Disorder Effects in the Bipolaron System Ti4_{4}O7_{7} Studied by Photoemission Spectroscopy

We have performed a photoemission study of Ti$_{4}$O$_{7}$ around its two transition temperatures so as to cover the metallic, high-temperature insulating (bipolaron-liquid), and low-temperature insulating (bipolaron-crystal) phases. While the spectra of the low-temperature insulating phase show a finite gap at the Fermi level, the spectra of the high-temperature insulating phase are gapless, which is interpreted as a soft Coulomb gap due to dynamical disorder. We suggest that the spectra of the high-temperature disordered phase of Fe$_{3}$O$_{4}$, which exhibits a charge order-disorder transition (Verwey transition), can be interpreted in terms of a Coulomb gap.Comment: 4 pages, 3 epsf figures embedde

Business events and friendship: Leveraging the sociable legacies

© 2014 Cognizant Comm. Corp. Business events are celebrated for their contributions to community and industry. They are understood to be shared social contexts in which people meet to advance knowledge, sell products, and network. Less celebrated and, arguably, less understood is that business events provide a context for the development of friendships. In 2011 an online survey was conducted with the delegates of five international business events held in Sydney, Australia in the period 2009-2011. The survey was designed to investigate business legacies of the events (such as investment opportunities, research collaborations) rather than sociable legacies. However, a surprising number of references to friendship were made in the "additional comments" sections of the questionnaire. Reflecting on this finding, this article argues that friendships forged at business events contribute to, respectively: the well-being of delegates, association membership levels, conference attendance, retention of personnel in the profession, successful research and professional collaborations, and creativity and innovation in the sector. Business event planners can maximize opportunities for sociable outcomes among delegates by designing warm and inviting event spaces that facilitate interaction, and by providing social space for the development of relationships, optimal conditions for sociability, and opportunities for play to stimulate creativity and build community

"All Shook Up" at the parkes elvis festival: The role of play in events

© 2015 Cognizant Comm. Corp. Leisure in the postmodern environment is often regarded as superficial, depthless, and meaningless, dominated by simulation and hyperreality. Many aspects of the Parkes Elvis Festival fall clearly into the category of simulation and hyperreality as attendees imitate Elvis Presley (and other associated characters) and are willing to accept the fake and contrived as real. However, the simulation does not, in the case of the Parkes Elvis Festival, lead to a depthless, meaningless, or inauthentic experience. Using Huizinga's ideas of play and Bateson's play frame we present the Elvis Festival as a liminal social space that invites playfulness and creativity. The theory of Georg Simmel is explored to show how sociability is created at the event to facilitate play. Finally, Csikszentmihalyi's theory of flow is used to demonstrate ways in which the enjoyment of the playful event experience is maximized for participants. We argue that play provides the substance that makes the Parkes Elvis Festival memorable and meaningful. An understanding of play theory may assist event managers to increase social facilitation at festivals and events, ensuring an enjoyable, sociable, creative, and authentic experience for attendees

Photoemission view of electron fractionalization in quasi-one dimensional metal Li0.9_{0.9}Mo6_6O17_{17}

We report Luttinger liquid line shapes better revealed by new angle resolved photoemission data taken with a much improved angle resolution on a quasi-1-dimensional metal Li$_{0.9}$Mo$_6$O$_{17}$. The new data indicate a larger spinon velocity than our previous lower resolution data indicated.Comment: submitted to SCES '0

Luttinger liquid ARPES spectra from samples of Li0.9_{0.9}Mo6_6O17_{17} grown by the temperature gradient flux technique

Angle resolved photoemission spectroscopy line shapes measured for quasi-one-dimensional Li$_{0.9}$Mo$_6$O$_{17}$ samples grown by a temperature gradient flux technique are found to show Luttinger liquid behavior, consistent with all previous data by us and other workers obtained from samples grown by the electrolyte reduction technique. This result eliminates the sample growth method as a possible origin of considerable differences in photoemission data reported in previous studies of Li$_{0.9}$Mo$_6$O$_{17}$.Comment: Some text adde

Two-dimensional Hubbard-Holstein bipolaron

We present a diagrammatic Monte Carlo study of the properties of the Hubbard-Holstein bipolaron on a two-dimensional square lattice. With a small Coulomb repulsion, U, and with increasing electron-phonon interaction, and when reaching a value about two times smaller than the one corresponding to the transition of light polaron to heavy polaron, the system suffers a sharp transition from a state formed by two weakly bound light polarons to a heavy, strongly bound on-site bipolaron. Aside from this rather conventional bipolaron a new bipolaron state is found for large U at intermediate and large electron-phonon coupling, corresponding to two polarons bound on nearest-neighbor sites. We discuss both the properties of the different bipolaron states and the transition from one state to another. We present a phase diagram in parameter space defined by the electron-phonon coupling and U. Our numerical method does not use any artificial approximation and can be easily modified to other bipolaron models with longer range electron-phonon and/or electron-electron interaction.Comment: 14 pages, 12 figure

The H.E.S.S. central data acquisition system

The High Energy Stereoscopic System (H.E.S.S.) is a system of Imaging Atmospheric Cherenkov Telescopes (IACTs) located in the Khomas Highland in Namibia. It measures cosmic gamma rays of very high energies (VHE; >100 GeV) using the Earth's atmosphere as a calorimeter. The H.E.S.S. Array entered Phase II in September 2012 with the inauguration of a fifth telescope that is larger and more complex than the other four. This paper will give an overview of the current H.E.S.S. central data acquisition (DAQ) system with particular emphasis on the upgrades made to integrate the fifth telescope into the array. At first, the various requirements for the central DAQ are discussed then the general design principles employed to fulfil these requirements are described. Finally, the performance, stability and reliability of the H.E.S.S. central DAQ are presented. One of the major accomplishments is that less than 0.8% of observation time has been lost due to central DAQ problems since 2009.Comment: 17 pages, 8 figures, published in Astroparticle Physic

Non-fermi-liquid single particle lineshape of the quasi-one-dimensional non-CDW metal Li_{0.9}Mo_{6}O_{17} : comparison to the Luttinger liquid

We report the detailed non-Fermi liquid (NFL) lineshape of the dispersing excitation which defines the Fermi surface (FS) for quasi-one-dimensional Li_{0.9}Mo_{6}O_{17}. The properties of Li_{0.9}Mo_{6}O_{17} strongly suggest that the NFL behavior has a purely electronic origin. Relative to the theoretical Luttinger liquid lineshape, we identify significant similarities, but also important differences.Comment: 5 pages, 3 eps figure