Boundary Conformal Field Theory and a Boundary Central Charge

We consider the structure of current and stress tensor two-point functions in conformal field theory with a boundary. The main result of this paper is a relation between a boundary central charge and the coefficient of a displacement operator correlation function in the boundary limit. The boundary central charge under consideration is the coefficient of the product of the extrinsic curvature and the Weyl curvature in the conformal anomaly. Along the way, we describe several auxiliary results. Three of the more notable are as follows: (1) we give the bulk and boundary conformal blocks for the current two-point function; (2) we show that the structure of these current and stress tensor two-point functions is essentially universal for all free theories; (3) we introduce a class of interacting conformal field theories with boundary degrees of freedom, where the interactions are confined to the boundary. The most interesting example we consider can be thought of as the infrared fixed point of graphene. This particular interacting conformal model in four dimensions provides a counterexample of a previously conjectured relation between a boundary central charge and a bulk central charge. The model also demonstrates that the boundary central charge can change in response to marginal deformations.Comment: 75 pages, 4 figures; v2: references added. v3: comments on anomalous dimension and references added. v4: minor corrections, published versio

Interdot Coulomb repulsion effect on the charge transport of parallel double single electron transistors

The charge transport behaviors of parallel double single electron transistors (SETs) are investigated by the Anderson model with two impurity levels. The nonequilibrium Keldysh Green's technique is used to calculate the current-voltage characteristics of system. For SETs implemented by quantum dots (QDs) embedded into a thin $SiO_2$ layer, the interdot Coulomb repulsion is more important than the interdot electron hopping as a result of high potential barrier height between QDs and $SiO_2$. We found that the interdot Coulomb repulsion not onlyleads to new resonant levels, but also creates negative differential conductances.Comment: 12 pages, 7 figure

A Dual Dutch Auction in Taipei: The Choice of Numeraire and Auction Form in Multi-Object Auctions with Bundling. .

In Taipei we observed a dual Dutch fish auction, like a conventional Dutch auction with bundling, but with reversed roles of price and quantity. We study dual and conventional auctions with symmetric, independent private values, when agents’ utilities are linear in money but strictly concave in fish. With known buyers’ values, conventional and dual auctions, English or Dutch, are equivalent. With values known to buyers but not the seller, the seller prefers conventional auctions. With private values, the seller can prefer a dual Dutch or a conventional English or Dutch auction, but prefers all three to a dual English auction.

Nonparametric identification of a class of nonlinear close-coupled dynamic systems

A nonparametric identification technique for the identification of close coupled dynamic systems with arbitrary memoryless nonlinearities is presented. The method utilizes noisy recorded data (acceleration, velocity and displacement) to identify the restoring forces in the system. The masses in the system are assumed to be known (or fairly well estimated from the design drawings). The restoring forces are expanded in a series of orthogonal polnomials and the coefficients of these polynomial expansions are obtained by using least square fit method. A particularly simple and computationally efficient method is proposed for dealing with separable restoring forces. The identified results are found to be relatively insensitive to measurement noise. An analysis of the effects of measurement noise on the quality of the estimates is given. The computations are shown to be relatively quick (when compared say to the Wiener identification method) and the core storage required relatively small, making the method suitable for onboard identification of large space structures

Stem-root flow effect on soil–atmosphere interactions and uncertainty assessments

Abstract. Soil water can rapidly enter deeper layers via vertical redistribution of soil water through the stem–root flow mechanism. This study develops the stem–root flow parameterization scheme and coupled this scheme with the Simplified Simple Biosphere model (SSiB) to analyze its effects on land–atmospheric interactions. The SSiB model was tested in a single column mode using the Lien Hua Chih (LHC) measurements conducted in Taiwan and HAPEX-Mobilhy (HAPEX) measurements in France. The results show that stem–root flow generally caused a decrease in the moisture content at the top soil layer and moistened the deeper soil layers. Such soil moisture redistribution results in significant changes in heat flux exchange between land and atmosphere. In the humid environment at LHC, the stem–root flow effect on transpiration was minimal, and the main influence on energy flux was through reduced soil evaporation that led to higher soil temperature and greater sensible heat flux. In the Mediterranean environment of HAPEX, the stem–root flow significantly affected plant transpiration and soil evaporation, as well as associated changes in canopy and soil temperatures. However, the effect on transpiration could either be positive or negative depending on the relative changes in the moisture content of the top soil vs. deeper soil layers due to stem–root flow and soil moisture diffusion processes

Evaluation of the benefits of transnational transportation projects

In this paper an analytical framework has been developed to evaluate the primary beneficiaries of cargo traffic generated by transnational transport projects. In the transportation economics literature, the economic impact of infrastructure projects on cargo traffic has not been developed as fully as for passenger traffic. In much of the previous literature it is often assumed that consumers of the traded goods would receive the full benefits from the reduction in logistics and transportation costs. This paper has shown that whether the goods are traded internationally or regionally is a key factor in the allocation of the economic benefits arising from the reduction in the cost of cargo transportation. The analytical framework developed in the paper is applied to the evaluation of the impacts of the proposed Buenos Aires-Colonia binational bridge project.Argentina, Uruguay, cargo traffic, transnational, transportation benefits