Micro-Raman and field emission studies of silicon nanowires prepared by metal assisted chemical etching

Micro-Raman scattering and electron field emission characteristics of silicon nanowires (SiNWs) synthesized by metal assisted chemical etching (MACE) are investigated. Scanning electron microscopy images reveal the growth of well aligned vertical SiNWs. Raman shift and size relation from bond-polarizability model has been used to calculate exact confinement sizes in SiNWs. The Si optical phonon peak for SiNWs showed a downshift and an asymmetric broadening with decreasing diameter of the SiNWs due to quantum confinement of optical phonons. The field emission characteristics of these SiNWs are studied based by carrying out current-voltage measurements followed by a theoretical analysis using Fowler-Nordheim equation. The electron field emission increased with decreasing diameter of SiNWs. Field emission from these SiNWs exhibits significant enhancement in turn-on field and total emission current with decreasing nanowire size. The reported results in the current study indicate that MACE is a simple technique to prepare well-aligned SiNWs with potentials for applications in field emission devices

Efficacy of brodifacoum (Talon) bait against three rodent species

Brodifacoum was fed to three rodent species, viz . M. hurrianae, R. rattus and F. pennanti, using a no-choice feeding trial for 7 days at various concentrations− 0.005%, 0.0025%, and 0.00125%. The compound was found effective, palatable, developed no sign of poison bait-shyness but indicated a slight aversion of poison. The death of the animals was due to pulmonary distress and hemorrhage

Maximal Independent Sets in Generalised Caterpillar Graphs

A caterpillar graph is a tree which on removal of all its pendant vertices leaves a chordless path. The chordless path is called the backbone of the graph. The edges from the backbone to the pendant vertices are called the hairs of the caterpillar graph. Ortiz and Villanueva (C.Ortiz and M.Villanueva, Discrete Applied Mathematics, 160(3): 259-266, 2012) describe an algorithm, linear in the size of the output, for finding a family of maximal independent sets in a caterpillar graph. In this paper, we propose an algorithm, again linear in the output size, for a generalised caterpillar graph, where at each vertex of the backbone, there can be any number of hairs of length one and at most one hair of length two

Maximum Cardinality Neighbourly Sets in Quadrilateral Free Graphs

Neighbourly set of a graph is a subset of edges which either share an end point or are joined by an edge of that graph. The maximum cardinality neighbourly set problem is known to be NP-complete for general graphs. Mahdian (M.Mahdian, On the computational complexity of strong edge coloring, Discrete Applied Mathematics, 118:239-248, 2002) proved that it is in polynomial time for quadrilateral-free graphs and proposed an O(n^{11}) algorithm for the same (along with a note that by a straightforward but lengthy argument it can be proved to be solvable in O(n^5) running time). In this paper we propose an O(n^2) time algorithm for finding a maximum cardinality neighbourly set in a quadrilateral-free graph

Fractional telegraph equation, Mittag-Leffler function, Hilfer derivative, Hadamard fractional derivative, Riesz-Feller space-fractional derivative

In this paper we consider space-time fractional telegraph equations, where the time derivatives are intended in the sense of Hilfer and Hadamard while the space fractional derivatives are meant in the sense of Riesz-Feller. We provide the Fourier transforms of the solutions of some Cauchy problems for these fractional equations. Probabilistic interpretations of some specific cases are also provided

Tailoring between network rigidity and nanosecond transient absorption in a-GexAs35-xSe65 thin films

In this letter, we report the first observation of dramatic decrease in nanosecond (ns) pulsed laser induced transient absorption (TA) in a-GexAs35-xSe65 thin films by tuning the amorphous network from floppy to rigid. Our results provide the direct experimental evidence of a self trapped exciton mechanism, where trapping of the excitons occurs through bond rearrangements. Taken together, a rigid amorphous network with more constraints than degrees of freedom, are unable to undergo any such bond rearrangements and results in weaker TA. However, we also demonstrate that excitation fluence can be effectively utilized as a simple tool to lift up enough constraints to introduce large TA even in rigid networks. Apart from this, we also show that TA is tunable with network rigidity as it blueshift when the mean coordination is increased from 2.35 to 2.6.Comment: 5 pages, 4 figure

Time Operators and Time Crystals

We investigate time operators in the context of quantum time crystals in ring systems. A generalized commutation relation called the generalized weak Weyl relation is used to derive a class of self-adjoint time operators for ring systems with a periodic time evolution: The conventional Aharonov-Bohm time operator is obtained by taking the infinite-radius limit. Then, we discuss the connection between time operators, time crystals and real-space topology. We also reveal the relationship between our time operators and a $\mathcal{PT}$-symmetric time operator. These time operators are then used to derive several energy-time uncertainty relations

A hybrid video quality metric for analyzing quality degradation due to frame drop

In last decade, ever growing internet technologies provided platform to share the multimedia data among different communities. As the ultimate users are human subjects who are concerned about quality of visual information, it is often desired to have good resumed perceptual quality of videos, thus arises the need of quality assessment. This paper presents a full reference hybrid video quality metric which is capable to analyse the video quality for spatially or temporally (frame drop) or spatio-temporally distorted video sequences. Simulated results show that the metric efficiently analyses the quality degradation and more closer to the developed human visual systemComment: 7 pages, 9 figure

Solutions of fractional reaction-diffusion equations in terms of Mittag-Leffler functions

This paper deals with the solution of unified fractional reaction-diffusion systems. The results are obtained in compact and elegant forms in terms of Mittag-Leffler functions and generalized Mittag-Leffler functions, which are suitable for numerical computation. On account of the most general character of the derived results, numerous results on fractional reaction, fractional diffusion, and fractional reaction-diffusion problems scattered in the literature, including the recently derived results by the authors for reaction-diffusion models, follow as special cases.Comment: 22 pages, LaTe

Computational solutions of unified fractional reaction-diffusion equations with composite fractional time derivative

This paper deals with the investigation of the computational solutions of an unified fractional reaction-diffusion equation, which is obtained from the standard diffusion equation by replacing the time derivative of first order by the generalized fractional time-derivative defined by Hilfer (2000), the space derivative of second order by the Riesz-Feller fractional derivative and adding the function phi(x,t) which is a nonlinear function overning reaction. The solution is derived by the application of the Laplace and Fourier transforms in a compact and closed form in terms of the H-function. The main result obtained in this paper provides an elegant extension of the fundamental solution for the space-time fractional diffusion equation obtained earlier by Mainardi et al. (2001, 2005) and a result very recently given by Tomovski et al. (2011). Computational representation of the fundamental solution is also obtained explicitly. Fractional order moments of the distribution are deduced. At the end, mild extensions of the derived results associated with a finite number of Riesz-Feller space fractional derivatives are also discussed.Comment: 14 pages, Te