6,188 research outputs found
SNIFFER WFD119: Enhancement of the River Invertebrate Classification Tool (RICT)
EXECUTIVE SUMMARY
Project funders/partners: Environment Agency (EA), Northern Ireland Environment Agency (NIEA), Scotland & Northern Ireland Forum for Environmental Research (SNIFFER), Scottish Environment Protection Agency (SEPA)
Background to research
The Regulatory Agencies in the UK (the Environment Agency; Scottish Environment Protection Agency; and the Northern Ireland Environment Agency) now use the River Invertebrate Classification Tool (RICT) to classify the ecological quality of rivers for Water Framework Directive compliance monitoring. RICT incorporates RIVPACS IV predictive models and is a highly capable tool written in a modern software programming language.
While RICT classifies waters for general degradation and organic pollution stress, producing assessments of status class and uncertainty, WFD compliance monitoring also requires the UK Agencies to assess the impacts of a wide range of pressures including hydromorphological and acidification stresses. Some of these pressures alter the predictor variables that current RIVPACS models use to derive predicted biotic indices. This project has sought to broaden the scope of RICT by developing one or more RIVPACS model(s) that do not use predictor variables that are affected by these stressors, but instead use alternative GIS based variables that are wholly independent of these pressures.
This project has also included a review of the wide range of biotic indices now available in RICT, identifying published sources, examining index performance, and where necessary making recommendations on further needs for index testing and development.
Objectives of research
•To remove and derive alternative predictive variables that are not affected by stressors, with particular emphasis on hydrological/acidification metric predictors.
•To construct one or more new RIVPACS model(s) using stressor independent variables.
•Review WFD reporting indices notably AWIC(species), LIFE (species), PSI & WHPT.
Key findings and recommendations :
Predictor variables and intellectual property rights :
An extensive suite of new variables have been derived by GIS for the RIVPACS reference sites that have been shown to act as stressor-independent predictor variables. These include measures of stream order, solid and drift geology, and a range of upstream catchment characteristics (e.g. catchment area, mean altitude of upstream catchment, and catchment aspect).
It is recommended that decisions are reached on which of the newly derived model(s) are implemented in RICT so that IPR issues for the relevant datasets can be quickly resolved and the datasets licensed. It is also recommended that licensing is sought for a point and click system (where the dataset cannot be reverse engineered) that is capable of calculating any of the time-invariant RIVPACS environmental predictor variables used by any of the newly derived (and existing) RIVPACS models, and for any potential users.
New stressor-independent RIVPACS models :
Using the existing predictor variables, together with new ones derived for their properties of stressor-independence, initial step-wise forward selection discriminant models suggested a range of 36 possible models that merited further testing. Following further testing, the following models are recommended for assessing watercourses affected by flow/hydromorphological and/or acidity stress:
• For flow/hydromorphological stressors that may have modified width, depth and/or substrate in GB, it is suggested that a new ‘RIVPACS IV – Hydromorphology Independent’ model (Model 24) is used (this does not use the predictor variables width, depth and substratum, but includes a suite of new stressor-independent variables).
• For acidity related stressors in GB, it is suggested that a new ‘RIVPACS IV – Alkalinity Independent’ model (Model 35) is used (this does not use the predictor variable alkalinity, but includes new stressor-independent variables).
• For flow/hydromorphological stressors and acidity related stressors in GB, it is suggested that a new ‘RIVPACS IV – Hydromorphology & Alkalinity Independent’ model (Model 13) is used (this does not use the predictor variables width, depth, substratum and alkalinity, but includes a suite of new stressor-independent variables).
• Reduced availability of appropriate GIS tools at this time has meant that no new models have been developed for Northern Ireland.
Discriminant functions and end group means have now been calculated to enable any of these models to be easily implemented in the RICT software.
Biotic indices :
The RIVPACS models in RICT can now produce expected values for a wide range of biotic indices addressing a variety of stressors. These indices will support the use of RICT as a primary tool for WFD classification and reporting of the quality of UK streams and rivers. There are however a number of outstanding issues with indices that need to be addressed:
• There is a need to develop a biotic index for assessing metal pollution.
• WFD EQR banding schemes are required for many of the indices to report what is considered an acceptable degree of stress (High-Good) and what is not (Moderate, Poor or Bad).
• A comprehensive objective testing process needs to be undertaken on the indices in RICT using UK-wide, large-scale, independent test datasets to quantify their index-stressor relationships and their associated uncertainty, for example following the approach to acidity index testing in Murphy et al., (in review) or organic/general degradation indices in Banks & McFarland (2010).
• Following objective testing, the UK Agencies should make efforts to address any index under-performance issues that have been identified, and where necessary new work should be commissioned to modify existing indices, or develop new ones where required so that indices for all stress types meet certain minimum performance criteria.
• Testing needs to be done to examine index-stressor relationships with both observed index scores and RIVPACS observed/expected ratios. Work should also be done to compare the existing RIVPACS IV and the new stressor-independent models (developed in this project) as alternative sources of the expected index values for these tests.
• Consideration should be given to assessing the extent to which chemical and biological monitoring points co-occur. Site-matched (rather than reach-matched) chemical and biological monitoring points would i) generate the substantial training datasets needed to refine or develop new indices and ii) generate the independent datasets for testing
Non-equilibrium Ionization Modeling of Petschek-type Shocks in Reconnecting Current Sheets in Solar Eruptions
Non-equilibrium ionization (NEI) is essentially required for astrophysical
plasma diagnostics once the plasma status departs from ionization equilibrium
assumptions. In this work, we perform fast NEI calculations combined with
magnetohydrodynamic (MHD) simulations and analyze the ionization properties of
a Petschek-type magnetic reconnection current sheet during solar eruptions. Our
simulation reveals Petschek-type slow-mode shocks in the classical Spitzer
thermal conduction models and conduction flux-limitation situations. The
results show that under-ionized features can be commonly found in shocked
reconnection outflows and thermal halo regions outside the shocks. The
departure from equilibrium ionization strongly depends on plasma density. In
addition, this departure is sensitive to the observable target temperature: the
high-temperature iron ions are strongly affected by NEI effects. The
under-ionization also affects the synthetic SDO/AIA intensities, which
indicates that the reconstructed hot reconnection current sheet structure may
be significantly under-estimated either for temperature or apparent width. We
also perform the MHD-NEI analysis on the reconnection current sheet in the
classical solar flare geometry. Finally, we show the potential reversal between
the under-ionized and over-ionized state at the lower tip of reconnection
current sheets where the downward outflow collides with closed magnetic loops,
which can strongly affect multiple SDO/AIA band ratios along the reconnection
current sheet
Radio Jet-Ambient Medium Interactions on Parsec Scales in the Blazar 1055+018
As part of our study of the magnetic fields of AGN we have recently observed
a large sample of blazars with the Very Long Baseline Array. Here we report the
discovery of a striking two-component jet in the source 1055+018, consisting of
an inner spine with a transverse magnetic field, and a fragmentary but distinct
boundary layer with a longitudinal magnetic field. The polarization
distribution in the spine strongly supports shocked-jet models while that in
the boundary layer suggests interaction with the surrounding medium. This
behavior suggests a new way to understand the differing polarization properties
of strong- and weak-lined blazars.Comment: LaTex; 10 pages; 6 figures; reference fix; to appear in ApJL, 518,
1999 June 2
A Randomized Controlled Trial of a Personalized Feedback Intervention for Problem Gamblers
<div><h3>Background</h3><p>Personalized feedback is a promising self-help for problem gamblers. Such interventions have shown consistently positive results with other addictive behaviours, and our own pilot test of personalized normative feedback materials for gamblers yielded positive findings. The current randomized controlled trial evaluated the effectiveness, and the sustained efficacy, of the personalized feedback intervention materials for problem gamblers.</p> <h3>Methodology/Principal Findings</h3><p>Respondents recruited by a general population telephone screener of Ontario adults included gamblers with moderate and severe gambling problems. Those who agreed to participate were randomly assigned to receive: 1) the full personalized normative feedback intervention; 2) a partial feedback that contained all the feedback information provided to those in condition 1 but without the normative feedback content (i.e., no comparisons provided to general population gambling norms); or 3) a waiting list control condition. The primary hypothesis was that problem gamblers who received the personalized normative feedback intervention would reduce their gambling more than problem gamblers who did not receive any intervention (waiting list control condition) by the six-month follow-up.</p> <h3>Conclusions/Significance</h3><p>The study found no evidence for the impact of normative personalized feedback. However, participants who received, the partial feedback (without norms) reduced the number of days they gambled compared to participants who did not receive the intervention. We concluded that personalized feedback interventions were well received and the materials may be helpful at reducing gambling. Realistically, it can be expected that the personalized feedback intervention may have a limited, short term impact on the severity of participants' problem gambling because the intervention is just a brief screener. An Internet-based version of the personalized feedback intervention tool, however, may offer an easy to access and non-threatening portal that can be used to motivate participants to seek further help online or in person.</p> <h3>Trial Registration</h3><p><a href="http://ClinicalTrials.gov">ClinicalTrials.gov</a><a href="http://www.clinicaltrials.gov/ct2/show/NCT00578357">NCT00578357</a></p> </div
Predicting the effects of unmodeled dynamics on an aircraft flight control system design using eigenspace assignment
When using eigenspace assignment to design an aircraft flight control system, one must first develop a model of the plant. Certain questions arise when creating this model as to which dynamics of the plant need to be included in the model and which dynamics can be left out or approximated. The answers to these questions are important because a poor choice can lead to closed-loop dynamics that are unpredicted by the design model. To alleviate this problem, a method has been developed for predicting the effect of not including certain dynamics in the design model on the final closed-loop eigenspace. This development provides insight as to which characteristics of unmodeled dynamics will ultimately affect the closed-loop rigid-body dynamics. What results from this insight is a guide for eigenstructure control law designers to aid them in determining which dynamics need or do not need to be included and a new way to include these dynamics in the flight control system design model to achieve a required accuracy in the closed-loop rigid-body dynamics. The method is illustrated for a lateral-directional flight control system design using eigenspace assignment for the NASA High Alpha Research Vehicle (HARV)
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