524,617 research outputs found
A typology of marine and estuarine hazards and risks as vectors of change : a review for vulnerable coasts and their management
This paper illustrates a typology of 14 natural and anthropogenic hazards, the evidence for their causes and consequences for society and their role as vectors of change in estuaries, vulnerable coasts and marine areas. It uses hazard as the potential that there will be damage to the natural or human system and so is the product of an event which could occur and the probability of it occurring whereas the degree of risk then relates to the amount of assets, natural or societal, which may be affected. We give long- and short-term and large- and small-scale perspectives showing that the hazards leading to disasters for society will include flooding, erosion and tsunamis. Global examples include the effects of wetland loss and the exacerbation of problems by building on vulnerable coasts. Hence we emphasise the importance of considering hazard and risk on such coasts and consider the tools for assessing and managing the impacts of risk and hazard. These allow policy-makers to determine the consequences for natural and human systems. We separate locally-derived problems from large-scale effects (e.g. climate change, sea-level rise and isostatic rebound); we emphasise that the latter unmanaged exogenic pressures require a response to the consequences rather than the causes whereas within a management area there are endogenic managed pressures in which we address both to causes and consequences. The problems are put into context by assessing hazards and the conflicts between different uses and users and hence the management responses needed. We emphasise that integrated and sustainable management of the hazards and risk requires 10-tenets to be fulfilled
Multi-objective optimization shapes ecological variation
Ecological systems contain a huge amount of quantitative variation between and within species and locations, which makes it difficult to obtain unambiguous verification of theoretical predictions. Ordinary experiments consider just a few explanatory factors and are prone to providing oversimplified answers because they ignore the complexity of the factors that underlie variation. We used multi-objective optimization (MO) for a mechanistic analysis of the potential ecological and evolutionary causes and consequences of variation in the life-history traits of a species of moth. Optimal life-history solutions were sought for environmental conditions where different life stages of the moth were subject to predation and other known fitness-reducing factors in a manner that was dependent on the duration of these life stages and on variable mortality rates. We found that multi-objective optimal solutions to these conditions that the moths regularly experience explained most of the life-history variation within this species. Our results demonstrate that variation can have a causal interpretation even for organisms under steady conditions. The results suggest that weather and species interactions can act as underlying causes of variation, and MO acts as a corresponding adaptive mechanism that maintains variation in the traits of organisms
Exploring the causes of adverse events in hospitals and potential prevention strategies
Objectives
To examine the causes of adverse events
(AEs) and potential prevention strategies to minimise the
occurrence of AEs in hospitalised patients.
Methods
For the 744 AEs identified in the patient record
review study in 21 Dutch hospitals, trained reviewers
were asked to select all causal factors that contributed
to the AE. The results were analysed together with data
on preventability and consequences of AEs. In addition,
the reviewers selected one or more prevention strategies
for each preventable AE. The recommended prevention
strategies were analysed together with four general
causal categories: technical, human, organisational and
patient-related factors.
Results
Human causes were predominantly involved in
the causation of AEs (in 61% of the AEs), 61% of those
being preventable and 13% leading to permanent
disability. In 39% of the AEs, patient-related factors were
involved, in 14% organisational factors and in 4%
technical factors. Organisational causes contributed
relatively often to preventable AEs (93%) and AEs
resulting in permanent disability (20%). Recommended
strategies to prevent AEs were quality assurance/peer
review, evaluation of safety behaviour, training and
procedures. For the AEs with human and patient-related
causes, reviewers predominantly recommended quality
assurance/peer review. AEs caused by organisational
factors were considered preventable by improving
procedures.
Discussion
Healthcare interventions directed at human
causes are recommended because these play a large
role in AE causation. In addition, it seems worthwhile to
direct interventions on organisational causes because the
AEs they cause are nearly always believed to be
preventable. Organisational factors are thus relatively
easy to tackle. Future research designs should allow
researchers to interview healthcare providers that were
involved in the event, as an additional source of
information on contributing factors.
Hermeneutic single-case efficacy design
In this article, I outline hermeneutic single-case efficacy design (HSCED), an interpretive approach to evaluating treatment causality in single therapy cases. This approach uses a mixture of quantitative and qualitative methods to create a network of evidence that first identifies direct demonstrations of causal links between therapy process and outcome and then evaluates plausible nontherapy explanations for apparent change in therapy. I illustrate the method with data from a depressed client who presented with unresolved loss and anger issues
Parameter analysis of copper-nickel-tungsten prepared via powder metallurgy process for electrical discharge machining of polycrystalline diamond
Polycrystalline Diamond (PCD) tools have an outstanding wear resistance. The electric conductivity of PCD caused by the conductive binding material (Cobalt) makes it possible to machine PCD tools with EDM. Electrode used in EDM of PCD must have better porosity, electrical and thermal conductivity. Therefore, this research presents the works in production of Cu-Ni-W electrode by powder metallurgy route. Production of powder metallurgy parts involve mixing of the powder with additives or lubricants, compacting the mixture and heating the green compacts in an Argon gas furnace so the particle bond to each other. Two levels of full factorial with six centre points and two replication technique was used to study the influence of main and interaction effects of the powder metallurgy parameter. There were four factors involved in this experiment. Factor A which is Type of Cu-Ni; Type A and Type B was defined as categorical factor. Factor B in which Composition of W; 5 Wt.%, 15 Wt. % and 25 Wt.%, was defined as numerical factor. Factor C which is the Compaction load; 7, 8 and 9 tonne and Factor D which is Sintering temperature; 635 â, 685 â and 735 â were also defined as numerical factor. Optical Microscope, Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) was used to analysed the microstructure and surface morphology of Cu-Ni-W electrode. The best parameter combination to produced better porosity, electrical and thermal conductivity for both Type A and Type B was 5 Wt.% of W, compaction load at 9 tonne and sintering temperature at 735â. The best response for Type A is 12.65% of porosity, 14.40 IACS% of electrical conductivity and 413.26 W/m.â of thermal conductivity. While that, the best response for Type B were 9.36% of porosity, 16.66 IACS% of electrical conductivity and 345.21W/m.â of thermal conductivity. From the calculation of Maxwellâs Equation, Type A and Type B had the highest electrical conductivity of 58.48 IACS% and 77.35 IACS% respectively at W content of 5Wt.%. Type A and Type B also had the highest thermal conductivity of 369.86 W/m.â and 310.24 W/m.â respectively at W content of 5 Wt.%. Besides that, thermal conductivity also increased with the temperature increased until 450â
An Interaction Model for Simulation and Mitigation of Cascading Failures
In this paper the interactions between component failures are quantified and
the interaction matrix and interaction network are obtained. The quantified
interactions can capture the general propagation patterns of the cascades from
utilities or simulation, thus helping to better understand how cascading
failures propagate and to identify key links and key components that are
crucial for cascading failure propagation. By utilizing these interactions a
high-level probabilistic model called interaction model is proposed to study
the influence of interactions on cascading failure risk and to support online
decision-making. It is much more time efficient to first quantify the
interactions between component failures with fewer original cascades from a
more detailed cascading failure model and then perform the interaction model
simulation than it is to directly simulate a large number of cascades with a
more detailed model. Interaction-based mitigation measures are suggested to
mitigate cascading failure risk by weakening key links, which can be achieved
in real systems by wide area protection such as blocking of some specific
protective relays. The proposed interaction quantifying method and interaction
model are validated with line outage data generated by the AC OPA cascading
simulations on the IEEE 118-bus system.Comment: Accepted by IEEE Transactions on Power System
An approach to safety analysis of clinical workflows
A clinical workflow considers the information and processes that are involved in providing a clinical service. They are safety critical since even minor faults have the potential to propagate and consequently cause harm to a patient, or even for a patient's life to be lost. Experiencing these kinds of failures has a destructive impact on all the involved parties. Due to the large number of processes and tasks included in the delivery of a clinical service, it can be difficult to determine the individuals or the processes that are responsible for adverse events, since such an analysis is typically complex and slow to do manually. Using automated tools to carry out an analysis can help in determining the root causes of potential adverse events and consequently help in avoiding preventable errors through either the alteration of existing workflows, or the design of a new workflow. This paper describes a technical approach to safety analysis of clinical workflows, utilising a safety analysis tool (Hierarchically-Performed Hazard Origin and Propagation Studies (HiP-HOPS)) that is already in use in the field of mechanical systems. The paper then demonstrates the applicability of the approach to clinical workflows by applying it to analyse the workflow in a radiology department. We conclude that the approach is applicable to this area of healthcare and provides a mechanism both for the systematic identification of adverse events and for the introduction of possible safeguards in clinical workflows
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