Wrinkling, creasing, and folding in fiber-reinforced soft tissues

Many biological tissues develop elaborate folds during growth and development. The onset of this folding is often understood in relation to the creasing and wrinkling of a thin elastic layer that grows whilst attached to a large elastic foundation. In reality, many biological tissues are reinforced by fibres and so are intrinsically anisotropic. However, the correlation between the fiber directions and the pattern formed during growth is not well understood. Here, we consider the stability of a two-layer tissue composed of a thin hyperelastic strip adhered to an elastic half-space in which are embedded elastic fibers. The combined object is subject to a uniform compression and, at a critical value of this compression, buckles out of the plane — it wrinkles. We characterize the wrinkle wavelength at onset as a function of the fiber orientation both computationally and analytically and show that the onset of surface instability can be either promoted or inhibited as the fiber stiffness increases, depending on the fibre angle. However, we find that the structure of the resulting folds is approximately independent of the fiber orientation. We also explore numerically the formation of large creases in fiber-reinforced tissue in the post-buckling regime

Is the Donnan effect sufficient to explain swelling in brain tissue slices?

Brain tissue swelling is a dangerous consequence of traumatic injury and is associated with raised intracranial pressure and restricted blood flow. We consider the mechanical effects that drive swelling of brain tissue slices in an ionic solution bath, motivated by recent experimental results that showed that the volume change of tissue slices depends on the ionic concentration of the bathing solution. This result was attributed to the presence of large charged molecules that induce ion concentration gradients to ensure electroneutrality (the Donnan effect), leading to osmotic pressures and water accumulation. We use a mathematical triphasic model for soft tissue to characterize the underlying processes that could lead to the volume changes observed experimentally. We suggest that swelling is caused by an osmotic pressure increase driven by both non-permeating solutes released by necrotic cells, in addition to the Donnan effect. Both effects are necessary to explain the dependence of the tissue slice volume on the ionic bath concentration that was observed experimentally

The corporate governance code and compliance by Maltese listed companies

Purpose: In this paper we lay out the evaluation of non-compliance with the Code of Principles of Good Corporate Governance and the analyses of the adequacy of the explanations provided thereof, including the overall effectiveness of the existing regulatory framework. Design/methodology/approach: To achieve the objectives of this study, a review of the non-compliance section of the corporate governance statements of each Maltese listed company was carried out for the years 2012, 2014 and 2016. Furthermore, 13 semi-structured interviews were held. Findings: The paper finds that a general insufficiency in the explanations provided for non-compliance exists. Some entities give only lip service to the provisions of the Code as they fail to realise the benefits an entity may reap from having good corporate governance structures in place. There is a lack of education and awareness in this regard, and not only on the part of companies but also on the part of shareholders who seem to make minimal use of the information provided in the corporate governance statements. Practical implications: The study raises awareness of the need of improving corporate governance practices, as well as education on corporate governance, across Maltese listed companies. It is hoped that the recommendations made may encourage entities to improve in their reporting and the regulator to provide further guidance to entities to do so. Originality/value: Prior to the amendment of existing rules, increased enforcement of the current regulatory framework and monitoring by the regulator is required. The study highlights the misconceptions on the auditor's role in corporate governance.peer-reviewe

Individual Differences and Computer User-Training Behaviour: Examination of an Empirical Model

A model that incorporates both stable and dynamic individual differences to the nomological net of the Technology Acceptance Model (TAM) in the context of computer user training is proposed. A study using 348 completed surveys from University students engaged in computer training found that stable traits (Negative Affects, Trait Anxiety and Personal Innovativeness in IT (PIIT)) explained 35% of variance in Computer Anxiety (CA). Significant support to the model provides evidence that stable individual differences are antecedents to and predict both Computer Self Efficacy and CA. In addition, the model demonstrates the relationship of these determinants to the TAM

Comparing the economic feasibility of offshore floating wind and solar photovoltaic technologies in Central Mediterranean deep waters

Malta, being a very small and densely populated island in the central Mediterranean, has little space for large scale onshore wind turbine or photovoltaic projects. Maltese territorial waters are mostly too deep for conventional offshore wind farms to be constructed save for a handful of near-shore reefs and shoals. The quest for offshore wind turbine structure designs capable of being installed in deeper waters will revolutionize prospects for offshore wind projects worldwide; but even more so in the Mediterranean region. This paper presents a preliminary engineering analysis to develop two cost-optimized offshore floating structures to support (1) a single multi-megawatt scale wind turbine and (2) a solar photovoltaic farm with the same energy production as that of the single wind turbine. The primary objective of this work is to determine the most economically feasibility option for harvesting renewable energy at sea: offshore wind or offshore solar photovoltaic energy.peer-reviewe

Inhibition of purple acid phosphatase with a-alkoxynaphthylmethylphosphonic acids

Purple acid phosphatases (PAPs) are binuclear hydrolases that catalyse the hydrolysis of a range of phosphorylated substrates. Human PAP is a major histochemical marker for the diagnosis of osteoporosis. In patients suffering from this disorder, PAP activity contributes to increased bone resorption and, therefore, human PAP is a key target for the development of anti-osteoporotic drugs. This manuscript describes the design and synthesis of derivatives of 1-naphthylmethylphosphonic acids as inhibitors of PAP. The Ki values of these compounds are as low as 4 lM, the lowest reported to date for a PAP inhibitor