Electrical excitation of surface plasmons

We exploit a plasmon mediated two-step momentum downconversion scheme to convert low-energy tunneling electrons into propagating photons. Surface plasmon polaritons (SPPs) propagating along an extended gold nanowire are excited on one end by low-energy electron tunneling and are then converted to free-propagating photons at the other end. The separation of excitation and outcoupling proofs that tunneling electrons excite gap plasmons that subsequently couple to propagating plasmons. Our work shows that electron tunneling provides a non-optical, voltage-controlled and low-energy pathway for launching SPPs in nanostructures, such as plasmonic waveguide

Dispersive Approach to Chiral Perturbation Theory

We generalise the reconstruction theorem of Stern, Sazdjian, and Fuchs based on the dispersion relations to the case of the (2 -> 2) scattering of all the pseudoscalar octet mesons (pi, K, eta). We formulate it in a general way and include also a discussion of the assumptions of the theorem. It is used to obtain the amplitudes of all such processes in the isospin limit to the one-loop order (and can be straightforwardly extended to two loops) independently on the particular power-counting scheme of the chiral perturbation theory in question. The results in this general form are presented.Comment: 25 pages, 1 figure; added one appendix and correction of typo

Random unitary dynamics of quantum networks

We investigate the asymptotic dynamics of quantum networks under repeated applications of random unitary operations. It is shown that in the asymptotic limit of large numbers of iterations this dynamics is generally governed by a typically low dimensional attractor space. This space is determined completely by the unitary operations involved and it is independent of the probabilities with which these unitary operations are applied. Based on this general feature analytical results are presented for the asymptotic dynamics of arbitrarily large cyclic qubit networks whose nodes are coupled by randomly applied controlled-NOT operations.Comment: 4 pages, 2 figure

Equilibrium temperatures of mass transfer cooled walls in high-speed flow of an absorbing-emitting gas

Equilibrium temperatures of mass transfer cooled walls in high speed flow of absorbing-emitting ga

(WP 2005-05) Assessing the Determinants of Willingness to Pay for Urban Flood Control: The Role of Locational, Demographic and Attitudinal Factors

The urbanization of urban watersheds can influence flooding risks. Traditional Federal Emergency Management Agency (FEMA) flood risk maps identify 100 year floodplains. These maps are updated infrequently. However, as a community urbanizes, flood risks can change, especially for downstream residents. Thus, one would expect that the willingness to pay (WTP) to prevent the worsening of flooding risk would depend in part on the location of the household in the community and their associated flooding risk. Economists and regional scientists have evaluated the role played by traditional demographic factors. However, attitudinal factors measuring community norms, political philosophy, and other psychological factors that may be unique to the individual have not received the same level of scrutiny. Milwaukee, WI has experienced major flooding events, classified as floods with an expected frequency of once every 100 years or less, in 1986 and most recently in 1997 and 1998. In this study, 1000 residents of the Menomonee watershed in Milwaukee were interviewed in a two-wave panel survey (i.e., telephone interviews took place in 2000 and 2001) to determine their willingness to pay for a referendum which would prevent flood risks from worsening. The interviews queried respondents about their attitudes concerning flooding and ecological risks, political beliefs, information seeking behavior, and other psychological factors unique to the respondent. Information was also gathered on demographic characteristics of the respondent, and also that individuals address. The address was geocoded and hydrologic modeling was used to determine the unique flood risk associated with the residence. A willingness to pay function was estimated using Tobit analysis. Preliminary findings indicated that all three categories of factors influence willingness to pay, with psychological factors and flood risk factors having a relatively strong impact on willingness to pay