Optical Scattering from Vitreous Floaters

Vitreous “floaters” are a common entoptic phenomenon that can result in significant reduction in quality of life in a proportion of sufferers. The authors use a computational mathematical model based on Fourier optics and reflection and transmission coefficients calculated for a planar type II collagen opacity suspended in aqueous to show that floaters are perceived by the patient through interference effects that result in significant variations in intensity on the retina when viewing a constant brightness surface. The model also predicts that backscattered intensity from floaters is ten thousand to one million times lower than the variations in intensity produced on the retina, which demonstrates that the visible effects of floaters for the patient can be highly significant, whereas clinical observation of the vitreous may be entirely unremarkable. Importantly, the results also demonstrate that floaters do not need to be opaque to cause symptoms, with only small differences in refractive index between the floater material and the surrounding vitreous needed to produce significant optical effects. The model predicts that pupil size is an important factor in determining the severity of symptoms from floaters, with constricted pupils giving much greater effect than dilated pupils. Finally, the authors’ model predicts that floaters degrade contrast sensitivity function, with greatest degradation occurring in the 5–40 cycles per degree spatial frequency range and that the effects of shadowing caused by floaters are very strongly correlated to the predicted degradation of contrast sensitivity function.© 2021 The Authors. Bioelectromagnetics published by Wiley Periodicals LLC on behalf of Bioelectromagnetics Society

Patient safety incidents involving sick children in primary care in England and Wales: a mixed methods analysis

Background: The UK performs poorly relative to other economically developed countries on numerous indicators of care quality for children. The contribution of iatrogenic harm to these outcomes is unclear. As primary care is the first point of healthcare contact for most children, we sought to investigate the safety of care provided to children in this setting. Methods and Findings: We undertook a mixed methods investigation of reports of primary care patient safety incidents involving sick children from England and Wales’ National Reporting and Learning System between 1 January 2005 and 1 December 2013. Two reviewers independently selected relevant incident reports meeting prespecified criteria, and then descriptively analyzed these reports to identify the most frequent and harmful incident types. This was followed by an in-depth thematic analysis of a purposive sample of reports to understand the reasons underpinning incidents. Key candidate areas for strengthening primary care provision and reducing the risks of systems failures were then identified through multidisciplinary discussions. Of 2,191 safety incidents identified from 2,178 reports, 30% (n = 658) were harmful, including 12 deaths and 41 cases of severe harm. The children involved in these incidents had respiratory conditions (n = 387; 18%), injuries (n = 289; 13%), nonspecific signs and symptoms, e.g., fever (n = 281; 13%), and gastrointestinal or genitourinary conditions (n = 268; 12%), among others. Priority areas for improvement included safer systems for medication provision in community pharmacies; triage processes to enable effective and timely assessment, diagnosis, and referral of acutely sick children attending out-of-hours services; and enhanced communication for robust safety netting between professionals and parents. The main limitations of this study result from underreporting of safety incidents and variable data quality. Our findings therefore require further exploration in longitudinal studies utilizing case review methods. Conclusions: This study highlights opportunities to reduce iatrogenic harm and avoidable child deaths. Globally, healthcare systems with primary-care-led models of delivery must now examine their existing practices to determine the prevalence and burden of these priority safety issues, and utilize improvement methods to achieve sustainable improvements in care quality

Building Trust in Human-Machine Partnerships

Artificial Intelligence (AI) is bringing radical change to our lives. Fostering trust in this technology requires the technology to be transparent, and one route to transparency is to make the decisions that are reached by AIs explainable to the humans that interact with them. This paper lays out an exploratory approach to developing explainability and trust, describing the specific technologies that we are adopting, the social and organizational context in which we are working, and some of the challenges that we are addressing

Future directions in international financial integration research. A crowdsourced perspective

This paper is the result of a crowdsourced effort to surface perspectives on the present and future direction of international finance. The authors are researchers in financial economics who attended the INFINITI 2017 conference in the University of Valencia in June 2017 and who participated in the crowdsourcing via the Overleaf platform. This paper highlights the actual state of scientific knowledge in a multitude of fields in finance and proposes different directions for future research

Global-scale quantification of mineralization pathways in marine sediments: A reaction-transport modeling approach

[1] The global-scale quantification of organic carbon (Corg) degradation pathways in marine sediments is difficult to achieve experimentally due to the limited availability of field data. In the present study, a numerical modeling approach is used as an alternative to quantify the major metabolic pathways of Corg oxidation (Cox) and associated fluxes of redox-sensitive species fluxes along a global ocean hypsometry, using the seafloor depth (SFD) as the master variable. The SFD dependency of the model parameters and forcing functions is extracted from existing empirical relationships or from the NOAA World Ocean Atlas. Results are in general agreement with estimates from the literature showing that the relative contribution of aerobic respiration to Cox increases from 80% in deep-sea sediments. Sulfate reduction essentially follows an inversed SFD dependency, the other metabolic pathways (denitrification, Mn and Fe reduction) only adding minor contributions to the global-scale mineralization of Corg. The hypsometric analysis allows the establishment of relationships between the individual terminal electron acceptor (TEA) fluxes across the sediment-water interface and their respective contributions to the Corg decomposition process. On a global average, simulation results indicate that sulfate reduction is the dominant metabolic pathway and accounts for approximately 76% of the total Cox, which is higher than reported so far by other authors. The results also demonstrate the importance of bioirrigation for the assessment of global species fluxes. Especially at shallow SFD most of the TEAs enter the sediments via bioirrigation, which complicates the use of concentration profiles for the determination of total TEA fluxes by molecular diffusion. Furthermore, bioirrigation accounts for major losses of reduced species from the sediment to the water column prohibiting their reoxidation inside the sediment. As a result, the total carbon mineralization rate exceeds the total flux of oxygen into the sediment by a factor of 2 globally

PlanVerb: Domain-Independent Verbalization and Summary of Task Plans

For users to trust planning algorithms, they must be able to understand the planner's outputs and the reasons for each action selection. This output does not tend to be user-friendly, often consisting of sequences of parametrised actions or task networks. And these may not be practical for non-expert users who may find it easier to read natural language descriptions. In this paper, we propose PlanVerb, a domain and planner-independent method for the verbalization of task plans. It is based on semantic tagging of actions and predicates. Our method can generate natural language descriptions of plans including causal explanations. The verbalized plans can be summarized by compressing the actions that act on the same parameters. We further extend the concept of verbalization space, previously applied to robot navigation, and apply it to planning to generate different kinds of plan descriptions for different user requirements. Our method can deal with PDDL and RDDL domains, provided that they are tagged accordingly. Our user survey evaluation shows that users can read our automatically generated plan descriptions and that the explanations help them answer questions about the plan

Prognostic factors that determine visual outcome following cataract surgery complicated by vitreous loss

Purpose: To identify prognostic factors that determine visual outcome following phacoemulsification cataract surgery complicated by vitreous loss. Methods: A retrospective cohort study. All cases of vitreous loss during phacoemulsification surgery at a university hospital, between June 2000 and December 2005, were identified from the hospital computer database. By reviewing the medical notes, preoperative, intraoperative, and postoperative data were collected. Outcome of interest was presence of poor visual outcome (best-corrected visual acuity [BCVA] <6/12). Chi-square and Mann-Whitney U tests were used to compare groups of poor and good visual outcome. Results: A total of 230 consecutive cases (eyes) were identified; medical notes were available for 228. Mean patient age was 78.4 years (SD 11); median follow-up 13.4 weeks (range 1-203). In multivariable logistic regression analysis poor visual outcome was independently associated with poor preoperative vision (BCVA <6/12) (OR 3.78, 95% CI 1.76-8.11), age-related macular degeneration (OR 3.04, 95% CI 1.16-8.00), cystoid macular edema (OR 3.85, 95% CI 1.29-11.51), and secondary pars plana vitrectomy (PPV) for nuclear fragment loss (OR 4.42, 95% CI 1.03-19.02). Primary PPV for nuclear fragment loss, age >70, ocular comorbidity, axial length, vitreous loss during irrigation/aspiration, or lens implantation, anterior chamber lens, and secondary lens implantation were not significant associations (p>or= 0.05). In 33 (14.5%) eyes BCVA was reduced by at least one Snellen line compared to before surgery. Conclusions: Poor visual outcome was associated with poor preoperative vision, age-related macular degeneration, cystoid macular edema, and secondary PPV following nuclear fragment loss. Primary PPV for nuclear fragment loss was not a significant association

Recommendations for evaluation of health care improvement initiatives

Intensive efforts are underway across the world to improve the quality of health care. It is important to use evaluation methods to identify improvement efforts that work well before they are replicated across a broad range of contexts. Evaluation methods need to provide an understanding of why an improvement initiative has or has not worked and how it can be improved in the future. However, improvement initiatives are complex, and evaluation is not always well aligned with the intent and maturity of the intervention, thus limiting the applicability of the results. We describe how initiatives can be grouped into 1 of 3 improvement phases—innovation, testing, and scale-up and spread—depending on the degree of belief in the associated interventions. We describe how many evaluation approaches often lead to a finding of no effect, consistent with what has been termed Rossi’s Iron Law of Evaluation. Alternatively, we recommend that the guiding question of evaluation in health care improvement be, “How and in what contexts does a new model work or can be amended to work?” To answer this, we argue for the adoption of formative, theory-driven evaluation. Specifically, evaluations start by identifying a program theory that comprises execution and content theories. These theories should be revised as the initiative develops by applying a rapid-cycle evaluation approach, in which evaluation findings are fed back to the initiative leaders on a regular basis. We describe such evaluation strategies, accounting for the phase of improvement as well as the context and setting in which the improvement concept is being deployed. Finally, we challenge the improvement and evaluation communities to come together to refine the specific methods required so as to avoid the trap of Rossi’s Iron Law