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Understanding the reliability of hazardous organizations and their protective systems is central to understanding the risk they produce. Work on "high reliability organization" has done much to illuminate the conditions in which social organization becomes reliable in highly demanding conditions. But risk depends just as much on how relying entities do their relying as it does on the reliability of the entities they rely on. Patterns of relying are often opaque in sociotechnical systems, and processes of relying and being relied on are mutually influencing in complex ways, so the relationship between relying and risk may not be at all obvious. This study was an attempt to study relying as a social practice, in particular analyzing how it had ecological validity in a social organization-how practice was responsive to the conditions in which it took place. This involved observational fieldwork and inductive, qualitative analysis on an offshore oil and gas production platform that was nearing the end of its design life and undergoing refurbishment. The analysis produced four main categories of ecological validity: responsiveness to formal organization, responsiveness to situational contingency, responsiveness to information asymmetry, and responsiveness to sociomateriality. This ecological validity of relying practice should be a primary focus of risk identification, assessing how relying can become mismatched to reliability in certain ways, both when relying practice is responsive to circumstances and when it is not.

Minimum Variance (MV) beamforming is known to improve the lateral resolution of ultrasound images and enhance the separation of isolated point scatterers. This paper aims to evaluate the adaptive beamformer’s performance with flowing microbubbles (MBs) which are relevant to super-resolution ultrasound imaging. Simulations using point scatterer data from single emissions were complemented by an experimental investigation performed using a capillary tube phantom and the Synthetic Aperture Real-time Ultrasound System (SARUS). The MV performance was assessed by the minimum distance that allows the display of two scatterers positioned side-by-side, the lateral Full-Width-at-Half-Maximum (FWHM), and the Peak-Sidelobe-Level (PSL). In the tube, scatterer responses separated by down to $196~\mu \text{m}$ (or $1.05\lambda $ ) were distinguished by the MV method, while the standard Delay-And-Sum (DAS) beamformers were unable to achieve such separation. Up to ninefold FWHM decrease was also measured in favor of the MV beamformer for individual echoes from MBs. The lateral distance between two scatterers impacted on their FWHM value, and additional differences in the scatterers’ axial or out-of-plane position also impacted on their size and appearance. The simulation and experimental results were in agreement in terms of lateral resolution. The point scatterer study showed that the proposed MV imaging scheme provided clear resolution benefits compared to DAS. Current super-resolution methods mainly depend on DAS beamformers. Instead, the use of the MV method may provide a larger number of detected, and potentially better localized, MB scatterers.

Over the last decade, we have seen a shift in the focus of cyber attacks, moving from traditional IT systems to include more specialised Industrial Control Systems (ICS), often found within Critical National Infrastructure (CNI). Despite a push from governments to introduce appropriate legislation and guidance for such systems, operators of ICS and CNI still face multiple challenges in their cyber incident response and recovery capabilities, a theme that is often viewed as a last line of defence in minimising the impact of cyber attacks. This paper provides the following contributions: Firstly, we analyse existing standards and guidelines within cyber incident response and recovery. This analysis provides a structure on key response and recovery phases, a foundational understanding of associated requirements for these, and identifies challenges that could affect the quality of in-practice response and recovery capabilities. Using this analysis as a baseline, we examine how response and recovery processes are currently undertaken in practice through engagement with UK-based CNI operators and regulators. Secondly, as a starting point towards improving identified challenges in existing standards and guidelines and their use in practice, we propose a framework, built using the outputs identified from the document analysis and the stakeholder engagement, for use by operators to support them in assessing and improving their response and recovery capabilities.

In this chapter, the authors introduce and describe the notion of resilience for networked computer systems. Central to our viewpoint is that such systems need to be designed and engineered to have resilience as a major property. This is in contrast to systems found in nature that may already have resilience, in some cases through a process of evolution. The networked systems on which the authors focus will generally be built using Internet technologies, which the authors briefly introduce. Engineered systems also require attention to their people and organizational aspects to produce a resilient outcome. Therefore, the material we present here is intended to combine the technological, organizational, and people aspects of resilient systems design and operation, with reference to utility networks—specifically to an electricity distribution case study. While the field of engineered resilience is advancing quickly and involves multiple systems, much of what is in this chapter still remains in the research phase, and has yet to be widely adopted in practice.

This paper explores a system that attempts to maximize high school students’ sense of choice when selecting elective subjects. We propose that individual schools can tailor the combinations of subjects they offer in order to maximize the number of prospective students who can study their preferred subjects, potentially increasing enrol- ment numbers and academic outcomes while also reducing administrative overheads. We analyze the underlying computational problem encountered in this task and describe a suitable AI-based optimization algorithm that we have made available for free download. We also discuss some outcomes of using this method on a small number of case study schools.

Human and organizational issues are able to create both vulnerabilities and resilience to threats. In this chapter, we investigate human and organizational factors, conducted through ethnographic studies of operators and sets of interviews with staff responsible for security, reliability and quality in two different organizations, which own and operate utility networks. Ethnography is a qualitative aspect of research that emphasizes the detailed observation and interviewing of people in naturally occurring settings. Our findings indicate that ‘human error’ forms the biggest threat to cyber-security and that there is a need for security operations centres to document all cyber-security incidents. Also, we conclude that it will always be insufficient to assess mental security models in terms of their technical correctness, as it is sometimes more important to know how well they represent prevailing social issues and requirements. As a practical recommendation from this work, we suggest that utility organizations (and others) engage in penetration testing and perhaps other forms of vulnerability analysis, not only to discover specific vulnerabilities but also to learn more about the mental models they use.

Quality assurance phantoms are made of tissue-mimicking materials (TMMs) the acoustic properties of which mimic those of soft tissue. However, the acoustic properties of many soft tissue types have not been measured at ultrasonic frequencies >9 MHz. With the increasing use of high-frequency ultrasound for both clinical and pre-clinical applications, it is of increasing interest to ensure that TMMs accurately reflect the acoustic properties of soft tissue at these higher frequencies. In this study, the acoustic properties of ex vivo brain, liver and kidney samples from 50 mice were assessed in the frequency range 12–32 MHz. Measurements were performed within 6 min of euthanasia in a phosphate-buffered saline solution maintained at 37.2 ± 0.2 °C. The measured mean values for the speed of sound for all organs were found to be higher than the International Electrotechnical Commission guideline recommended value for TMMs. The attenuation coefficients measured for brain, liver and kidney samples were compared with the results of previous studies at lower frequencies. Only the measured kidney attenuation coefficient was found to be in good agreement with the International Electrotechnical Commission guideline. The information provided in this study can be used as a baseline on which to manufacture a TMM suitable for high-frequency applications.

Super-resolution ultrasound imaging deploys contrast microbubble (MB) tracking to delineate micro-vessels. The potential application spans to a large number of diseases which cause compromised vascular networks. Current super-resolution methods are mainly based on image processing. Sharpness-based localization is an alternative to such methods for scatterer localization in the axial direction, and can be implemented using both image and signal data. A 7-MHz, linear ultrasound transducer $(\lambda = 212 \mu \mathrm{m})$ and the Synthetic Aperture Real-time Ultrasound System (SARUS) were used to image a wire-target (point scatterer) at different depth positions. The method predicts a depth estimate and its difference from the true scatterer position demonstrates its accuracy. This average difference can be as low as $27.41 \mu \mathrm{m}($ or $\approx \lambda /8)$ for the image-derived sharpness and drops to $2.84 \mu \mathrm{m}($ or $\approx \quad \lambda /75)$ when the signals are used. These figures were calculated for a 8 mm depth range, which can be extended subject to further processing. The process of image formation involves interpolation and logarithmic compression that reduce the overall performance of the method when using image data. Such details may be significant when reconstructing micro-vessels of the order of tens of micrometres in diameter.

Super-resolution ultrasound mostly uses image-based methods for the localization of single scatterers. These methods are largely based on the center of mass (COM) calculation. Sharpness-based localization is an alternative to COM for scatterer localization in the axial direction. Simulated ultrasound point scatterer data (center frequency $f_{0} = 7$ MHz and wavelength $\lambda = 220\,\,\mu \text{m}$ ) showed that the normalized sharpness method can provide scatterer axial localization with an accuracy down to $2~\mu \text{m}$ ( $< 0.01\lambda $ ), which is a two-order of magnitude improvement compared to that achievable by the conventional imaging ( $\approx \lambda $ ), and a five-fold improvement compared to the COM estimate ( $\approx 10~\mu \text{m}$ or $0.05\lambda $ ). Similar results were obtained experimentally using wire-target data acquired by the Synthetic Aperture Real-time Ultrasound System. The performance of the proposed method was also found to be consistent across different types of ultrasound transmission. The localization precision deteriorates in the presence of noise, but even in very low signal-to-noise ratio (SNR = 0 dB), the uncertainty was not higher than $6~\mu \text{m}$ , which outperforms the COM estimate. The method can be implemented in image data as well as by using the raw signals. It is proposed that the signal-derived localization should replace the image-based equivalent, as it provides at least 10 times improved accuracy.

Background Higher prevalence of selected birth defects has been reported among American Indian/Alaska Native (AI/AN) newborns. We examine whether known risk factors for birth defects explain the higher prevalence observed for selected birth defects among this population. Methods Data from 12 population-based birth defects surveillance systems, covering a birth population of 11 million from 1999 to 2007, were used to examine prevalence of birth defects that have previously been reported to have elevated prevalence among AI/ANs. Prevalence ratios (PRs) were calculated for non-Hispanic AI/ANs and any AI/ANs (regardless of Hispanic ethnicity), adjusting for maternal age, education, diabetes, and smoking, as well as type of case-finding ascertainment surveillance system. Results After adjustment, the birth prevalence of two of seven birth defects remained significantly elevated among AI/ANs compared to non-Hispanic whites (NHWs): anotia/microtia was almost threefold higher, and cleft lip +/- cleft palate was almost 70% higher compared to NHWs. Excluding AI/AN subjects who were also Hispanic had only a negligible impact on adjusted PRs. Conclusions Additional covariates accounted for some of the elevated birth defect prevalences among AI/ANs compared to NHWs. Exclusion of Hispanic ethnicity from the AI/AN category had little impact on birth defects prevalences in AI/ANs. NHWs serve as a viable comparison group for analysis. Birth defects among AI/ANs require additional scrutiny to identify modifiable risk and protective factors.