Increasing the response of PIN photodiodes to the ultraviolet

Solid state device uses sapphire windows and avoids coatings which absorb ultraviolet radiation and ultimately alter detector geometry. Ultimate solution for ultraviolet response is geometry with maximum peripheral area and horizontal field structure to draw out photon induced current carriers

On the Existence of Radiation Gauges in Petrov type II spacetimes

The radiation gauges used by Chrzanowski (his IRG/ORG) for metric reconstruction in the Kerr spacetime seem to be over-specified. Their specification consists of five conditions: four, which we treat here as valid gauge conditions, plus an additional condition on the trace of the metric perturbation. In this work, we utilize a newly developed form of the perturbed Einstein equations to establish a condition -- on a particular tetrad component of the stress-energy tensor -- under which the full IRG/ORG can be imposed. Using gauge freedom, we are able to impose the full IRG for Petrov type II and type D backgrounds, using a different tetrad for each case. As a specific example, we work through the process of imposing the IRG in a Schwarzschild background, using a more traditional approach. Implications for metric reconstruction using the Teukolsky curvature perturbations in type D spacetimes are briefly discussed.Comment: 21 pages, uses iop style files. v2: proved a stronger result for type II backgrounds, added a subsection on remaining gauge freedom in the full IRG and improved calrity and readability throughout due to insightful referee comments; published as Class. Quantum Grav. 24 (2007) 2367-238

Theoretical Description of the Role of Halides, Silver, and Surfactants on the Structure of Gold Nanorods

Density functional theory simulations including dispersion provide an atomistic description of the role of different compounds in the synthesis of gold-nanorods. Anisotropy is caused by the formation of a complex between the surfactant, bromine, and silver that preferentially adsorbs on some facets of the seeds, blocking them from further growth. In turn, the nanorod structure is driven by the perferential adsorption of the surfactant, which induces the appearance of open {520} lateral facets

Comparative Costs of Iron Pretreatment

A Considerable amount of information is now available on the methods of pretreatment of blast furnace iron. This paper does not discuss the detailed operations involved, but attempts to compare the economics of the capital investment and process cost involved. Preatment can be divided into two main types: Type 1: Methods which seek to remove a proportion of the silicon. TypeII: Methods which seek to remove the silicon and some part of the phosphorus. As this paper is intended as a basis of discussion on the circumstances which apply in India it deals only with Type 1 pretreatment. The phosphorus contents of Indian irons at present used, and the future sources of iron ore are such that it is suggested that phosphorus removal would give no real advantage in subsequent steelmaking operations

Incorporating project uncertainty in novel environmental biotechnologies: illustrated using phytoremediation

"Pollution of the environment by metals and organic contaminants is an intractable global problem, with cleanup costs running into billions of dollars using current engineering technologies. The availability of alternative, cheap and effective technologies would significantly improve the prospects of cleaning-up metal contaminated sites. Phytoremediation has been proposed as an economical and ‘green' method of exploiting plants to extract or degrade the contaminants in the soil. To date, the majority of phytoremediation efforts have been directed at leaping the biological, biochemical and agronomic hurdles to deliver a working technology, with scant attention to the economic outlook other than simple estimates of the cost advantages of phytoremediation over other techniques. In this paper we use a deterministic actuarial model to show that uncertainty in project success (the possibility that full clean up may not be realized) may significantly increase the perceived costs of remediation works for decision-makers." Authors' Abstractbiotechnology, Soil contaminants, Environmental remediation Economic aspects, Industrial crop technologies,

A new solid-state logarithmic radiometer

Combination of temperature-compensated logarithmic amplifiers and p-i-n photodiodes operating in zero-bias mode provides lightweight radiometer for detecting spectral intensities encompassing more than three decades over a range of at least 300 to 800 nanometers at low power levels

Floating or sinking? The state of democracy in Turkey and the rise of the HDP

This just serves to highlight the pessimistic state of Turkish democracy today. What is more, it should certainly not be assumed that the HDP are the great democratic hope of Turkish politics

The Kurdish question

This chapter traces the origins of the Kurdish question back to its roots in the Ottoman Empire. It examines how the Kurdish question emerged, how to characterise the nature of the confrontation and the basis of different perspectives on the issue, how it evolved under the Turkish republic up until the present day, and the future prospects for the Kurdish question in Turkey. It makes two modest but important points: (1) the Kurdish question needs to be placed in its historical context for any adequate understanding; and, (2) at its core is a political contestation whose form and shape is defined by the political response of the state as well as its own internal political dynamics

An Integral Spectral Representation of the Propagator for the Wave Equation in the Kerr Geometry

We consider the scalar wave equation in the Kerr geometry for Cauchy data which is smooth and compactly supported outside the event horizon. We derive an integral representation which expresses the solution as a superposition of solutions of the radial and angular ODEs which arise in the separation of variables. In particular, we prove completeness of the solutions of the separated ODEs. This integral representation is a suitable starting point for a detailed analysis of the long-time dynamics of scalar waves in the Kerr geometry.Comment: 41 pages, 4 figures, minor correction