A series of coverings of the regular n-gon

We define an infinite series of translation coverings of Veech's double-n-gon for odd n greater or equal to 5 which share the same Veech group. Additionally we give an infinite series of translation coverings with constant Veech group of a regular n-gon for even n greater or equal to 8. These families give rise to explicit examples of infinite translation surfaces with lattice Veech group.Comment: A missing case in step 1 in the proof of Thm. 1 b was added. (To appear in Geometriae Dedicata.

A Tonnetz Model for pentachords

This article deals with the construction of surfaces that are suitable for representing pentachords or 5-pitch segments that are in the same $T/I$ class. It is a generalization of the well known \"Ottingen-Riemann torus for triads of neo-Riemannian theories. Two pentachords are near if they differ by a particular set of contextual inversions and the whole contextual group of inversions produces a Tiling (Tessellation) by pentagons on the surfaces. A description of the surfaces as coverings of a particular Tiling is given in the twelve-tone enharmonic scale case.Comment: 27 pages, 12 figure

Computational Modelling of Patella Femoral Kinematics During Gait Cycle and Experimental Validation

The effect of loading and boundary conditions on patellar mechanics is significant due to the complications arising in patella femoral joints during total knee replacements. To understand the patellar mechanics with respect to loading and motion, a computational model representing the patella femoral joint was developed and validated against experimental results. The computational model was created in IDEAS NX and simulated in MSC ADAMS/VIEW software. The results obtained in the form of internal external rotations and anterior posterior displacements for a new and experimentally simulated specimen for patella femoral joint under standard gait condition were compared with experimental measurements performed on the Leeds ProSim knee simulator. A good overall agreement between the computational prediction and the experimental data was obtained for patella femoral kinematics. Good agreement between the model and the past studies was observed when the ligament load was removed and the medial lateral displacement was constrained. The model is sensitive to ±5 % change in kinematics, frictional, force and stiffness coefficients and insensitive to time step

Dynamic in vitro measurement of patellar movement after total knee arthroplasty: an in vitro study

BACKGROUND: Changing the kinematic behaviour of patellar movement could be one of the reasons for anterior knee pain after implantation of a total knee arthroplasty (TKA). The aim of the current study was to measure the potential influence on patellar kinematics of patellar resurfacing during TKA. METHODS: Patellar movement before and after TKA with and without patellar resurfacing was measured under dynamic conditions in an in vitro cadaver simulation. Physiologic Musculus quadriceps forces were applied to five physiologic human knee specimens undergoing simulated isokinetic extension motions, patellar movement was measured using an ultrasonic measurement system. Thereafter, the Interax(® )I.S.A.-prosthesis system was implanted without and with resurfacing the patella, and patellar movement was again measured. RESULTS: The physiologic patella center moved on a semilunar path up to 6.4 mm (SD 6.4 mm) medially during extension. After TKA, the unresurfaced patella showed significantly less medial translation (p = 0.04) than the resurfaced patella. Subsequent resurfacing of the patella then resulted in a return to mediolateral positioning of the patella similar to the physiological case, whereas the resurfaced patella tilted up to twice as much as physiologic. CONCLUSION: The results of this study suggest that resurfacing of the patella during TKA can result in a restoration of the physiologic mediolateral shift of the patellofemoral joint while angulation of the patella remains unphysiologic

Complement C3 Inhibitor Pegcetacoplan for Geographic Atrophy Secondary to Age-Related Macular Degeneration : A Randomized Phase 2 Trial

Copyright © 2019 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.Peer reviewedPublisher PD

Neither participation nor revolution: the strategy of the Moroccan Jamiat al-Adl wal-Ihsan

Scholars and students of Islamist movements are divided over the issue of Islamists' commitment to democracy and a number of studies have attempted to discover the true nature of Islamist parties. This paper rejects this approach and argues that the behaviour of Islamist parties can be better understood through an analysis of the constraints and opportunities that their surrounding environment provides. Specifically, the paper aims at explaining the choice of the Moroccan Jamiat al-Adl wal-Ihsan neither to participate in institutional politics nor to undertake violent actions to transform the regime. This is done through an examination of its relations with the other political actors. The paper argues that Jamiat al-Adl wal-Ihsan's behaviour is as much the product of rational thinking as it is of ideology and provides evidence to support this claim. Such findings are important not only in the Moroccan context, but contribute to a growing literature claiming that Islamist movements should be treated as rational political actors operating under 'environmental' constraints and opportunities

The ascent from the maelstrom: Art Students Observed and its descriptive resonance 40 years on

Between 1967 and 1973 Barbara Weinberger and Charles Madge undertook a longitudinal study of art students at Coventry and Birmingham Colleges of Art, incorporating pre-diploma to final year students and their teachers, with a focus on fine art students. This article revisits the study in light of accounts from participants, archival documents and reviews. It also looks at the study's value both as an accurate description of art school socialisation and its effectiveness as a piece of sociology. It then looks at some of the main issues raised by the study and how they have influenced writing since and their value today. The article aims to clarify some of the obscurities of the study and offer a critical context within which it can be read as a now unique historical document