Surface-State Localization at Adatoms

Low-temperature scanning tunneling spectroscopy of magnetic and non-magnetic metal atoms on Ag(111) and on Cu(111) surfaces reveals the existence of a common electronic resonance at an energy below the binding energies of the surface states. Using an extended Newns-Anderson model, we assign this resonance to an adsorbate-induced bound state, split off from the bottom of the surface-state band, and broadened by the interaction with bulk states. A lineshape analysis of the bound state indicates that native adatoms decrease the surface-state lifetime, while a cobalt adatom causes no significant change.Comment: 4 pages, 4 figure

The Influence of Model Features on Goodness-of-Fit Indices: Choosing Indices to Evaluate Your Model

Two studies were conducted to examine the performance of eight goodness-of-fit indices (i.e., the chi-square statistic, Comparative fit index, Critical N; Goodness-of-fit index, Normed fit index, Nonnormed fit index, Root mean square error of approximation, and Relative noncentrality index) used in structural equation applications. Study 1 consisted of (a) an empirical review in four journals (1986-1996) to determine the typical application, (b) a recreation of the goodness-of-fit indices from the published research, (c) a multiple regression analysis of the recreated indices to determine if values were predicted based on model and sample features, and (d) the development of a representative sample for model selection in Study 2. Study 1 identified 366 articles, and recreated indices for 187 of those articles. The regression analysis demonstrated that several indices were predicted by sample size and the hypothesized model\u27s degrees of freedom. Study 2 consisted of (a) three Monte Carlo simulations differing in model complexity which assessed the performance of the indices under conditions of sample size, number of indicators, and model misspecifications, and (b) an evaluation of recommended and alternative cutoff values for the indices. In Study 2, simulated results replicated effects for sample size and number of indicators and extended findings to single indicator models. In agreement with prior research, indices were successful at detecting omitted misspecifications, but unsuccessful at detecting inclusion misspecifications. Most indices favored simple over complex models. Previously recommended values of indices were often inappropriate, but alternative values were suggested to reduce the frequency of accepted models with omission errors. When evaluating model fit with indices, researchers should consider the effects of sample and model features to avoid drawing erroneous conclusions

Entanglement conditions and polynomial identities

We develop a rather general approach to entanglement characterization based on convexity properties and polynomial identities. This approach is applied to obtain simple and efficient entanglement conditions which work equally well in both discrete as well as continuous-variable environments. Examples of violations of our conditions are presented.Comment: 5 pages, no figure

The Lerch Zeta Function II. Analytic Continuation

This is the second of four papers that study algebraic and analytic structures associated with the Lerch zeta function. In this paper we analytically continue it as a function of three complex variables. We that it is well defined as a multivalued function on the manifold M equal to C^3 with the hyperplanes corresponding to integer values of the two variables a and c removed. We show that it becomes single valued on the maximal abelian cover of M. We compute the monodromy functions describing the multivalued nature of this function on M, and determine various of their properties.Comment: 29 pages, 3 figures; v2 notation changes, homotopy action on lef

New limits on "odderon" amplitudes from analyticity constraints

In studies of high energy $pp$ and $\bar pp$ scattering, the odd (under crossing) forward scattering amplitude accounts for the difference between the $pp$ and $\bar pp$ cross sections. Typically, it is taken as $f_-=-\frac{p}{4\pi}Ds^{\alpha-1}e^{i\pi(1-\alpha)/2}$ ($\alpha\sim 0.5$), which has $\Delta\sigma, \Delta\rho\to0$ as $s\to\infty$, where $\rho$ is the ratio of the real to the imaginary portion of the forward scattering amplitude. However, the odd-signatured amplitude can have in principle a strikingly different behavior, ranging from having $\Delta\sigma\to$non-zero constant to having $\Delta\sigma \to \ln s/s_0$ as $s\to\infty$, the maximal behavior allowed by analyticity and the Froissart bound. We reanalyze high energy $pp$ and $\bar pp$ scattering data, using new analyticity constraints, in order to put new and precise limits on the magnitude of ``odderon'' amplitudes.Comment: 13 pages LaTex, 6 figure

Evolution of unoccupied resonance during the synthesis of a silver dimer on Ag(111)

Silver dimers were fabricated on Ag(111) by single-atom manipulation using the tip of a cryogenic scanning tunnelling microscope. An unoccupied electronic resonance was observed to shift toward the Fermi level with decreasing atom-atom distance as monitored by spatially resolved scanning tunnelling spectroscopy. Density functional calculations were used to analyse the experimental observations and revealed that the coupling between the adsorbed atoms is predominantly direct rather than indirect via the Ag(111) substrate.Comment: 9 pages, 3 figure

Determination and Monitoring of through Hole Diameters in Thin Plates Using Acoustic Diffraction

In this paper, we describe a method to monitor changes in the diameter of through holes in thin plates. The method has the potential for applications in the industry