The concept of system resilience is important and popular—in fact, hyper-popular over the last few years. Clarifying the technical meanings and foundations of the concept of resilience would appear ...to be necessary. Proposals for defining resilience are flourishing as well. This paper organizes the different technical approaches to the question of what is resilience and how to engineer it in complex adaptive systems. This paper groups the different uses of the label ‘resilience’ around four basic concepts: (1) resilience as rebound from trauma and return to equilibrium; (2) resilience as a synonym for robustness; (3) resilience as the opposite of brittleness, i.e., as graceful extensibility when surprise challenges boundaries; (4) resilience as network architectures that can sustain the ability to adapt to future surprises as conditions evolve.
•There continues to be a wide diversity of definitions of the label resilience.•Research progress points to 4 basic concepts underneath diverse uses of.•Each of the four core concepts defines different research agendas.•The 4 concepts provide guides on how to engineer resilience for safety.
Resilience engineering depends on four abilities: the ability a) to respond to what happens, b) to monitor critical developments, c) to anticipate future threats and opportunities, and d) to learn ...from past experience - successes as well as failures. They provide a structured way of analysing problems and proposing practical solutions. This book is divided into four sections which describe issues relating to each of the four abilities. The section's chapters emphasise practical ways of engineering resilience, featuring case studies and real applications.
•Safety management approaches can be categorised as either a mode of centralised control or a mode of guided adaptability.•Safety professionals and their organisations are focussed on a safety ...management mode of centralised control and this can be detrimental to safety.•Resilience engineering, safety II and safety differently offer an alternative approach to safety management that resolve the shortcomings in traditional approaches to managing safety in complex systems.•This paper provides the first practical description of the purpose, tasks and activities of a safety professional through the theoretical lens of resilience engineering and safety II.
The safety management literature describes two distinct modes through which safety is achieved. These can be described as safety management through centralized control, or safety management through guided adaptability. Safety management through centralized control, labelled by Hollnagel as ‘Safety-I’, aims to align and control the organization and its people through the central determination of what is safe. Safety management through guided adaptability, or ‘Safety-II’, aims to enable the organization and its people to safely adapt to emergent situations and conditions. Safety-II has been presented as a paradigm shift in safety theory, but it has created practical difficulties for safety professional practice. In this paper, we define the two modes of safety management and explain the challenges in changing the role of a safety professional to support Safety-II. When should safety professionals re-enforce alignment, and when should they support frontline adaptations? We outline specific activities for safety professionals to adopt in their role to move towards a guided adaptability mode of safety management. This will move the safety professional further towards their fundamental responsibility – ‘to create foresight about the changing shape of risk, and facilitate action, before people are harmed.’
The paper introduces the theory of graceful extensibility which expresses fundamental characteristics of the adaptive universe that constrain the search for sustained adaptability. The theory ...explains the contrast between successful and unsuccessful cases of sustained adaptability for systems that serve human purposes. Sustained adaptability refers to the ability to continue to adapt to changing environments, stakeholders, demands, contexts, and constraints (in effect, to adapt how the system in question adapts). The key new concept at the heart of the theory is graceful extensibility. Graceful extensibility is the opposite of brittleness, where brittleness is a sudden collapse or failure when events push the system up to and beyond its boundaries for handling changing disturbances and variations. As the opposite of brittleness, graceful extensibility is the ability of a system to extend its capacity to adapt when surprise events challenge its boundaries. The theory is presented in the form of a set of 10 proto-theorems derived from just two assumptions—in the adaptive universe, resources are always finite and change continues. The theory contains three subsets of fundamentals: managing the risk of saturation, networks of adaptive units, and outmaneuvering constraints. The theory attempts to provide a formal base and common language that characterizes how complex systems sustain and fail to sustain adaptability as demands change.
The prediction of crystal structures from first-principles requires highly accurate energies for large numbers of putative crystal structures. High accuracy of solid state density functional theory ...(DFT) calculations is often required, but hundreds or more structures can be present in the low energy region of interest, so that the associated computational costs are prohibitive. Here, we apply statistical machine learning to predict expensive hybrid functional DFT (PBE0) calculations using a multifidelity approach to re-evaluate the energies of crystal structures predicted with an inexpensive force field. The method uses an autoregressive Gaussian process, making use of less expensive GGA DFT (PBE) calculations to bridge the gap between the force field and PBE0 energies. The method is benchmarked on the crystal structure landscapes of three small, hydrogen-bonded organic molecules and shown to produce accurate predictions of energies and crystal structure ranking using small numbers of the most expensive calculations; the PBE0 energies can be predicted with errors of less than 1 kJ mol–1 with between 4.2 and 6.8% of the cost of the full calculations. As the model that we have developed is probabilistic, we discuss how the uncertainties in predicted energies impact the assessment of the energetic ranking of crystal structures.
From track and field to swimming and diving, and of course
basketball and soccer, Indiana University Olympians
celebrates over a century of Indiana University Olympic
competitors. Beginning in 1904, ...at the 3rd summer games in St.
Louis, IU's first Olympic medal went to pole vaulter LeRoy Samse
who earned a silver medal. In 2016, swimmer Lilly King rocketed
onto the world stage with two gold medals in the 31st Summer Games
in Rio de Janeiro.
Featuring profiles of 49 athletes who attended IU, Indiana
University Olympians includes the stories of well-known
figures like Milt Campbell, the first African American to win
decathlon gold and who went on to play pro football, and Mark
Spitz, winner of seven swimming gold medals. The book also
highlights fascinating anecdotes and the accomplishments of their
less well-known colleagues, including one athlete's humble
beginnings in a chicken house and another who earned a Silver Star
for heroism in the Vietnam War. Despite their different lives, they
share one key similarity-these remarkable athletes all called
Indiana University home.
Simple reaction time (SRT), the minimal time needed to respond to a stimulus, is a basic measure of processing speed. SRTs were first measured by Francis Galton in the 19th century, who reported ...visual SRT latencies below 190 ms in young subjects. However, recent large-scale studies have reported substantially increased SRT latencies that differ markedly in different laboratories, in part due to timing delays introduced by the computer hardware and software used for SRT measurement. We developed a calibrated and temporally precise SRT test to analyze the factors that influence SRT latencies in a paradigm where visual stimuli were presented to the left or right hemifield at varying stimulus onset asynchronies (SOAs). Experiment 1 examined a community sample of 1469 subjects ranging in age from 18 to 65. Mean SRT latencies were short (231, 213 ms when corrected for hardware delays) and increased significantly with age (0.55 ms/year), but were unaffected by sex or education. As in previous studies, SRTs were prolonged at shorter SOAs and were slightly faster for stimuli presented in the visual field contralateral to the responding hand. Stimulus detection time (SDT) was estimated by subtracting movement initiation time, measured in a speeded finger tapping test, from SRTs. SDT latencies averaged 131 ms and were unaffected by age. Experiment 2 tested 189 subjects ranging in age from 18 to 82 years in a different laboratory using a larger range of SOAs. Both SRTs and SDTs were slightly prolonged (by 7 ms). SRT latencies increased with age while SDT latencies remained stable. Precise computer-based measurements of SRT latencies show that processing speed is as fast in contemporary populations as in the Victorian era, and that age-related increases in SRT latencies are due primarily to slowed motor output.
Whilst the link between physical factors and risk of high altitude (HA)-related illness and acute mountain sickness (AMS) have been extensively explored, the influence of psychological factors has ...been less well examined. In this study we aimed to investigate the relationship between 'anxiety and AMS risk during a progressive ascent to very HA.
Eighty health adults were assessed at baseline (848m) and over 9 consecutive altitudes during a progressive trek to 5140m. HA-related symptoms (Lake Louise LLS and AMS-C Scores) and state anxiety (State-Trait-Anxiety-Score STAI Y-1) were examined at each altitude with trait anxiety (STAI Y-2) at baseline.
The average age was 32.1 ± 8.3 years (67.5% men). STAI Y-1 scores fell from 848m to 3619m, before increasing to above baseline scores (848m) at ≥4072m (p = 0.01). STAI Y-1 scores correlated with LLS (r = 0.31; 0.24-0.3; P<0.0001) and AMS-C Scores (r = 0.29; 0.22-0.35; P<0.0001). There was significant main effect for sex (higher STAI Y-1 scores in women) and altitude with no sex-x-altitude interaction on STAI Y-1 Scores. Independent predictors of significant state anxiety included female sex, lower age, higher heart rate and increasing LLS and AMS-C scores (p<0.0001). A total of 38/80 subjects (47.5%) developed AMS which was mild in 20 (25%) and severe in 18 (22.5%). Baseline STAI Y-2 scores were an independent predictor of future severe AMS (B = 1.13; 1.009-1.28; p = 0.04; r2 = 0.23) and STAI Y-1 scores at HA independently predicted AMS and its severity.
Trait anxiety at low altitude was an independent predictor of future severe AMS development at HA. State anxiety at HA was independently associated with AMS and its severity.
The trail making test (TMT) is widely used to assess speed of processing and executive function. However, normative data sets gathered at different sites show significant inconsistencies. Here, we ...describe a computerized version of the TMT (C-TMT) that increases the precision and replicability of the TMT by permitting a segment-by-segment analysis of performance and separate analyses of dwell-time, move-time, and error time. Experiment 1 examined 165 subjects of various ages and found that completion times on both the C-TMT-A (where subjects connect successively numbered circles) and the C-TMT-B (where subjects connect circles containing alternating letters and numbers) were strongly influenced by age. Experiment 2 examined 50 subjects who underwent three test sessions. The results of the first test session were well fit by the normative data gathered in Experiment 1. Sessions 2 and 3 demonstrated significant learning effects, particularly on the C-TMT-B, and showed good test-retest reliability. Experiment 3 examined performance in subjects instructed to feign symptoms of traumatic brain injury: 44% of subjects produced abnormal completion times on the C-TMT-A, and 18% on the C-TMT-B. Malingering subjects could be distinguished from abnormally slow controls based on (1) disproportionate increases in dwell-time on the C-TMT-A, and (2) greater deficits on the C-TMT-A than on the C-TMT-B. Experiment 4 examined the performance of 28 patients with traumatic brain injury: C-TMT-B completion times were slowed, and TBI patients showed reduced movement velocities on both tests. The C-TMT improves the reliability and sensitivity of the trail making test of processing speed and executive function.
We meta-analyzed 115 functional magnetic resonance imaging (fMRI) studies reporting auditory-cortex (AC) coordinates for activations related to active and passive processing of pitch and spatial ...location of non-speech sounds, as well as to the active and passive speech and voice processing. We aimed at revealing any systematic differences between AC surface locations of these activations by statistically analyzing the activation loci using the open-source Matlab toolbox VAMCA (Visualization and Meta-analysis on Cortical Anatomy). AC activations associated with pitch processing (e.g., active or passive listening to tones with a varying vs. fixed pitch) had median loci in the middle superior temporal gyrus (STG), lateral to Heschl's gyrus. However, median loci of activations due to the processing of infrequent pitch changes in a tone stream were centered in the STG or planum temporale (PT), significantly posterior to the median loci for other types of pitch processing. Median loci of attention-related modulations due to focused attention to pitch (e.g., attending selectively to low or high tones delivered in concurrent sequences) were, in turn, centered in the STG or superior temporal sulcus (STS), posterior to median loci for passive pitch processing. Activations due to spatial processing were centered in the posterior STG or PT, significantly posterior to pitch processing loci (processing of infrequent pitch changes excluded). In the right-hemisphere AC, the median locus of spatial attention-related modulations was in the STS, significantly inferior to the median locus for passive spatial processing. Activations associated with speech processing and those associated with voice processing had indistinguishable median loci at the border of mid-STG and mid-STS. Median loci of attention-related modulations due to attention to speech were in the same mid-STG/STS region. Thus, while attention to the pitch or location of non-speech sounds seems to recruit AC areas less involved in passive pitch or location processing, focused attention to speech predominantly enhances activations in regions that already respond to human vocalizations during passive listening. This suggests that distinct attention mechanisms might be engaged by attention to speech and attention to more elemental auditory features such as tone pitch or location.
This article is part of a Special Issue entitled <Human Auditory Neuroimaging>.
•The results of 115 auditory fMRI studies were meta-analyzed.•Pitch processing and spatial processing have different median auditory-cortex loci.•Processing of infrequent pitch changes is separable from other types of pitch processing.•Auditory attention modulates activity in the superior temporal gyrus and sulcus.•Speech and voice processing activate similar regions of the auditory cortex.
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