Novel, Inexpensive Portable Respiratory Protection Unit (PRPU) for Healthcare Workers

Introduction: Given concern for increased aerosolization during intubation of patients with severe acute respiratory syndrome coronavirus, we sought to create a portable, inexpensive, and easily constructed device to help protect healthcare workers.Methods: A respiratory protection unit can be constructed in approximately 30 minutes and for less than 50 United States dollars in materials, using polyvinylchloride pipe and automobile collision wrap.Conclusion: This device provides possible increased protection during video laryngoscopy and can easily be replicated

Rfviz: An Interactive Visualization Package for Random Forests in R

Random forests are very popular tools for predictive analysis and data science. They work for both classification (where there is a categorical response variable) and regression (where the response is continuous). Random forests provide proximities, and both local and global measures of variable importance. However, these quantities require special tools to be effectively used to interpret the forest. Rfviz is a sophisticated interactive visualization package and toolkit in R, specially designed for interpreting the results of a random forest in a user-friendly way. Rfviz uses a recently developed R package (loon) from the Comprehensive R Archive Network (CRAN) to create parallel coordinate plots of the predictor variables, the local importance values, and the MDS plot of the proximities. The visualizations allow users to highlight or brush observations in one plot and have the same observations show up as highlighted in other plots. This allows users to explore unusual subsets of their data and to potentially discover previously-unknown relationships between the predictor variables and the response

Effect of Temperature Variation on the Structural Capacity of a Multi-Span Horizontally Curved Steel I-Girder Bridge

Horizontally curved steel I-girder bridges have become a popular bridge design choice among bridge engineers. The current level of knowledge regarding the design and analysis of curved I-girder bridges under thermal loading is incomplete. The thermal expansion of curved bridges is rather complicated and current standards provide little guidance when designing a bearing plan to prevent the development of thermal stresses and out-of-plane distortional behavior. Thermal stresses, in the form of axial compressive stresses, will develop if thermal expansion is constrained. This study examines the effect of different bearing arrangements on the development of thermal stresses and out-of-plane web distortions in a newly constructed bridge located in West Virginia. Three dimensional finite element modeling and analysis is performed in order to predict bridge response. The research shows that uniform thermal loading significantly increases the magnitude of out-of-plane web distortions. Finite element modeling also shows that very significant levels of thermal stress develop in the curved steel I-girders, consuming a considerable percentage of the bridge\u27s total capacity. The web distortions and thermal stresses will result in major serviceability issues, shortening the life of the structure. However, this behavior is largely eliminated with the implementation of a new bearing arrangement, which removes the constraints from the original bearing plan

The Role of Material Structure in Compacted Earthen Building Materials: Implications for Design and Construction

Rammed earth is an earthen construction material and an ancient construction technique. It is formed by compacting layers of moist sandy loam subsoil into formwork which is then removed, exposing the material and creating a freestanding, monolithic structure. In this thesis, the behaviour of rammed earth is investigated in terms of unsaturated soil mechanics of compacted earthen materials. Basic unsaturated soil mechanics theory is discussed and a method for linking the behaviour and material structure of an unsaturated soil is presented through the development of a model for predicting a soil's water retention curve using the soil pore size distribution and capillary and adsorption phenomena. A series of experiments is then performed in order to explain the behaviour of rammed earth in tension and compression under varying conditions in terms of the material micro-- and macrostructures. An analysis of the sample manufacturing process is presented in order to understand formation of rammed earth's structure in both natural and laboratory-prepared materials. The effects of temperature and humidity, related to a number of sites around the world, on the compressive strength and of changing water content and clay flocculation on the tensile strength of rammed earth are then investigated and combined in order to determine the sources of strength in rammed earth. The pore networks of several rammed earth samples under compression and those of rammed earth samples comprising multiple compacted layers are then investigated using X-Ray computed tomography in order to determine the effects of loading and layering on the material macrostructure and to support results presented in previous chapters. In the final chapter, implications for the design, construction and conservation of rammed earth structures are discussed based on the findings of investigations presented in the preceding chapters