Gauge invariant nonlinear electric transport in mesoscopic conductors

We use the scattering approach to investigate the nonlinear current-voltage characteristic of mesoscopic conductors. We discuss the leading nonlinearity by taking into account the self-consistent nonequilibrium potential. We emphasize conservation of the overall charge and current which are connected to the invariance under a global voltage shift (gauge invariance). As examples, we discuss the rectification coefficient of a quantum point contact and the nonlinear current-voltage characteristic of a resonant level in a double barrier structure.Comment: (Replaced version, with corrected Eq.(4)); 5 pages, RevTeX, 1 figure, uuencode

A Comparison of Blocking Methods for Record Linkage

Record linkage seeks to merge databases and to remove duplicates when unique identifiers are not available. Most approaches use blocking techniques to reduce the computational complexity associated with record linkage. We review traditional blocking techniques, which typically partition the records according to a set of field attributes, and consider two variants of a method known as locality sensitive hashing, sometimes referred to as "private blocking." We compare these approaches in terms of their recall, reduction ratio, and computational complexity. We evaluate these methods using different synthetic datafiles and conclude with a discussion of privacy-related issues.Comment: 22 pages, 2 tables, 7 figure

Low Frequency Quantum Transport in a Three-probe Mesoscopic Conductor

The low frequency quantum transport properties of a three-probe mesoscopic conductor are studied using B\"uttiker's AC transport formalism. The static transmission coefficients and emittance matrix of the system were computed by explicitly evaluating the various partial density of states (PDOS). We have investigated the finite size effect of the scattering volume on the global PDOS. By increasing the scattering volume we observed a gradual improvement in the agreement of the total DOS as computed externally or locally. Our numerical data permits a particular fitting form of the finite size effect.Comment: 13 pages, LaTeX, submitted to Phys. Rev.

Diffusivity and Surface Emissivity in Wood Drying

Edge and end-coated sweetgum (Liquidambar styraciflua L.) and redwood (Sequoia sempervirens (D. Don.) Endl.) 6 X 10 cm samples, of thicknesses ranging from 0.5 to 3.0 cm in either the longitudinal or tangential directions, were dried, from either the water-soaked condition or from slightly below fiber saturation, to equilibrium in circulated air (300 ft/min) at 100 F and 75% relative humidity.A constant-rate drying period was observed during the early stages of drying for the initially water-soaked samples but not for those initially below fiber saturation. The apparent diffusion coefficient D', calculated for the samples initially below fiber saturation on the assumption that surface resistance to drying was negligible, that is D' ≈ 0.2 a2/t0.5 (where a is the half-thickness and t0.5 is the half-drying time), increased with increasing wood thickness. The true diffusion coefficient D and the surface emission coefficient S (which is inversely proportional to the surface resistance to drying) were calculated from the linear relationships observed between t0.5/a2 (or 0.2/D') and 1/a, or between t0.5/a (or 0.2a/D') and a, using Newman's solution to the diffusion equation.The diffusion coefficient D was higher for longitudinal than for tangential drying for both woods, and higher for sapwood than for heartwood of redwood. The surface emission coefficient S for redwood was found to be 60% greater than for sweetgum, presumably because redwood is less hygroscopic and also less dense than sweetgum

Unusual Closed Traumatic Avulsion of Both Flexor Tendons in Zones 1 and 3 of the Little Finger.

Closed tendon avulsion of both flexor tendons in the same finger is an extremely rare condition. We encountered the case of a patient who presented a rupture of the flexor digitorum profundus in zone 1 and flexor digitorum superficialis in zone 3 in the little finger. This occurrence has not been reported previously. We hereby present our case, make a review of the literature of avulsion of both flexor tendons of the same finger, and propose a treatment according to the site of the ruptures

Charge injection instability in perfect insulators

We show that in a macroscopic perfect insulator, charge injection at a field-enhancing defect is associated with an instability of the insulating state or with bistability of the insulating and the charged state. The effect of a nonlinear carrier mobility is emphasized. The formation of the charged state is governed by two different processes with clearly separated time scales. First, due to a fast growth of a charge-injection mode, a localized charge cloud forms near the injecting defect (or contact). Charge injection stops when the field enhancement is screened below criticality. Secondly, the charge slowly redistributes in the bulk. The linear instability mechanism and the final charged steady state are discussed for a simple model and for cylindrical and spherical geometries. The theory explains an experimentally observed increase of the critical electric field with decreasing size of the injecting contact. Numerical results are presented for dc and ac biased insulators.Comment: Revtex, 7pages, 4 ps figure

Colorado AgrAbility: Enhancing the Effectiveness of Outreach Efforts Targeting Farmers and Ranchers With Disabilities

The Colorado AgrAbility Project (CAP) provides farmers and ranchers who have disabilities with the information and assistive technologies needed to remain successful producers. At present, however, CAP services are underutilized, and the rate of use is declining. This study investigates awareness and attitudinal barriers that might constrain farmers and ranchers with disabilities from seeking assistance. It also identifies preferred outlets for distributing agricultural information in the hope that this will improve the efficacy of outreach efforts. Mail survey research involving 798 randomly selected Colorado farmers and ranchers was conducted in the spring of 2006. Findings suggest that lack of awareness constituted the primary obstacle to increased use of CAP services. Farmers and ranchers were more inclined to refer others in need farmers and ranchers as preferred sources for information and expressed interest in the stories of farmers and ranchers with disabilities who had been helped by CAP. Based on Survey findings, strategies for improving the effectiveness of outreach efforts are proposed, including mobilizing opinion leaders in the farming and ranching communities, recruiting past CAP clients as spokespeople, and placing CAP success stories in agricultural publications

Different methods of evaluation of Monilinia laxa on apricot flowers and branches

- Organic apricot production is currently not profitable. - The main obstacle to sustainable profitability is brown rot caused by the fungus Monilinia laxa (Aderh. & Ruhl). - In the current apricot germplasm no source of total resistance has been shown, but some varieties are expressing interesting levels of tolerance. - A good evaluation of the M. laxa symptoms is essential for a precise diagnosis of the infection and to appreciate differences between tolerant and susceptible varieties and genotypes

Partial Densities of States, Scattering Matrices, and Green's Functions

The response of an arbitrary scattering problem to quasi-static perturbations in the scattering potential is naturally expressed in terms of a set of local partial densities of states and a set of sensitivities each associated with one element of the scattering matrix. We define the local partial densities of states and the sensitivities in terms of functional derivatives of the scattering matrix and discuss their relation to the Green's function. Certain combinations of the local partial densities of states represent the injectivity of a scattering channel into the system and the emissivity into a scattering channel. It is shown that the injectivities and emissivities are simply related to the absolute square of the scattering wave-function. We discuss also the connection of the partial densities of states and the sensitivities to characteristic times. We apply these concepts to a delta-barrier and to the local Larmor clock.Comment: 13 pages (revtex), 4 figure

Electrochemical capacitance of a leaky nano-capacitor

We report a detailed theoretical investigation on electrochemical capacitance of a nanoscale capacitor where there is a DC coupling between the two conductors. For this ``leaky'' quantum capacitor, we have derived general analytic expressions of the linear and second order nonlinear electrochemical capacitance within a first principles quantum theory in the discrete potential approximation. Linear and nonlinear capacitance coefficients are also derived in a self-consistent manner without the latter approximation and the self-consistent analysis is suitable for numerical calculations. At linear order, the full quantum formula improves the semiclassical analysis in the tunneling regime. At nonlinear order which has not been studied before for leaky capacitors, the nonlinear capacitance and nonlinear nonequilibrium charge show interesting behavior. Our theory allows the investigation of crossover of capacitance from a full quantum to classical regimes as the distance between the two conductors is changed