Bridging Scales in 2- and 3-Dimensional Atmospheric Modeling with Adaptive Mesh Refinement

Complex multi-scale atmospheric phenomena, like tropical cyclones, challenge conventional weather and climate models, which use relatively coarse uniform-grid resolutions to cope with computational costs. Adaptive Mesh Refinement (AMR) techniques mitigate these challenges by dynamically and transiently placing high-resolution grids over salient features, thus providing sufficient local resolution while limiting the computational burden. This thesis explores the development of AMR, a technique that has been featured only sporadically in the atmospheric science literature, within a new nonhydrostatic, finite-volume dynamical core and demonstrates AMR's effectiveness in improving model accuracy and ability to resolve multi-scale features. This high-order finite-volume model implements adaptive refinement in both space and time on a cubed-sphere grid using a mapped-multiblock mesh technique developed with the Chombo AMR library. The AMR dynamical core is implemented in a hierarchy of models of increasing complexity, from an idealized 2D shallow water configuration to the nonhydrostatic 3D equation set with subgrid-scale parameterizations schemes. AMR's numerical accuracy, computational efficiency, and ability to track and resolve multifaceted and evolving features are assessed with a variety of existing and new test cases, implemented within each model iteration. Both static and dynamic refinements are analyzed to determine the strengths and weaknesses of AMR in both complex flows with small-scale features and large-scale smooth flows. The different test cases required different AMR criteria, such as vorticity, or minimum pressure based thresholds, in order to achieve the best accuracy for cost. Simulations show that the model's AMR can accurately resolve key local features in both shallow water and 3D test cases without requiring global high-resolution grids, as the adaptive grids are able to track features of interest reliably without inducing noise or visible distortions at the coarse-fine interfaces. Furthermore, the AMR grids keep degradation of the large-scale smooth flows to a minimum. 2D and 3D physics parameterizations are able to function effectively over multiple levels of refinement, though the parameterizations are sensitive to grid resolution. AMR is most effective when refinement is triggered early or when the base uniform resolution can partially resolve the features of interests. Very coarse base resolutions lead to large initial errors that cannot be overcome by AMR. However, the addition of refinement later in the simulation still results in significant improvements, especially in resolving small-scale features. The research showed that flow properties, such as strong gradients or rainbands, can be sensitive to small changes in AMR criteria. These may delay the onset of the refinement or alter the shape of the refined area, which impacts the evolution of the flow. With coarse base resolutions, the tagging criteria must therefore be uniquely tailored to capture the early growth phases of the feature of interest. A promising refinement technique is a combination of some initial refinement and AMR. The initial refinement limits error growth at the base resolution and ensures that the model can resolve the feature of interest. Overall, AMR is shown to be a powerful modeling approach that bridges the resolution gap for extreme weather events.PHDApplied PhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/147504/1/joferg_1.pd

The Unseen Life of Tom Hill

The office that Dr. Thomas Hill works in is large, complete with a wood paneled desk, wall-to-wall bookshelf and conference table. Iowa State University’s vice president of student affairs uses all this space, bouncing back and forth from desk to conference table—whichever is the least covered in stacks of paper at the time. His day is filled with meetings and phone calls, whether it’s a meeting to advise a group of graduate students working on a project or taking a call from an old Olympic teammate who’s looking to get one of his athletes a scholarship

NDM-523: USE OF AN UNMANNED AERIAL VEHICLE (UAV) TO ASSESS TRANSPORTATION INFRASTRUCTURE, IMMEDIATELY AFTER A CATASTROPHIC STORM EVENT

From September 29 to October 1, 2015 over 200 mm of rain deluged parts of southern New Brunswick. The catastrophic rain event washed away bridge size culverts and conventional bridges, including the surrounding soil and asphaltic concrete pavement. Also erosion encroached on the driving lane of road and highway embankments at over 100 locations. Several homes and businesses were left stranded. A fast and efficient means was required to assess the impact on infrastructure after the storm. This paper presents the procedure and outcomes of using digital imagery captured with Unmanned Aerial Vehicles (UAVs) for post-disaster assessment. The use of a UAV to gather site images, at hard to access locations, allowed for the timely prioritization of needs and allocation of limited resources to areas most urgently in demand of emergency repairs. High quality aerial images were processed using commercial software specifically designed for the creation of 3D models and orthomosaics from aerial photos. This information, along with ground-level panoramas communicated the current condition of assets and roads. It provided engineers with the ability to complete initial assessment, create 3D models for design, and provide highly qualitative evaluation records. The successful use of a UAV for this storm event was preceded by other uses of UAVs for asset management within the New Brunswick Department of Transportation and Infrastructure

Uncertainty as a Key Influence in the Decision To Admit Patients with Transient Ischemic Attack

Background Patients with transient ischemic attacks (TIA) are at high risk of subsequent vascular events. Hospitalization improves quality of care, yet admission rates for TIA patients vary considerably. Objectives We sought to identify factors associated with the decision to admit patents with TIA. Design We conducted a secondary analysis of a prior study’s data including semi-structured interviews, administrative data, and chart review. Participants We interviewed multidisciplinary clinical staff involved with TIA care. Administrative data included information for TIA patients in emergency departments or inpatient settings at VA medical centers (VAMCs) for fiscal years (FY) 2011 and 2014. Chart reviews were conducted on a subset of patients from 12 VAMCs in FY 2011. Approach For the qualitative data, we focused on interviewees’ responses to the prompt: “Tell me what influences you in the decision to or not to admit TIA patients.” We used administrative data to identify admission rates and chart review data to identify ABCD2 scores (a tool to classify stroke risk after TIA). Key Results Providers’ decisions to admit TIA patients were related to uncertainty in several domains: lack of a facility TIA-specific policy, inconsistent use of ABCD2 score, and concerns about facilities’ ability to complete a timely workup. There was a disconnect between staff perceptions about TIA admission and facility admission rates. According to chart review data, staff at facilities with higher admission rates in FY 2011 reported consistent reliance on ABCD2 scores and related guidelines in admission decision-making. Conclusions Many factors contributed to decisions regarding admitting a patient with TIA; however, clinicians’ uncertainty appeared to be a key driver. Further quality improvement interventions for TIA care should focus on facility adoption of TIA protocols to address uncertainty in TIA admission decision-making and to standardize timely evaluation of TIA patients and delivery of secondary prevention strategies

Circumstances and consequences of falls among people with chronic stroke

Falls are common after stroke; however, circumstances and consequences are relatively unknown. Our objectives were to identify the differences between fallers and non-fallers among people with chronic stroke, identify the circumstances of fall events, and examine the consequences of the falls. This is a secondary data analysis; all participants included sustained a stroke. Variables included demographics, stroke characteristics, and comorbidities. Falls were collected via self-report, and circumstances and consequences were derived from participant description of the event and categorized as appropriate. Among 160 participants, 53 (33%) reported a fall during the 1 yr period. Circumstances of falls were categorized as intrinsic or extrinsic. Location and circumstance of the fall were included: 70% occurred at home and 40% were associated with impaired physical or mental state (e.g., inattention to tying shoes). Additionally, 21% of falls were associated with activities of daily living and mobility and 34% with slips or trips. The majority who fell sustained an injury (72%). Injuries ranged from bruising to fractures, and 55% of those with an injury sought medical care (32% to emergency department). Poststroke falls are associated with an alarming rate of injury and healthcare utilization. Targeting mental and physical states may be key to fall prevention

Barriers and facilitators to provide quality TIA care in the Veterans Healthcare Administration

Objective: To identify key barriers and facilitators to the delivery of guideline-based care of patients with TIA in the national Veterans Health Administration (VHA). Methods: We conducted a cross-sectional, observational study of 70 audiotaped interviews of multidisciplinary clinical staff involved in TIA care at 14 VHA hospitals. We de-identified and analyzed all transcribed interviews. We identified emergent themes and patterns of barriers to providing TIA care and of facilitators applied to overcome these barriers. Results: Identified barriers to providing timely acute and follow-up TIA care included difficulties accessing brain imaging, a constantly rotating pool of housestaff, lack of care coordination, resource constraints, and inadequate staff education. Key informants revealed that both stroke nurse coordinators and system-level factors facilitated the provision of TIA care. Few facilities had specific TIA protocols. However, stroke nurse coordinators often expanded upon their role to include TIA. They facilitated TIA care by (1) coordinating patient care across services, communicating across service lines, and educating clinical staff about facility policies and evidence-based practices; (2) tracking individual patients from emergency departments to inpatient settings and to discharge for timely follow-up care; (3) providing and referring TIA patients to risk factor management programs; and (4) performing regular audit and feedback of quality performance data. System-level facilitators included clinical service leadership engagement and use of electronic tools for continuous care across services. Conclusions: The local organization within a health care facility may be targeted to cultivate internal facilitators and a systemic infrastructure to provide evidence-based TIA care