1,510 research outputs found

    Sea-level driven land conversion and the formation of ghost forests

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    Ghost forests created by the submergence of low-lying land are one of the most striking indicators of climate change along the Atlantic coast of North America. Although dead trees at the margin of estuaries were described as early as 1910, recent research has led to new recognition that the submergence of terrestrial land is geographically widespread, ecologically and economically important, and globally relevant to the survival of coastal wetlands in the face of rapid sea level rise. This emerging understanding has in turn generated widespread interest in the physical and ecological mechanisms influencing the extent and pace of upland to wetland conversion. Choices between defending the coast from sea level rise and facilitating ecosystem transgression will play a fundamental role in determining the fate and function of low-lying coastal land

    Skills, knowledge and senior managers’ demonstrations of safety commitment.

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    Senior managers’ safety commitment is emphasised in the safety literature as a crucial influence on organisational safety. Yet there is little understanding of the characteristics that underpin their ability to engage in behaviours that demonstrate safety commitment. This study investigates the contribution of problem-solving, social competence and safety knowledge to such behaviours. Senior managers (N = 60) from European and North American air traffic management organisations participated in interviews consisting of open questions designed to trigger safety knowledge and descriptions of behaviours that demonstrate safety commitment as well as scenarios designed to trigger problem-solving and social competence. Reliable scores were generated through systematic scoring procedures involving two independent coders. The results indicated that problem-solving, namely the number of issues and information sources considered when understanding problems and generating ideas to solve a problem were positively related to demonstrations of safety commitment. The ability to perceive others was also found to correlate with safety commitment, whereas safety knowledge was not associated with behaviours that demonstrate safety commitment. It is proposed that training and guidance designed for senior managers should focus on their problem-solving abilities and perception of others in order to support them in demonstrating safety commitment

    Assessing Human Error Against a Benchmark of Perfection

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    An increasing number of domains are providing us with detailed trace data on human decisions in settings where we can evaluate the quality of these decisions via an algorithm. Motivated by this development, an emerging line of work has begun to consider whether we can characterize and predict the kinds of decisions where people are likely to make errors. To investigate what a general framework for human error prediction might look like, we focus on a model system with a rich history in the behavioral sciences: the decisions made by chess players as they select moves in a game. We carry out our analysis at a large scale, employing datasets with several million recorded games, and using chess tablebases to acquire a form of ground truth for a subset of chess positions that have been completely solved by computers but remain challenging even for the best players in the world. We organize our analysis around three categories of features that we argue are present in most settings where the analysis of human error is applicable: the skill of the decision-maker, the time available to make the decision, and the inherent difficulty of the decision. We identify rich structure in all three of these categories of features, and find strong evidence that in our domain, features describing the inherent difficulty of an instance are significantly more powerful than features based on skill or time.Comment: KDD 2016; 10 page

    Stratifying quotient stacks and moduli stacks

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    Recent results in geometric invariant theory (GIT) for non-reductive linear algebraic group actions allow us to stratify quotient stacks of the form [X/H], where X is a projective scheme and H is a linear algebraic group with internally graded unipotent radical acting linearly on X, in such a way that each stratum [S/H] has a geometric quotient S/H. This leads to stratifications of moduli stacks (for example, sheaves over a projective scheme) such that each stratum has a coarse moduli space.Comment: 25 pages, submitted to the Proceedings of the Abel Symposium 201

    Carbon nanotube: a low-loss spin-current waveguide

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    We demonstrate with a quantum-mechanical approach that carbon nanotubes are excellent spin-current waveguides and are able to carry information stored in a precessing magnetic moment for long distances with very little dispersion and with tunable degrees of attenuation. Pulsed magnetic excitations are predicted to travel with the nanotube Fermi velocity and are able to induce similar excitations in remote locations. Such an efficient way of transporting magnetic information suggests that nanotubes are promising candidates for memory devices with fast magnetization switchings

    How Old Are Marshes on the East Coast, USA? Complex Patterns in Wetland Age Within and Among Regions

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    Sea‚Äźlevel dynamics, sediment availability, and marine energy are critical drivers of coastal wetland formation and persistence, but their roles as continental‚Äźscale drivers remain unknown. We evaluated the timing and spatial variability of wetland formation from new and existing cores collected along the Atlantic and Gulf coasts of the United States. Most basal peat ages occurred after sea‚Äźlevel rise slowed (after ~4,000 years before present), but predominance of sea‚Äźlevel rise studies may skew age estimates toward older sites. Near‚Äźcoastal sites tended to be younger, indicating creation of wetlands through basin infilling and overwash events. Age distributions differed among regions, with younger wetlands in the northeast and southeast corresponding to European colonization and deforestation. Across all cores, wetland age correlated strongly with basal peat depth. Marsh age elucidates the complex interactions between sea‚Äźlevel rise, sediment supply, and geomorphic setting in determining timing and location of marsh formation and future wetland persistence

    Safety and Cost Considerations during the Introduction Period of Laparoscopic Radical Hysterectomy

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    Objective. To compare the safety, efficacy, and direct cost during the introduction of laparoscopic radical hysterectomy within an enhanced recovery pathway. Methods. A 1‚ÄČ:‚ÄČ1 single centre retrospective case control study of 36 propensity matched pairs of patients receiving open or laparoscopic surgery for early cervical cancer. Results. There were no significant differences in the baseline characteristics of the two cohorts. Open surgery cohort had significantly higher intraoperative blood loss (189 versus 934‚ÄČmL) and longer postoperative hospital stay (2.3 versus 4.1 days). Although no significant difference in the intraoperative or postoperative complications was found more urinary tract injuries were recorded in the laparoscopic cohort. Laparoscopic surgery had significantly longer duration (206 versus 159 minutes), lower lymph node harvest (12.6 versus 16.9), and slower bladder function recovery. The median direct hospital cost was ¬£4850 for laparoscopic radical hysterectomy and ¬£4400 for open surgery. Conclusions. Laparoscopic radical hysterectomy can be safely introduced in an enhanced recovery environment without significant increase in perioperative morbidity. The 10% higher direct hospital cost is not statistically significant and is expected to even out when indirect costs are included

    Cities lead on climate change

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    Clinical Judgment Analysis

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    SUMMARY Judgment is central to the practice of medicine and occurs between making clinical observations and taking clinical decisions. Clinical judgment analysis has developed as a method of making statistically firm models of doctors' judgments. Computed models reveal the differential importance attached to items of clinical, social, or other data which are determinants of clinical decisions. These models can both reveal the causes of conflicts of judgment and may help resolve them in a way that unaided discussion cannot. Revealing experts' models to students speeds learning of diagnostic skills. Clinical judgment analysis offers a method of probing the judgments not just of students and doctors but also of patients who have shown systematic differences in their perceptions of risk and benefit. The power and relevance of clinical trials can be improved by the consistent application of judgment policies generated from both the trialists and those who will use their result
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