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With the evolving Global Navigation Satellite System (GNSS) landscape, the International GNSS Service (IGS) has started the Multi-GNSS Experiment (MGEX) to produce precise products for new generation systems. Various analysis centres are working on the estimation of precise orbits, clocks and bias for Galileo, Beidou and Quasi-Zenith Satellite System (QZSS) satellites. However, at the moment these products can only be used for post-processing applications. Indeed, the IGS Real-Time service only broadcasts Global Positioning System (GPS) and Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS) corrections. In this research, a simulator of multi-GNSS observations and real-time precise products has been developed to analyse the performance of GPS-only, Galileo-only and GPS plus Galileo Precise Point Positioning (PPP). The error models in the simulated orbits and clocks were based on the difference between the GPS Real-Time and the Final products. Multiple scenarios were analysed, considering different signals combined in the Ionosphere Free linear combination. Results in a simulated open area environment show better performance of the Galileo-only case over the GPS-only case. Indeed, up 33% and 29% of improvement, respectively, in the accuracy level and convergence time can be observed when using the full Galileo constellation compared to GPS. The dual constellation case provides good improvements, in particular in the convergence time (47% faster than GPS). This paper will also consider the impact of different linear combinations of the Galileo signals, and the potential of the E5 Alternative Binary Offset Carrier (AltBOC) signal. Even though it is significantly more precise than E5a, the PPP performance obtained with the Galileo E1-E5a combination is either better or similar to the one with Galileo E1-E5. The reason for this inconsistency was found in the use of the ionosphere free combination with E1. Finally, alternative methods of ionosphere error mitigation are considered in order to ensure the best possible positioning performance from the Galileo E5 signal in multi-frequency PPP.
As multi-core computing is now standard, it seems irresponsible for constraints researchers to ignore the implications of it. Researchers need to address a number of issues to exploit parallelism, such as: investigating which constraint algorithms are amenable to parallelisation; whether to use shared memory or distributed computation; whether to use static or dynamic decomposition; and how to best exploit portfolios and cooperating search. We review the literature, and see that we can sometimes do quite well, some of the time, on some instances, but we are far from a general solution. Yet there seems to be little overall guidance that can be given on how best to exploit multi-core computers to speed up constraint solving. We hope at least that this survey will provide useful pointers to future researchers wishing to correct this situation.
Patients who experience Transient Ischaemic Attack (TIA) should be assessed and treated in a specialist clinic to reduce risk of further TIA or stroke. But referrals are often delayed. We aimed to identify published studies describing pathways for emergency assessment and referral of patients with suspected TIA at first medical contact: primary care; ambulance services; and emergency department.
We conducted a scoping literature review. We searched four databases (PubMed, CINAHL, Web of Science, Scopus). We screened studies for eligibility. We extracted and analysed data to describe setting, assessment and referral processes reported in primary research on referral of suspected TIA patients directly to specialist outpatient services.
We identified eight studies in nine papers from five countries: 1/9 randomized trial; 6/9 before-and-after designs; 2/9 descriptive account. Five pathways were used by family doctors and three by Emergency Department (ED) physicians. None were used by paramedics. Clinicians identified TIA patients using a checklist incorporating the ABCD2 tool to describe risk of further stroke, online decision support tool or clinical judgement. They referred to a specialist clinic, either directly or via a telephone helpline. Anti-platelet medication was often given, usually aspirin unless contraindicated. Some patients underwent neurological and blood tests before referral and discharge. Five studies reported reduced incident of stroke at 90 days, from 6–10 percent predicted rate to 1.2-2.1 percent actual rate. Between 44 percent and 83 percent of suspected TIA cases in these studies were directly referred to stroke clinics through the pathways.
Research literature has focused on assessment and referral by family doctors and ED physicians to reduce hospitalization of TIA patients. No pathways for paramedic use were reported. Since many suspected TIA patients present to ambulance services, effective pre-hospital assessment and referral pathways are needed. We will use review results to develop a paramedic referral pathway to test in a feasibility trial.
Transient Ischaemic Attack (TIA) is a neurologic event with symptom resolution within 24 hours. Early specialist assessment of TIA reduces risk of stroke and death. National United Kingdom (UK) guidelines recommend patients with TIA are seen in specialist clinics within 24 hours (high risk) or seven days (low risk).
We aimed to develop a complex intervention for patients with low risk TIA presenting to the emergency ambulance service. The intervention is being tested in the TIER feasibility trial, in line with Medical Research Council (MRC) guidance on staged development and evaluation of complex interventions.
We conducted three interrelated activities to produce the TIER intervention:
•Survey of UK Ambulance Services (n = 13) to gather information about TIA pathways already in use
•Scoping review of literature describing prehospital care of patients with TIA
•Synthesis of data and definition of intervention by specialist panel of: paramedics; Emergency Department (ED) and stroke consultants; service users; ambulance service managers.
The panel used results to define the TIER intervention, to include:
1.Protocol for paramedics to assess patients presenting with TIA and identify and refer low risk patients for prompt (< 7day) specialist review at TIA clinic
2.Patient Group Directive and information pack to allow paramedic administration of aspirin to patients left at home with referral to TIA clinic
3.Referral process via ambulance control room
4.Training package for paramedics
5.Agreement with TIA clinic service provider including rapid review of referred patients
We followed MRC guidance to develop a clinical intervention for assessment and referral of low risk TIA patients attended by emergency ambulance paramedic. We are testing feasibility of implementing and evaluating this intervention in the TIER feasibility trial which may lead to fully powered multicentre randomized controlled trial (RCT) if predefined progression criteria are met.
The development of algorithms for agile science and autonomous exploration has been pursued in contexts ranging from spacecraft to planetary rovers to unmanned aerial vehicles to autonomous underwater vehicles. In situations where time, mission resources and communications are limited and the future state of the operating environment is unknown, the capability of a vehicle to dynamically respond to changing circumstances without human guidance can substantially improve science return. Such capabilities are difficult to achieve in practice, however, because they require intelligent reasoning to utilize limited resources in an inherently uncertain environment. Here we discuss the development, characterization and field performance of two algorithms for autonomously collecting water samples on VALKYRIE (Very deep Autonomous Laser-powered Kilowatt-class Yo-yoing Robotic Ice Explorer), a glacier-penetrating cryobot deployed to the Matanuska Glacier, Alaska (Mission Control location: 61°42′09.3″N 147°37′23.2″W). We show performance on par with human performance across a wide range of mission morphologies using simulated mission data, and demonstrate the effectiveness of the algorithms at autonomously collecting samples with high relative cell concentration during field operation. The development of such algorithms will help enable autonomous science operations in environments where constant real-time human supervision is impractical, such as penetration of ice sheets on Earth and high-priority planetary science targets like Europa.
Reducing the excess nutrient and sediment pollution that is damaging habitat and diminishing recreational experiences in coastal estuaries requires actions by people and communities that are within the boundaries of the watershed but may be far from the resource itself, thus complicating efforts to understand tradeoffs associated with pollution control measures. Such is the case with the Chesapeake Bay, one of the most iconic water resources in the United States. All seven states containing part of the Chesapeake Bay Watershed were required under the Clean Water Act to submit detailed plans to achieve nutrient and sediment pollution reductions. The implementation plans provide information on the location and type of management practices making it possible to project not only water quality improvements in the Chesapeake Bay but also improvements in freshwater lakes throughout the watershed, which provide important ancillary benefits to people bearing the cost of reducing pollution to the Bay but unlikely to benefit directly. This paper reports the results of a benefits study that links the forecasted water quality improvements to ecological endpoints and administers a stated preference survey to estimate use and nonuse value for aesthetic and ecological improvements in the Chesapeake Bay and watershed lakes. Our results show that ancillary benefits and nonuse values account for a substantial proportion of total willingness to pay and would have a significant impact on the net benefits of pollution reduction programs.
Place has always been central to studies of language, variation and change. Since the eighteenth century, dialectologists have been mapping language features according to boundaries - both physical and institutional. In the twentieth century, variationist sociolinguists developed techniques to correlate language use with speakers' orientations to place. More recently, perceptual dialectologists are examining the cognitive and ideological processes involved in language-place correlations and working on ways to understand how speakers mentally process space. Bringing together research from across the field of language variation, this volume explores the extent of twenty-first century approaches to place. It features work from both established and influential scholars, and up and coming researchers, and brings language variation research up to date. The volume focuses on four key areas of research: processes of language variation and change across time and space; methods and datasets for regional analysis; perceptions of the local in language research; and ideological representations of place.