Accurate determination of the scattering length of metastable Helium atoms using dark resonances between atoms and exotic molecules

We present a new measurement of the s-wave scattering length a of spin-polarized helium atoms in the 2^3S_1 metastable state. Using two-photon photoassociation spectroscopy and dark resonances we measure the energy E_{v=14}= -91.35 +/- 0.06 MHz of the least bound state v=14 in the interaction potential of the two atoms. We deduce a value of a = 7.512 +/- 0.005 nm, which is at least one hundred times more precise than the best previous determinations and is in disagreement with some of them. This experiment also demonstrates the possibility to create exotic molecules binding two metastable atoms with a lifetime of the order of 1 microsecond.Comment: 4 pages, 4 figure

Instability, Intermittency and Multiscaling in Discrete Growth Models of Kinetic Roughening

We show by numerical simulations that discretized versions of commonly studied continuum nonlinear growth equations (such as the Kardar-Parisi-Zhang equation and the Lai-Das Sarma equation) and related atomistic models of epitaxial growth have a generic instability in which isolated pillars (or grooves) on an otherwise flat interface grow in time when their height (or depth) exceeds a critical value. Depending on the details of the model, the instability found in the discretized version may or may not be present in the truly continuum growth equation, indicating that the behavior of discretized nonlinear growth equations may be very different from that of their continuum counterparts. This instability can be controlled either by the introduction of higher-order nonlinear terms with appropriate coefficients or by restricting the growth of pillars (or grooves) by other means. A number of such ``controlled instability'' models are studied by simulation. For appropriate choice of the parameters used for controlling the instability, these models exhibit intermittent behavior, characterized by multiexponent scaling of height fluctuations, over the time interval during which the instability is active. The behavior found in this regime is very similar to the ``turbulent'' behavior observed in recent simulations of several one- and two-dimensional atomistic models of epitaxial growth. [pacs{61.50.Cj, 68.55.Bd, 05.70.Ln, 64.60.Ht}]Comment: 47 pages + 26 postscript figures, submitted to Phys. Rev.

Strong attachment to heroes: How does it occur and affect people’s self-efficacy and ultimately quality of life?

In spite of increasing evidence on the influence of heroes on the lives of ordinary people, there has been no formal study on the subject in relation to people’s attachment to a hero (or hero attachment). The current study proposed a consumer model to examine how a hero makes a positive impact on people’s lives in terms of their hero attachment, self-efficacy, and life satisfaction. Using observations from a survey, we examined both the direct and indirect effects that the contribution of a hero in people’s fundamental A-R-C (autonomy, relatedness, and competence) need fulfillment has on self-efficacy and ultimately on life satisfaction. We found that the impact of a hero in fulfilling the A-R-C needs has a direct, differential effect on self-efficacy and life satisfaction. More importantly, we found that the fulfillment of A-R-C needs by a hero significantly influences hero attachment, which in turn positively affects life satisfaction through self-efficacy. As the first empirical study on hero attachment in relation to people’s self-efficacy and life satisfaction, the study yields significant theoretical contributions and practical implications for practitioners and policy makers in the areas of public health, education, and quality of life

First-principles study of the effects of gold adsorption on the Al(001) surface properties

In this work, we have studied theoretically the effects of gold adsorption on the Al(001) surface, using {\it ab initio} pseudo-potential method in the framework of the density functional theory. Having found the hollow sites at the Al(001) surface as the most preferred adsorption sites, we have investigated the effects of the Au adsorption with different coverages ($\Theta$=0.11, 0.25, 0.50, 0.75, 1.00 ML) on the geometry, adsorption energy, surface dipole moment, and the work-function of the Al(001) surface. The results show that, even though the work-function of the Al substrate increases with the Au coverage, the surface dipole moment decreases with the changes in coverage from $\Theta=0.11$ ML to $\Theta=0.25$ ML. We have explained this behavior by analyzing the electronic and ionic charge distributions. Furthermore, by studying the diffusion of Au atoms in to the substrate, we have shown that at room temperature the diffusion rate of Au atoms in to the substrate is negligible but, increasing the temperature to about 200$^\circ$ C the Au atoms significantly diffuse in to the substrate, in agreement with the experiment.Comment: 19 pages, 9 eps figure

20 K superconductivity in heavily electron doped surface layer of FeSe bulk crystal

A superconducting transition temperature Tc as high as 100 K was recently discovered in 1 monolayer (1ML) FeSe grown on SrTiO3 (STO). The discovery immediately ignited efforts to identify the mechanism for the dramatically enhanced Tc from its bulk value of 7 K. Currently, there are two main views on the origin of the enhanced Tc; in the first view, the enhancement comes from an interfacial effect while in the other it is from excess electrons with strong correlation strength. The issue is controversial and there are evidences that support each view. Finding the origin of the Tc enhancement could be the key to achieving even higher Tc and to identifying the microscopic mechanism for the superconductivity in iron-based materials. Here, we report the observation of 20 K superconductivity in the electron doped surface layer of FeSe. The electronic state of the surface layer possesses all the key spectroscopic aspects of the 1ML FeSe on STO. Without any interface effect, the surface layer state is found to have a moderate Tc of 20 K with a smaller gap opening of 4 meV. Our results clearly show that excess electrons with strong correlation strength alone cannot induce the maximum Tc, which in turn strongly suggests need for an interfacial effect to reach the enhanced Tc found in 1ML FeSe/STO.Comment: 5 pages, 4 figure

The EDEM methodology for housing upgrade analysis, carbon and energy labelling and national policy development

The ESRU Domestic Energy Model (EDEM) has been developed in response to demand from policy makers for a tool to assist in analysis of options for improving carbon and energy performance of housing across a range of possible future technologies, behaviours and environmental factors. A major challenge is to comprehend the large variation in fabric, systems (heating, hot water, lighting and appliances) and behaviours across the housing stock as well as uncertainty over future trends. Existing static models have limited ability to represent dynamic behaviour while use of detailed simulation has been based on modelling only a small number of representative designs. To address these challenges, EDEM has been developed as an easy to use, Web based tool, built on detailed simulation models aligned with national house survey data. From pragmatic inputs, EDEM can determine energy use and carbon emissions at any scale, from individual dwelling to national housing stock. EDEM was used at the behest of the Scottish Building Standards Agency and South Ayrshire Council to quantify the impact of upgrades including new and renewable energy systems. EDEM was also used to rate energy/carbon performance of dwellings as required by the EU Directive (EU, 2002). This paper describes the evolving EDEM methodology, its structure and operation then presents findings from applications. While initial EDEM projects have been for the Scottish housing stock the methodology is structured to facilitate project development and application to other countries

Hierarchical Mass Structure of Fermions in Warped Extra Dimension

The warped bulk standard model has been studied in the Randall-Sundrum background on $S^1/\Z\times\Z'$ interval with the bulk gauge symmetry $SU(3)\times SU(2)_L\times SU(2)_R\times U(1)_{B-L}$. With the assumption of no large cancellation between the fermion flavor mixing matrices, we present a simple analytic method to determine the bulk masses of standard model fermions in the almost universal bulk Yukawa coupling model. We also predict $U_{e3}$ element of MNS matrix to be near the experimental upper bound when the neutrino masses are of Dirac type.Comment: 16 page