Time Pressure and System Delays in Information Search

We report preliminary results of the impact of time pres- sure and system delays on search behavior from a laboratory study with forty-three participants. To induce time pres- sure, we randomly assigned half of our study participants to a treatment condition where they were only allowed five minutes to search for each of four ad-hoc search topics. The other half of the participants were given no task time limits. For half of participants’ search tasks (n=2), five second de- lays were introduced after queries were submitted and SERP results were clicked. Results showed that participants in the time pressure condition queried at a significantly higher rate, viewed significantly fewer documents per query, had significantly shallower hover and view depths, and spent sig- nificantly less time examining documents and SERPs. We found few significant differences in search behavior for sys- tem delay or interaction effects between time pressure and system delay. These initial results show time pressure has a significant impact on search behavior and suggest the de- sign of search interfaces and features that support people who are searching under time pressure

Long-term monitoring of geodynamic surface deformation using SAR interferometry

Thesis (Ph.D.) University of Alaska Fairbanks, 2014Synthetic Aperture Radar Interferometry (InSAR) is a powerful tool to measure surface deformation and is well suited for surveying active volcanoes using historical and existing satellites. However, the value and applicability of InSAR for geodynamic monitoring problems is limited by the influence of temporal decorrelation and electromagnetic path delay variations in the atmosphere, both of which reduce the sensitivity and accuracy of the technique. The aim of this PhD thesis research is: how to optimize the quantity and quality of deformation signals extracted from InSAR stacks that contain only a low number of images in order to facilitate volcano monitoring and the study of their geophysical signatures. In particular, the focus is on methods of mitigating atmospheric artifacts in interferograms by combining time-series InSAR techniques and external atmospheric delay maps derived by Numerical Weather Prediction (NWP) models. In the first chapter of the thesis, the potential of the NWP Weather Research & Forecasting (WRF) model for InSAR data correction has been studied extensively. Forecasted atmospheric delays derived from operational High Resolution Rapid Refresh for the Alaska region (HRRRAK) products have been compared to radiosonding measurements in the first chapter. The result suggests that the HRRR-AK operational products are a good data source for correcting atmospheric delays in spaceborne geodetic radar observations, if the geophysical signal to be observed is larger than 20 mm. In the second chapter, an advanced method for integrating NWP products into the time series InSAR workflow is developed. The efficiency of the algorithm is tested via simulated data experiments, which demonstrate the method outperforms other more conventional methods. In Chapter 3, a geophysical case study is performed by applying the developed algorithm to the active volcanoes of Unimak Island Alaska (Westdahl, Fisher and Shishaldin) for long term volcano deformation monitoring. The volcano source location at Westdahl is determined to be approx. 7 km below sea level and approx. 3.5 km north of the Westdahl peak. This study demonstrates that Fisher caldera has had continuous subsidence over more than 10 years and there is no evident deformation signal around Shishaldin peak.Chapter 1. Performance of the High Resolution Atmospheric Model HRRR-AK for Correcting Geodetic Observations from Spaceborne Radars -- Chapter 2. Robust atmospheric filtering of InSAR data based on numerical weather prediction models -- Chapter 3. Subtle motion long term monitoring of Unimak Island from 2003 to 2010 by advanced time series SAR interferometry -- Chapter 4. Conclusion and future work

The Impact of Inter-Hospital Transfer on Clinical Outcomes following Endovascular Treatment for Acute Ischemic Stroke

PURPOSE Hospitals designated as primary stroke centers offer noninvasive treatment for acute ischemic stroke, but only comprehensive stroke centers are equipped to provide endovascular treatment. When stroke patients needing endovascular treatment present to the emergency department at a primary stroke center, they then require inter-hospital transfer to a comprehensive center for definitive treatment. Recent studies have found significant treatment delays and poor clinical outcomes in patients requiring inter-hospital transfer1,2. The primary aim of this study is to determine if inter-hospital transfer impacts clinical outcomes after endovascular treatment for acute ischemic stroke. A secondary aim is to determine whether inter-hospital transfer coincides with any significant treatment delay. METHODS This study involves retrospective chart review for 107 patients undergoing endovascular treatment for acute ischemic stroke at one of three hospitals in Austin, Texas from October 2016 to September 2018. 26 patients required inter-hospital transfer, while 81 (the control group) presented directly to a hospital offering endovascular treatment. Two-tailed T- and U-tests were used for analysis of parametric and non-parametric variables pertaining to time intervals and baseline characteristics. Odds ratios were calculated to compare dichotomized outcomes between groups, with significance determined by chi-square. RESULTS Inter-hospital transfer significantly prolonged onset to groin (mean difference = 37.2 min, p=.02). The transfer group was more likely to experience intracranial hemorrhage (53.9% > 22.2%, p<.01). Clinical outcomes did not significantly differ between groups. CONCLUSIONS Although observed trends in these data suggest poor outcomes for transfer patients, small sample size limits the significance of these findings. However, the significant treatment delay seen in the transfer group warrants a discussion on city protocol changes regarding patient transport via emergency services. Protocol changes favoring direct delivery of patients to comprehensive stroke centers may reduce treatment delay and yield improved clinical outcomes.Dell Medical Schoo

Model and Integrate Medical Resource Available Times and Relationships in Verifiably Correct Executable Medical Best Practice Guideline Models (Extended Version)

Improving patient care safety is an ultimate objective for medical cyber-physical systems. A recent study shows that the patients' death rate is significantly reduced by computerizing medical best practice guidelines. Recent data also show that some morbidity and mortality in emergency care are directly caused by delayed or interrupted treatment due to lack of medical resources. However, medical guidelines usually do not provide guidance on medical resource demands and how to manage potential unexpected delays in resource availability. If medical resources are temporarily unavailable, safety properties in existing executable medical guideline models may fail which may cause increased risk to patients under care. The paper presents a separately model and jointly verify (SMJV) architecture to separately model medical resource available times and relationships and jointly verify safety properties of existing medical best practice guideline models with resource models being integrated in. The SMJV architecture allows medical staff to effectively manage medical resource demands and unexpected resource availability delays during emergency care. The separated modeling approach also allows different domain professionals to make independent model modifications, facilitates the management of frequent resource availability changes, and enables resource statechart reuse in multiple medical guideline models. A simplified stroke scenario is used as a case study to investigate the effectiveness and validity of the SMJV architecture. The case study indicates that the SMJV architecture is able to identify unsafe properties caused by unexpected resource delays.Comment: full version, 12 page

A delay recruitment model of the cardiovascular control system.

Copyright will be owned by Springer. We develop a nonlinear delay-differential equation for the human cardiovascular control system, and use it to explore blood pressure and heart rate variability under short-term baroreflex control. The model incorporates an intrinsically stable heart rate in the absence of nervous control, and features baroreflex influence on both heart rate and peripheral resistance. Analytical simplifications of the model allow a general investigation of the rôles played by gain and delay, and the effects of ageing.