Nuclear Energy in the UK: Safety Culture and Industrial Organisation

In this paper we seek to explore the relationship between professionalism and nuclear safety in the UK. We consider the history of civil nuclear energy in Britain and the near complete shift in emphasis from state owned enterprises to the private sector. We show how in recent years government has acknowledged that a truly liberalised electricity industry is unable to deliver the construction of new nuclear power stations as part of a future low carbon electricity system. Throughout, however, the intention has been for policy merely to incentivise the private sector rather than to steer industry strategy directly. Having said that, the line between strong incentives and weak control can be hard to see. We present illustrative examples, real and fictional, that give insight into the UK nuclear safety culture and we discuss the wider nature of UK society with respect to corruption. We conclude that the unique basis of safety regulation in the UK, essentially permissive rather than prescriptive, has a key role to play in promoting and maintaining nuclear professionalism

Instantons on Sasakian 7-manifolds

We study a natural contact instanton (CI) equation on gauge fields over 7-dimensional Sasakian manifolds, which is closely related both to the transverse Hermitian Yang-Mills (tHYM) condition and the G_2-instanton equation. We obtain, by Fredholm theory, a finite-dimensional local model for the moduli space of irreducible solutions. We derive cohomological conditions for smoothness, and we express its dimension in terms of the index of a transverse elliptic operator. Finally we show that the moduli space of selfdual contact instantons (ASDI) is K\"ahler, in the Sasakian case. As an instance of concrete interest, we specialise to transversely holomorphic Sasakian bundles over contact Calabi-Yau 7-manifolds, and we show that, in this context, the notions of contact instanton, integrable G_2-instanton and HYM connection coincide.Comment: This is the updated version, published in The Quarterly Journal of Mathematics (2023

Magnetogasdynamic Flow Control of a Mach Reflection

Two-dimensional regular and Mach reflections have been studied in the Mach 4.96 dual-solution domain for a 25° and 26° double-fin inlet. The steady-state computational Mach and regular reflections were subjected to magnetogasdynamic forces to determine whether these forces could be used as a possible flow control mechanism. The numerical code employed for this research solved the inviscid Euler equations with added source terms for the ponderomotive force and accompanying energy interactions. The 25° regular reflection was determined to be extremely sensitive to a decelerating Lorentz force. Transient application of the force led to the transition of the regular reflection to a Mach reflection, increasing the total pressure losses and decreasing the compression ratio. Sustained application of the force resulted in inlet unstart. An accelerating Lorentz force was also examined with the goal of transitioning the 26° Mach reflection to a more efficient regular reflection. The location of the accelerating force and the parameters governing its magnitude were examined. Such forces push the Mach reflection back to a more stable location and reduce the Mach stem height. For the interaction parameters considered, fully regular reflections were not obtained. However, the accelerating Lorentz force proved capable of increasing the total pressure recovery and the static pressure compression beyond the regular reflection values

An asymptotic theorem for minimal surfaces and existence results for minimal graphs in H2×RH^2 \times R

In this paper we prove a general and sharp Asymptotic Theorem for minimal surfaces in $H^2\times R$. As a consequence, we prove that there is no properly immersed minimal surface whose asymptotic boundary $C$ is a Jordan curve homologous to zero in the asymptotic boundary of $H^2\times R,$ say $\partial_\infty H^2\times R$, such that $C$ is contained in a slab between two horizontal circles of $\partial_\infty H^2\times R$ with width equal to $\pi.$ We construct minimal vertical graphs in $H^2\times R$ over certain unbounded admissible domains taking certain prescribed finite boundary data and certain prescribed asymptotic boundary data. Our admissible unbounded domains \Om in $H^2\times \{0\}$ are non necessarily convex and non necessarily bounded by convex arcs; each component of its boundary is properly embedded with zero, one or two points on its asymptotic boundary, satisfying a further geometric condition.Comment: This paper was presented in the International Congress on Minimal and Constant Mean Curvature Surfaces, Buzios, Brazil, August 2007 (27 pages 7 figures

A constructive algorithm for the Cartan decomposition of SU(2^N)

We present an explicit numerical method to obtain the Cartan-Khaneja-Glaser decomposition of a general element G of SU(2^N) in terms of its `Cartan' and `non-Cartan' components. This effectively factors G in terms of group elements that belong in SU(2^n) with n<N, a procedure that can be iterated down to n=2. We show that every step reduces to solving the zeros of a matrix polynomial, obtained by truncation of the Baker-Campbell-Hausdorff formula, numerically. All computational tasks involved are straightforward and the overall truncation errors are well under control.Comment: 15 pages, no figures, matlab file at http://cam.qubit.org/users/jiannis

Faster movement speed results in greater tendon strain during the loaded squat exercise

Introduction: Tendon dynamics influence movement performance and provide the stimulus for long-term tendon adaptation. As tendon strain increases with load magnitude and decreases with loading rate, changes in movement speed during exercise should influence tendon strain. Methods: Ten resistance-trained men [squat one repetition maximum (1RM) to body mass ratio: 1.65 ± 0.12] performed parallel-depth back squat lifts with 60% of 1RM load at three different speeds: slow fixed-tempo (TS: 2-s eccentric, 1-s pause, 2-s concentric), volitional-speed without a pause (VS) and maximum-speed jump (JS). In each condition joint kinetics, quadriceps tendon length (LT), patellar tendon force (FT), and rate of force development (RFDT) were estimated using integrated ultrasonography, motion-capture, and force platform recordings. Results: Peak LT, FT, and RFDT were greater in JS than TS (p < 0.05), however no differences were observed between VS and TS. Thus, moving at faster speeds resulted in both greater tendon stress and strain despite an increased RFDT, as would be predicted of an elastic, but not a viscous, structure. Temporal comparisons showed that LT was greater in TS than JS during the early eccentric phase (10–14% movement duration) where peak RFDT occurred, demonstrating that the tendon's viscous properties predominated during initial eccentric loading. However, during the concentric phase (61–70 and 76–83% movement duration) differing FT and similar RFDT between conditions allowed for the tendon's elastic properties to predominate such that peak tendon strain was greater in JS than TS. Conclusions: Based on our current understanding, there may be an additional mechanical stimulus for tendon adaptation when performing large range-of-motion isoinertial exercises at faster movement speeds

Age-specific trends in health-related quality of life among US adults: Findings from National Health and Nutrition Examination Survey, 2001-2016

Purpose Health-related quality of life (HRQoL) is an important indicator of population health, yet no age-specific trend analyses in HRQoL have been conducted with a nationally representative sample since 2004. Therefore, to address this gap, an age-specific trend analysis of HRQoL was conducted using National Health and Nutrition Examination Surveys (NHANES) data. Methods NHANES 2001–2016 data (8 cycles) were examined to evaluate trends in HRQoL by age group (young adults: 21–39, middle-aged: 40–64, older adults: 65+). HRQoL was assessed by self-reported health (SRH) and number of physically unhealthy, mentally unhealthy, and inactive days to due to physical or mental health in the past 30 days. Multiple linear or logistic regression analyses explored trends in HRQoL by age group, adjusting for demographics over time. Results Analysis revealed increasing fair/poor SRH over time for the entire sample (β = 0.34, 95% CI 0.08, 0.60, p = 0.011). However, age-specific analysis identified a bi-annual increase in fair/poor SRH only among young adults (β = 0.49, 95% CI 0.22, 0.76, p \u3c 0.001) and a decrease among older adults (β = − 0.60, 95% CI − 1.14, − 0.06, p = 0.03). Closer inspection revealed increasing fair/poor SRH increased among young women (β = 0.52, 95% CI 0.11, 0.93, p = 0.013) and young men (β = 0.46, 95% CI 0.04, 0.88, p = 0.03) but decreased among older women (β = − 0.81, 95% CI − 1.59, − 0.03, p = 0.042) over time. Analyses also determined that there was a trend for a decreasing number of physically unhealthy days among young adults (p \u3c 0.001), although no trends were observed for the other HRQoL items. Conclusions Although there was a significant trend over time for increasing fair/poor SRH when considering the entire sample, this trend was not consistent between age groups or sexes. Given increasing fair/poor SRH among young adults, there is a need to understand and address factors relating to HRQoL among this age group

Epithelial cell-directed efferocytosis in the post-partum mammary gland is necessary for tissue homeostasis and future lactation

<p>Abstract</p> <p>Background</p> <p>Mammary glands harbor a profound burden of apoptotic cells (ACs) during post-lactational involution, but little is known regarding mechanisms by which ACs are cleared from the mammary gland, or consequences if this process is interrupted. We investigated AC clearance, also termed efferocytosis, during post-lactational remodeling, using mice deficient for MerTK, Axl, and Tyro3, three related receptor tyrosine kinases (RTKs) regulating macrophage-mediated efferocytosis in monocytes. MerTK expression, apoptosis and the accumulation of apoptotic debris were examined in histological sections of MerTK-deficient, Axl/Tyro3-deficient, and wild-type mammary glands harvested at specific time points during lactation and synchronized involution. The ability of primary mammary epithelial cells (MECs) to engulf ACs was assessed in culture. Transplant of MerTK-deficient mammary epithelium into cleared WT mammary fat pads was used to assess the contribution of WT mammary macrophages to post-lactational efferocytosis.</p> <p>Results</p> <p>ACs induced MerTK expression in MECs, resulting in elevated MerTK levels at the earliest stages of involution. Loss of MerTK resulted in AC accumulation in post-lactational MerTK-deficient mammary glands, but not in Axl and Tyro3-deficient mammary glands. Increased vascularization, fibrosis, and epithelial hyperproliferation were observed in MerTK-deficient mammary glands through at least 60 days post-weaning, due to failed efferocytosis after lactation, but did not manifest in nulliparous mice. WT host-derived macrophages failed to rescue efferocytosis in transplanted MerTK-deficient mammary epithelium.</p> <p>Conclusion</p> <p>Efferocytosis by MECs through MerTK is crucial for mammary gland homeostasis and function during the post-lactational period. Efferocytosis by MECs thus limits pathologic consequences associated with the apoptotic load following lactation.</p