the results with the function E-g = E-g(bulk) + beta/d(alpha). We find that the quantum confinement effect becomes significant for d < 25 angstrom, and a notable anisotropy exists that arises from the anisotropy of the effective masses. We also evaluate the imaginary part of the frequency-dependent dielectric function [epsilon(2)(omega)] within the electric-dipole approximation, for both the polarization parallel [epsilon(parallel to)(2)(omega)] and the perpendicular [epsilon 1/2(omega)] to the axial (c) direction. The band structure of the nanowires is calculated, with which the fine structure of epsilon(parallel to)(2)(omega) has been analyzed.

Optical constants of cubic GaN/GaAs(001): Experiment and modeling

The optical constants epsilon(E)=epsilon(1)(E)+iepsilon(2)(E) of unintentionally doped cubic GaN grown on GaAs(001) have been measured at 300 K using spectral ellipsometry in the range of 1.5-5.0 eV. The epsilon(E) spectra display a structure, associated with the critical point at E-0 (direct gap) and some contribution mainly coming from the E-1 critical point. The experimental data over the entire measured spectral range (after oxide removal) has been fit using the Holden-Munoz model dielectric function [M. Munoz et al., J. Appl. Phys. 92, 5878 (2002)]. This model is based on the electronic energy-band structure near critical points plus excitonic and band-to-band Coulomb-enhancement effects at E-0, E-0 + Delta(0) and the E-1, E-1 + Delta(1), doublet. In addition to evaluating the energy of the E-0 critical point, the binding energy (R-1) of the two-dimensional exciton related to the E-1 critical point was estimated using the effective mass/k.p theory. The line, shape of the imaginary part of the cubic-GaN dielectric function shows excitonic effects at room temperature not withstanding that the exciton was not resolved. (C) 2003 American Institute of Physics.

Synthesis, structural and electrical characterizations of Sr2Fe1-xMxNbO6 (M = Zn and Cu) with double perovskite structure

Sr2Fe1-xZnxNbO6-x/2 (0 <= x <= 0.5) and Sr2Fe1-xCuxNbO6-x/2 (0.01 <= x <= 0.05) with the double perovskite structure have been synthesized. The crystal structures at room temperature were determined from Rietveld refinements of X-ray powder diffraction data. The plots of the imaginary parts of the impedance spectrum, Z '', and the electric modulus, M '', versus log (frequency), possess maxima for both curves separated by less than a half decade in frequency with associated capacities of 2 nF. The enhancement of the overall conductivity Of Sr2Fe1-xMxNbO6-x/2 (M = Cu and Zn) is observed, as increases from 2.48 (3) x 10(-4) S/cm for Sr2FeNbO6 to 3.82 (5) x 10(-3) S/cm for Sr2Fe0.8Zn0.2NbO5.9 at 673 K. Sr2Fe0.8Zn0.2NbO5.9 is chemically stable under the oxygen partial pressure from 1 atm to 10(-22) atm at 873 K. The p and n-type electronic conductions are dominant under oxidizing and reducing conditions, respectively, suggesting a small-polaron hopping mechanism of electronic conduction.

Study of the ionic conductivity of polymer electrolyte using imaginary impedance spectroscopy

Polymeric electrolytes of (PEO1)(10) LiClO4-Al2O3 (PEO: poly (ethyleneoxide)) and (PEO2)(16)LiClO4-EC (EC: ethylene carbonate) were prepared. We proposed an equivalent circuit and gave the meaning of the concerned circuit elements. When the impedance spectrum deformed severely, the ionic conductivity of polymer electrolyte was determined by using the maximum of imaginary impedance, which is a convenient method.

In situ analysis of electropolymerization of aniline by combined electrochemistry and surface plasmon resonance

The combination of electrochemistry with surface plasmon resonance (SPR) has been used to characterize the growth of polyaniline (PAn) on a gold electrode surface during potential cycling. Potential-modulated SPR characteristics of the PAn film were also revealed. The potential switch between the oxidized and reduced states of PAn can lead to a large change of SPR response due to the variation in the imaginary part of the dielectric constant of PAn film resulting from the transition of the film in conductivity. The redox transition of the PAn film during potential cycling is very profitable to the SPR measurements. Two modes of SPR measurement, SPR angular scan (R-theta) and the time evolution of the reflectivity change at a fixed angle (R-t), were displayed to study the growth process of the PAn film. The angle shift of the resonance minimum recorded at each cathodic limit of cyclic potential scanning allows for the unambiguous measurement of the film growth. During cyclic potential scanning, the R-t curve was repeatedly modulated with the direction of the potential ramp as a result of the redox switch of the PAn film, and the amplitude of potential-modulated reflectivity change was well correlated with the cyclic number. The time differential of the R-t curve permits continuous monitoring of the film growth process. These results illustrate that the combined technique is suitable for studying the electropolymerization process of a conducting polymer.

One century record of contamination by polycyclic aromatic hydrocarbons and polychlorinated biphenyls in core sediments from the southern Yellow Sea

Sixteen polycyclic aromatic hydrocarbons (PAHs) and 28 polychlorinated biphenyls (PCBs) were measured at a 2-cm interval in a core sample from the middle of the southern Yellow Sea for elucidating their historical variations in inflow and sources. The chronology was obtained using the Pb-210 method. PAHs concentrations decreased generally with depth and two climax values occurred in 14-16 cm and 20-22 cm layers, demonstrating that the production and usage of PAHs might reach peaks in the periods of 1956-1962 and 1938-1944. The booming economy and the navy battles of the Second World War might explain why the higher levels were detected in the two layers. The result of principal component analysis (PCA) revealed that PAHs were primarily owing to the combustion product. Down-cored variation of PCB concentrations was complex. Higher concentrations besides the two peaks being the same as PAHs were detected from 4 to 8 cm, depositing from 1980 to 1992, which probably resulted from the disposal of the out-dated PCB-containing equipment. The average Cl percentage of PCBs detected was similar to that of the mixture of Aroclor 1254 and 1242, suggesting they might origin from the dielectrical and heat-transfer fluid. The total organic carbon (TOC) content played a prevalent role in the adsorption of high molecular weight PAHs (>= 4-ring), while no obvious relationship among total PCBs, the concentration of congeners, and TOC was found.

Spectator Sport War: The West and Contemporary Conflict

McInnes, Colin, Spectator Sport War: The West and Contemporary Conflict (Boulder, CO: Lynne Rienner, 2002) pp.vii+187 RAE2008

A different kind of war? : September 11 and the United States' Afghan War

McInnes, C., 'A different kind of war? 11 September and the United States' Afghan war'. Review of International Studies, 29 (2), 165-184. RAE2008

Peace and Peacemaking in Paul Against the Backdrop of Greco-Roman Conceptions of Peace

Peace in the ancient world has been studied primarily from the perspective of pacifism and questions related to war and peace. This study employs a socio-historical method to determine how peace was understood in itself, not just with respect to war. It demonstrates that the Greco-Roman world viewed peace as brief periods of tranquility in an existence where conflict was the norm, while Paul regarded peace as the norm and conflict as an intrusive aberration. Through a historical and literary survey of Greco-Roman thought and culture, this study shows that myth, legend, religion, education, philosophy, and science created and perpetuated the idea that conflict was necessary for existence. Wars were fought to attain peace, which meant periods of calm, quiet, and security with respect to the gods, one's inner self, nature, others who are insiders, and others who are outsiders. Despite the desirability of peace, genuine peace was seldom experienced, and even then, only briefly, as underlying enmity persisted without resolution. While Paul supports the prevailing conception of peace as tranquility and felicity in relation to God, self, nature, and others, he differs as to the origin, attainment, and maintenance of peace. In Paul, peace originates in God and is graciously given to those who are justified and reconciled to God through Jesus Christ. God removes the enmity caused by sin and provides the indwelling Spirit to empower believers to think and behave in ways that promote and maintain peace. This study also examines how three social dynamics (honor-shame, patron-client, friendship-enmity) affect Paul's approach to conflict resolution with Philemon and Onesimus, Euodia and Syntyche, believers who are prosecuting one another in civil courts, and Peter. Rather than giving specific procedures for resolving conflict, Paul reinforces the believer's new identity in Christ and the implications of God's grace, love, and peace upon their thoughts, words, and behavior toward one another. Paul uses these three social dynamics to encourage believers in the right direction, but their ultimate accountability is to God. The study concludes with four strategic principles for educating the church and developing an atmosphere and attitude within the church for peacemaking.

Homosexuality and the United Methodist Church: An Ecclesiological Dilemma

Since 1968 The United Methodist Church has publicly debated the status and roles of homosexual persons in the life of the Church, creating considerable conflict within the Denomination. Academic research on the question of homosexuality and the Church has often focused on theological understandings of homosexuality and on the ways the conflict reflects broader "culture wars" in society. Yet little attention has been given to how the Church's concrete practices and polity toward homosexual persons reflect underlying tensions within the ecclesiological identity of the Denomination. This dissertation proposes that the issue of homosexuality is a critically important case study for exploring the practical ecclesiology of The United Methodist Church. In an effort to identify tensions within contemporary United Methodism's practical ecclesiology, it traces in detail the history of the denominational debate over homosexuality since 1968 and articulates the diverse and often conflicting ecclesiological commitments embedded within that debate. Focusing on the debate itself as a practice of the Church, this dissertation illustrates the ways in which the controversy over sexuality reflects the Denomination's conflicted practical ecclesiology. By examining the rhetoric of the sexuality debates in The United Methodist Church from 1968 to 2008, and by articulating the ecclesiological commitments embedded in those debates, the dissertation reveals a fundamental conflict over interpretations of ecclesial unity. Moreover, the dissertation explores the extent to which the conflict over unity reflects ecclesiological tensions present in John Wesley's own practical ecclesiology; and it asks whether or not contemporary interpretations of United Methodist ecclesiology might provide a normative framework for assessing and resolving the underlying ecclesial conflict at work in sexuality debates. The dissertation concludes by exploring the practice of public narrative as a concrete strategy that might be employed by the Denomination to reconcile the diverging ecclesiological visions within the contemporary church so that a clear and consensual ecclesiology might emerge.

ELGAR AND MART&: THE CELLO WORKS AND MUSICAL CHARACTERISTICS OF TWO REMARKABLE, SELF-TAUGHT, NATIONALISTIC COMPOSERS

The British Edward Elgar and Czech Bohuslav MartinB were two of the most prominent Nationalistic composers of their respective countries during the late nineteenth and early twentieth centuries. Their musical patriotism incorporates the unique paths of their lives as socially isolated and self-taught composers as expressed their outstanding Nationalistic compositions produced through the period of history encompassing the two World Wars.In the first chapter of this dissertation, a brief biography of Elgar is presented and the essential aspects of his formative years influencing him to become a self-taught musician are discussed. The second chapter demonstrates Elgar's musical characteristics through the study of a selection of his masterpieces. In the third chapter, a brief biography of Martinti is presented along with a history of his musical development, characterized by his social isolation during four different periods of his life-his residences in PoliCka, Prague, Paris, and then in the United States. The fourth chapter considers MartinB's musical characteristics as revealed through the study of a selection of his greatest works. In support of this doctoral project, I performed two recitals of cello works by Elgar and Martini3 at the University of Maryland, College Park. The first recital, accompanied by Susan Slingland and Hiroko Yamazaki, included three of Martini3's works, Sonata No. 2 for Cello and Piano (1941); Variations on a Theme of Rossini for Cello and Piano (1 942); and Sonata No. 3 for Cello and Piano (1952). The second recital, accompanied by Wonyoung Chang and Naoko Takao, presented Martini3's Sonata No. 1 for Cello and Piano (1939) and Elgar's Concerto for Cello and Orchestra Op. 85 in E minor (1 919).