Effect of many modes on self-polarization and photochemical suppression in cavities

The standard description of cavity-modified molecular reactions typically involves a single (resonant) mode, while in reality, the quantum cavity supports a range of photon modes. Here, we demonstrate that as more photon modes are accounted for, physicochemical phenomena can dramatically change, as illustrated by the cavity-induced suppression of the important and ubiquitous process of proton-coupled electron-transfer. Using a multi-trajectory Ehrenfest treatment for the photon-modes, we find that self-polarization effects become essential, and we introduce the concept of self-polarization-modified Born–Oppenheimer surfaces as a new construct to analyze dynamics. As the number of cavity photon modes increases, the increasing deviation of these surfaces from the cavity-free Born–Oppenheimer surfaces, together with the interplay between photon emission and absorption inside the widening bands of these surfaces, leads to enhanced suppression. The present findings are general and will have implications for the description and control of cavity-driven physical processes of molecules, nanostructures, and solids embedded in cavities

The nucleon-nucleon interaction and properties of the nucleon in a πρω\pi\rho\omega soliton model including a dilaton field with anomalous dimension

We investigate an extended chiral soliton model which includes $\pi, \rho, \omega$ and $\sigma$ mesons as explicit degrees of freedom. The Lagrangian incorporates chiral symmetry and broken scale invariance. A scalar-isoscalar meson $\sigma$ is associated with a quarkonium dilaton field with a mass \msig\approx 550 MeV. We show that the scalar field with anomalous dimension slightly changes the static and electromagnetic properties of the nucleon. In contrast, it plays a significant role in nucleon-nucleon dynamics and gives an opportunity to describe well the two-nucleon interaction.Comment: 14 pages, REVTeX, 3 figures (Ps), 83 k

Parametrization of Realistic Bethe-Salpeter Amplitude for the Deuteron

The parametrization of the realistic Bethe-Salpeter amplitude for the deuteron is given. Eight components of the amplitude in the Euclidean space are presented as an analytical fit to the numerical solution of the Bethe-Salpeter equation in the ladder approximation. An applicability of the parametrization to the observables of the deuteron is briefly discussed.Comment: LaTeX, 11 pages, 2 Postscript figures; Text of the Fortran program is available from the author by reques

Phase Stability and Segregation in Alloy 22 Base Metal and Weldments

The current design of the waste disposal containers relies heavily on encasement in a multi-layered container, featuring a corrosion barrier of Alloy 22, a Ni-Cr-Mo-W based alloy with excellent corrosion resistance over a wide range of conditions. The fundamental concern from the perspective of the Yucca Mountain Project, however, is the inherent uncertainty in the (very) long-term stability of the base metal and welds. Should the properties of the selected materials change over the long service life of the waste packages, it is conceivable that the desired performance characteristics (such as corrosion reistance) will become compromised, leading to premature failure of the system. To address this, we will study the phase stability and solute segregation characteristics of Alloy 22 base metal and welds. A better understanding of the underlying microstructural evolution tendencies, and their connections with corrosion behavior will (in turn) produce a higher confidence in the extrapolated behavior of the container materials over time periods that are not feasibly tested in a laboratory. Additionally, the knowledge gained here may potentially lead to cost savings through development of safe and realistic design constraints and model assumptions throughout the entire disposal system

First NACO observations of the Brown Dwarf LHS 2397aB

Observations of the standard late type M8 star LHS 2397aA were obtained at the ESO-VLT 8m telescope ``Yepun'' using the NAOS/CONICA Adaptive Optics facility. The observations were taken during the NACO commissioning, and the infrared standard star LHS 2397aA was observed in the H, and Ks broad band filters. In both bands the brown dwarf companion LHS2397aB was detected. Using a program recently developed (Bouy et al., 2003) for the detection of stellar binaries we calculated the principal astrometric parameters (angular binary separation and position angle P.A.) and the photometry of LHS 2397aA and LHS 2397aB. Our study largely confirms previous results obtained with the AO-Hokupa'a facility at Gemini-North (Freed et al., 2003); however a few discrepancies are observed.Comment: 5 page

Agro-environmental evaluation of vineyard management using organic farming and integrated plant production systems

Organic farming is often considered to be the most environmentally-friendly crop management system, even if integrated production also aims at decreasing the impact of agriculture on the natural environment. In order to establish references for the agro-environmental evaluation of these two production systems in relation to grape growing, INRA carried out an initial study from 2001 to 2004 at the plot scale. This study focused on two grape varieties (Merlot N and Cabernet Sauvignon) in its Couhins vineyard (Graves cru classé), located on two organically-farmed plots and two plots using integrated production, a system based on the implementation of decision rules aimed at limiting the number of pest control treatments. Production means only differed in terms of pest control management (choice of products and application strategy). Each of the parcels covered approximately 0.30 ha. An agro-environmental evaluation of these two systems was made for 2003, using the INDIGO Vigne method at the plot level. Because of their nature, the choice of parameters for the indicators used determines the interpretation of the results. Nevertheless, it appears that the environmental impact of integrated production is more favourable in this case than that of organic farming, particularly in terms of pest control and energy indicators. One of the reasons for this is the high number of applications of pest control treatments in organic farming and, as a result, higher energy consumption, as well as the use of copper that has a major impact on deep waters, the ground and the air. The two systems can decrease their environmental impact by limiting the number of tractor runs for soil maintenance. Flexibility appears to be greater in the case of integrated production since, contrary to organic farming, it can use herbicides under the row. The calculation of the agro-environmental evaluation on the parcel using integrated protection with chemical weeding under the row leads to a clear improvement of the energy indicator, without significantly decreasing the value of the pest control indicator. Natural sodding of the inter-row, when the vigour of the vineyard allows it, provides an effective solution since the decrease in the number of tractor runs leads to an improvement of erosion and organic matter indicators. This type of evaluation should be carried out at the scale of a group of plots or of an entire wine-farm. Ground maintenance is an important factor in decreasing the impact of grape growing on the environment. In this respect, organic farming offers some promising prospects