Computational Modelling of Water Transport in Hydrocolloid Wound Dressing, DuoDERMⓇ CGF, and Design Recommendations

Hydrocolloids, and further hydrogels, have arisen as attractive next-generation wound dressings because of their modularity and ability to retain moisture. Hydrocolloids, like DuoDERM Ⓡ CGF, are intended for partial and full thickness wounds. They may be used for minor burns, cuts, tears, abrasions, as well as lacerations, ulcers, and some traumatic or surgical wounds. A computational simulation of water transport in wounds with hydrocolloid dressings was implemented in order to understand the mechanisms of hydrocolloid wound dressings as they relate to water transport. The ideal dressing will maintain the wounded tissue at physiological water content levels while also retaining moisture within the dressing itself to promote re-epithelialization of tissue. This study aims to determine the effectiveness of current wound dressings with respect to retaining moisture and maintaining the skin at physiological levels of water content. This study further seeks to optimize current wound dressing design parameters in order to improve water retention above the wound bed and maintenance of physiological skin water content. To study the transfer of liquid water in skin and an example hydrocolloid wound dressing, a computational model was built in COMSOL Multiphysics Ⓡ Modeling Software using a multifrontal direct solver (MUMPS). This model primarily detailed water transport processes in the skin (stratum corneum, epidermis, and dermis) with an example hydrocolloid dressing DuoDERM Ⓡ CGF (hydrocolloid and polymeric barrier layer). The use of the model can be extended to larger or smaller wound areas as well as different types of hydrocolloid dressings. The parameters of the materials can be easily altered to fit new materials being simulated, however the model is only valid up to the time right before the hydrocolloid would start to degrade. The model considered the skin layers, wound surface, hydrocolloid, and polymeric barrier layer to be a 2D, axisymmetric cylinder. Water (mass) transport was considered diffusion in porous media in the skin and diffusion in the hydrocolloid and polymeric layers. The swelling effect, typical of hydrocolloids, was modeled using deforming geometry. After validating the model, an objective function was created in order to quantify the performance of the model based on its ability to maintain physiological water content in the skin as well as its ability to retain moisture in the hydrocolloid domain above the wound bed. Using this objective function, the material properties of the hydrocolloid dressing were altered in order to obtain an optimal solution, where the dressing would maintain an ideally moist environment. The results confirmed that the hydrocolloid wound dressing retains moisture but does not satisfactorily maintain wounded tissue near physiological levels of water content. The optimization suggested the variation of two hydrocolloid parameters, the diffusivity and the partitioning coefficient between the skin and hydrocolloid, in order to improve its performance. Lowering the diffusivity of the hydrocolloid resulted in a higher water concentration above the wound bed. Decreasing the partition coefficient (an effect observed by increasing the hydrophobicity of the hydrocolloid) reduced the flux of water from the wound to the dressing. The combined effect of a reduced diffusivity and partition coefficient allowed greater regions of the wound to retain physiological water content levels and improved water retention near the wound bed. These results will inform the design of future generations of wound dressings and elucidate difficulties in the use of hydrophilic wound dressings like hydrocolloids and hydrogels

Implementing QVT-R bidirectional model transformations using alloy

QVT Relations (QVT-R) is the standard language proposed by the OMG to specify bidirectional model transformations. Unfortunately, in part due to ambiguities and omissions in the original semantics, acceptance and development of effective tool support has been slow. Recently, the checking semantics of QVT-R has been clarified and formalized. In this paper we propose a QVT-R tool that complies to such semantics. Unlike any other existing tool, it also supports meta-models enriched with OCL constraints (thus avoiding returning ill-formed models), and proposes an alternative enforcement semantics that works according to the simple and predictable “principle of least change”. The implementation is based on an embedding of both QVT-R transformations and UML class diagrams (annotated with OCL) in Alloy, a lightweight formal specification language with support for automatic model finding via SAT solving.Fundação para a Ciência e a Tecnologi

Least - change bidirectional model transformation With QVT- R and ATL

QVT Relations (QVT-R) is the standard language proposed by the OMG to specify bidirectional model transformations. Unfortunately, in part due to ambiguities and omissions in the original semantics, acceptance and development of effective tool support has been slow. Recently, the checking semantics of QVTR has been clarified and formalized. In this article we propose a QVT-R tool that complies to such semantics. Unlike any other existing tool, it also supports metamodels enriched with OCL constraints (thus avoiding returning ill-formed models), and proposes an alternative enforcement semantics that works according to the simple and predictable “principle of least change”. The implementation is based on an embedding of both QVT-R transformations and UML class diagrams (annotated with OCL) in Alloy, a lightweight formal specification language with support for automatic model finding via SAT solving. We also show how this technique can be applied to bidirectionalize ATL, a popular (but unidirectional) model transformation language.This work is funded by ERDF-European Regional Development Fund through the COMPETE Programme (operational programme for competitiveness) and by national funds through the FCT-Fundacao para a Ciencia e a Tecnologia (Portuguese Foundation for Science and Technology) within project FCOMP-01-0124-FEDER-020532. The first author is also sponsored by FCT grant SFRH/BD/69585/2010. The authors would also like to thank all anonymous reviewers for the valuable comments and suggestions

The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe

The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.Comment: Major update of previous version. This is the reference document for LBNE science program and current status. Chapters 1, 3, and 9 provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess. 288 pages, 116 figure

One step forward, two tweets back: exploring cultural backlash and hockey masculinity on Twitter

Between 2000 and 2018, the number of fights in professional hockey decreased by more than half, reflecting rule changes intended to preserve player health. A 2019 playoff fight ignited debate on social media over the place of fighting in hockey. This research involved a content analysis of an incendiary tweet and the 920 replies it solicited. Content analysis confirmed that cultural backlash exists in sport, and provided insight into manifestations of backlash. Comments exhibiting backlash varied by subject (i.e. what or who is being discussed in the tweet) and attitude (i.e. positive approval for fighting, negative attitude toward change), with many defending hockey masculinity (Allain, 2015). Connections are drawn to manifestations of backlash in the political realm, the extant hockey masculinity literature, and implications for sociological theory and the sport of hockey are discussed

Lawson criterion for ignition exceeded in an inertial fusion experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion