9,865 research outputs found
A comparison of variable valve strategies at part load for throttled and un-throttled SI engine configurations
The presented work concerns the study of the fuel consumption and emissions benefits achieved at part load by employing a fully variable valve train in a 1.6L SI gasoline engine. The benefits achieved when using variable valve timing alone, and combined with an early intake closing strategy for un-throttled operation were explored in order to highlight the merits of throttle versus un-throttled engine operation in conjunction with variable valve timing and lift. In addition, particular interest was given to the presence of internal Exhaust Gas Recirculation (EGR) and its ability to reduce pumping loss at part load. An engine model employing multiple sub models to handle variable valve operation was constructed using a commercial gas dynamics engine code, allowing detailed analysis of three valve strategies. Using the engine model, a theoretical study validated by experimentally available data was carried out to study key valve timing cases. A detailed breakdown of the mechanisms present in each case allowed a comprehensive understanding of the influence of valve timing on gas exchange efficiency and fuel consumption
Familial vasculitides: granulomatosis with polyangitis and microscopic polyangitis in two brothers with differing anti-neutrophil cytoplasm antibody specificity
Anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV) is a group of rare autoimmune diseases. Although the aetiology of AAV is uncertain, it is likely that genetic and environmental factors contribute. We report the unusual case of two brothers presenting with AAV with differing clinical pictures and differing ANCA specificity. There is a recently identified difference in genetic risk factors associated with ANCA specificity, making it surprising that first-degree relatives develop AAV with differing clinical and serological features. Our report illustrates the complex aetiology of AAV and suggests that further research on the interaction of genetic and environmental factors is needed
Questioning calls to consensus in conservation: a Q study of conservation discourses on Galápagos
Efforts to frame conservation interventions in terms of idealized outcomes that benefit both human well-being and biodiversity, and the rhetoric of consensus that often accompanies these, have been criticized. Acknowledgement of trade–offs between often incommensurable interests and perspectives, has been argued to be more democratic and transparent. This paper critically examines calls to consensus in conservation on the Galápagos Islands, where the population has been urged to unite around a shared vision of conservation in order to secure a sustainable future. Q methodology was used to examine the discourses of conservation on the islands, and to assess whether a shared vision of Galápagos is either achievable or desirable. Thirty-three participants carried out Q sorts about Galápagos conservation. Three discourses emerged from the analysis: conservation of Galápagos as an international/global concern; conservation linked with sustainable development; and social welfare and equitable development. The results highlight the subjective and political nature of the different discourses, and the paper concludes that calls to consensus or shared visions, while seductive in their promise of harmonious cooperation for conservation, can be read as attempts to depoliticize debates around conservation, and as such should be treated with caution
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The Impact of Covid-19 on Future Higher-Age Mortality
Covid-19 has predominantly affected mortality at high ages. It kills by inflaming and clogging the air sacs in the lungs, depriving the body of oxygen ‒ inducing hypoxia ‒ which closes down essential organs, in particular the heart, kidneys and liver, and causes blood clots (which can lead to stroke or pulmonary embolism) and neurological malfunction.
Evidence from different countries points to the fact that people who die from Covid-19 are often, but not always, much less healthy than the average for their age group. This is true for England & Wales – the two countries we focus on in this study. The implication is that the years of life lost through early death are less than the average for each age group, with how much less being a source of considerable debate. We argue that many of those who die from coronavirus would have died anyway in the relatively near future due to their existing frailties or co-morbidities. We demonstrate how to capture this link to poorer-than-average health using a model in which individual deaths are ‘accelerated’ ahead of schedule due to Covid-19. The model structure and its parameterization build on the observation that Covid-19 mortality by age is approximately proportional to all-cause mortality. This, in combination with current predictions of total deaths, results in the important conclusion that, everything else being equal, the impact of Covid-19 on the mortality rates of the surviving population will be very modest. Specifically, the degree of anti-selection is likely to be very small, since the life expectancy of survivors does not increase by a significant amount over pre-pandemic levels.
We also analyze the degree to which Covid-19 mortality varies with socio-economic status. Headline statistics suggest that the most deprived groups have been disproportionately affected by Covid-19. However, once we control for regional differences in mortality rates, Covid-19 deaths in both the most and least deprived groups are also proportional to the all-cause mortality of these groups. However, the groups in between have approximately 10-15% lower Covid-19 deaths compared with their all-cause mortality.
We argue that useful lessons about the potential pattern of accelerated deaths from Covid-19 can be drawn from examining deaths from respiratory diseases, especially at different age ranges. We also argue that it is possible to draw useful lessons about volatility spikes in Covid-19 deaths from examining past seasonal flu epidemics. However, there is an important difference. Whereas the spikes in seasonal flu increase with age, our finding that Covid-19 death rates are approximately proportional to all-cause mortality suggests that any spike in Covid-19 mortality in percentage terms would be similar across all age ranges.
Finally, we discuss some of the indirect consequences for future mortality of the pandemic and the ‘lockdown’ measures governments have imposed to contain it. For example, there is evidence that some surviving patients at all ages who needed intensive care could end up with a new impairment, such as organ damage, which will reduce their life expectancy. There is also evidence that many people in lockdown did not seek a timely medical assessment for a potential new illness, such as cancer, or deferred seeking treatment for an existing serious illness, with the consequence that non-Covid-19-related mortality rates could increase in future. Self-isolation during lockdown has contributed to an increase in alcohol and drug consumption by some people which might, in turn, reduce their life expectancy. If another consequence of the pandemic is a recession and/or an acceleration in job automation, resulting in long-term unemployment, then this could lead to so-called ‘deaths of despair’ in future. Other people, by contrast, might permanently change their social behaviour or seek treatments that delay the impact or onset of age-related diseases, one of the primary factors that make people more susceptible to the virus – both of which could have the effect of increasing their life expectancy. It is, however, too early to quantify these possibilities, although it is conceivable that these indirect consequences could have a bigger impact on future average life expectancy than the direct consequences measured by the accelerated deaths model
Simultaneous multi-frequency single-pulse properties of AXP XTE J1810-197
We have used the 76-m Lovell, 94-m equivalent WSRT and 100-m Effelsberg radio
telescopes to investigate the simultaneous single-pulse properties of the radio
emitting magnetar AXP XTE J1810-197 at frequencies of 1.4, 4.8 and 8.35 GHz
during May and July 2006. We study the magnetar's pulse-energy distributions
which are found to be very peculiar as they are changing on time-scales of days
and cannot be fit by a single statistical model. The magnetar exhibits strong
spiky single giant-pulse-like subpulses, but they do not fit the definition of
the giant pulse or giant micropulse phenomena. Measurements of the
longitude-resolved modulation index reveal a high degree of intensity
fluctuations on day-to-day time-scales and dramatic changes across pulse phase.
We find the frequency evolution of the modulation index values differs
significantly from what is observed in normal radio pulsars. We find that no
regular drifting subpulse phenomenon is present at any of the observed
frequencies at any observing epoch. However, we find a quasi-periodicity of the
subpulses present in the majority of the observing sessions. A correlation
analysis indicates a relationship between components from different
frequencies. We discuss the results of our analysis in light of the emission
properties of normal radio pulsars and a recently proposed model which takes
radio emission from magnetars into consideration.Comment: 15 pages, 11 figures, accepted for publication by MNRA
Gold Standards Training and Evaluator Calibration of Pilot School Check Instructors
A key component of air carrier advanced qualification programs is the calibration and training of instructors and evaluators and assurance of reliable and valid data in support of such programs. A significant amount of research is available concerning the calibration of air carrier evaluators, but no research exists regarding the calibration of pilot school check instructors. This study was designed to determine if pilot school check instructors can be calibrated against a gold standard to perform reliable and accurate evaluations. Calibration followed the principles and theories of andragogy and adult learning and teaching, including emphasis on the cognitive domain of learning, learnercentered instruction, and human resource development. These in combination with methods commonly used in aviation instruction aimed to increase the effectiveness of the calibration. Discussion of these combinations is included. A specific method for delivery of the calibration was provided along with a complete lesson plan. This study used a one group pretest-posttest design. A group of 10 pilot school check instructors were measured before and after receiving rater calibration training. Statistical measures included raw inter- and referent-rater agreement percentages, Cohen’s kappa and kappa-like statistics for inter- and referent-rater reliability, Pearson product-moment correlations for sensitivity to true changes in pilot performance, and a standardized mean absolute difference for grading accuracy. Improvement in all the measurements from pretest to posttest was expected, but actual results were mixed. However, a holistic interpretation of the results combined with feedback from the check instructors showed promise in calibration training for pilot school check instructors. Thorough discussion of the limitations and lessons learned from the study, recommendations for pilot schools, and recommendations for future research is included
The Glasgow School of Art: An Architectural Totality
This Thesis presents a study of the Glasgow School of Art, based primarily upon study and analysis of the building's technology and spatial functionality, rather than of the visual attributes of the design. In so doing, the study analyses key factors relating to the School's origins, the means of its procurement and the likely contributions of parties other than Charles Rennie Mackintosh to the overall design process. A 3-dimensional drawn study is presented which was prepared as an analytical tool in the study of the building's technology. The drawings also provide a record of the spatial assemblage of the School, the contrasts of openness and enclosure, the changes of scale and the interpenetration of spaces which cannot be presented either by photography or by 2-dimensional drawing. It presents views of the building which cannot be appreciated by observation, due to the nature of the surrounding developments. In researching the origins of the building's functional requirements and of the means by which it was procured the writer has come upon documentation which has not, to his knowledge, been referred to in previous studies. This documentation records the requirements of British industry and the aims of the educational system which were to lead to the development of a substantial number of new Art Schools in Britain at the end of the nineteenth century. It also relates details of the means by which these developments were financed and presents information relating to the involvement of various members of the Glasgow architectural establishment with the Glasgow School of Art and with the competition for the design of the building. The technical study is concentrated, primarily, upon the original system of warm air heating and mechanical ventilation, which was fully integrated into the design and construction of the building. This system was taken out of use in the 1920's and has, to a large extent, been ignored both in previous studies of the building and in the continuing existence of the major items of plant. In relation to the design origins of the environmental system employed and to its technical performance, the writer has uncovered a substantial amount of documentation which has not previously been related to the architectural history of the design and which demonstrates the likely design input of John Keppie. Study of the system shows it to be of major historical significance in relation to the development of environmental systems during the period 1890-1910. This significance has not been noted in the major work relating to the development of environmental design in relation to architecture. It is hoped that this study, read in conjunction with earlier studies, will assist students of the building in reaching a greater understanding of the totality of the design
Social Justice, The Common Weal and Children and Young People in Scotland
This paper argues that: • Scotland should organise itself around social justice, which addresses entitlements, redistribution, recognition and respect. • Children and young people have particular views on what social justice means for them. • Rights have a particular contribution to make to social justice in term of entitlements, claims and minimal standards. • The combination of piecemeal incorporation of children’s rights, an apolitical wellbeing framework and a lack of strong legislation to hold local authorities and other public services, private sector organisations and the third sector to account, results in children and young people encountering discrimination on an everyday basis. • To achieve social justice, a change is needed in how adults perceive children and childhood, young people and youth. Children and young people need to be recognised as contributors to their families, institutions and communities now – and not just in the future. • For children and young people to be included in the Common Weal, it needs to be concerned with the full and diverse range of structural, cultural and individual barriers that they encounter in their lives
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