Templates as heuristics for proving properties of medical devices

This paper briefly describes how property templates have been used to analyse and explore the interactive behaviour of a specific medical device (an IV infusion pump). It is proposed that interactive devices that satisfy properties based on the templates are easier and safer to use. The property templates act as heuristics for the development of suitable properties tailored to the details of the particular device. A mathematically based approach is used to prove that a specification of the device satisfies the properties

Verification of User Interface Software: The Example of Use-Related Safety Requirements and Programmable Medical Devices

One part of demonstrating that a device is acceptably safe, often required by regulatory standards, is to show that it satisfies a set of requirements known to mitigate hazards. This paper is concerned with how to demonstrate that a user interface software design is compliant with use-related safety requirements. A methodology is presented based on the use of formal methods technologies to provide guidance to developers about addressing three key verification challenges: 1) how to validate a model, and show that it is a faithful representation of the device; 2) how to formalize requirements given in natural language, and demonstrate the benefits of the formalization process; and 3) how to prove requirements of a model using readily available formal verification tools. A model of a commercial device is used throughout the paper to demonstrate the methodology. A representative set of requirements are considered. They are based on US Food and Drug Administration (FDA) draft documentation for programmable medical devices, and on best practice in user interface design illustrated in relevant international standards. The methodology aims to demonstrate how to achieve the FDA's agenda of using formal methods to support the approval process for medical devices.This work was supported by the EPSRC research Grant EP/G059063/1: CHI+MED (Computer-Human Interaction for Medical Devices). The work of P. Masci and J.C. Campos was supported under Project NORTE-01-0145-FEDER-000016, financed by the North Portugal Regional Operational Programme (NORTE 2020), through the PORTUGAL 2020 Partnership Agreement, and through the European Regional Development Fund (ERDF)

A simple ZVI-Fenton pre-oxidation using steel-nails for NOM degradation in water treatment

The feasibility of a heterogeneous Fenton Process (ZVI/H2O2) using commercial low-carbon-steel nails as the Zero-Valent Iron (ZVI) source was evaluated for the first time for the removal of natural organic matter (NOM) from natural surface waters with distinct physico-chemical characteristics. The synergistic effect of ZVI nails and H2O2 on the process was confirmed. Results showed similar removal efficiencies of NOM in water samples from Thames river and Regent's Park lake (both in London, UK) (under initial pH 3.5 and 100% excess of H2O2 dosage), reaching dissolved organic carbon (DOC) removals of 61.6% ± 3.0 and 59.6% ± 4.7, and UV254 removals of 79.9% ± 0.6 and 77.3 ± 6.2, respectively with 60 min of batch reaction time. ZVI nail surface characterization by scanning electron microscopy (SEM), X-ray energy-dispersive spectroscopy (EDS), and X-ray photoemission spectroscopy (XPS) revealed the formation of a passivating oxide-hydroxide layer on the nail during the reaction, which reduces its surface activity with 20% in continuous use. Results indicate that ZVI/H2O2 process using commercial iron nails is a promising pre-oxidation step for drinking water treatment. The low cost of commercial nails together with the facility of separating them from the water are the main advantages for the application of this process in remote regions with limitations in infrastructure and/or finance

Impacts of behavioural factors on the household water consumption in urban areas

Gaps in understanding what influences household water consumption has led water providers failing to convince their customers to report sustainable practices. To this end, the present study aimed to answer the question, “How do social and cultural factors influence water consumption in urban areas”? The response to this issue has been identified through an investigation that involved a group of selected socio-cultural factors, whose analysis was based on collected survey data from participants in Lagos-Nigeria, Salvador-Brazil, Sao Paulo-Brazil, London-UK and Los Angeles-USA. The Capability-Opportunity-Motivation-Behaviour (COM-B) model was used as a data analysis framework to identify influences. The investigation revealed that Motivation is the most reported driver of water consumption. In a scale from 0 (lowest) to 5 (highest), this component presented the most significant scores in Lagos (3.93), Salvador (4.13), Sao Paulo (3.88), London (4.13) and Los Angeles (3.59). The Capability dimension had the second-highest weight in Lagos, Salvador, Sao Paulo, and Los Angeles, with scores of 2.80, 3.60, 3.60 and 3.20, respectively. Participants from London have Opportunity (score= 2.88) as the second influential pillar in water consumption. These findings are aimed at helping to best drive water saving practices by gaining insight into factors underpinning water consumption in a structured manner

Response of spectral reflectances and vegetation indices on varying juniper cone densities

Juniper trees are widely distributed throughout the world and are common sources of allergies when microscopic pollen grains are transported by wind and inhaled. In this study, we investigated the spectral influences of pollen-discharging male juniper cones within a juniper canopy. This was done through a controlled outdoor experiment involving ASD FieldSpec Pro Spectroradiometer measurements over juniper canopies of varying cone densities. Broadband and narrowband spectral reflectance and vegetation index (VI) patterns were evaluated as to their sensitivity and their ability to discriminate the presence of cones. The overall aim of this research was to assess remotely sensed phenological capabilities to detect pollen-bearing juniper trees for public health applications. A general decrease in reflectance values with increasing juniper cone density was found, particularly in the Green (545-565 nm) and NIR (750-1,350 nm) regions. In contrast, reflectances in the shortwave-infrared (SWIR, 2,000 nm to 2,350 nm) region decreased from no cone presence to intermediate amounts (90 g/m2) and then increased from intermediate levels tothe highest cone densities (200 g/m2). Reflectance patterns in the Red (620-700 nm) were more complex due to shifting contrast patterns in absorptance between cones and juniper foliage, where juniper foliage is more absorbing than cones only within the intense narrowband region of maximum chlorophyll absorption near 680 nm. Overall, narrowband reflectances were more sensitive to cone density changes than the equivalent MODIS broadbands. In all VIs analyzed, there were significant relationships with cone density levels, particularly with the narrowband versions and the two-band vegetation index (TBVI) based on Green and Red bands, a promising outcome for the use of phenocams in juniper phenology trait studies. These results indicate that spectral indices are sensitive to certain juniper phenologic traits that can potentially be used for juniper cone detection in support of public health applications. © 2013 by the authors

Development of dependable controllers in the context of machines design

Proceedings of ICMD 2013In the domain of machines' design, one of the most important issues to solve is related with the controller's design, mainly, guaranteeing that the machine will behave as expected. In order to achieve a dependable controller, some steps can be considered, such as the formalization of its specification - before being translated to the program that will be inserted in the controller device - and the respective analysis and verification. Nowadays, some formal analysis techniques, such as formal verification, are used to achieve this purpose. The dependability of a controller, however, is impacted by its execution context. This paper proposes an approach for the formal verification of the specification of mechatronic system's controllers, which considers, on the formal verification tasks, the behavior of the plant and the behavior of the Human Machine Interface of the Mechatronic system. Some conclusions are extrapolated for other systems of the same kind

Degradation of Metaldehyde in Aqueous Solution by Nano-Sized Photocatalysts and Granular Activated Carbon

Metaldehyde has been detected in drinking water system in relatively high concentration exceeding European water quality standard. In order to address this problem, the aim of this project was to treat metaldehyde aqueous solution by advanced oxidation processes (AOPs) and granular activated carbon (GAC) column. Ten novel materials were tested for degradation rates of metaldehyde under ultraviolet light irradiation (UVC). For treatment of 1 mg/L metaldehyde solution by AOPs, the highest degradation rate is 16.59% under UVC light with the aid of nitrogen doped titanium dioxide coated graphene (NTiO2/Gr). Furthermore, 0.5 mg/L is the optimal concentration for degradation of metaldehyde with N–TiO2/Gr under UVC light. Apart from that, the lifetime of GAC column could be elongated on condition that metaldehyde has been treated by AOPs previously. Hence, combination of AOPs and GAC column is promising in treating water containing metaldehyde

Reusing models and properties in the analysis of similar interactive devices

"Published online: 03 Apr. 2013"The paper is concerned with the comparative analysis of interactive devices. It compares two devices by checking a battery of template properties that are designed to explore important interface characteristics. The two devices are designed to support similar tasks in a clinical setting but differ in a number of respects as a result of judgements based on a range of considerations including software. Variations between designs are often relatively subtle and do not always become evident through even relatively thorough user testing. Notwithstanding their subtlety these differences may be important to the safety or usability of the device. The illustrated approach uses formal techniques to provide the analysis. This means that similar analysis can be applied systematically.This project was partly funded by the CHI+MED project: Multidisciplinary Computer Human Interaction Research for the design and safe use of interactive medical devices (UK EPSRC Grant EP/G059063/1). Patrick Oladimeji of Swansea University provided help with the Alaris pump and Chris Vincent of UCL provided access to the B. Braun simulation. We are grateful to reviewers for helpful comments

Insights into the unique characteristics of hepatitis C virus genotype 3 revealed by development of a robust sub-genomic DBN3a replicon

Hepatitis C virus (HCV) is an important human pathogen causing 400 000 chronic liver disease-related deaths annually. Until recently, the majority of laboratory-based investigations into the biology of HCV have focused on the genotype 2 isolate, JFH-1, involving replicons and infectious cell culture systems. However, genotype 2 is one of eight major genotypes of HCV and there is great sequence variation among these genotypes (>30 % nucleotide divergence). In this regard, genotype 3 is the second most common genotype and accounts for 30 % of global HCV cases. Further, genotype 3 is associated with both high levels of inherent resistance to direct-acting antiviral (DAA) therapy, and a more rapid progression to chronic liver diseases. Neither of these two attributes are fully understood, thus robust genotype 3 culture systems to unravel viral replication are required. Here we describe the generation of robust genotype 3 sub-genomic replicons (SGRs) based on the adapted HCV NS3-NS5B replicase from the DBN3a cell culture infectious clone. Such infectious cell culture-adaptive mutations could potentially promote the development of robust SGRs for other HCV strains and genotypes. The novel genotype 3 SGRs have been used both transiently and to establish stable SGR-harbouring cell lines. We show that these resources can be used to investigate aspects of genotype 3 biology, including NS5A function and DAA resistance. They will be useful tools for these studies, circumventing the need to work under the biosafety level 3 (BSL3) containment required in many countries