Symmetric angular momentum coupling, the quantum volume operator and the 7-spin network: a computational perspective

A unified vision of the symmetric coupling of angular momenta and of the quantum mechanical volume operator is illustrated. The focus is on the quantum mechanical angular momentum theory of Wigner's 6j symbols and on the volume operator of the symmetric coupling in spin network approaches: here, crucial to our presentation are an appreciation of the role of the Racah sum rule and the simplification arising from the use of Regge symmetry. The projective geometry approach permits the introduction of a symmetric representation of a network of seven spins or angular momenta. Results of extensive computational investigations are summarized, presented and briefly discussed.Comment: 15 pages, 10 figures, presented at ICCSA 2014, 14th International Conference on Computational Science and Application

The Screen representation of spin networks: 2D recurrence, eigenvalue equation for 6j symbols, geometric interpretation and Hamiltonian dynamics

This paper treats 6j symbols or their orthonormal forms as a function of two variables spanning a square manifold which we call the "screen". We show that this approach gives important and interesting insight. This two dimensional perspective provides the most natural extension to exhibit the role of these discrete functions as matrix elements that appear at the very foundation of the modern theory of classical discrete orthogonal polynomials. Here we present 2D and 1D recursion relations that are useful for the direct computation of the orthonormal 6j, which we name U. We present a convention for the order of the arguments of the 6j that is based on their classical and Regge symmetries, and a detailed investigation of new geometrical aspects of the 6j symbols. Specifically we compare the geometric recursion analysis of Schulten and Gordon with the methods of this paper. The 1D recursion relation, written as a matrix diagonalization problem, permits an interpretation as a discrete Schr\"odinger-like equations and an asymptotic analysis illustrates semiclassical and classical limits in terms of Hamiltonian evolution.Comment: 14 pages,9 figures, presented at ICCSA 2013 13th International Conference on Computational Science and Applicatio

Risk homeostasis theory - A study of intrinsic compensation

Risk homeostasis theory (RHT) suggests that changes made to the intrinsic risk of environments are negated in one of three ways: behavioural adjustments within the environment, mode migration, and avoidance of the physical risk. To date, this three-way model of RHT has little empirical support, whilst research findings on RHT have at times been diametrically opposed. A reconciliation of apparently opposing findings might be possible by suggesting that extrinsic compensation fails to restore previously existing levels of actual risk in cases where behavioural adjustments within the environment are incapable of negating intrinsic risk changes. This paper reports a study in which behavioural adjustments within the physical risk-taking environment are capable of reconciling target with actual risk. The results provide positive support for RHT in the form of overcompensation for the intrinsic risk change on specific driver behaviours

The Screen representation of spin networks. Images of 6j symbols and semiclassical features

This article presents and discusses in detail the results of extensive exact calculations of the most basic ingredients of spin networks, the Racah coefficients (or Wigner 6j symbols), exhibiting their salient features when considered as a function of two variables - a natural choice due to their origin as elements of a square orthogonal matrix - and illustrated by use of a projection on a square "screen" introduced recently. On these screens, shown are images which provide a systematic classification of features previously introduced to represent the caustic and ridge curves (which delimit the boundaries between oscillatory and evanescent behaviour according to the asymptotic analysis of semiclassical approaches). Particular relevance is given to the surprising role of the intriguing symmetries discovered long ago by Regge and recently revisited; from their use, together with other newly discovered properties and in conjunction with the traditional combinatorial ones, a picture emerges of the amplitudes and phases of these discrete wavefunctions, of interest in wide areas as building blocks of basic and applied quantum mechanics.Comment: 16 pages, 13 figures, presented at ICCSA 2013 13th International Conference on Computational Science and Applicatio

Does congenital deafness affect the structural and functional architecture of primary visual cortex?

Deafness results in greater reliance on the remaining senses. It is unknown whether the cortical architecture of the intact senses is optimized to compensate for lost input. Here we performed widefield population receptive field (pRF) mapping of primary visual cortex (V1) with functional magnetic resonance imaging (fMRI) in hearing and congenitally deaf participants, all of whom had learnt sign language after the age of 10 years. We found larger pRFs encoding the peripheral visual field of deaf compared to hearing participants. This was likely driven by larger facilitatory center zones of the pRF profile concentrated in the near and far periphery in the deaf group. pRF density was comparable between groups, indicating pRFs overlapped more in the deaf group. This could suggest that a coarse coding strategy underlies enhanced peripheral visual skills in deaf people. Cortical thickness was also decreased in V1 in the deaf group. These findings suggest deafness causes structural and functional plasticity at the earliest stages of visual cortex

Associations of autozygosity with a broad range of human phenotypes

In many species, the offspring of related parents suffer reduced reproductive success, a phenomenon known as inbreeding depression. In humans, the importance of this effect has remained unclear, partly because reproduction between close relatives is both rare and frequently associated with confounding social factors. Here, using genomic inbreeding coefficients (F-ROH) for >1.4 million individuals, we show that F-ROH is significantly associated (p <0.0005) with apparently deleterious changes in 32 out of 100 traits analysed. These changes are associated with runs of homozygosity (ROH), but not with common variant homozygosity, suggesting that genetic variants associated with inbreeding depression are predominantly rare. The effect on fertility is striking: F-ROH equivalent to the offspring of first cousins is associated with a 55% decrease [95% CI 44-66%] in the odds of having children. Finally, the effects of F-ROH are confirmed within full-sibling pairs, where the variation in F-ROH is independent of all environmental confounding.Peer reviewe

An academic, pharmaceutical and practice collaboration to implement asthma guidelines

AIMS: To investigate whether a patient review service changes the management of asthma in accordance with BTS/SIGN Guidelines. METHODS: An observational study of routine review consultations for patients with asthma registered at 862 practices throughout the United Kingdom. Practices recorded reviews on a computer template and returned the information to an academic unit for analysis. RESULTS: 41,493 patients had data returned with 14,790 (36%) patients reporting symptoms at rest or on a daily basis and 15,840 (38%) patients overusing their short-acting ?2-agonist. 4,556 (74%) of patients with symptoms who had a subsequent consultation reported a reduction in their symptoms, whilst 3,932 (63%) reported a reduction in short-acting ?2-agonist use. Night-time, daytime, and activity symptom scores, and short-acting ?2-agonist use, were significantly reduced for patients reviewed more than once. CONCLUSION: There are a large proportion of patients suffering symptoms at rest or on a daily basis. There was a significant reduction in symptom levels and use of reliever medication for patients who were reviewed. A review service implementing the BTS/SIGN guidelines for asthma management would seem to improve patient outcomes

Pragmatic 'real world' study of the effect of audit of asthma on clinical outcome

AIMS: To test whether participation in clinical audit is associated with improved care of a long-term health condition. METHODS: Real world study comparing 1339 patients of all ages and severity of asthma managed by 77 self-selected highly motivated general practices in Scotland with 9617 patients from 319 practices from a national sample. RESULTS: Patients managed by audit practices had more structured clinical reviews by nurses [817 (61%) versus 4301 (45%) OR 0.52, 95% CI 0.46?0.58] and less acute GP contacts [440 (33%) v 4161 (43%) OR 1.56, CI 1.38?1.56]. Consequently they experienced more checking of inhaler technique, use of peak flow meters and self- management plans. Audit patients had more symptom free days [365 (42%) v 2216 (23%) OR 0.80, CI 0.70.0.91], and fewer asthma attacks [217 (16%) v 1938 (20%) OR 1.30, CI 1.12.1.53]. They made less use of hospital services including A&#38;E [30 (2%) v 326 (3%) OR 1.53, CI 1.03,2.28] and outpatients [42 (3%) v 459 (5%) OR 1.55, CI 1.11.2.16]. CONCLUSIONS: Patients with asthma benefit from being managed by a practice involved in a programme of audit