Visible and infrared mapping spectrometer for exploration of comets,asteroids, and the saturnian system of rings and moons

The science objectives and system design for a Visible and Infrared Mapping Spectrometer (VIMS), an imaging spectrometer for planetary exploration, are described. The instrument development is the result of a collaboration between scientists and engineers from the United States, Italy, and France. NASA has selected VIMS as a facility instrument for the Comet Rendezvous Asteroid Flyby (CRAF) Mission, and as a candidate facility instrument for the Cassini Mission to explore Saturn and its rings and moons. (A facility instrument is provided by the project for the use of a science team which was selected on the basis of individual competitive science proposals.) VIMS covers the spectral range from 0.35 to 5.2 μm with a nominal spatial resolution of 0.5 milliradians (pixel size) and spectral resolutions (spectral width) of 7 nm at 0.35–1.0- μm wavelength and 16nm at 1.0–5.2-μm wavelength. The nominal pixel size is 0.5 × 0.5 mrad². The two separate missions are scheduled to be launched by NASA from the Eastern Test Range at Cape Canaveral, Florida, using the Titan IV Launch Vehicle. The planned launch date for the Cassini Mission is November 1995. The planned launch date for the CRAF Mission is February 1996.     

An aquatic respirometer for use in sublethal studies

A computer-controlled respirometer system which permits measurement of oxygen consumption of marine and freshwater organisms at regular intervals over a period of several days is described. The system enables assessment of changes in respiration during and after exposure to sublethal concentration of pollutants.     

Molecular epidemiology provides evidence of genotypic heterogeneity of multidrug-resistant Pseudomonas aeruginosa serotype O:12 outbreak isolates from a pediatric hospital

Ribotyping randomly amplified polymorphic DNA analysis, and pulsed-field gel electrophoresis were used for the epidemiologic evaluation of eight Pseudomonas aeruginosa O:12 isolates obtained from eight children and two P. aeruginosa O:12 environmental isolates from a hematology ward. Randomly amplified polymorphic DNA analysis and pulsed-field gel electrophoresis were able to discriminate isolates that were indistinguishable by biochemical typing, O serotyping or ribotyping.     

Etude de la reaction du carbone avec le sulfure d'hydrogene H2S a hautes temperatures et sous basses pressions

Reaction of carbon with hydrogen sulfide at high temperature (1000–2000°C) and low pressure (10^?4–10^?2 Torr) exhibits the following features:—carbon disulfide CS₂ is the only carbonaceous reaction product. There is no indication that CS₂ would originate from a secondary reaction of the unstable carbon monosulfide CS. Some decomposition of H₂S into its elements is also observed (Figs. 1–3).—as already observed in other high temperature carbon gasification reactions, the intrinsic reactivity of the sample surface is temperature and pressure dependent. Consequently, transitory or stationary rates are observed, depending respectively upon a changing or a stationary surface state of the carbon sample (Fig. 4). The changes in the surface state are more marked for amorphous than for graphitized samples (Fig. 5).—below 1700°C, the true reaction order is smaller than one, as a consequence of the high stability of the carbon-sulfur surface complexes.—for ungraphitized samples, the carbon surface loses slowly and irreversibly its ability to change with changes in pressure and temperature.All these features were previously observed in the reaction of carbon with sulfur vapor: consequently hydrogen sulfide appears to behave simply as a gaseous sulfur carrier. The kinetic behaviour is in agreement with former interpretations assuming presence of peculiar reactive sites, which originate from chemical attack of the solid but disappear due to a surface thermal heating process.Confirming also previous assumptions, sulfur chemisorption strongly affects the reaction kinetics, as shown by the influence of H₂S traces on the kinetics of the C-O₂ reaction (Fig. 10):—at lower temperatures (< 1300°C) there is an important inhibiting effect on the CO production: H₂S is adsorbed strongly on the reactive sites which become inaccessible to O₂ molecules.—in the intermediate temperature range an enhancing effect is observed which is attributed to a hindrance of thermal healing (caused by chemisorption still present).Finally, the kinetic features as a whole are tentatively summarized in a comprehensive diagram where the consistency of experimental results appears clearly.     

Design,analysis and fabrication of high frequency piezoelectric transducers

Applicability of the finite element method to optimize high frequency transducers is reported. Two recent studies on piezoelectric transducers or systems are presented, in which the FEM algorithm is used for the optimization of transducers performance. They provide resonance frequencies from greater than 1 MHz to below 10 kHz. First, miniature multimode monolithic flextensional transducers, with active shells, are described. They combine the advantages of small size and low-cost manufacturing with control of the shape of the acoustic radiation/receive pattern. Then, linear arrays are studied and a technique is developed to reduce cross-coupling in acoustical arrays. In each case, numerical results are compared to experiments and show how the finite element tool is used to improve the understanding of the physical behavior of the system.     

What should we expect from innovation? A model-based assessment of the environmental and mitigation cost implications of climate-related R&D

This paper addresses two basic issues related to technological innovation and climate stabilization objectives: can innovation policies be effective in stabilizing climate? To what extent can innovation policies complement carbon pricing (taxes or permit trading) and improve the economic efficiency of a mitigation policy package? To answer these questions, we use an integrated assessment model with multiple externalities and an endogenous representation of the technical progress in the energy sector. We evaluate a range of innovation policies, both as stand-alone and in combination with other mitigation policies. Our analysis indicates that innovation policies alone are unlikely to stabilize global concentration and temperature. As for the benefits of combining climate and innovation policies, we find efficiency gains of 10% (6 USD Trillions in net present value terms) for a stringent climate policy, and 30% (3 USD Trillions) for a milder one. However, such gains are reduced when more plausible (sub-optimal) global innovation policy arrangements are considered.