956 research outputs found
Space power technology into the 21st Century
The space power systems of the early 21st century are discussed. The capabilities which are anticipated to evolve from today's state of the art and the technology development programs presently in place or planned for the remainder of the century are emphasized. The power system technologies considered include: solar thermal, nuclear, radioisotope, photovoltaic, thermionic, thermoelectric, and dynamic conversion systems such as the Brayton and Stirling cycles. Energy storage technologies considered include: nickel hydrogen biopolar batteries, advanced high energy rechargeable batteries, regenerative fuel cells, and advanced primary batteries. The present state of the art of these space power and energy technologies is discussed along with their projections, trends and goals. A speculative future mission model is postulated which includes manned orbiting space stations, manned lunar bases, unmanned Earth orbital and interplanetary spacecraft, manned interplanetary missions, military applications, and Earth to space and space to space transportation systems. The various space power/energy system technologies which are anticipated to be operational by the early 21st century are matched to these missions
Soil, grain and water chemistry and human selenium imbalances in Enshi district, Hubei Province, China
Many elements which are essential to human and other animal health in small doses can
be toxic if ingested in excess. Selenium (Se), a naturally occurring metalloid element is
found in all natural materials on earth including rocks, soils, waters, air, plant and
animal tissues. Since the early 1930ās, it has been recognised that Se toxicity causes
hoof disorders and hair loss in livestock. Se was also identified as an essential trace
element to humans and other animals in the late 1950ās. It forms a vital constituent of
the biologically important enzyme glutathione peroxidase which acts as an anti-oxidant
preventing cell degeneration. Se deficiency has been implicated in the aetiology of
several diseases including cancer, muscular dystrophy, muscular sclerosis and cystic
fibrosis. Se can be assimilated in humans through several pathways including food,
drinking water and inhalation of Se-bearing particles from the atmosphere. In the
majority of situations, food is the most important source of Se, as levels in water are
very low. The narrow range between deficiency levels (<40 pg per day) and toxic
levels in susceptible people (> 900 pg per day) makes it necessary to carefully control
the amount of Se in the diet.
In China, Se deficiency has been linked to an endemic degenerative heart disease
known as Keshan Disease (KD) and an endemic osteoarthropathy which causes
deformity of affected joints, known as Kaschin-Beck Disease. These diseases occur in
a geographic belt stretching from Heilongjiang Province in north-east China to Yunnan
Province in the south-west. In the period between 1959 and 1970, peak KD incidence
rates exceeded 40 per 100 000 (approximately 8500 cases per annum) with 1400 - 3000
deaths recorded each year. Incidence rates have since fallen to less than 5 per 100 000
with approximately 1000 new cases reported annually (Levander, 1986). Se toxicity
(selenosis) resulting in hair and nail loss and disorders of the nervous system in the
human population, has also been recorded in Enshi District, Hubei Province and in
Ziyang County, Shanxi Province. China possesses one of the best epidemiological
databases in the world on Se-related diseases which has been used in conjunction with
geochemical data to demonstrate a significant geochemical control on human Se
exposure. However, the precise geographical areas at risk and the geochemical controls
on selenium availability have yet to be established
The Forum of European Geological Surveys Geochemistry Task Group 1994-1996 inventory
The Forum of European Geological Surveys (FOREGS) includes representatives from 33 European countries and is responsible for co-ordinating Geological Survey activities in Europe. The FOREGS Geochemistry Task Group was established in 1994 to develop a strategy for the preparation of European geochemical maps following the recommendations of the International Geological Correlation Programme (IGCP) Project 259 āInternational Geochemical Mappingā (now the International Union of Geological Sciences (IUGS) /International Association of Geochemistry and Cosmochemistry (IAGC) Working Group on Global Geochemical Baselines).
The FOREGS geochemistry programme is aimed at preparing a standardised European geochemical baseline to IGCP-259 standards. The principal aims of this dataset will be for environmental purposes, as a baseline for the assessment of the extent and distribution of contaminated land in the context of variations in the natural geochemical background, but it will also have applications in resource assessment and for the development of policy for the sustainable management of metalliferous mineral and other resources.
The first phase of the programme was the compilation of an inventory of geochemical data based on the results of a questionnaire completed by Geological Surveys and related organisations throughout the FOREGS community. The results show that the sample types which have been used most extensively are stream sediment (26% coverage), surface water (19% coverage) and soil (11% coverage). Stream sediments have been collected using a narrow range of mesh sizes (< 150ā< 200 Ī¼m), but soil samples have been collected according to two different conventions: some surveys used a similar mesh size range to that used for stream sediments while others employed the < 1000 or < 2000 Ī¼m fractions traditionally used by soil surveys. Sample densities range from 1 sample per 0.5 km2 to 1 per 3500 km2. Various analytical methods have been used, but most of the available data have been calibrated using international reference materials, and data for the most important of the potentially harmful elements (PHEs) are available for most datasets. Systematic radiometric data are available for only a small proportion of Europe, a situation which compares very unfavourably with that in Australia, North America, the former Soviet Union and many developing countries.
Recommendations are made for increasing the compatibility of geochemical methods between national geochemical surveys as a basis for the preparation of a series of European geochemical maps. The next stage of the FOREGS Geochemistry Task Group will be the collection of the Global Reference Network of samples against which to standardise national datasets according to the methods recommended in the final report of the IGCP 259 programme
Higher Education Strategy in Responding to the Generative AI Revolution Decolonising the Standard Response and Action Planning Protocols
Background: The Generative Artifical Intelligence (AI) revolution is here, and the availability of resources such as ChatGPT has triggered rapid responses, actions, and strategy to address the implications this has on education in the United Kingdom (UK). ChatGPT and other Generative AI provisions are viewed as both problematic and beneficial by Higher Education Institutes (HEIās). Alongside HEIās, Higher Education England (HEE) Technology Enhanced Learning (TEL) forums are just 1 of many additional UK national groups prioritising the discussion, Continual Professional Development (CPD), and strategical approaches to analysing Generative AI, in determining how it should be addressed in education and practice.
In terms of standard practice at London South Bank University (LSBU), the planning of projects and research to explore new technology lies predominantly with those deemed as the most āskilledā, ātechnicalā or āawareā of the technology. People who are in specific roles within the institute are expected to āleadā on strategy, and this onus of responsibility often remains with them throughout the process from start to finish. Recognising the imbalance of power and the benefits of privilege this practice could create, a decision was made to explore and propose re-design of the current protocols in place at LSBU.
Aim: Demonstrate the inclusion of a Decolonising step at the earliest designing stage of the project, to influence a practice change in how a HEI could respond to major items affecting education and any subsequent action-planning or project designing.
Method: 3 academic members of staff, and 3 undergraduate students, of Black, Asian, African or Minority ethnicity, will be recruited. Individual and group sessions will be conducted using Microsoft Teams. Sessions will involve the participants leading on the discussion and development of the project proposal and associated documents being used in the larger study. This will occur between 19th May ā 1st June 2023, after which the project proposal will be registered with the LSBU research ethics committee and internal registration system (Haplo).
The Decolonising strategy and effects will be appraised by an independent investigator making objective comparisons to a version of the project protocol originally written by the Principal Investigator as a lone researcher. Themes and major highlights to demonstrate these comparisons, will be presented as the outcome for this project. All results and recommendations will be ready for presentation by no later than 15th June 2023.
Expected Outcomes: Recommendations based on the outcome could feasibly affect changes in the future strategy for responding to major items requiring adaptation and evolution in education/practices, and potential other general and/or specific response/action-planning protocols, at London South Bank University.
Additional information: This project forms part of a larger LSBU Generative AI project to explore a potential solution to the issues surrounding Generative AI in Higher Education
Translational control of gene expression via interacting feedback loops
Translation is a key step in the synthesis of proteins. Accordingly, cells
have evolved an intricate array of control mechanisms to regulate this process.
By constructing a multi-component mathematical framework for translation we
uncover how translation may be controlled via interacting feedback loops. Our
results reveal that this interplay gives rise to a remarkable range of protein
synthesis dynamics, including oscillations, step-change and bistability. This
suggests that cells may have recourse to a much richer set of control
mechanisms than was previously understood.Comment: Supplementary Material Available on Reques
Liveweight prediction from hip height, condition score, fetal age and breed in tropical female cattle
Hip height, body condition, subcutaneous fat, eye muscle area, percentage Bos taurus, fetal age and diet digestibility data were collected at 17 372 assessments on 2181 Brahman and tropical composite (average 28% Brahman) female cattle aged between 0.5 and 7.5 years of age at five sites across Queensland. The study validated the subtraction of previously published estimates of gravid uterine weight to correct liveweight to the non-pregnant status. Hip height and liveweight were linearly related (Brahman: P<0.001, R-2 = 58%; tropical composite P<0.001, R-2 = 67%). Liveweight varied by 12-14% per body condition score (5-point scale) as cows differed from moderate condition (P<0.01). Parallel effects were also found due to subcutaneous rump fat depth and eye muscle area, which were highly correlated with each other and body condition score (r = 0.7-0.8). Liveweight differed from average by 1.65-1.66% per mm of rump fat depth and 0.71-0.76% per cm(2) of eye muscle area (P<0.01). Estimated dry matter digestibility of pasture consumed had no consistent effect in predicting liveweight and was therefore excluded from final models. A method developed to estimate full liveweight of post-weaning age female beef cattle from the other measures taken predicted liveweight to within 10 and 23% of that recorded for 65 and 95% of cases, respectively. For a 95% chance of predicted group average liveweight (body condition score used) being within 5, 4, 3, 2 and 1% of actual group average liveweight required 23, 36, 62, 137 and 521 females, respectively, if precision and accuracy of measurements matches that used in the research. Non-pregnant Bos taurus female cattle were calculated to be 10-40% heavier than Brahmans at the same hip height and body condition, indicating a substantial conformational difference. The liveweight prediction method was applied to a validation population of 83 unrelated groups of cattle weighed in extensive commercial situations on 119 days over 18 months (20 917 assessments). Liveweight prediction in the validation population exceeded average recorded liveweight for weigh groups by an average of 19 kg (similar to 6%) demonstrating the difficulty of achieving accurate and precise animal measurements under extensive commercial grazing conditions
- ā¦