The Traveling Salesman Problem in the Natural Environment

Is it possible for humans to navigate in the natural environment wherein the path taken between various destinations is 'optimal' in some way? In the domain of optimization this challenge is traditionally framed as the "Traveling Salesman Problem" (TSP). What strategies and ecological considerations are plausible for human navigation? When given a two-dimensional map-like presentation of the destinations, participants solve this optimization exceptionally well (only 2-3% longer than optimum)^1, 2^. In the following experiments we investigate the effect of effort and its environmental affordance on navigation decisions when humans solve the TSP in the natural environment. Fifteen locations were marked on two outdoor landscapes with flat and varied terrains respectively. Performance in the flat-field condition was excellent (∼6% error) and was worse but still quite good in the variable-terrain condition (∼20% error), suggesting participants do not globally pre-plan routes but rather develop them on the fly. We suggest that perceived effort guides participant solutions due to the dynamic constraints of effortful locomotion and obstacle avoidance

What is the problem to which interactive multimedia is the solution?

This is something of an unusual paper. It serves as both the reason for and the result of a small number of leading academics in the field, coming together to focus on the question that serves as the title to this paper: What is the problem to which interactive multimedia is the solution? Each of the authors addresses this question from their own viewpoint, offering informed insights into the development, implementation and evaluation of multimedia. The result of their collective work was also the focus of a Western Australian Institute of Educational Research seminar, convened at Edith Cowan University on 18 October, 1994. The question posed is deliberately rhetorical - it is asked to allow those represented here to consider what they think are the significant issues in the fast-growing field of multimedia. More directly, the question is also asked here because nobody else has considered it worth asking: for many multimedia is done because it is technically possible, not because it offers anything that is of value or provides the solution to a particular problem. The question, then, is answered in various ways by each of the authors involved and each, in their own way, consider a range of fundamental issues concerning the nature, place and use of multimedia - both in education and in society generally. By way of an introduction, the following provides a unifying context for the various contributions made here

Perspectives on the changing healthcare system: teaching systems-based practice to medical residents

Purpose: The Accreditation Council for Graduate Medical Education restructured its accreditation system to be based on educational outcomes in six core competencies. Systems-based practice is one of the six core competencies. The purpose of this report is to describe Weill Cornell Medical College's Internal Medicine Residency program curriculum for systems-based practice (SBP) and its evaluation process. Methods: To examine potential outcomes of the POCHS curriculum, an evaluation was conducted, examining participants': (1) knowledge gain; (2) course ratings; and (3) qualitative feedback. Results: On average, there was a 19 percentage point increase in knowledge test scores for all three cohorts. The course was rated overall highly, receiving an average of 4.6 on a 1–5 scale. Lastly, the qualitative comments supported that the material is needed and valued. Conclusion: The course, entitled Perspectives on the Changing Healthcare System (POCHS) and its evaluation process support that systems-based practice is crucial to residency education. The course is designed not only to educate residents about the current health care system but also to enable them to think critically about the risk and benefits of the changes. POCHS provides a framework for teaching and assessing this competency and can serve as a template for other residency programs looking to create or restructure their SBP curriculum

Integration in European Retail Banking : Evidence from savings and lending rates to non-financial corporations

The aim of this paper is to investigate the integration process in the European Union retail banking sector during the period 1995-2008, by analysing deposit and lending rates to nonfinancial corporations which represent one of the main constituents of retail banking. An important contribution of the paper is the application of the recently developed Phillips and Sul (2007a) panel convergence methodology which has not hitherto been employed in this area. This method analyses the degree as well as the speed of convergence, identifies the presence of club formation, and measures the behaviour of each country’s transition path relative to the panel average. The results obtained point to the presence of close convergence in all deposit rates and in the short-term lending rates to non-financial corporations. However, we also detect the presence of heterogeneity in the European retail banking sector with notably some diverse convergence patterns observed for the transition paths for the deposit and lending rates with longer maturities.Submitted Versio

Increasing dominance of large lianas in Amazonian forests

Ecological orthodoxy suggests that old-growth forests should be close to dynamic equilibrium, but this view has been challenged by recent findings that neotropical forests are accumulating carbon and biomass, possibly in response to the increasing atmospheric concentrations of carbon dioxide. However, it is unclear whether the recent increase in tree biomass has been accompanied by a shift in community composition. Such changes could reduce or enhance the carbon storage potential of old-growth forests in the long term. Here we show that non-fragmented Amazon forests are experiencing a concerted increase in the density, basal area and mean size of woody climbing plants (lianas). Over the last two decades of the twentieth century the dominance of large lianas relative to trees has increased by 1.7–4.6% a year. Lianas enhance tree mortality and suppress tree growth, so their rapid increase implies that the tropical terrestrial carbon sink may shut down sooner than current models suggest. Predictions of future tropical carbon fluxes will need to account for the changing composition and dynamics of supposedly undisturbed forests

Seasonal pattern of incidence and outcome of acute kidney injury: A national study of Welsh AKI electronic alerts

Objectives To identify any seasonal variation in the occurrence of, and outcome following Acute Kidney Injury. Methods The study utilised the biochemistry based AKI electronic (e)-alert system established across the Welsh National Health Service to collect data on all AKI episodes to identify changes in incidence and outcome over one calendar year (1st October 2015 and the 30th September 2016). Results There were total of 48 457 incident AKI alerts. The highest proportion of AKI episodes was seen in the quarter of January to March (26.2%), and the lowest in the quarter of October to December (23.3%, P < .001). The same trend was seen for both community-acquired and hospital-acquired AKI sub-sets. Overall 90 day mortality for all AKI was 27.3%. In contrast with the seasonal trend in AKI occurrence, 90 day mortality after the incident AKI alert was significantly higher in the quarters of January to March and October to December compared with the quarters of April to June and July to September (P < .001) consistent with excess winter mortality reported for likely underlying diseases which precipitate AKI. Conclusions In summary we report for the first time in a large national cohort, a seasonal variation in the incidence and outcomes of AKI. The results demonstrate distinct trends in the incidence and outcome of AKI

Increasing biomass in Amazonian forest plots

A previous study by Phillips et al. of changes in the biomass of permanent sample plots in Amazonian forests was used to infer the presence of a regional carbon sink. However, these results generated a vigorous debate about sampling and methodological issues. Therefore we present a new analysis of biomass change in old-growth Amazonian forest plots using updated inventory data. We find that across 59 sites, the above-ground dry biomass in trees that are more than 10 cm in diameter (AGB) has increased since plot establishment by 1.22 ± 0.43 Mg per hectare per year (ha-1 yr-1), where 1 ha = 104 m2), or 0.98 ± 0.38 Mg ha-1 yr-1 if individual plot values are weighted by the number of hectare years of monitoring. This significant increase is neither confounded by spatial or temporal variation in wood specific gravity, nor dependent on the allometric equation used to estimate AGB. The conclusion is also robust to uncertainty about diameter measurements for problematic trees: for 34 plots in western Amazon forests a significant increase in AGB is found even with a conservative assumption of zero growth for all trees where diameter measurements were made using optical methods and/or growth rates needed to be estimated following fieldwork. Overall, our results suggest a slightly greater rate of net stand-level change than was reported by Phillips et al. Considering the spatial and temporal scale of sampling and associated studies showing increases in forest growth and stem turnover, the results presented here suggest that the total biomass of these plots has on average increased and that there has been a regional-scale carbon sink in old-growth Amazonian forests during the previous two decades