Uncertainty representation in software models: a survey

Author(s):  
Javier Troya ◽  
Nathalie Moreno ◽  
Manuel F. Bertoa ◽  
Antonio Vallecillo
2021 ◽  
Author(s):  
Stephen C. L. Watson ◽  
Adrian C. Newton ◽  
Lucy E. Ridding ◽  
Paul M. Evans ◽  
Steven Brand ◽  
...  

Abstract Context Agricultural intensification is being widely pursued as a policy option to improve food security and human development. Yet, there is a need to understand the impact of agricultural intensification on the provision of multiple ecosystem services, and to evaluate the possible occurrence of tipping points. Objectives To quantify and assess the long-term spatial dynamics of ecosystem service (ES) provision in a landscape undergoing agricultural intensification at four time points 1930, 1950, 1980 and 2015. Determine if thresholds or tipping points in ES provision may have occurred and if there are any detectable impacts on economic development and employment. Methods We used the InVEST suite of software models together with a time series of historical land cover maps and an Input–Output model to evaluate these dynamics over an 85-year period in the county of Dorset, southern England. Results Results indicated that trends in ES were often non-linear, highlighting the potential for abrupt changes in ES provision to occur in response to slight changes in underlying drivers. Despite the fluctuations in provision of different ES, overall economic activity increased almost linearly during the study interval, in line with the increase in agricultural productivity. Conclusions Such non-linear thresholds in ES will need to be avoided in the future by approaches aiming to deliver sustainable agricultural intensification. A number of positive feedback mechanisms are identified that suggest these thresholds could be considered as tipping points. However, further research into these feedbacks is required to fully determine the occurrence of tipping points in agricultural systems.


Author(s):  
George Hripcsak ◽  
Martijn J. Schuemie ◽  
David Madigan ◽  
Patrick B. Ryan ◽  
Marc A. Suchard

Summary Objective: The current observational research literature shows extensive publication bias and contradiction. The Observational Health Data Sciences and Informatics (OHDSI) initiative seeks to improve research reproducibility through open science. Methods: OHDSI has created an international federated data source of electronic health records and administrative claims that covers nearly 10% of the world’s population. Using a common data model with a practical schema and extensive vocabulary mappings, data from around the world follow the identical format. OHDSI’s research methods emphasize reproducibility, with a large-scale approach to addressing confounding using propensity score adjustment with extensive diagnostics; negative and positive control hypotheses to test for residual systematic error; a variety of data sources to assess consistency and generalizability; a completely open approach including protocol, software, models, parameters, and raw results so that studies can be externally verified; and the study of many hypotheses in parallel so that the operating characteristics of the methods can be assessed. Results: OHDSI has already produced findings in areas like hypertension treatment that are being incorporated into practice, and it has produced rigorous studies of COVID-19 that have aided government agencies in their treatment decisions, that have characterized the disease extensively, that have estimated the comparative effects of treatments, and that the predict likelihood of advancing to serious complications. Conclusions: OHDSI practices open science and incorporates a series of methods to address reproducibility. It has produced important results in several areas, including hypertension therapy and COVID-19 research.


SIMULATION ◽  
1966 ◽  
Vol 7 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Madeline M. Sullivan

A hybrid simulation of the guidance and navigation system of the Apollo spacecraft is underway at the Massachusetts Institute of Technology Instrumentation Laboratory. The Apollo Guidance and Navigation equipment is digital, elec tronic, and electromechanical. The guidance and naviga tion analog and digital hardware is combined in simulation with analog and digital computers so that the hardware will be subjected to dynamic conditions approaching those found in a space environment. The instrumentation of the Apollo Guidance and Navi gation System is described as well as its adaptation to the hybrid simulation. Software models are discussed to indi cate some of the varied problems considered. Digital pro cedures which are designed to support the operator and enhance the reliability of the simulation are described. In conclusion, it becomes apparent that the judicious use of computers, together with guidance and navigation hardware and software, makes it possible to simulate in real time any part of the Apollo mission from lift-off to splash-down.


2017 ◽  
Author(s):  
Jean Godot ◽  
Adil Alif ◽  
Sébastien Saudrais ◽  
Bertrand Barbedette ◽  
Cherif Larouci

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