6,387 research outputs found
Agent Street: An Environment for Exploring Agent-Based Models in Second Life
Get PDFUrban models can be seen on a continuum between iconic and symbolic. Generally speaking, iconic models are physical versions of the real world at some scaled down representation, while symbolic models represent the system in terms of the way they function replacing the physical or material system by some logical and/or mathematical formulae. Traditionally iconic and symbolic models were distinct classes of model but due to the rise of digital computing the distinction between the two is becoming blurred, with symbolic models being embedded into iconic models. However, such models tend to be single user. This paper demonstrates how 3D symbolic models in the form of agent-based simulations can be embedded into iconic models using the multi-user virtual world of Second Life. Furthermore, the paper demonstrates Second Life\'s potential for social science simulation. To demonstrate this, we first introduce Second Life and provide two exemplar models; Conway\'s Game of Life, and Schelling\'s Segregation Model which highlight how symbolic models can be viewed in an iconic environment. We then present a simple pedestrian evacuation model which merges the iconic and symbolic together and extends the model to directly incorporate avatars and agents in the same environment illustrating how \'real\' participants can influence simulation outcomes. Such examples demonstrate the potential for creating highly visual, immersive, interactive agent-based models for social scientists in multi-user real time virtual worlds. The paper concludes with some final comments on problems with representing models in current virtual worlds and future avenues of research.Agent-Based Modelling, Pedestrian Evacuation, Segregation, Virtual Worlds, Second Life
Conservative management of oesophageal soft food bolus impaction
Get PDFBackground: Impaction of a soft food bolus in the oesophagus causes dysphagia and regurgitation. If the bolus does not pass spontaneously, then the patient is at risk of aspiration, dehydration, perforation, and death. Definitive management is with endoscopic intervention, recommended within 24 hours. Prior to endoscopy, many patients undergo a period of observation, awaiting spontaneous disimpaction, or may undergo enteral or parenteral treatments to attempt to dislodge the bolus. There is little consensus as to which of these conservative strategies is safe and effective to be used in this initial period, before resorting to definitive endoscopic management for persistent impaction.
Objectives: To evaluate the efficacy of non-endoscopic conservative treatments in the management of soft food boluses impacted within the oesophagus.
Search methods: We searched the following databases, using relevant search terms: Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase and CINAHL. The date of the search was 18 August 2019. We screened the reference lists of relevant studies and reviews on the topic to identify any additional studies.
Selection criteria: We included randomised controlled trials of the management of acute oesophageal soft food bolus impaction, in adults and children, reporting the incidence of disimpaction (confirmed radiologically or clinically by return to oral diet) without the need for endoscopic intervention. We did not include studies focusing on sharp or solid object impaction.
Data collection and analysis: We used standard methodological procedures recommended by Cochrane.
Main results: We identified 890 unique records through the electronic searches. We excluded 809 clearly irrelevant records and retrieved 81 records for further assessment. We subsequently included one randomised controlled trial that met the eligibility criteria, which was conducted in four Swedish centres and randomised 43 participants to receive either intravenous diazepam followed by glucagon, or intravenous placebos. The effect of the active substances compared with placebo on rates of disimpaction without intervention is uncertain, as the numbers from this single study were small, and the rates were similar (38% versus 32%; risk ratio 1.19, 95% confidence interval 0.51 to 2.75, P = 0.69). The certainty of the evidence using GRADE for this outcome is low. Data on adverse events were lacking.
Authors' conclusions: There is currently inadequate data to recommend the use of any enteral or parenteral treatments in the management of acute oesophageal soft food bolus impaction. There is also inadequate data regarding potential adverse events from the use of these treatments, or from potential delays in definitive endoscopic management. Caution should be exercised when using any conservative management strategies in these patients.This article is freely available via Open Access. Click on the Publisher URL to access it via the publisher's site.published versio
Supplemental Environmental Projects’ Wild Ride is a Call for Legislative Action to Protect a Valuable Negotiation Tool
Get PDFIn March 2020, the head of the Department of Justice’s Environmental Natural Resources Division (“DOJ ENRD”) issued a decision that fundamentally altered the federal government’s ability to address environmental harm. The decision removed a valuable tool from the negotiation toolbox that Department of Justice (“DOJ”) attorneys used for decades when negotiating settlements in civil enforcement of federal environmental protection laws. This policy change had the potential to significantly impact resolution of complex environmental disputes. In February 2021, the new Chief of the DOJ ENRD rescinded the 2020 memo in response to an executive order from newly elected President Joe Biden. While the rescinding of the 2020 memo does restore the pre-2020 status quo, both actions show the power that executive leadership has to unilaterally alter the course of environmental dispute resolution. The tool the 2020 memo prohibited is called a Supplemental Environmental Project (“SEP”)
Review of Naomi Eilan, Christoph Hoerl, Teresa McCormack & Johannes Roessler (eds.), Joint Attention: Communication and Other Minds
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