1,099 research outputs found

    Fifty Years of the Lanham Act: A Retrospective of Section 43(a)

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    Automated Identification of Unhealthy Drinking Using Routinely Collected Data: A Machine Learning Approach

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    Background: Unhealthy drinking is prevalent in the United States and can lead to serious health and social consequences, yet it is under-diagnosed and under-treated. Identifying unhealthy drinkers can be time-consuming for primary care providers. An automated tool for identification would allow attention to be focused on patients most likely to need care and therefore increase efficiency and effectiveness. Objectives: To build a clinical prediction tool for unhealthy drinking based solely on routinely collected demographic and laboratory data. Methods: We obtained demographic and laboratory data on 89,325 adults seen at the University of Vermont Medical Center from 2011-2017. Logistic regression, support vector machines (SVM), k-nearest neighbor, and random forests were each used to build clinical prediction models. The model with the largest area under the receiver operator curve (AUC) was selected. Results: SVM with polynomials of degree 3 produced the largest AUC. The most influential predictors were alkaline phosphatase, gender, glucose, and serum bicarbonate. The optimum operating point had sensitivity 31.1%, specificity 91.2%, positive predictive value 50.4%, and negative predictive value 82.1%. Application of the tool increased the prevalence of unhealthy drinking from 18.3% to 32.4%, while reducing the target population by 22%. Limitations: Universal screening was not used during the time data was collected. The prevalence of unhealthy drinking among those screened was 60% suggesting the AUDIT-C was administered to confirm rather than screen for unhealthy drinking. Conclusion: An automated tool, using commonly available data, can identify a subset of patients who appear to warrant clinical attention for unhealthy drinking

    Quantitative modeling and control of nascent sprout geometry in in vitro Angiogenesis

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 121-127).Nascent blood vessel growth in angiogenesis is a complex process involving cellular response to biochemical growth factors, degradation of the surrounding matrix, and coordinated migration of multiple endothelial cells up a growth factor gradient. Mechanistic understanding and quantitative modeling of the dominant dynamics involved in nascent vessel growth will enable new strategies for regulating vessel growth rate and geometry, and will have implications in controlling growth of complete vascular networks in many research areas, ranging from cancer treatment and wound healing to tissue engineering. In this thesis, we investigate the dynamics of nascent vessel growth in 3D microfluidic assays, formulate a quantitative process model based on our experimental characterization, and formulate a feedback approach to regulate growth. We begin by developing a new microfluidic assay consisting of a collagen gel scaffold with features to reduce assay-to-assay variability and increase experimental throughput. This high throughput assay reveals that there is an inverse relationship between nascent vessel elongation rate and diameter under diverse biochemical conditions. This finding is supported by immuno-fluorescent staining and biochemical inhibition studies, which give insight into the dominant mechanisms determining nascent vessel diameter. Based on our experimental characterization, we formulate a simple quantitative reaction-diffusion model that relates vessel diameter to elongation rate, and supports our understanding of the relevant dynamics. We conclude by formulating a model-based optimization approach for planning the optimal trajectory of elongation rate vs. time needed to obtain desired sprout geometry, and illustrate in simulation that model predictive feedback control can be used to correct for noise in the response of elongation rate to growth factor inputs.by Levi Benjamin Wood.Ph.D

    Motion artifact reduction for wearable photoplethysmogram sensors using micro accelerometers and laguerre series adaptive filters

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    Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (p. 73-74).The photoplethysmogram (PPG) is an extremely useful wearable sensing medical diagnostic tool. However, the PPG signal becomes highly corrupted when the wearer is in motion, rendering the measured signal useless. This thesis develops an adaptive motion artifact reduction scheme to recover the underlying physiologic information from the corrupted signal using a collocated accelerometer as a motion reference and adaptively estimating the motion-to-artifact system dynamics. It has previously been shown that this artifact reduction scheme can be utilized, but many tunable parameters were required to model the system dynamics and performance was poor. This work quantifies algorithm performance based on confidence in the estimated system dynamics, which shows low confidence using the previous parameterization when the wearer is jogging. To improve confidence, the form of the system dynamics is established and a Laguerre series is implimented to compactly represent the system dynamics using just a few parameters that can be confidently estimated. Using the new model, heart rate and amplitude can be estimated from typical jogger data with variance similar to separate PPG sensors located on contralateral motionless hands. The standard artifact reduction scheme does not work when the physiologic signal is correlated with wearer motion. Since the signals may become correlated, this work develops a method of recovering the physiological signal even when it is correlated with wearer motion by adapting blind source seperation techniques. However, the success of this new method is limited.by Levi Benjamin Wood.S.M

    Absolute frequency measurement of the 1S0 - 3P0 transition of 171Yb

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    We report the absolute frequency measurement of the unperturbed transition 1S0 - 3P0 at 578 nm in 171Yb realized in an optical lattice frequency standard. The absolute frequency is measured 518 295 836 590 863.55(28) Hz relative to a cryogenic caesium fountain with a fractional uncertainty of 5.4x10-16 . This value is in agreement with the ytterbium frequency recommended as a secondary representation of the second in the International System of Units.Comment: This is an author-created, un-copyedited version of an article accepted for publication/published in Metrologia. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at http://dx.doi.org/10.1088/1681-7575/aa4e62. It is published under a CC BY licenc

    A Study of the Hierarchical Culture Gaps Within Unionized Utilities Companies

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    The purpose of this study was to measure the culture gaps between hierarchical subgroups within unionized utilities companies. We conducted a mixed methods study. Using archival survey data, we compared hierarchically-defined subgroups’ perceptions of performance-linked culture traits within five unionized utilities companies. We later conducted interviews and focus groups, followed by qualitative coding and analysis. As compared to non-union employees, union employees viewed their companies as substantially less involving, consistent, adaptable, and clear about purpose and direction. Our qualitative analysis highlighted two prior management decisions as illustrative of the contrast between high and low levels of union involvement and clarity. Culture scholars and practitioners have suggested that leaders must align subcultures where they exist. Our study demonstrates large culture gaps between union employees and other subgroups and suggests that management’s involvement of the workforce in strategic decisions may have unique consequences for how subgroups perceive and interpret the culture

    Rupture of the profunda femoris artery in a patient with alcoholic liver disease: a case report

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    Introduction: Profunda femoris artery aneurysms are rare and often present with rupture. However, to the best of our knowledge, rupture of a non-aneurismal profunda femoris artery has never been reported before. Case presentation: We report the case of a 31-year-old Caucasian man with alcoholic liver disease who presented with rupture of the profunda femoris artery following blunt trauma which was treated by endovascular embolization. Conclusion: Coagulopathy secondary to alcoholic liver disease is a major contributory factor and a high index of suspicion of vascular injury must be attached to such patients following blunt trauma. Although there have no previous documented cases, treatment by endovascular embolization appears to be effective and safe

    The performance of farm tractors as reported by CAN-BUS measures

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    Tractors and agricultural machinery have been designed specifically for land preparation, tillage, and other agricultural operation’s tasks. Tractors are the primary source of power in farms and fields. Thus, to obtain the optimum output from them, proper management and utilization is needed. Agricultural machinery performance has been studied over the past three decades and optimum results have been obtained for different kinds of agricultural machinery. In general, the evaluation of agricultural machinery using traditional methods is problematic as they are time consuming and labor intensive. Moreover, by using the common evaluation methods it is typically difficult to obtain accurate and instant results. Accurate measurements of field performance parameters are required for monitoring machinery performance and management decisions. Recently, the improvement in the electronics technology has made field operational management easier to monitor. Controller Area Network (CAN) Bus technology is being used as a communication system in tractors and allows connections between Electrical Control Units (ECU). CAN Bus technology broadcast unique electronic messages which contain continuously updated information about the engine, power train, equipment, power take off, hydraulic system, and other parts of the machines. To evaluate the performance of agricultural machinery, there is no longer a need for myriad measurement instruments producing widely varying output to individually measuring fuel consumption for each speed, gear shift and the whole operation. As a result, this study was conducted to evaluate tractor performance by CAN Bus technology as a simple to use, easy to install, high speed data collection, and convenient to retrieve the stored data. These techniques allow for substantial saving of money and time, reducing our workload and eliminating training necessary for specialized measurement tools
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