Tidal resource extraction in the Pentland Firth, UK : Potential impacts on flow regime and sediment transport in the Inner Sound of Stroma

Large-scale extraction of power from tidal streams within the Pentland Firth is expected to be underway in the near future. The Inner Sound of Stroma in particular has attracted significant commercial interest. To understand potential environmental impacts of the installation of a tidal turbine array a case study based upon the Inner Sound is considered. A numerical computational fluid dynamics model, Fluidity, is used to conduct a series of depth-averaged simulations to investigate velocity and bed shear stress changes due to the presence of idealised tidal turbine arrays. The number of turbines is increased from zero to 400. It is found that arrays in excess of 85 turbines have the potential to affect bed shear stress distributions in such a way that the most favourable sites for sediment accumulation migrate from the edges of the Inner Sound towards its centre. Deposits of fine gravel and coarse sand are indicated to occur within arrays of greater than 240 turbines with removal of existing deposits in the shallower channel margins also possible. The effects of the turbine array may be seen several kilometres from the site which has implications not only on sediment accumulation, but also on the benthic fauna

Using the Long Head of Biceps Tendon Autograft as an Anatomical Reconstruction of the Rotator Cable: An Arthroscopic Technique for Patients With Massive Rotator Cuff Tears

The treatment of massive rotator cuff tears (MRCT) is challenging. Insufficient tissue quality, size, and retraction of the cuff often lead to failures of repair. Different techniques like direct repair, partial repair, and graft applications have been developed, but results are not yet predictable. In this arthroscopic technique the objective is not to reconstruct the rotator cuff as a tissue layer but to restore the biomechanical function of the rotator cable with an autograft of the long head of the biceps tendon. After glenohumeral inspection, the long head of the biceps tendon is harvested and the retracted cuff is released and, if possible, closed partially side-to-side. The biceps graft is positioned from the posterior aspect of the greater tubercle to the superior part of the lesser tubercle and fixed with 2 biotenodesis anchors. Finally, the cuff remnants are securely sutured to the biceps graft with standard cuff repair sutures. This arthroscopic technique has several advantages because the biceps autograft is easily harvested, autologous, and rich in collagen. Previous studies show use of the biceps tendon differently for reconstruction of the rotator cuff, with promising results. Future studies are needed to evaluate clinical outcomes

Integrating behavior and autopoiesis: An exploration in computational chemo-ethology

It has been argued that the difference between an autonomous entity and an agent is in the ability of the latter to perform behaviors supplemental to processes of self-maintenance (autopoiesis). Theories have been proposed concerning how such behaviors might relate to autopoiesis, but so far, computational models of autopoiesis have paid little attention to these relations. In this article we present a new model designed to explore the relationship between mechanisms of autopoiesis and behavior. We report on three clarifications of the theory provided by the model: (a) mechanisms of behavior can be related to mechanisms of autopoiesis while remaining operationally distinct, (b) the organization of an operationally closed system can change over time while remaining operationally closed, and (c) behavior modulation based upon autopoietic efficacy has limitations that can be avoided through the use of a partially decoupled behavioral system. Finally, we discuss questions that have surfaced during examination of the model