Monatomic Co, CoO2_2, and CoO3_3 Nanowires on Ir(100) and Pt(100) surfaces: Formation, Structure, and Energetics

In this study we investigate the structural and chemical changes of monatomic CoO$_2$ chains grown self-organized on the Ir(100) surface [P. Ferstl et al., PRL 117, 2016, 046101] and on Pt(100) under reducing and oxidizing conditions. By a combination of quantitative low-energy electron diffraction, scanning tunnelling microscopy, and density functional theory we show that the cobalt oxide wires are completely reduced by H$_2$ at temperatures above 320 K and a 3x1 ordered Ir$_2$Co or Pt$_2$Co surface alloy is formed. Depending on temperature the surface alloy on Ir(100) is either hydrogen covered (T < 400 K) or clean and eventually undergoes an irreversible order-disorder transition at about 570 K. The Pt$_2$Co surface alloy disorders with the desorption of hydrogen, whereby Co submerges into subsurface sites. Vice versa, applying stronger oxidants than O$_2$ such as NO$_2$ leads to the formation of CoO3 chains on Ir(100) in a 3x1 superstructure. On Pt(100) such a CoO$_3$ phase could not be prepared so far, which however, is due to the UHV conditions of our experiments. As revealed by theory this phase will become stable in a regime of higher pressure. In general, the structures can be reversibly switched on both surfaces using the respective agents O$_2$, NO$_2$ and H$_2$.Comment: 13 pages, 10 figure

How are affective word ratings related to lexicosemantic properties?:evidence from the Sussex Affective Word List

Emotional content of verbal material affects the speed of visual word recognition in various cognitive tasks, independently of lexicosemantic variables. However, little is known about how the dimensions of emotional arousal and valence interact with the lexicosemantic properties of words such as age of acquisition, familiarity, and imageability, that determine word recognition performance. This study aimed to examine these relationships using English ratings for affective and lexicosemantic features. Eighty-two native English speakers rated 300 words for emotional valence, arousal, familiarity, age of acquisition, and imageability. Although both dimensions of emotion were correlated with lexicosemantic variables, a unique emotion cluster produced the strongest quadratic relationship. This finding suggests that emotion should be included in models of word recognition as it is likely to make an independent contribution

Observation of an optical non-Fermi-liquid behavior in the heavy fermion state of YbRh2_{2}Si2_{2}

We report far-infrared optical properties of YbRh$_{2}$Si$_{2}$ for photon energies down to 2 meV and temperatures 0.4 -- 300 K. In the coherent heavy quasiparticle state, a linear dependence of the low-energy scattering rate on both temperature and photon energy was found. We relate this distinct dynamical behavior different from that of Fermi liquid materials to the non-Fermi liquid nature of YbRh$_{2}$Si$_{2}$ which is due to its close vicinity to an antiferromagnetic quantum critical point.Comment: 5 pages, 4 figures. submitte

Effects of valence and arousal on written word recognition:Time course and ERP correlates

Models of affect assume a two-dimensional framework, composed of emotional valence and arousal. Although neuroimaging evidence supports a neuro-functional distinction of their effects during single word processing, electrophysiological studies have not yet compared the effects of arousal within the same category of valence (positive and negative). Here we investigate effects of arousal and valence on written lexical decision. Amplitude differences between emotion and neutral words were seen in the early posterior negativity (EPN), the late positive complex and in a sustained slow positivity. In addition, trends towards interactive effects of valence and arousal were observed in the EPN, showing larger amplitude for positive, high-arousal and negative, low-arousal words. The results provide initial evidence for interactions between arousal and valence during processing of positive words and highlight the importance of both variables in studies of emotional stimulus processing. Crown Copyright (C) 2012 Published by Elsevier Ireland Ltd. All rights reserved

Arousal and emotional valence interact in written word recognition

Behavioural, psychophysiological and neuroimaging studies reveal a prioritisation for emotional material in a variety of cognitive tasks. Although emotion is comprised of two dimensions (valence and arousal), previous research using verbal materials has mostly focused on valence, while controlling level of arousal. The aim of the present study is to investigate the effects of valence and arousal on lexical decision (LD) by manipulating both dimensions while controlling correlated psycholinguistic variables (e.g., word length, frequency, imageability). Results showed that valence and arousal affect word recognition in an interactive way: LD latencies are slower for positive high-arousal and negative low-arousal words compared to positive low-arousal and negative high-arousal words, in line with an approach-withdrawal tendency model. Furthermore, principal component analysis (PCA) on the latencies revealed a unique contribution of a distinct cluster of emotion variables, independent of lexico-semantic variables, to explaining written word recognition. We conclude that the dimensions of valence and arousal both need to be taken into account in studies of emotion word processing as they have an interactive relationship

Gravitating Instantons In 3 Dimensions

We study the Einstein-Chern-Simons gravity coupled to Yang-Mills-Higgs theory in three dimensional Euclidean space with cosmological constant. The classical equations reduce to Bogomol'nyi type first order equations in curved space. There are BPS type gauge theory instanton (monopole) solutions of finite action in a gravitational instanton which itself has a finite action. We also discuss gauge theory instantons in the vacuum (zero action) AdS space. In addition we point out to some exact solutions which are singular.Comment: 17 pages, 4 figures, title has changed, gravitational instanton actions are adde

The HERMES Back Drift Chambers

The tracking system of the HERMES spectrometer behind the bending magnet consists of two pairs of large planar 6-plane drift chambers. The design and performance of these chambers is described. This description comprises details on the mechanical and electronical design, information about the gas mixture used and its properties, results on alignment, calibration, resolution, and efficiencies, and a discussion of the experience gained through the first three years of operation.Comment: 21 pages, LaTex, 16 figures include

Direct Detection of Dark Matter in the MSSM with Non-Universal Higgs Masses

We calculate dark matter scattering rates in the minimal supersymmetric extension of the Standard Model (MSSM), allowing the soft supersymmetry-breaking masses of the Higgs multiplets, m_{1,2}, to be non-universal (NUHM). Compared with the constrained MSSM (CMSSM) in which m_{1,2} are required to be equal to the soft supersymmetry-breaking masses m_0 of the squark and slepton masses, we find that the elastic scattering cross sections may be up to two orders of magnitude larger than values in the CMSSM for similar LSP masses. We find the following preferred ranges for the spin-independent cross section: 10^{-6} pb \ga \sigma_{SI} \ga 10^{-10} pb, and for the spin-dependent cross section: 10^{-3} pb \ga \sigma_{SD}, with the lower bound on \sigma_{SI} dependent on using the putative constraint from the muon anomalous magnetic moment. We stress the importance of incorporating accelerator and dark matter constraints in restricting the NUHM parameter space, and also of requiring that no undesirable vacuum appear below the GUT scale. In particular, values of the spin-independent cross section another order of magnitude larger would appear to be allowed, for small \tan \beta, if the GUT vacuum stability requirement were relaxed, and much lower cross-section values would be permitted if the muon anomalous magnetic moment constraint were dropped.Comment: 30 pages LaTeX, 40 eps figure

Fermi-liquid instabilities at magnetic quantum phase transitions

This review discusses instabilities of the Fermi-liquid state of conduction electrons in metals with particular emphasis on magnetic quantum critical points. Both the existing theoretical concepts and experimental data on selected materials are presented; with the aim of assessing the validity of presently available theory. After briefly recalling the fundamentals of Fermi-liquid theory, the local Fermi-liquid state in quantum impurity models and their lattice versions is described. Next, the scaling concepts applicable to quantum phase transitions are presented. The Hertz-Millis-Moriya theory of quantum phase transitions is described in detail. The breakdown of the latter is analyzed in several examples. In the final part experimental data on heavy-fermion materials and transition-metal alloys are reviewed and confronted with existing theory.Comment: 62 pages, 29 figs, review article for Rev. Mod. Phys; (v2) discussion extended, refs added; (v3) shortened; final version as publishe