Quasi-exact-solution of the Generalized Exe Jahn-Teller Hamiltonian

We consider the solution of a generalized Exe Jahn-Teller Hamiltonian in the context of quasi-exactly solvable spectral problems. This Hamiltonian is expressed in terms of the generators of the osp(2,2) Lie algebra. Analytical expressions are obtained for eigenstates and eigenvalues. The solutions lead to a number of earlier results discussed in the literature. However, our approach renders a new understanding of ``exact isolated'' solutions

Optical properties and electronic band structure of topological insulators (on A5 2B6 3 compound based)

Cataloged from PDF version of article.We have performed a first principles study of structural, electronic, and optical properties of rhombohedral Sb2Te3 and Bi 2Te3 compounds using the density functional theory within the local density approximation. The lattice parameters, bulk modulus, and its pressure derivatives of these compounds have been obtained. The linear photon-energy dependent dielectric functions and some optical properties such as the energy-loss function, the effective number of valance electrons and the effective optical dielectric constant are calculated and presented in the study. © 2013 Copyright Taylor and Francis Group, LLC

On the Definition of Averagely Trapped Surfaces

Previously suggested definitions of averagely trapped surfaces are not well-defined properties of 2-surfaces, and can include surfaces in flat space-time. A natural definition of averagely trapped surfaces is that the product of the null expansions be positive on average. A surface is averagely trapped in the latter sense if and only if its area $A$ and Hawking mass $M$ satisfy the isoperimetric inequality $16\pi M^2 > A$, with similar inequalities existing for other definitions of quasi-local energy.Comment: 4 page

Electron Spectroscopy and the Electronic Structure of KNbO3: First Principle Calculations

Cataloged from PDF version of article.The electronic structures of KNbO(3)were calculated within the density functional theory, and their evolution was analyzed as the crystal-field symmetry changes from cubic to rhombohedral via tetragonal phase. We carried out electron-energy loss spectroscopy experiments by using synchrotron radiation and compared the results with the theoretical spectra calculated within Density Functional Theory. The dominant role of the NbO(6)octahedra in the formation of the energy spectra of KNbO(3)compound was demonstrated. The anomalous behavior of plasmons in ferroelectrics was exhibited by the function representing the characteristic energy loss in the region of phase transition

Mechanical, electronic and optical properties of Bi2S3 and Bi2Se3 compounds: first principle investigations

Cataloged from PDF version of article.The structural, mechanical, electronic, and optical properties of orthorhombic Bi2S3 and Bi2Se3 compounds have been investigated by means of first principles calculations. The calculated lattice parameters and internal coordinates are in very good agreement with the experimental findings. The elastic constants are obtained, then the secondary results such as bulk modulus, shear modulus, Young's modulus, Poisson's ratio, anisotropy factor, and Debye temperature of polycrystalline aggregates are derived, and the relevant mechanical properties are also discussed. Furthermore, the band structures and optical properties such as real and imaginary parts of dielectric functions, energy-loss function, the effective number of valance electrons, and the effective optical dielectric constant have been computed. We also calculated some non-linearities for Bi2S3 and Bi2Se3 (tensors of elasto-optical coefficients) under pressur

Effect of Thidiazuron used as an Elicitor in the Production of Capsaicin on Total Protein and Phenolic Amounts, Antioxidant Enzyme Activities of Pepper Plants

The effect of thidiazuron (TDZ) used as an elicitor on the total phenolic, total protein, superoxide dismutase (SOD) and catalase (CAT) enzyme activities, and production of capsaicin in the cell suspension culture of Maraş-1 pepper seeds was determined. TDZ was applied in four levels (0, 0.1 mM, 0.2 mM, 0.4 mM) and at three times (days 8, 10, and 12) to the cell suspensions. The content of the capsaicin in suspended cells was identified by high-performance liquid chromatography after extraction with ethyl acetate. It was identified that TDZ had a variable effect on the capsaicin accumulation. The highest capsaicin content was determined by84.859 µg/g f.w. at 0.4 mM TDZ 10d. The highest increase by 181.48% at 0.2 mM TDZ 10d, the highestdecrease by 49.83% at 0.4 mM TDZ 10d was determined intotal phenolic amount. The total protein amount decreased at 0.4 mM TDZ 8dand 12d. The highest SOD (457.983 enzyme units/g f.w.) and CAT (0.143 enzyme units/g f.w.) activities at 0.4 mM TDZ 8d, the lowest SOD (73.526 enzyme units/g f.w.) and CAT (0.030 enzyme units/g f.w.) activities at 0.2 mM TDZ 12d were measured

A generalized quantum nonlinear oscillator

We examine various generalizations, e.g. exactly solvable, quasi-exactly solvable and non-Hermitian variants, of a quantum nonlinear oscillator. For all these cases, the same mass function has been used and it has also been shown that the new exactly solvable potentials possess shape invariance symmetry. The solutions are obtained in terms of classical orthogonal polynomials

Digital Politics: Mobilization, Engagement, and Participation

The article provides insights into the driving forces that underpin new forms of political participation. Digital technologies offer opportunities for engaging in a wide range of civicallyoriented activities, each of which can contribute to deeper democratic engagement. Conventional acts of political participation are argued to be driven primarily by intrinsic motivations relating to self-efficacy and empowerment with participants feeling they can have influence over decision makers. Little research explores whether similar motivations drive participation in less conventional acts, as well as whether mobilisation attempts via social media by peers or political organisations mediate those motivations. Drawing on data from a survey among a representative sample of the UK electorate, we find the offline and online spheres of agency remain fairly distinct. Intrinsic and extrinsic motivations both matter but extrinsic motivations have the strongest explanatory power independent of the sphere of activity. The mediating effect of mobilisation tactics has a minimal effect on extrinsic motivations, online or offline, but online intrinsic motivations lose their explanatory power. As intrinsic factors offer little explanatory power some forms of online political participation may lack meaning to the individual. Rather, these non-conventional acts result from reward seeking and are more likely to be encouraged by non-governmental campaigning organizations suggesting social media users are most likely to perform simple acts in support of non-contentious causes

Urban agriculture: a global analysis of the space constraint to meet urban vegetable demand

Urban agriculture (UA) has been drawing a lot of attention recently for several reasons: the majority of the world population has shifted from living in rural to urban areas; the environmental impact of agriculture is a matter of rising concern; and food insecurity, especially the accessibility of food, remains a major challenge. UA has often been proposed as a solution to some of these issues, for example by producing food in places where population density is highest, reducing transportation costs, connecting people directly to food systems and using urban areas efficiently. However, to date no study has examined how much food could actually be produced in urban areas at the global scale. Here we use a simple approach, based on different global-scale datasets, to assess to what extent UA is constrained by the existing amount of urban space. Our results suggest that UA would require roughly one third of the total global urban area to meet the global vegetable consumption of urban dwellers. This estimate does not consider how much urban area may actually be suitable and available for UA, which likely varies substantially around the world and according to the type of UA performed. Further, this global average value masks variations of more than two orders of magnitude among individual countries. The variations in the space required across countries derive mostly from variations in urban population density, and much less from variations in yields or per capita consumption. Overall, the space required is regrettably the highest where UA is most needed, i.e., in more food insecure countries. We also show that smaller urban clusters (i.e., <100 km2 each) together represent about two thirds of the global urban extent; thus UA discourse and policies should not focus on large cities exclusively, but should also target smaller urban areas that offer the greatest potential in terms of physical space