Respiratory assist using an intravenous catheter may be a potential treatment for patients suffering from acute or acute-on-chronic lung failure. The objective of this study was to evaluate a novel respiratory catheter that uses an impeller within the fiber bundle to enhance gas exchange efficiency, thus requiring a smaller fiber bundle and insertional size (25 Fr) and permitting simple percutaneous insertion. Bench testing of gas exchange in deionized water was used to evaluate eight impeller designs. The three best performing impeller designs were evaluated in acute studies in four calves (122 + or - 10 kg). Gas exchange increased significantly with increasing impeller rotation rate. The degree of enhancement varied with impeller geometry. The maximum gas exchange efficiency (exchange per unit surface area) for the catheter with the best performing impeller was 529 + or - 20 ml CO(2)/min/m(2) and 513 + or - 21 ml CO(2)/min/m(2) for bench and animal studies, respectively, at a rotation rate of 20,000 rpm. Absolute CO(2) exchange was 37 and 36 ml CO(2)/min, respectively. Active mixing by rotating impellers produced 70% higher gas exchange efficiency than pulsating balloon catheters. The sensitivity of gas exchange to impeller design suggests that further improvements can be made by computational fluid dynamics-based optimization of the impeller.

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A balanced mix design (BMD) approach for asphalt mixtures incorporates laboratory performance tests into the mix design acceptance process. However, test selection and subsequent performance thresholds must be selected, which is no easy endeavor when considering the number of promising tests and the variation in asphalt mix designs and components between states or regions. While the Virginia Department of Transportation’s (VDOT) BMD specification has been circulated for multiple years now, this article presents the approach taken by VDOT to investigate the various tests, considerations taken in selecting tests, and the establishment of performance thresholds. Data and discussion of six different performance tests encompassing durability, rutting, and cracking for 11 common Virginia mixes are presented. The performance threshold selection process is outlined. Further considerations in the final test selection process are discussed. In conclusion, the initial draft specification for BMD is provided.

The IDEAL-CT (InDirect tEnsile AsphaLt Cracking Test) has rapidly become a popular cracking test for asphalt mixture acceptance. There have been several studies conducted to ensure this test is sufficient and acceptable for mixture acceptance purposes with respect to testing variability and the test’s ability to detect mixture quality improvements. A potential source of testing variability yet to be comprehensively studied is the variability introduced between testing devices. This paper provides a case study for the potential CTIndex variability, which can be attributed to the test device and the impact this has on determining whether devices are equivalent. The two one-sided tests (TOST) equivalence test, applied to this study, is a more appropriate statistical test to determine device equivalence when compared with typical hypothesis tests like analysis of variance. The TOST requires the user to have an understanding of an acceptable limit of deviation between two devices to determine both the statistical and practical equivalence between devices. This paper details the equivalence testing of 100 unique device-to-device comparisons and provides an example of the importance of using an appropriate number of samples to set achievable limits for accepting device equivalency. A relatively simple approach to assessing equivalence is recommended to IDEAL-CT users in situations in which device-to-device comparisons have real-world consequences. Finally, guidance is provided for selecting a minimum number of samples required to adequately test for device-to-device equivalence.

This study used infrastructure and cyclist survey data from Auburn, Alabama, to compare the rankings of common bicycle level-of-service (LOS) measures, perceived bicycle route suitability for different types of cyclists, and roadway characteristics. Specifically, four common types of bicycle LOS measures were identified, and a representative measure from each was calculated for all the major roadway segments within the city. Additionally, results from a survey of cyclists on the perceived bicycle route suitability were collected and summarized. The comparisons highlighted a surprising disconnection between LOS measures and suitability. Namely, suitability was perceived to be the same across different types of cyclists, but those segments that were ranked highly suitable did not correspond to those with high levels of service. Additionally, suitability was evaluated in terms of routes, whereas LOS rankings treated segments independently. The distribution of suitability and LOS rankings were significantly different as well: suitability had a few highly suitable routes and an increasing number of less-suitable locations, but the different LOS measures had varying distributions of what was acceptable or not. Significant recommendations are made on how city and regional transportation planners may make better-informed decisions about bicycle facility improvements.