Condensation of preformed charge density waves in kagome metals

Charge density wave (CDW) is a spontaneous spatial modulation of electric charges in solids whose general microscopic descriptions are yet to be completed. Layered kagome metals of $A$V$_3$Sb$_5$ ($A$ = K, Rb, Cs) provide a unique chance to realize its emergence intertwined with dimensional effects as well as their special lattice. Here, based on a state-of-the-art molecular dynamics simulation, we uncover that the phase transition to charge ordered states in kagome metals is a condensation process of incoherently preformed CDWs. We demonstrate that charge modulation first preforms on each kagome layer at a well defined temperature but its phase fluctuation proliferates across the entire layers with a $10^5$ times slower frequency than typical phonon vibrations until reaching its freezing temperature. We find that the fluctuation is not random but confined to a limited number of states as a consequence of unavoidable degeneracy in stacking layered charge orders. As the size of interfacial alkali atom increases, the fluctuating phases are shown to counterbalance the condensation of orderings, resulting in a maximized transition temperature for RbV$_3$Sb$_5$. Our results resolve several controversial observations on their CDW formations and highlight a crucial role of interlayer interactions for the charge ordering in kagome metals

A Study of Safety Culture Assessment Framework for Process Industries and Its Application to a Bayesian Belief Network Analysis

Investigations of major catastrophes in process industries have revealed that deficiency of good safety culture is one of the underlying causes of such disasters. Not only has safety culture been recognized as a root cause, but also it is increasingly accepted as an influential factor in a risk analysis and considered as a legal requirement. Most of current quantitative risk analyses (QRA) rely on technical factors but more and more effort is being made for the incorporation of human and organizational factors (HOFs). Especially, safety culture largely represents an organizational attitude towards safety. Thus, how to measure safety culture in more effective manners and how to utilize such assessment data in a QRA are chosen as major objectives of this research. For the measurement of safety culture, this study suggests an approach that assesses values and assumptions by looking through artifacts, e.g., management level and employee’s behavior. Such approach employs following two methods: a matrix structure composed of safety culture dimensions, and grading schemes that provide different levels of safety practices. Using such an approach and suggested methods, a safety culture assessment questionnaire is developed as a results. For the incorporation of such safety culture data into a risk analysis, this study employs a risk model based on Hybrid Causal Logic (HCL) and a Bayesian Belief Network (BBN) to represent cause and effect relationships among variables. Mock-up safety culture data is generated for this analysis. Findings from investigation of Universal Form Clamp incident (2006) are used to establish a case scenario upon which a fault tree and an event tree are constructed. To make a transition from qualitative knowledge about safety culture to quantitative probability data, some of the safety culture dimensions are selected as Risk Influencing Factors (RIFs), while Safety Culture Influencing Factors (SCIFs) are developed and introduced in this work. Using the established BBN, prior generic probability data are updated with newly obtained evidences such as mock-up safety culture assessment data. In addition, several analyses, e.g., predictive and diagnostic reasoning are conducted to determine how a change in safety culture affects the probabilities of safety-related events and also to identify which safety culture aspects need improvement

Conceptualizing Multiagency Emergency Management System as Joint Cognitive System

PresentationEmergency management system (EMS) provides a crucial barrier for the protection of socio-ecological infrastructure from man-made disasters and natural threats. To meet diverse demands from hazardous events, resilience engineering is considered as an effective approach to enhance the performance of EMS. While conceptual and qualitative descriptions of resilience are abundant, ideas of operationalizing resilience are scarce. In this regard, the present work redefines resilience in the EMS and proposes a framework of measuring resilience by abstracting the EMS as a joint cognitive system

Analyzing Procedure Performance using Abstraction Hierarchy: Implications of Designing Procedures for High-risk Process Operations

PresentationStandard operating procedures (SOPs) are a vital element of everyday operations in chemical process industries. Incident investigations also indicate that a majority of adverse events in the processing operations are ascribed to issues associated with SOPs. Although there have been continuous efforts to improve informational and perceptual aspects of SOPs, assessing them from a systems perspective remains a persistent gap. As one novel way to address such gap, this study employs an ecological approach to understand the functional structure of the work domain, that is, abstraction hierarchy (AH) and its relations to SOPs and operator performance. First, this study models a 3-phase separation system, a common gas-oil-water separation process, using an abstraction-decomposition space as a work domain of the system. Second, we assess the AH level, one dimension of the abstraction-decomposition space, of the SOPs developed for three tasks in the 3-phase separation system. In order to consider operators’ knowledge about the tasks, experience-task familiarity (E-TF) level is also assessed as a combinatory factor. To this end, a two-way analysis of variance is conducted to find out the effect of E-TF level (high vs. low) and AH level of the SOPs (physical vs. functional) on the operator’s performance. Results show significant main effects of the E-TF level and AH level on the successful performance of the SOPs. The interaction effect of the two variables is considered marginally significant. Based on the results, several implications for the design of SOPs in relation to the AH of the chemical processing domain are discussed

Team Cognition for Coordinated Decision-Making during Hurricane Harvey: A Case Study from Interviews with Responding Commanders

PresentationTo protect and assist threatened populations and infrastructures in response to natural and man- made disasters, emergency responders from diverse backgrounds collectively work as ad hoc teams. However, responders’ coordinated decision-making in real-time has not been adequately addressed in terms of team cognition. Here team cognition is a binding mechanism that produces coordinated behaviors among responders (adapted from Fiore & Salas, 2004). We are particularly interested in cognition of an incident management team (IMT), an ad hoc strategic decision-making team of command-level responders co-located at the incident command post of major incidents such as Hurricane Harvey. To develop and provide an incident action plan to subordinate branch directors in the field, an IMT continuously manages information based on incoming cues from outside, following a cyclical planning process. Interestingly, an IMT is a team of functional sub-teams, and each sub-team is also a team of functional units. The purpose of this on-going case study is to investigate the role of team cognition for coordinated real-time decision-making in emergency response, through a case study of a recent disaster, Hurricane Harvey. During the interviews with subject matter experts (SMEs, i.e., responding commanders worked during Hurricane Harvey), we asked how responding commanders as a cognitive system-of-systems (or a team-of-teams) continuously made coordinated decisions, especially in terms of communication and information management. In a prior work, a P∙D∙A (Perceive∙Diagnose∙Adapt) model, a theoretical interactionist model of team cognition in emergency response, was proposed as a proof-of-concept that depicts nonlinear, interdependent, and dynamic interactions observed within and among three functional sub-teams of a planning team of an IMT at a simulated incident command post (Moon, Son, Sasangohar, Peres, & Neville, 2018). Through interviews with SMEs, this case study is expected to validate the P∙D∙A model

A Multifaceted Approach to Understanding Resilience of Incident Management Teams

At the onset of the disasters, incident management teams (IMTs) are established to direct and support on-scene tactical activities in the field. IMTs cope with challenges of disasters such as constantly changing situations, limited resources, and inaccurate information. Therefore, resilience, an ability to adjust performance to such challenges, has emerged as an essential attribute of IMTs. As a narrated collection of journal articles, this dissertation aims to answer two general research questions: ‘What are characteristics of resilience of IMTs?’ and ‘How can we analyze the characteristics of resilience of IMTs?’ To answer these questions, this dissertation consists of six journal articles (five peer-reviewed publications [Articles #1 - #5] and one journal manuscript in preparation [Article #6]). Articles #1, #2, and #3 address the first research question regarding the characteristics of resilience of IMTs and Articles #4, #5, and #6 address the second research question regarding the analysis of resilience of IMTs. Specifically, the analysis of resilience of IMTs is conducted through two essential lenses of organizational resilience: work-as-done (WAD) and work-as-imagined (WAI). With respect to the traits of IMT resilience, Article #1 documents an integrative review of 55 articles and presents findings about definitions, characteristics of IMT resilience, and common tools used to support resilience of IMTs. Regarding resilience of real-world IMTs, Articles #2 and #3 provide characteristics of resilience of government and hospital IMTs that responded to Hurricane Harvey in 2017 based on semi-structured interviews. With respect to the analysis of the characteristics of IMT resilience, Article #4 develops a cognitive system model of an IMT and develops a novel Interaction Episode Analysis (IEA) method that incorporates interactions between three cognitive system elements (i.e., humans, technical tools, and tasks) in IMTs to enable granular analyses of WAI and WAD. Next, by applying the IEA to data collected from naturalistic observations of two high-fidelity IMT exercises at Emergency Operations Training Center (EOTC), Article #5 presents six WAD episodes regarding the IMT’s information management tasks and reveals qualitative and quantitative differences between the WAD episodes and between the two IMTs. Article #6 elicits WAI episodes corresponding to the WAD episodes and investigates the reasons behind the differences between the two IMTs. Based on semi-structured interviews with seven IMT training course designers and instructors, the WAI episodes were generated. Quantitative analyses revealed of notable differences between the two IMTs and subsequent qualitative analyses have revealed possible reasons why the differences between the two IMTs have taken place. Such reasons include the non-occurrence of critical interactions that were anticipated to occur in the WAI episodes and the occurrence of unexpected interactions in the WAD episodes. Findings regarding the characteristics of IMT resilience and the IEA method to identify gaps between WAI and WAD in IMTs presented in this dissertation serve as a basis for future research to better examine and enhance IMT’s resilient actions in future disasters

Use of a Mobile Biofeedback App to Provide Health Coaching for Stress Self-management: Pilot Quasi-Experiment

BackgroundMental health is an increasing concern among vulnerable populations, including college students and veterans. ObjectiveThe purpose of this study was to determine if mobile health technology combined with health coaching can better enable a user to self-manage their mental health. MethodsThis study evaluated the mobile app “Biofeedback” that provided health coaching on stress self-management for college student veterans’ mental health concerns. Twenty-four college student veterans were recruited from a large public university in Texas during the spring 2020 semester, impacted by COVID-19. Ten participants were assigned to the intervention group where they used the mobile Biofeedback app on their smartphones and smartwatches, and 14 were assigned to the control group without the app; assignment was based on mobile phone compatibility. Both groups participated in one initial lab session where they learned a deep-breathing exercise technique. The intervention group was then asked to use the mobile Biofeedback app during their daily lives and a smartwatch, and the control group was asked to perform the breathing exercises on their own. Both groups filled out Patient Health Questionnaire (PHQ-9) and Generalized Anxiety Disorder (GAD-7) self-assessments at 2-week intervals. At the end of the semester, both groups were given an exit interview to provide user experience and perceived benefits of health coaching via the mobile biofeedback app. ResultsThe deep-breathing exercise in the initial lab session reduced stress in both groups. Over the course of the study, the app recorded 565 coached breathing exercises with a significant decrease (approximately 3 beats per minute) in participants’ heart rate during the 6-minute time period immediately after conducting the breathing exercises (Spearman rank correlation coefficient –0.61, P<.001; S=9,816,176). There was no significant difference between the two groups for PHQ-9 and GAD-7 scores over the course of the semester. Exit interview responses indicated that participants perceived that the mobile Biofeedback app improved their health and helped them address stress challenges. All participants reported that the intervention helped them manage their stress better and expressed that health coaching via a mobile device would improve their overall health. ConclusionsParticipants reported a positive perception of the app for their mental health self-management during a stressful semester. Future work should examine long-term effects of the app with a larger sample size balanced between male and female participants, randomized participant allocation, real-time detection of mental health symptoms, and additional features of the app

Border tissue morphology is associated with the pattern of visual field progression in open-angle glaucoma

Abstract The etiology of open-angle glaucoma (OAG) is yet unclear. This study investigated possible risk factors, such as the morphology of the border tissue that affect the pattern of visual field (VF) progression in eyes with OAG. 166 eyes of 166 OAG patients with an externally oblique border tissue (EOBT) at least in one direction were included. EOBT was obtained by analyzing enhanced depth imaging spectral-domain optical coherence tomography images. A pointwise linear regression was used to determine VF progression by measuring the deterioration rate of each point in the VF. The odds ratio of VF progression for each risk factor was estimated using logistic regression analysis. Seventy (42.2%) eyes showed VF deterioration. In multivariate analysis, longer follow-up period, higher baseline intraocular pressure (IOP), lower mean ocular perfusion pressure (MOPP), and smaller angular location of the longest EOBT were associated with VF progression (all p values were below 0.05). In the multivariate analysis, the location of the longest EOBT was significantly associated with inferior (p = 0.002) and central (p = 0.017) VF progression. In conclusion, VF progression pattern in OAG eyes is associated with the location of the longest EOBT as well as other known risk factors