Tissue fixation security in transosseous rotator cuff repairs: a mechanical comparison of simple versus mattress sutures

The primary purpose of this investigation was to compare tissue fixation security by simple sutures versus mattress sutures in transosseous rotator cuff repair. These two repair techniques were each performed in 17 human cadaver shoulders, with two bone tunnels being used for the repair by two simple sutures and two other bone tunnels being used for the repair by one mattress suture. The repairs were loaded to failure in a servohydraulic materials test system. Rotator cuff repair by simple sutures was found to be significantly stronger than repair by mattress sutures (P = .0007). The average ultimate load to failure for the simple suture construct (189.62 N) was 39.72% greater than that for the mattress suture construct (135.71 N). Most of the failures occurred by suture breakage at the knot. Load-sharing by multiple suture tails and multiple knots in the simple suture configuration likely contributed to its superior strength characteristics compared with the mattress suture configuration.     

A meta-modelling framework for knowledge consistency in collaborative design

The design of complex system requires a lot of interactions between experts and then between numerous Computer Aided X software (CAX) (where X can be Design (CAD), Engineering (CAE), Manufacturing (CAM), etc.). In order to improve the consistency of the whole system design and the related data and information, knowledge crossing the expertises must be tracked and formalized regarding a shared reference. That means that instead of defining a large reference models to which each expert refers to, a light collaborative model is defined enabling to connect data from each expert model to adhoc data from other expert models, following the least commitment principle. In this topic, a new meta-model is proposed in a Model-Driven Engineering approach to manage the integration of heterogeneous experts’ knowledge models in a collaborative process. The structure of the proposed knowledge meta-model is defined taking into account the complexity of knowledge definition and the properties of its components. This meta-model is split in a meta-model of data on one hand and a Collaboration Meta-Model in the other hand, to represent the distinction between the core concepts of knowledge and additional elements serving to represent the relation between these concepts, and between concepts of heterogeneous experts’ models. The proposed meta-model is illustrated on an industrial case study to highlight the way to put it in use, and its interests to enable collaboration between experts throughout the design process.     

Controlling Salmonella infections in pig farms: A framework modelling approach

Human salmonellosis is an important food-borne disease and S. Typhimurium is the most common serotype attributed to pork products. Under a farm-to-fork strategy, reducing the levels of Salmonella-positive pigs entering the slaughterhouse is an important goal. A framework model was developed, where the effect of dynamic (infection characteristics) and non-dynamic (cleanness and disinfection, biosecurity measures, etc.) factors were considered. Four baseline scenarios were created, corresponding to different levels associated with national Salmonella monitoring programs, and sensitivity analyses were run for the non-dynamic factors. Moreover, the option of vaccination was incorporated into the model, in order to provide with a tool for the formulation of an optimum vaccination strategy depending on the characteristics of the vaccine.     

Water quality of Scottish rivers: spatial and temporal trends

The Harmonised Monitoring Scheme (HMS) was initiated in 1974 and represents the best-organised source of temporal and spatial data describing water quality for the major mainland rivers of Scotland, England and Wales. This paper presents the first detailed analysis of HMS data for Scotland, and identifies temporal changes in water quality from 1974 to 1995. From a concomitant analysis of catchment land cover characteristics, water quality indices have been linked with potential 'drivers' of change, influencing both point and diffuse sources. Nitrate concentrations between rivers are highly correlated with the amount of arable land, and relationships exist between grassland cover, orthphosphate-P and suspended solids concentrations. Similarly, urban catchments are highly correlated with ammonium-N, orthophosphate-P and suspended solids. Spatial and temporal trends in water quality for the rivers of Scotland are discussed.     

Fatigue-loading effect on RC beams strengthened with externally bonded FRP

External bonding of fiber-reinforced polymers (FRP) on concrete beams is particularly attractive for the strengthening of civil engineering structures in order to increase their strength and stiffness. Principles for design of such strengthening methods are now established and many guidelines exist. However, fatigue design procedure is still an ongoing research topic.This paper focuses on the damage behavior of FRP-strengthened reinforced concrete (RC) structures subjected to fatigue loading.In order to design bonded reinforcements, an iterative computational method based on section equilibrium and material properties (concrete, steel, adhesive and composite) has been previously developed by authors [1], [2], [3]. In the present study, this method is extended to describe the fatigue behavior of RC beams.A specific modeling coupled with an experimental investigation on large-scale beams made it possible to compare the theoretical and experimental fatigue behaviors of RC beams with and without composite reinforcements. The model is developed and calibrated using data of the literature or recorded during experiments specifically carried out for this study. Results showed that the beam deflection and the strain in each material could be calculated with a sufficient accuracy, so that the fatigue behavior of the FRP-strengthened beams was correctly estimated by the model.     

Creep behavior of adhesives used for external FRP strengthening of RC structures

It is technologically possible to strengthen steel-reinforced concrete structures with externally bonded carbon–epoxy composites. The durability and performance of those reinforcements directly depend on the rheological behavior of the concrete–composite interface. We propose a methodology to evaluate the permissible shear stress of the interface, based on thermo-stimulated tensile shear tests performed on the interface, and taking into account the effects of time and temperature. Four polymers used for bonding were tested and a value for the permissible shear stress is proposed for each strengthening system.     

Sustainability of Scottish water quality in the early 21st century

This paper reviews some of the current water quality issues relating to the surface waters of Scotland and highlights some of the key issues likely to be significant over the next decade. The sustainable management of water quality requires an appreciation of the temporal and spatial assessment of the resource, together with an identification of reference or natural conditions from which to determine change, and the elucidation of the drivers of change. Only through this integrated approach, can appropriate management strategies be developed and prioritised, bearing in mind that impacts may be decoupled from sources in both time and space. This paper highlights recent trends in water quality (from a hydrochemical perspective) with separation into three broad groups: rivers, lochs and estuaries. For rivers, a general reduction in concentration of determinants that are more indicative of urban point sources (phosphorus, ammonium, suspended solids, biochemical oxygen demand etc.) is apparent, while in more agriculturally-dominated areas, an increase in concentration of solutes that are considered more diffuse in origin, (e.g. nitrate) is reported. The increasing contribution to total loads from diffuse pollutants is a priority area for both research and policy. Current scientific challenges are to define the most appropriate spatial context within which regional water quality issues can be monitored and managed. It is likely that future emphasis will be placed on making an initial ecoregion based grouping in conjunction with physically defined catchment, which will be used to quantify site-specific impacts. Such an organisational approach will provide a mechanism that enables a targeted monitoring strategy to be developed. This will allow the establishment of ecologically based targets for water quality, and an improved understanding the biogeochemistry of pollution reversibility and ecosystem recovery. It is also fundamental to the development of tools through which to predict the time scale and magnitude of any recovery, such that environmental benefit can be optimised against realistic socio-economic constraints. The inter-relations between water quality objectives and the development of legislation for water resources management in Europe are discussed.