The Egyptian Cardiothoracic Surgeon (ECTS - E-Journal)
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Fire Resistance of Unprotected Ultra Shallow Floor Beams (USFB): A Numerical Investigation
No full textDimensional Change, Irradiation creep and Thermal/Mechanical Property Changes in Nuclear Graphite
No full textSince the start of the ‘nuclear age’ graphite has been employed as a moderator in around 100 nuclear reactors, and today there are still some 30 graphite-moderated reactors operating and there are plans for new Generation IV high-temperature reactors. Many of the graphite moderator reactors now producing power are operating beyond their original design life. Therefore in some cases, to aid the reactor operators and designers, the existing graphite irradiation databases need to be extended either to a higher temperature or higher neutron fluence. Furthermore, data are needed for the different grades of graphite that are available at present. This can either be achieved by expensive, time consuming irradiation programmes or by improving the understanding of the mechanisms and processes which lead to irradiation-induced dimensional and property changes in the graphite core components. This review looks at three of the most important graphite properties which change with exposure to irradiation, namely dimensional change, irradiation creep and thermal expansion. The behaviour of UK AGR, Magnox and an experimental grade of German reactor graphite are explored in some detail. First graphite reactor core design is briefly discussed, giving examples of typical graphite components and core arrangements. Issues related to aging graphite component and core behaviour are illustrated through examples of component internal and thermal stress generation, and issues related to whole core behaviour are also outlined. Second the manufacture and microstructure of different nuclear graphite grades are discussed, highlighting how the choice of raw materials and manufacturing technique influences the graphite properties. Third the coefficient of thermal expansion, dimensional change and irradiation creep are analysed using microstructural and averaging methods which are used to relate crystal to bulk properties by accounting for graphite crystal orientation and porosity. These techniques, which were first applied to nuclear graphite in the 1960s, are extended and discussed with the aim of trying to lend some understanding to the role the microstructural crystallite and porosity distributions play in defining the dimensional stability and properties of virgin graphite, irradiated graphite and stressed graphite
Women's and Clinicians Perspectives of Presentation with Reduced Fetal Movements: a qualitative study
No full textBackgroundWorldwide maternal perception of fetal movements has been used for many years to evaluate fetal wellbeing. It is intuitively regarded as an expression of fetal well-being as pregnancies in which women consistently report regular fetal movements have very low morbidity and mortality. Conversely, maternal perception of reduced fetal movements is associated with adverse pregnancy outcomes. We sought to gain insight into pregnant women’s and clinicians views and experiences of reduced movements.MethodWe performed qualitative semi-structured interviews with pregnant women who experienced reduced fetal movements in their current pregnancy and health professionals who provide maternity care. Our aim was to develop a better understanding of events, facilitators and barriers to presentation with reduced fetal movements. Data analysis was conducted using framework analysis principles.ResultsTwenty-one women and 10 clinicians were interviewed. The themes that emerged following the final coding were influences of social network, facilitators and barriers to presentation and the desire for normality.ConclusionsThis study aids understanding about why women present with reduced movements and how they reach the decision to attend hospital. This should inform professionals’ views and practice, such that appreciating and addressing women’s concerns may reduce anxiety and make presentation with further reduced movements more likely, which is desirable as this group is at increased risk of adverse outcome. To address problems with information about normal and abnormal fetal movements, high-quality information is needed that is accessible to women and their families.<br/
Making Hybrid [n]-Rotaxanes as Supramolecular Arrays of Molecular Electron Spin Qubits
No full textQuantum information processing (QIP) would require that the individual units involved—qubits—communicate to other qubits while retaining their identity. In many ways this resembles the way supramolecular chemistry brings together individual molecules into interlocked structures, where the assembly has one identity but where the individual components are still recognizable. Here a fully modular supramolecular strategy has been to link hybrid organic–inorganic [2]- and [3]-rotaxanes into still larger [4]-, [5]- and [7]-rotaxanes. The ring components are heterometallic octanuclear [Cr7NiF8(O2CtBu)16]– coordination cages and the thread components template the formation of the ring about the organic axle, and are further functionalized to act as a ligand, which leads to large supramolecular arrays of these heterometallic rings. As the rings have been proposed as qubits for QIP, the strategy provides a possible route towards scalable molecular electron spin devices for QIP. Double electron–electron resonance experiments demonstrate inter-qubit interactions suitable for mediating two-qubit quantum logic gates
Seismic probabilistic risk analysis based on stochastic simulation of accelerograms for nuclear power plants in the UK
No full textThis article presents an approach to probabilistically assess the seismic risk of nuclear power plants (NPPs) in the UK. The approach proposed is based on direct stochastic simulation of the seismic input to conduct nonlinear dynamic analysis of a structural model of the NPP analysed. Therefore, it does not require the use of ground motion prediction equations and scaling/matching procedures to define suitable accelerograms as is done in conventional approaches. Additionally, as the structural response is directly calculated, it does not require the use of Monte Carlo-type algorithms to simulate the damage state of the NPP analysed. However, it demands longer use of computer resources as a relatively large number of nonlinear dynamic analyses are needed to perform. The approach is illustrated using an example of a 1000 MW Pressurised Water Reactor building located in a representative UK nuclear site. A comparison of risk assessment is made between the conventional and proposed approaches. Results obtained are reasonable and well constrained by conventional procedures; hence, it can confidently be used by the UK New Build Programme in the next two decades to generate 16 GWe of new nuclear capacity
Escaping Accountability: A Case of Australia’s Asylum Seeker Policy
No full textAbstract Purpose: The paper addresses two questions. First, what contracts, instruments and accounting activities constitute Australia’s offshore asylum seeker processing policy in practice? Second, how are notions of legitimacy and accountability mediated through the network constituted by this policy? Design/methodology/approach: The paper is located in the critical interpretivist approach to accounting research. It is based on an exhaustive documentary analysis. Policy documents, contract documents, records of parliamentary inquiries (Hansard) and legislation were analysed drawing on a network policy perspective. Findings: The paper finds that the Australian Government has sought to escape its accountability obligations by employing a range of approaches. The first of these approaches is the construction of a network involving foreign states, private corporations and nongovernment organizations. The second is through a watered down accountability regime and refusal to be accountable for the day to day life of asylum seekers in offshore processing centres through a play with the meaning of “effective control”. Yet while the policy network seems designed to create accountability gaps, the requirement within the network to remain financially accountable undermines the government’s claims not to be responsible for the conditions in the detention camps. Research limitations/implications: The paper focuses largely on the period starting from when Kevin Rudd became Prime Minister to the death in Papua New Guinea of asylum seeker Reza Barati on 17 February 2014. Earlier and later periods are beyond the scope of this paper. Social implications: The paper will result in the identification of deficiencies in human rights accountability for extra-territorialized and privatised immigration detention and may contribute towards the formulation of effective policy recommendations to overcome such deficiencies. The paper also provides empirical data on, and academic understanding of, immigration detention outsourcing and offshoring. Originality/value: The article provides the first detailed and full understanding of the way Australia’s offshore asylum seeker processing policy is practiced. The paper also provides an empirical analysis of the way national policy and its associated accountability mechanisms emerge in response to the competing legitimacy claims of the international community and national electorate
Altered immunogenicity of donor lungs via removal of passenger leukocytes using ex-vivo lung perfusion
No full textPassenger leukocyte transfer from the donor lung to the recipient is intrinsically involved in acute rejection. Direct presentation of alloantigen expressed on donor leukocytes is recognized by recipient T cells, promoting acute cellular rejection. We utilized ex vivo lung perfusion (EVLP) to study passenger leukocyte migration from donor lungs into the recipient and to evaluate the effects of donor leukocyte depletion prior to transplantation. For this purpose, female pigs received male left lungs either following 3 h of EVLP or retrieved using standard protocols. Recipients were monitored for 24 h and sequential samples were collected. EVLP-reduced donor leukocyte transfer into the recipient and migration to recipient lymph nodes was markedly reduced. Recipient T cell infiltration of the donor lung was significantly diminished via EVLP. Donor leukocyte removal during EVLP reduces direct allorecognition and T cell priming, diminishing recipient T cell infiltration, the hallmark of acute rejection.</p
