Investigation of spiral blood flow in a model of arterial stenosis

The spiral component of blood flow has both beneficial and detrimental effects in human circulatory system [Stonebridge PA, Brophy CM. Spiral laminar flow in arteries? Lancet 1991; 338: 1360–1]. We investigate the effects of the spiral blood flow in a model of three-dimensional arterial stenosis with a 75% cross-sectional area reduction at the centre by means of computational fluid dynamics (CFD) techniques. The standard κ–ω model is employed for simulation of the blood flow for the Reynolds number of 500 and 1000. We find that for Re = 500 the spiral component of the blood flow increases both the total pressure and velocity of the blood, and some significant differences are found between the wall shear stresses of the spiral and non-spiral induced flow downstream of the stenosis. The turbulent kinetic energy is reduced by the spiral flow as it induces the rotational stabilities in the forward flow. For Re = 1000 the tangential component of the blood velocity is most influenced by the spiral speed, but the effect of the spiral flow on the centreline turbulent kinetic energy and shear stress is mild. The results of the effects of the spiral flow are discussed in the paper along with the relevant pathological issues

Large-Eddy simulation of pulsatile blood flow

Large-Eddy simulation (LES) is performed to study pulsatile blood flow through a 3D model of arterial stenosis. The model is chosen as a simple channel with a biological type stenosis formed on the top wall. A sinusoidal non-additive type pulsation is assumed at the inlet of the model to generate time dependent oscillating flow in the channel and the Reynolds number of 1200, based on the channel height and the bulk velocity, is chosen in the simulations. We investigate in detail the transition-to-turbulent phenomena of the non-additive pulsatile blood flow downstream of the stenosis. Results show that the high level of flow recirculation associated with complex patterns of transient blood flow have a significant contribution to the generation of the turbulent fluctuations found in the post-stenosis region. The importance of using LES in modelling pulsatile blood flow is also assessed in the paper through the prediction of its sub-grid scale contributions. In addition, some important results of the flow physics are achieved from the simulations, these are presented in the paper in terms of blood flow velocity, pressure distribution, vortices, shear stress, turbulent fluctuations and energy spectra, along with their importance to the relevant medical pathophysiology

Mythic Banality::Jonathan Glazer and Hannah Arendt

The worst is that man has come to seem mindless.John Berger, “Francis Bacon and Walt Disney”The Zone of Interest is a film that has been shot at least twice: once through the lens ofits director, Jonathan Glazer, and then again through the lens of the 7 October Hamasattack and the subsequent war on Gaza. Few Holocaust films have spoken to our timesso directly. When Glazer made that connection implicit in his Oscar’s acceptancespeech – “Not to say ‘look what they did then’ – rather, ‘look what we do now’” – hetoo became part of the proxy cultural conflict that has raged from Berlin to New York.Throughout all of this, the ghost of Hannah Arendt has been a notable presence.Before its general release, Glazer said that while working on the film he was “constantlythinking” of Arendt’s description of how it was not radical evil but an outrageous mind-lessness that powered the industrialized genocide of the Holocaust. Whether judged anachingly timely masterpiece or denounced as “Holokitsch,” the film’s critics have followedGlazer’s lead and regularly evoked Arendt’s “banality of evil,” the phrase she used in hercontroversial reports on the 1961 trial of the Nazi Adolf Eichmann.1 In fact, whetherpeople love or loathe the film often seems to turn on whether they approve or disapproveArendt’s thesis. Or, indeed, of Arendt herself, for just as her debunking of the myth ofdemonic Nazis earned her public opprobrium, so too has Glazer’s Oscar’s speechturned him into a controversial figure in the very history he is asking us to understand.The Zone of Interest comes with a ready-made Arendtian imprimatur. I think this is also a problem

Mythic Banality::Jonathan Glazer and Hannah Arendt

The worst is that man has come to seem mindless.John Berger, “Francis Bacon and Walt Disney”The Zone of Interest is a film that has been shot at least twice: once through the lens ofits director, Jonathan Glazer, and then again through the lens of the 7 October Hamasattack and the subsequent war on Gaza. Few Holocaust films have spoken to our timesso directly. When Glazer made that connection implicit in his Oscar’s acceptancespeech – “Not to say ‘look what they did then’ – rather, ‘look what we do now’” – hetoo became part of the proxy cultural conflict that has raged from Berlin to New York.Throughout all of this, the ghost of Hannah Arendt has been a notable presence.Before its general release, Glazer said that while working on the film he was “constantlythinking” of Arendt’s description of how it was not radical evil but an outrageous mind-lessness that powered the industrialized genocide of the Holocaust. Whether judged anachingly timely masterpiece or denounced as “Holokitsch,” the film’s critics have followedGlazer’s lead and regularly evoked Arendt’s “banality of evil,” the phrase she used in hercontroversial reports on the 1961 trial of the Nazi Adolf Eichmann.1 In fact, whetherpeople love or loathe the film often seems to turn on whether they approve or disapproveArendt’s thesis. Or, indeed, of Arendt herself, for just as her debunking of the myth ofdemonic Nazis earned her public opprobrium, so too has Glazer’s Oscar’s speechturned him into a controversial figure in the very history he is asking us to understand.The Zone of Interest comes with a ready-made Arendtian imprimatur. I think this is also a problem

Haemodynamics and flow modification stents for peripheral arterial disease:a review

Endovascular stents are widely used for the treatment of peripheral arterial disease (PAD). However, the development of in-stent restenosis and downstream PAD progression remain a challenge. Stent revascularisation of PAD causes arterial trauma and introduces abnormal haemodynamics, which initiate complicated biological processes detrimental to the arterial wall. The interaction between stent struts and arterial cells in contact, and the blood flow field created in a stented region, are highly affected by stent design. Spiral flow is known as a normal physiologic characteristic of arterial circulation and is believed to prevent the development of flow disturbances. This secondary flow motion is lost in atheromatous disease and its re-introduction after endovascular treatment of PAD has been suggested as a method to induce stabilised and coherent haemodynamics. Stent designs able to generate spiral flow may support endothelial function and therefore increase patency rates. This review is focused on secondary flow phenomena in arteries and the development of flow modification stent technologies for the treatment of PAD

Engaging with Histories and Narratives of Displacement

In humanitarian contexts, poetry and creative approaches are often side-lined or presented as superfluous to the pressing needs that arise in emergency situations. A short-term emphasis on immediate needs has also led to creative approaches being side-lined, with such approaches often addressing narrative, memory, and history. However, as shown by the Refugee Hosts project’s research with nine local communities responding to displacement in Lebanon, Jordan and Turkey, creative approaches, such as poetry and writing workshops with communities, enable people to share past and ongoing experiences, and to build and sustain different forms of solidarity in the present and future. Creative approaches can develop insights into historical, political, religious, and communal ways of being that provide important counterweights to short-term decision making. Finding ways to engage with communities through creative approaches helps to make space for the articulation of memories and narratives that better inform interventions in the short and long-term. Creative writing, historical narratives and the arts allow practitioners to better acknowledge the multi-layered, historical, and emotional complexity that exists in displacement contexts and offers approaches that support community dialogue. This Research Brief calls for humanitarian practitioners to meaningfully engage with creative writing, history and the arts when working in displacement-affected contexts

Diagonal Approximations to the Observation Error Covariance Matrix in Sea Ice Thickness Data Assimilation

Data assimilation is a statistical technique for combining observations of a physical system with the state of a numerical model of that system. The procedure yields a new and ideally improved state estimate called the analysis. A critical component of data assimilation is the observation error covariance matrix, which describes the magnitude and the correlation of the errors in the observations. When the observation error correlation structure is unknown, an approximation can yield a poor analysis and an incorrect estimate of the quality of the analysis. Little is known about the error correlation structure of remotely-sensed sea ice thickness observations. However, sea ice prediction centres are beginning to move forward with ice thickness assimilation under the simplifying assumption that the observation errors are uncorrelated. The assumption of uncorrelated observation errors is attractive because the errors can be represented by a diagonal observation error covariance matrix, which is inexpensive to invert. The purpose of this thesis was to develop an understanding of how the diagonal approximation might affect the quality of the sea ice state estimate. This thesis describes a set of twin assimilation experiments that were conducted using a one-dimensional sea ice model. The twin experiment design enabled an investigation of the differences between the estimated and actual errors in the analysis state. The first part of this investigation explored how the diagonal approximation can impact the estimated mean analysis error standard deviation. The second component of the investigation explored the spatial scales of the errors present in the analysis. The experimental results indicated that the diagonal approximation can be used without increasing the mean analysis error standard deviation so long as the observation error variances are multiplied by a sufficiently-large inflation factor. The results also indicated that the inflation factor can be conservatively overestimated without adversely impacting the analysis. For some of the experiments, the diagonal approximation resulted in an increase in the analysis error spectral variance at lower wavenumbers. The approximation had little effect at higher wavenumbers. The main finding of this thesis is that diagonal approximations to the ice thickness observation error covariance matrix can likely be incorporated into ice prediction systems without adverse effects. One caveat of this statement is that an inflation factor should be used to increase the observation error variance estimates. A second caveat is that the analysis error covariance matrix may underestimate the correlation of analysis errors at the largest spatial scales. A final finding is that large improvements in analysis quality may be obtained if better approximations to the ice thickness observation error covariance matrix can be found and used in the analysis

An exploration of the relationship between educational background and the coaching behaviours and practice activities of professional youth soccer coaches

Background and purpose: Despite the proliferation in recent years of higher education establishments offering tertiary-level study in the field of sports coaching, there is a lack of research into the impact of such courses on coaching practice. The behaviours employed and activities used by coaches during practice sessions is an area where one might expect to see such impact, indeed certain studies have tentatively noted the educational qualifications of coaches and suggested that this may play a role in the application of behaviours more aligned with player learning. The purpose of this study was therefore to compare youth soccer coaches with and without tertiary-level qualifications, examining their coaching behaviours and practice activities. Method: The participants were 10 male professional youth soccer coaches aged 24–55 with an average of 13 years coaching experience. Five of the coaches had completed undergraduate degree courses related to sport coaching. All of the coaches worked with players aged under 9 to under 18 in the youth academy of an English professional soccer club. Systematic observation of coach behaviour and practice activities was carried out using the Coach Analysis and Intervention System (Cushion et al. 2012), while follow-up interviews were used to elicit the coaches’ perceptions of, and rationale for, their behaviour. Findings: The observation data showed that graduate coaches used significantly more divergent questioning than non-graduate coaches, while the interview data revealed a general trend for graduate coaches to show greater self-awareness of behaviours and changes in behaviour between practice types. Graduate coaches also provided more comprehensive rationales, for example, seeing silence as a means of facilitating player decision-making as well as for observation. In contrast to previous research, sessions featured a higher proportion of playing form than training form activities and at over 20% of session duration, the ‘other’ practice state was a prominent feature of contact time with players. While some coaches saw ‘other’ as wasted time, graduate coaches identified this as an opportunity for group discussion and social interaction. The study adds to existing data about coach behaviours and practice activities, providing evidence that education background may indeed influence coaching practice

Preventing Another Pandemic: How Changing the Legal Paradigm Governing Intensive Animal Agriculture Will Reduce the Risk of Future Zoonoses

The public health consequences tied to our relationships with animals are significant. The COVID-19 pandemic and previous instances of zo- onotic disease emergence and re-emergence have demonstrated that human relationships with animals can have a profound impact on our health. In the US, the most prevalent human-animal relationship is the one we have with the animals that we eat. This relationship is defined and facilitated by intensive animal agriculture, a practice at high risk of causing zoonotic disease emergence. This Article explores the current regulatory regime governing intensive animal agriculture and argues that it is deficient in the context of zoonotic disease. It argues that this deficiency is a result of the legal anthropocentrism that manifests in practices inherent to intensive animal agriculture and demonstrates that such an approach is unable to adequately manage the risk of future zoonoses. This Article argues for a regulatory approach that acknowl- edges the interdependence of humans, animals, and the environment. It proposes Wild Law as the most appropriate framework to address the risk of zoonotic disease and concludes that intensive animal agriculture would not be permitted under a Wild Law approach due to its inherent inability to operate within the context of an interdependent human-an- imal-environment relationship