The Effects of Automation Transparency and Reliability on Task Shedding and Operator Trust

Because automation use is common in many domains, understanding how to design it to optimize human-automation system performance is vital. Well-calibrated trust ensures good performance when using imperfect automation. Two factors that may jointly affect trust calibration are automation transparency and perceived reliability. Transparency information that explains automated processes and analyses to the operator may help the operator choose appropriate times to shed task control to automation. Because operator trust is positively correlated with automation use, behaviors such as task shedding to automation can indicate the presence of trust. This study used a 2 (reliability; between) × 3 (transparency; within) split-plot design to study the effects that reliability and amount of transparency information have on operators’ subjective trust and task shedding behaviors. Results showed a significant effect of reliability on trust, in which high reliability resulted in more trust. There was no effect of transparency on trust. There was no effect of either reliability or transparency on task shedding frequency or time to task shed. This may be due to high workload of the primary task, restricting participants’ ability to utilize transparency information beyond the automation recommendation. Another influence on these findings was participant hesitance to task shed which could have influenced behavior regardless of automation reliability. These findings contribute to the understanding of automation trust and operator task shedding behavior. Consistent with literature, reliability increased trust. However, there was no effect of transparency, demonstrating the complexity of the relationship between transparency and trust. Participants demonstrated a bias to retain personal control, even with highly reliable automation and at the cost of time-out errors. Future research should examine the relationship between workload and transparency and the influence of task importance on task shedding

Altering the stability of the Cdc8 overlap region modulates the ability of this tropomyosin to bind cooperatively to actin and regulate myosin.

Tropomyosin (Tm) is an evolutionarily conserved ?-helical coiled-coil protein, dimers of which form end-to-end polymers capable of associating with and stabilising actin-filaments and regulate myosin function. The fission yeast, Schizosaccharomyces pombe, possesses a single essential Tm, Cdc8, which can be acetylated on its amino terminal methionine to increase its affinity for actin and enhance its ability to regulate myosin function. We have designed and generated a number of novel Cdc8 mutant proteins with amino terminal substitutions to explore how stability of the Cdc8-polymer overlap region affects the regulatory function of this Tm. By correlating the stability of each protein, its propensity to form stable polymers, its ability to associate with actin and to regulate myosin, we have shown the stability of the amino terminal of the Cdc8 ?-helix is crucial for Tm function. In addition we have identified a novel Cdc8 mutant with increased amino-terminal stability, dimers of which are capable of forming Tm-polymers significantly longer than the wild-type protein. This protein had a reduced affinity for actin with respect to wild type, and was unable to regulate actomyosin interactions. The data presented here are consistent with acetylation providing a mechanism for modulating the formation and stability of Cdc8 polymers within the fission yeast cell. The data also provide evidence for a mechanism in which Tm dimers form end-to-end polymers on the actin-filament, consistent with a cooperative model for Tm binding to actin

Latent topic discovery of clinical concepts from hospital discharge summaries of a heterogeneous patient cohort

Patients in critical care often exhibit complex disease patterns. A fundamental challenge in clinical research is to identify clinical features that may be characteristic of adverse patient outcomes. In this work, we propose a data-driven approach for phenotype discovery of patients in critical care. We used Hierarchical Dirichlet Process (HDP) as a non-parametric topic modeling technique to automatically discover the latent "topic" structure of diseases, symptoms, and findings documented in hospital discharge summaries. We show that the latent topic structure can be used to reveal phenotypic patterns of diseases and symptoms shared across subgroups of a patient cohort, and may contain prognostic value in stratifying patients' post hospital discharge mortality risks. Using discharge summaries of a large patient cohort from the MIMIC II database, we evaluate the clinical utility of the discovered topic structure in identifying patients who are at high risk of mortality within one year post hospital discharge. We demonstrate that the learned topic structure has statistically significant associations with mortality post hospital discharge, and may provide valuable insights in defining new feature sets for predicting patient outcomes.National Institutes of Health (U.S.) (Grant R01-EB001659)National Institute of Biomedical Imaging and Bioengineering (U.S.) (Grant R01GM104987

Exploring the concept of applied nucleation as a restoration tool in a previously invaded Mediterranean climate vegetation type

Thesis (MScConsEcol)--Stellenbosch University, 2022.ENGLISH ABSTRACT: There is a need to scale-up ecological restoration efforts. The urgency to restore degraded habitats means that we, as researchers, need to be at the forefront of new and innovative restoration techniques. Sometimes this means assessing the efficacy of techniques which are not commonly employed in the vegetation type in need of restoration. In the case of this study, it involved exploring the concept of applied nucleation as a restoration tool in Cape Flats Sand Fynbos (CFSF). Applied nucleation involves establishing clusters of vegetation (nuclei) either by sowing or planting, and these clusters then produce and set seed into the surrounding area, facilitating nucleation. Colonization is further facilitated when the clusters of vegetation establish and are able to capture seed from other species (Corbin & Holl, 2012). This thesis assessed whether applied nucleation would be an effective restoration method in a vegetation type where it has not been employed before. This was done by resurveying previously restored plots to assess whether sown species had begun to set seed and nucleate into the surrounding environment (Chapter 2), and by designing a simulation model to assess which invasion management regimes and Cape Flats Sand Fynbos Species would most effectively facilitate nucleation (Chapter 3). The management regimes were fell & stack whereby felled Acacia biomass was stacked into brushpiles and fell & burn involved burning the felled Acacia biomass. A resurvey of active restoration plots established in 2013 through sowing indigenous Cape Flats Sand Fynbos investigated which species had established and persisted, as well as determined which species had set seed outside the initial 10m x 5m sowed plot. Fourteen plots were resurveyed in 2019 by determining species presence and abundance. This information was then compared to survey data from 2014 and 2017 to assess how the restored plots were faring. Of the 30 species sown in 2013, only 11 were observed to still be persisting in 2019. By establishing a larger 20m x 20m plot around the initial sowing plot, young plants of the species inside in sowing plot were identified, and these species were assumed to be nucleating species. The size (volume) of these young plants as well as their distance to the sowing plot was measured. This was to determine whether there was a significant difference between plant size inside the plot as opposed to outside, as well as to determine the distribution of plants of different ages. Plant size was used as a surrogate for plant age. Four species were seen to have consistently set seed outside the initial sowing plots, and these were Anthospermum aethiopicum, Ifloga repens, Dimorphotheca pluvialis, and Pelargonium capitatum. A practical simulation model was designed to assess which management regimes and species would facilitate nucleation the most effectively. The model was designed using the principles of inverse modelling, which is a modelling technique commonly used when certain model parameters are not available, as it makes use of model outputs to infer the values of model parameters. Management regimes were simulated by arranging theoretical felled Acacia brush piles in different patterns and distances around the initial sowed plot as seed traps. Furthermore, the dispersal and colonization of the four nucleating species identified in Chapter 2 was simulated to determine which species possessed the highest colonization and nucleation potential by manipulating certain biological parameters. The models showed that a fell and stack management regime where brush piles were arranged in a radial pattern facilitated nucleation the best, as this obstacle arrangement initially allowed for long distance dispersal, whereafter seed was trapped when it reached the Acacia brushpiles. This resulted in new sources of seed to continue to facilitate nucleation. The Acacia reinvasion simulation resulted in the poorest nucleation, as seed was trapped nearby the sowing plot and not allowed to disperse further. The species which displayed the highest nucleation potential was Dimorphotheca pluvialis, as this species had a high dispersal distance and reproductive rate. By analysing and interpreting the results from this study, certain management recommendations and recommendations for future research are proposed to provide a more in-depth understanding of using applied nucleation as a restoration tool in Cape Flats Sand Fynbos. It was concluded that this technique shows promise, but that further research is needed, particularly on the nucleation potential of species that require fire for seed germination.AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar.Master

Neurons of origin and fiber trajectory of amygdalofugal projections to the medial preoptic area in syrian hamsters

The amygdaloid neurons of origin and the trajectory of amygdaloid fibers to the medial preoptic area of the adult male Syrian hamster were identified by using horseradish peroxidase (HRP) histochemistry. After iontophoresis of HRP into the medial preoptic area, retrogradely labeled amygdaloid neurons were located in the dorsal and caudal parts of the medial amygdaloid nucleus and throughout the amygdalohippocampal area. No amygdaloid neurons were labeled after HRP applications confined to the most rostral portion of the medial preoptic area (anterior to the body of the anterior commissure). Following more caudal medial preoptic area injections (body of the anterior commissure to the suprachiasmatic nucleus) the distribution of retrogradely labeled cells in the medial amygdaloid nucleus and the amygdalohippocampal area revealed no topographic organization of the amygdalopreoptic connections. When amygdaloid neurons were labeled, the amygdalohippocampal area contained two to five times as many HRP-filled cells as the medial amygdaloid nucleus. Retrogradely transported HRP could be followed from the medial preoptic area to the amygdala through fibers in the dorsomedial quadrant of the stria terminalis. In addition, electrolytic lesions of the stria terminalis prior to iontophoresis of HRP into the medial preoptic area prevented retrograde transport to neurons in both the dorsocaudal medial amygdaloid nucleus and the amygdalohippocampal area. These results confirm earlier observations describing the location of autoradiographically labeled efferents from the medial amygdaloid nucleus to the medial preoptic area and provide new information about the restricted region within the medial amygdaloid nucleus from which these projections arise. They also suggest that, unlike the projections from the medial amygdaloid nucleus to the bed nucleus of the stria terminalis, the efferents to the medial preoptic area travel entirely in the stria terminalis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50043/1/902800106_ftp.pd

Phenotyping hypotensive patients in critical care using hospital discharge summaries

Among critically-ill patients, hypotension represents a failure in compensatory mechanisms and may lead to organ hypoperfusion and failure. In this work, we adopt a datadriven approach for phenotype discovery and visualization of patient similarity and cohort structure in the intensive care unit (ICU). We used Hierarchical Dirichlet Process (HDP) as a non-parametric topic modeling technique to automatically learn a d-dimensional feature representation of patients that captures the latent 'topic' structure of diseases, symptoms, medications, and findings documented in hospital discharge summaries. We then used the t-Distributed Stochastic Neighbor Embedding (t-SNE) algorithm to convert the d-dimensional latent structure learned from HDP into a matrix of pairwise similarities for visualizing patient similarity and cohort structure. Using discharge summaries of a large patient cohort from the MIMIC II database, we evaluated the clinical utility of the discovered topic structure in phenotyping critically-ill patients who experienced hypotensive episodes. Our results indicate that the approach is able to reveal clinically interpretable clustering structure within our cohort and may potentially provide valuable insights to better understand the association between disease phenotypes and outcomes.National Institutes of Health (U.S.) (Grant R01-EB017205)National Institutes of Health (U.S.) (Grant R01-EB001659)National Institutes of Health (U.S.) (Grant R01GM104987