The Hilbert-Space Structure of Non-Hermitian Theories with Real Spectra

We investigate the quantum-mechanical interpretation of models with non-Hermitian Hamiltonians and real spectra. After describing a general framework to reformulate such models in terms of Hermitian Hamiltonians defined on the Hilbert space $L_2(-\infty,\infty)$, we discuss the significance of the algebra of physical observables.Comment: 5 pages, uses iopart.cls. Talk given by R. Kretschmer at the 1st International Workshop on Pseudo-Hermitian Hamiltonians in Quantum Physics, Prague, Czech Republic, June 16-17, 2003. To appear in the proceeding

Music in electronic markets: an empirical study

Music plays an important, and sometimes overlooked part in the transformation of communication and distribution channels. With a global market volume exceeding US$40 billion, music is not only one of the primary entertainment goods in its own right. Since music is easily personalized and transmitted, it also permeates many other services across cultural borders, anticipating social and economic trends. This article presents one of the first detailed empirical studies on the impact of internet technologies on a specific industry. Drawing on more than 100 interviews conducted between 1996 and 2000 with multinational and independent music companies in 10 markets, strategies of the major players, current business models, future scenarios and regulatory responses to the online distribution of music files are identified and evaluated. The data suggest that changes in the music industry will indeed be far-reaching, but disintermediation is not the likely outcome

Multi-channel Bethe-Salpeter equation

A general form of multi-channel Bethe-Salpeter equation is considered. In contradistinction to the hitherto applied approaches, our coupled system of equations leads to the simultaneous solutions for all relativistic four-point Green functions (elastic and inelastic) appearing in a given theory. A set of relations which may be helpful in approximate treatments is given. An example of extracting useful information from the equations is discussed: we consider the most general trilinear coupling of N different scalar fields and obtain - in the ladder approximation - closed expressions for the Regge trajectories and their couplings to different channels in the vicinity of l = -1. Sum rules and an example containing non-obvious symmetry are discussed.Comment: 16 pages. Extended version published in JHEP. Uses JHEP.cls (included

Employee voice and human resource management: an empirical analysis using British data

The definition of formal employee voice employed in this paper is a variant of the definition developed by Hirschman (1970) in his seminal monograph and later elaborated and appropriated to unions in the labour market by Freeman and Medoff (1984). What we refer to as formal voice is any institutionalised form of two-way communication between management and employees. This is not the same as information sharing or other types of one-way consultation. Meaningful two-way dialogue, as that found typically in union collective bargained voice, is what formal employee voice refers to. As we endeavour to show in this paper, these forms of two-way communication typically extend beyond union voice to non-union forms of representation and direct forms of two-way dialogue, such as problem-solving groups and the statutory systems of works council voice developed as part of deeper European Union (EU) integration. Broader definitions of voice can also be invoked for the labour market as a whole or even for society more generally. In this context see recent work by Adrian Wilkinson and his colleagues (Dundon et al., 2004) and also John Budd’s Employment with a Human Face (2004). Some may take our definition of voice above and simply state that a formal voice system is 'the way workers communicate with management'. For us that would not be a poor workable definition. But how does that play out when we talk about Human Resource Management (HRM) techniques and their role in either abetting or inhibiting voice at work? HRM is not a voice system. Instead we assert that it has a different purpose altogether but may employ voice alongside in order to achieve the end goal of improving worker performance. This assertion flies against most received wisdom and evidence from the US, where union voice (the only real form permitted by the Wagner Act) often sits uncomfortably with HR. In England, up to now, the only thorough evidence by Wood and Machin (2005) suggested no correlation between voice (union) and HRM adoption. In this paper, however, we offer a new explanation for these findings above and in the process contribute some important new findings of our own. The principal source of formal employee voice has typically been provided by trade unions. However, in Britain, where our empirical analysis resides, unions have not been the sole, or even main, conduit for worker-management voice relations for more than three decades. Since the 1960s, firms in Britain have been combining traditional collective bargaining over wages and working conditions with independent non-union channels of two-way communication. Practically, this means things like having a non-union employee-employer committee to handle health-safety issues, promotion criteria or disability concerns. In my own university, a traditional collective bargaining process has neatly resided alongside a plethora of non-union administration and staff committees that discuss nearly every aspect of day-to-day work life and even strategic university planning goals. How these varying types and intensity of voice systems at work can (and do) sit alongside certain managerial innovations for the improvement of employee productivity, is the subject matter of our paper

Concentrations of leptin and C-reactive protein in serum and follicular fluid during assisted reproductive cycles

BACKGROUND: There are only a few studies that have investigated inflammatory processes during ovarian hyperstimulation, with contradictory results especially concerning outcome. The aim of the study was to investigate the inflammatory markers C-reactive protein and leptin in serum and follicular fluid and to correlate these with the outcome. METHODS: One hundred and sixty-two gonadotrophin stimulated cycles were evaluated. Serum concentrations of leptin and C-reactive protein were measured at the initiation of stimulation, on the day of hCG administration or the day before, and on the day of oocyte retrieval. They were also determined in the follicular fluid. RESULTS: Serum leptin and C-reactive protein levels increased significantly during stimulation until the day of oocyte pick up, but following different patterns. After stimulation, they correlated with each other in serum and follicular fluid, but not with estradiol or progesterone concentration, embryo quality, or the pregnancy rate. CONCLUSIONS: Leptin and C-reactive protein levels change significantly during assisted reproductive treatment. In contrast to estradiol they are, however, not a marker of succes

Kinematics of massive star ejecta in the Milky Way as traced by 26^26Al

Context. Massive stars form in groups and their winds and supernova explosions create superbubbles up to kpc in size. The fate of their ejecta is of vital importance for the dynamics of the interstellar medium, for chemical evolution models, and the chemical enrichment of galactic halos and the intergalactic medium. However, ejecta kinematics and the characteristic scales in space and time have not been explored in great detail beyond ~10 Ka. Aims: Through measurement of radioactive 26Al with its decay time constant at ~106 years, we aim to trace the kinematics of cumulative massive-star and supernova ejecta independent of the uncertain gas parameters over million-year time scales. Our goal is to identify the mixing time scale and the spatio-kinematics of such ejecta from the pc to kpc scale in our Milky Way. Methods: We use the SPI spectrometer on the INTEGRAL observatory and its observations along the Galactic ridge to trace the detailed line shape systematics of the 1808.63 keV gamma-ray line from 26Al decay. We determine line centroids and compare these to Doppler shift expectations from large-scale systematic rotation around the Galaxy centre, as observed in other Galactic objects. Results: We measure the radial velocities of gas traced by 26Al, averaged over the line of sight, as a function of Galactic longitude. We find substantially higher velocities than expected from Galactic rotation, the average bulk velocity being ~200 km s-1 larger than predicted from Galactic rotation. The observed radial velocity spread implies a Doppler broadening of the gamma-ray line that is consistent with our measurements of the overall line width. We can reproduce the observed characteristics with 26Al sources located along the inner spiral arms, when we add a global blow-out preference into the forward direction away from arms into the inter-arm region, as is expected when massive stars are offset towards the spiral-arm leading edge. With the known connection of superbubbles to the gaseous halo, this implies angular-momentum transfer in the disk-halo system and consequently also radial gas flows. The structure of the interstellar gas above the disk affects how ionizing radiation may escape and ionize intergalactic gas.Peer reviewe