On the Path-Integral Derivation of the Anomaly for the Hermitian Equivalent of the Complex PTPT-Symmetric Quartic Hamiltonian

It can be shown using operator techniques that the non-Hermitian $PT$-symmetric quantum mechanical Hamiltonian with a "wrong-sign" quartic potential $-gx^4$ is equivalent to a Hermitian Hamiltonian with a positive quartic potential together with a linear term. A naive derivation of the same result in the path-integral approach misses this linear term. In a recent paper by Bender et al. it was pointed out that this term was in the nature of a parity anomaly and a more careful, discretized treatment of the path integral appeared to reproduce it successfully. However, on re-examination of this derivation we find that a yet more careful treatment is necessary, keeping terms that were ignored in that paper. An alternative, much simpler derivation is given using the additional potential that has been shown to appear whenever a change of variables to curvilinear coordinates is made in a functional integral.Comment: LaTeX, 12 pages, no figure

Selected results on Strong and Coulomb-induced correlations from the STAR experiment

Using recent high-statistics STAR data from Au+Au and Cu+Cu collisions at full RHIC energy I discuss strong and Coulomb-induced final state interaction effects on identical ($\pi-\pi$) and non-identical ($\pi-\Xi$) particle correlations. Analysis of $\pi-\Xi$ correlations reveals the strong and Coulomb-induced FSI effects allowing for the first time to estimate space extension of $\pi$ and $\Xi$ sources and average shift between them. Source imaging technique providing clean separation of these effects from effects due to the source function itself is applied to one-dimensional relative momentum correlation function of identical pions. For low momentum pions and/or non-central collisions large departure from a single-Gaussian shape is observed

How well does NLO pQCD describe strangeness in p+pp+p collisions at s\sqrt{s}= 200 GeV in STAR?

We present measurements of the transverse momentum spectra for $\mathrm{K^{0}_{S}}$, $\Lambda$, $\Xi$ and their antiparticles in p+p collisions at $\sqrt{s}=200 GeV$. The extracted mid-rapidity yields and $$ are in agreement with previous $p+\bar{p}$ experiments while they have smaller statistical errors. We compare the measured spectra for $\mathrm{K^{0}_{S}}$ and $\Lambda$ to the latest available calculations from NLO pQCD and see good agreement for the $\mathrm{K^{0}_{S}}$ above 1.5 GeV/c.Comment: conference proceedings, Strangeness in Quark Matter 2004, 5 pages, submitted to Journal Physics G, final version submitted to journal incl. modifications requested by edito

Centrality Dependence of Azimuthal Anisotropy of Strange Hadrons in 200 GeV Au+Au Collisions

Measurements of azimuthal anisotropy for strange and multi-strange hadrons are presented for the first time in their centrality dependence. The high statistics results of v2(pT) allow for a more detailed comparison to hydrodynamical model calculations. Number-of-constituent-quark scaling was tested for different centrality classes separately. Higher order anisotropies like v4(pT) are measured for multi-strange hadrons. While we observe agreement between measured data and models a deeper understanding and refinement of the models seem to be necessary in order to fully understand the details of the data.Comment: 4 pages, 2 figures; Strange Quark Matter 2006 conference proceedings, to appear in J. Phys.

Remote rehabilitation (telerehabilitation) in the sight loss sector: Reflections on challenges and opportunities from service providers in the United Kingdom

Background: Vision rehabilitation services are increasingly being delivered remotely (i.e., telerehabilitation); yet, limited research has explored practitioners’ attitudes towards this approach or considered the wider implications of re-designing services. This qualitative study investigates perspectives on delivering telerehabilitation among sight loss support organisations. Methods: Twelve participants from 9 sight loss charities in the United Kingdom took part in a semi-structured interview. Participants were professionals from large national rehabilitation service providers (n = 5), regional charities (n = 3), or local community organisations (n = 4). Qualitative data were analysed using thematic analysis. Results: Four themes were identified (1) Delivery of telerehabilitation; (2) Opportunities associated with telerehabilitation; (3) challenges associated with telerehabilitation; and (4) wider challenges in the vision rehabilitation sector. Greater utilisation of telerehabilitation was viewed positively; however, questions arose regarding cost-effectiveness and the appropriateness of this method of service delivery. Factors such as workforce decline, access to training, and understanding of vision rehabilitation were identified as wider problems affecting the future landscape of vision rehabilitation. Conclusion: Digital innovation has facilitated local and national organisations to provide largely successful and accessible telerehabilitation services. Wider challenges call for investment in strategies and policies to ensure people with visual impairment can continue to benefit from vision rehabilitation services

Pick-up ion dynamics at the structured quasi-perpendicular shock

We study the pickup ion dynamics and mechanism of multiple reflection and acceleration at the structured quasi-perpendicular supercritical shock. The motion of the pickup ions in the shock is studied analytically and numerically using the test particle analysis in the model shock front. The analysis shows that slow pickup ions may be accelerated at the shock ramp to high energies. The maximum ion energy is determined by the fine structure of the electro-magnetic field at the shock ramp and decreases when the angle between magnetic field and shock normal decreases. Evolution of pickup ion distribution across the nearly-perpendicular shock and pickup ion spectrum is also studied by direct numerical analysis.Comment: LaTeX (elsart.cls), packages: times,amsmath,amssymb; 15 pages + 13 figures (GIF). To appear in Planetary and Space Science

Petrography and Geochemistry of Metals in Almahata Sitta Ureilites

Ureilites are ultramafic achondrites, predominantly composed of olivine and pyroxenes with accessory carbon, metal and sulfide. The majority of ureilites are believed to represent the mantle of the ureilite parent body (UPB) [1]. Although ureilites have lost much of their original metal [2], the metal that remains retains a record of the formative processes. Almahata Sitta is predominantly composed of unbrecciated ureilites with a wide range of silicate compositions [3,4]. As a fall it presents a rare opportunity to examine fresh ureilite metal in-situ, and analyzing their highly siderophile element (HSE) ratios gives clues to their formation. Bulk siderophile element analyses of Almahata Sitta fall within the range observed in other ureilites [5]. We have examined the metals in seven ureilitic samples of Almahata Sitta (AS) and one associated chondrite fragment (AS#25)

Geothermal probabilistic cost study

A tool is presented to quantify the risks of geothermal projects, the Geothermal Probabilistic Cost Model (GPCM). The GPCM model was used to evaluate a geothermal reservoir for a binary-cycle electric plant at Heber, California. Three institutional aspects of the geothermal risk which can shift the risk among different agents was analyzed. The leasing of geothermal land, contracting between the producer and the user of the geothermal heat, and insurance against faulty performance were examined

Dynamical Decoupling in Optical Fibers: Preserving Polarization Qubits from Birefringent Dephasing

One of the major challenges in quantum computation has been to preserve the coherence of a quantum system against dephasing effects of the environment. The information stored in photon polarization, for example, is quickly lost due to such dephasing, and it is crucial to preserve the input states when one tries to transmit quantum information encoded in the photons through a communication channel. We propose a dynamical decoupling sequence to protect photonic qubits from dephasing by integrating wave plates into optical fiber at prescribed locations. We simulate random birefringent noise along realistic lengths of optical fiber and study preservation of polarization qubits through such fibers enhanced with Carr-Purcell-Meiboom-Gill (CPMG) dynamical decoupling. This technique can maintain photonic qubit coherence at high fidelity, making a step towards achieving scalable and useful quantum communication with photonic qubits.Comment: 8 pages, 5 figure