Coulomb gauge confinement in the heavy quark limit

The relationship between the nonperturbative Green's functions of Yang-Mills theory and the confinement potential is investigated. By rewriting the generating functional of quantum chromodynamics in terms of a heavy quark mass expansion in Coulomb gauge, restricting to leading order in this expansion and considering only the two-point functions of the Yang-Mills sector, the rainbow-ladder approximation to the gap and Bethe-Salpeter equations is shown to be exact in this case and an analytic, nonperturbative solution is presented. It is found that there is a direct connection between the string tension and the temporal gluon propagator. Further, it is shown that for the 4-point quark correlation functions, only confined bound states of color-singlet quark-antiquark (meson) and quark-quark (baryon) pairs exist.Comment: 22 pages, 6 figure

Polynomial Response Surface Approximations for the Multidisciplinary Design Optimization of a High Speed Civil Transport

Surrogate functions have become an important tool in multidisciplinary design optimization to deal with noisy functions, high computational cost, and the practical difficulty of integrating legacy disciplinary computer codes. A combination of mathematical, statistical, and engineering techniques, well known in other contexts, have made polynomial surrogate functions viable for MDO. Despite the obvious limitations imposed by sparse high fidelity data in high dimensions and the locality of low order polynomial approximations, the success of the panoply of techniques based on polynomial response surface approximations for MDO shows that the implementation details are more important than the underlying approximation method (polynomial, spline, DACE, kernel regression, etc.). This paper surveys some of the ancillary techniques—statistics, global search, parallel computing, variable complexity modeling—that augment the construction and use of polynomial surrogates

Baker Street Wonderpass: evaluation of improvement works

Summary: Baker Street Quarter Partnership identified the pedestrian subway under the Marylebone Road as an area that many of its members would like to see improved. Researchers from the Policy Studies Institute were commissioned to provide an impartial evaluation of improvement works that were carried out to transform the subway into the ‘Baker Street Wonderpass’. The views of users were assessed through an online survey of Baker Street Quarter members (June 2015), pedestrian counting and face-to-face surveys both before the improvement works (July 2015) and after the Wonderpass had opened (February 2016). The pre-works surveys took place in July 2015, with 206 subway users’ answering a total of 12 questions. The post-works surveys took place in February 2016 with 163 subway users answering a total of 15 questions. The survey was supplemented by ‘vox-pop’ interviews. Pedestrian counts before and after the improvement works show a very large increase in pedestrian traffic after the improvement works were completed. After the improvement works, morning usage increased by 153.8%, afternoon usage increasing by 27.8%, and evening usage increasing by 70.8%. Survey results showed a substantial improvement in user’s satisfaction with the lighting, cleanliness, overall appearance, safety, signage and visibility of the subway. The redevelopment of the subway and the opening of the Wonderpass have been a clear success. 83.9% of users said that the subway was ‘much better’, and 98.4% of users said that they thought the subway was ‘better’ or ‘much better’ after the improvement works. Overall, the investment in the Marylebone Road underpass has greatly improved usage levels and user perceptions of the subway and some users stated that they used the subway solely to see the renovations and new displays. While users previously complained about the cleanliness, lighting and appearance of the subway, by February 2016 it has been successfully transformed into a much safer, cleaner, and more desirable ‘Wonderpass’ to cross Marylebon

Magnetic Phase Diagrams of Erbium

The magnetic phase diagrams of erbium in the magnetic field–temperature plane have been constructed for applied magnetic fields along the a and b axes. For an a-axis applied field our H–T phase diagrams determined from magnetization and magnetoresistance data are in good agreement and consistent with that of Jehan et al. for temperatures below 50 K. A splitting of the basal plane Néel temperature (TN⊥) above 3.75 T introduces two new magnetic phases. Also a transition from a fan to a canted fan phase as suggested by Jehan et al. is observed in an increasing field below TC. Our phase diagram for a b-axis applied field constructed from magnetization data is very similar to the phase diagram of Watson and Ali using magnetoresistance measurements. However, the anomaly at 42 K reported by Watson and Ali is not observed in the present study. No splitting of the TN⊥ transition is observed in either work for a field applied along the b axis

The silenced voices of architectural discourse: promoting inclusion through qualitative research

Contemporary architectural discourse is primarily framed by institutional hegemony. Scholarly works written in a voice derived from this privilege inherently exclude the voices of those untrained individuals who inhabit the built environment. The field of architecture, most notably in the AIA's policies and positions, calls for more diverse viewpoints and a more complex understanding of the public's relationship with architecture. It is not possible to make this complexity apparent through the monolithic viewpoints of institutional scholarship. This essay explores a variety of more inclusive research methods established in the social sciences under the banner of qualitative research. We focus on how qualitative research satisfies contemporary research expectations more effectively than positivist institutional scholarship and how qualitative research has a specific congruency with the field of architecture

Siderophile Element Profile Measurements in Iron Meteorites Using Laser Ablation ICP-MS

Understanding the behaviour of siderophile elements during cooling of iron meteorites can lead to insight into the general thermal histories of the meteorites as well as their respective parent bodies. Traditionally trace element analyses in meteorites have been done using techniques that only measure the average concentration in each phase. With these methods, all of the spatial information with respect to the distribution of an element within one phase is lost. Measuring concentration profiles of trace elements in meteorites is now possible, with the advent of high-resolution analytical techniques such as laser ablation, inductively coupled plasma mass spectrometry (LA-ICP-MS) with spatial resolution <20 microns. [e.g. 1,2] and secondary ion mass spectrometry [3]. These profiles can give more insight into both the partitioning and diffusive behavior of siderophile elements in metal systems relevant to iron meteorites, as well as parent body cooling rates

Volume Stabilization and Acceleration in Brane Gas Cosmology

We investigate toy cosmological models in (1+m+p)-dimensions with gas of p-branes wrapping over p-compact dimensions. In addition to winding modes, we consider the effects of momentum modes corresponding to small vibrations of branes and find that the extra dimensions are dynamically stabilized while the others expand. Adding matter, the compact volume may grow slowly depending on the equation of state. We also obtain solutions with winding and momentum modes where the observed space undergoes accelerated expansion.Comment: 20 pages, 3 figures, v2: comments and references added, to appear in JCA

Scalar Casimir effect between two concentric D-dimensional spheres

The Casimir energy for a massless scalar field between the closely spaced two concentric D-dimensional (for D>3) spheres is calculated by using the mode summation with contour integration in the complex plane of eigenfrequencies and the generalized Abel-Plana formula for evenly spaced eigenfrequency at large argument. The sign of the Casimir energy between closely spaced two concentric D-dimensional spheres for a massless scalar field satisfying the Dirichlet boundary conditions is strictly negative. The Casimir energy between D-1 dimensional surfaces close to each other is regarded as interesting both by itself and as the key to describing of stability of the attractive Casimir force. PACS number(s): 03.70.+k, 11.10.Kk, 11.10.Gh, 03.65.GeComment: 14 pages. arXiv admin note: substantial text overlap with arXiv:1207.418

Notations and conventions in molecular spectroscopy: part 1. General spectroscopic notation

The field of Molecular Spectroscopy was surveyed in order to determine a set of conventions and symbols which are in common use in the spectroscopic literature. This document, which is Part I in a series, establishes the notations and conventions used for general spectroscopic notations and deals with quantum mechanics, quantum numbers (vibrational states, angular momentum and energy levels), spectroscopic transitions, and miscellaneous notations (e.g. spectroscopic terms). Further parts will follow, dealing inter alia with symmetry notation, permutation and permutation-inversion symmetry notation, vibration-rotation spectroscopy and electronic spectroscopy