Notes on Spinoptics in a Stationary Spacetime

In arXiv:1105.5629, equations of the modified geometrical optics for circularly polarized photon trajectories in a stationary spacetime are derived by using a (1+3)-decomposed form of Maxwell's equations. We derive the same results by using a four-dimensional covariant description. In our procedure, the null nature of the modified photon trajectory naturally appears and the energy flux is apparently null. We find that, in contrast to the standard geometrical optics, the inner product of the stationary Killing vector and the tangent null vector to the modified photon trajectory is no longer a conserved quantity along light paths. This quantity is furthermore different for left and right handed photon. A similar analysis is performed for gravitational waves and an additional factor of 2 appears in the modification due to the spin-2 nature of gravitational waves.Comment: 15 pages, to appear in PR

On the modeling of low-Reynolds-number turbulence

A full Reynolds-stress closure that is capable of describing the flow all the way to the wall was formulated for turbulent flow through circular pipe. Since viscosity does not appear explicitly in the pressure redistribution terms, conventional high-number models for these terms are found to be applicable. However, the models for turbulent diffusion and viscous dissipation have to be modified to account for viscous diffusion near a wall. Two redistribution and two diffusion models are investigated for their effects on the model calculations. Wall correction to pressure redistribution modeling is also examined. Diffusion effects on calculated turbulent properties are further investigated by simplifying the transport equations to algebraic equations for Reynolds stress. Two approximations are explored. These are the equilibrium and nonequilibrium turbulence assumptions. Finally, the two-equation closure is also used to calculate the flow in question and the results compared with all the other model calculations. Fully developed pipe flows at two moderate Reynolds numbers are used to validate these model calculations

Depressed clad hollow optical fiber with fundamental LP01 mode cut-off

We propose a depressed clad hollow optical fiber with fundamental (LP01) mode cut-off suitable for high power short-wavelength, especially three-level, fiber laser operation by introducing highly wavelength dependent losses at longer wavelengths. The cut-off characteristic of such fiber structure was investigated. A Yb-doped depressed clad hollow optical fiber laser generating 59.1W of output power at 1046nm with 86% of slope efficiency with respect to the absorbed pump power was realised by placing the LP01 mode cut-off at ~1100nm

Young\u27s modulus of [111] germanium nanowires

This paper reports a diameter-independent Young’s modulus of 91.9 ± 8.2 GPa for [111] Germaniumnanowires (Ge NWs). When the surface oxide layer is accounted for using a core-shell NW approximation, the YM of the Ge core approaches a near theoretical value of 147.6 ± 23.4 GPa. The ultimate strength of a NW device was measured at 10.9 GPa, which represents a very high experimental-to-theoretical strength ratio of ∼75%. With increasing interest in this material system as a high-capacity lithium-ion battery anode, the presented data provide inputs that are essential in predicting its lithiation-induced stress fields and fracture behavior

Optical Response of Solid CO2_2 as a Tool for the Determination of the High Pressure Phase

We report first-principles calculations of the frequency dependent linear and second-order optical properties of the two probable extended-solid phases of CO$_2$--V, i.e. $I\bar42d$ and $P2_12_12_1$. Compared to the parent $Cmca$ phase the linear optical susceptibility of both phases is much smaller. We find that $I\bar42d$ and $P2_12_12_1$ differ substantially in their linear optical response in the higher energy regime. The nonlinear optical responses of the two possible crystal structures differ by roughly a factor of five. Since the differences in the nonlinear optical spectra are pronounced in the low energy regime, i.e. below the band gap of diamond, measurements with the sample inside the diamond anvil cell are feasible. We therefore suggest optical experiments in comparison with our calculated data as a tool for the unambiguous identification of the high pressure phase of CO$_2$.Comment: 4 pages 2 fig

Peace Through Law? The Failure of a Noble Experiment

Ever since its publication in 1929, Erich Maria Remarque\u27s All Quiet on the Western Front has been regarded as a landmark of antiwar literature. Appearing a decade after the end of the First World War, the novel became a literary sensation almost overnight. Within a year of publication, it had been translated into twenty languages, including Chinese, and by April 1930, sales for twelve of the twenty editions stood at 2.5 million. Remarque was reputed to have the largest readership in the world. Hollywood took note, and an equally successful film appeared in 1930. The success of the novel was as unexpected as it was spectacular. Readers across Europe had displayed little interest in books about the war throughout the 1920s, but after Remarque\u27s success, the public\u27s appetite proved voracious. It was as if the publics of the great belligerents needed the perspective of a decade before they could begin to relive the experience of the war

Peace Through Law? The Failure of a Noble Experiment

Ever since its publication in 1929, Erich Maria Remarque\u27s All Quiet on the Western Front has been regarded as a landmark of antiwar literature. Appearing a decade after the end of the First World War, the novel became a literary sensation almost overnight. Within a year of publication, it had been translated into twenty languages, including Chinese, and by April 1930, sales for twelve of the twenty editions stood at 2.5 million. Remarque was reputed to have the largest readership in the world. Hollywood took note, and an equally successful film appeared in 1930. The success of the novel was as unexpected as it was spectacular. Readers across Europe had displayed little interest in books about the war throughout the 1920s, but after Remarque\u27s success, the public\u27s appetite proved voracious. It was as if the publics of the great belligerents needed the perspective of a decade before they could begin to relive the experience of the war