All-optical photochromic spatial light modulators based on photoinduced electron transfer in rigid matrices

A single material (not a multi-element structure) spatial light modulator may be written to, as well as read out from, using light. The device has tailorable rise and hold times dependent on the composition and concentration of the molecular species used as the active components. The spatial resolution of this device is limited only by light diffraction as in volume holograms. The device may function as a two-dimensional mask (transmission or reflection) or as a three-dimensional volume holographic medium. This device, based on optically-induced electron transfer, is able to perform incoherent to coherent image conversion or wavelength conversion over a wide spectral range (ultraviolet, visible, or near-infrared regions)

Flex flap

To provide flap with large upper surface radius as required for airplanes with over-the-wing blowing, distort upper surface of flap by actuator. Flap can be used as control surface at leading as well as trailing edges and, with minor modification, as variant of Jacobs-Hurkamp air flap

Direct picosecond time resolution of unimolecular reactions initiated by local mode excitation

The concept of local mode (LM) states [1] in large molecules raises the possibilty of inducing chemical reactions from a well-defined initial state (bond-selective chemistry). The results of linewidth and energy measurements in gases, [2(a)] and low temperature solids, [2(b)] however, indicate that the relaxation times for such high energy (> 15000 cm^-1) states can be extremely short, < 1ps. Because of the lack of direct time-resolved measurements, the following fundamental questions have not been unequivocally answered: What are the homogeneous linewidths of LM states and what are the rates of energy relaxation or reaction out of these states? Over the past five years we have made several attempts to observe the picosecond dynamics of LM states. Due to the inherent difficulties associated with making these measurements, such as the very small oscillator strength (σ < 10^-23 cm^2), an extremely sensitive probing technique becomes imperative

Nonlinearity in Bacterial Population Dynamics: Proposal for Experiments for the Observation of Abrupt Transitions in Patches

An explicit proposal for experiments leading to abrupt transitions in spatially extended bacterial populations in a Petri dish is presented on the basis of an exact formula obtained through an analytic theory. The theory provides accurately the transition expressions in spite of the fact that the actual solutions, which involve strong nonlinearity, are inaccessible to it. The analytic expressions are verified through numerical solutions of the relevant nonlinear equation. The experimental set-up suggested uses opaque masks in a Petri dish bathed in ultraviolet radiation as in Lin et al., Biophys. J. {\bf 87}, 75 (2004) and Perry, J. R. Soc. Interface {\bf 2}, 379 (2005) but is based on the interplay of two distances the bacteria must traverse, one of them favorable and the other adverse. As a result of this interplay feature, the experiments proposed introduce highly enhanced reliability in interpretation of observations and in the potential for extraction of system parameters.Comment: 5 figure

Waste Management and Personal Hygiene for Extended Spacecraft Missions

Waste management and personal hygiene for extended manned spacecraft mission

Nuclear Development Strategies with Limited Natural Uranium Requirements

In view of the fact that the world's high-grade natural uranium resources are limited, alternative ways of using these resources more efficiently are of interest in the line of research undertaken by IIASA's Energy Systems Program. Sole reliance on the currently predominant Light Water Reactors (LWRs) would mean to deplete these natural uranium resources rapidly. The present paper considers different strategies of uranium use involving, in addition to burners (LWRs), Fast Breeder Reactors (FBRs) and Advanced Converter Reactors (ACR) with an extremely high efficiency in using natural uranium. Breeder reactors in fact require only depleted natural uranium (left over from enriched LWR fuel), once a certain endowment of fissile plutonium (from burnt LWR fuel) has accumulated. Given such an endowment, the breeder output can be increased on the basis of self-generated plutonium. Although the efficiency in using natural uranium is less in advanced converter reactors, their uranium savings are enormous compared to the amounts used up in burners. Such considerations of a more efficient future uranium use by deploying advanced reactors in addition to burner reactors are based on a hypothetical trajectory of a total installed nuclear capacity increasing to 10 TW(e) by the year 2030. The analysis shows that a combination of advanced and burner reactors, as compared to the use of burners only, could lead to cumulative, high-grade uranium savings greater than 70% from 1980 to 2030