Superlattice electrodynamics as a source of Terahertz radiation

Charge-carriers propagating in superlattices exhibit the related phenomena known as negative differential conductivity and Bloch oscillation. This behaviour may be utilised for the generation of tunable electromagnetic radiation. In this work, the dependence of the drift velocity and displacement of charge-carriers on external, applied electric fields is investigated. The theory is extended to incorporate a different miniband structure, with the aim of modelling a superlattice made from graphene. I predict that, for a chosen set of electric field parameters, a semiconductor superlattice will emit radiation in the terahertz range. I create an original mathematical framework within which to calculate the charge-carrier behaviour in a triangular miniband structure, while incorporating an arbitrary variable to account for the effects of corrugation or disorder, and predict the appearance of conductivity multistability. This may be of interest to further work done on the use of graphene for superlattice device construction

Technological literacy reconsidered: a model for enactment

The final publication is available at: http://link.springer.com/article/10.1007%2Fs10798-009-9108-6.This paper presents a model to describe technological literacy as enacted by individuals in the course of shaping their lives and the world around them. The model has two interrelated facets – the potential for and enactment of technological literacy – where enactment and potential mutually constitute each other. This potential is made up of knowledge of a particular situation, personal engagement with a situation, and social engagement in the world. Enactment requires a particular set of competencies in action, which together helps shape the situation: recognizing needs; articulating problems; contributing towards the technological process; and analysing consequences. The implications of this model for technological literacy in the context of the individual and society, and the role of technology education in developing technological literacy, are discussed

An instrument to determine the technological literacy levels of upper secondary school students

In this article, an instrument for assessing upper secondary school students’ levels of technological literacy is presented. The items making up the instrument emerged from a previous study that employed a phenomenographic research approach to explore students’ conceptions of technology in terms of their understanding of the nature of technology and their interaction with technological artefacts. The instrument was validated through administration to 1,245 students on completion of their 12 years of formal schooling. A factor analysis was conducted on the data and Cronbach alpha reliability coefficients determined. The results show that a five-dimension factor structure (namely, artefact, process, direction/instruction, tinkering, and engagement) strongly supported the dimensions as developed during the original phenomenographic study. The Cronbach alpha reliability co-efficient of each dimension was satisfactory. Based on these findings, the instrument has been shown to be valid and reliable and can be used with confidence

Convalescent plasma in patients admitted to hospital with COVID-19 (RECOVERY): a randomised controlled, open-label, platform trial

Background: Many patients with COVID-19 have been treated with plasma containing anti-SARS-CoV-2 antibodies. We aimed to evaluate the safety and efficacy of convalescent plasma therapy in patients admitted to hospital with COVID-19. Methods: This randomised, controlled, open-label, platform trial (Randomised Evaluation of COVID-19 Therapy [RECOVERY]) is assessing several possible treatments in patients hospitalised with COVID-19 in the UK. The trial is underway at 177 NHS hospitals from across the UK. Eligible and consenting patients were randomly assigned (1:1) to receive either usual care alone (usual care group) or usual care plus high-titre convalescent plasma (convalescent plasma group). The primary outcome was 28-day mortality, analysed on an intention-to-treat basis. The trial is registered with ISRCTN, 50189673, and ClinicalTrials.gov, NCT04381936. Findings: Between May 28, 2020, and Jan 15, 2021, 11558 (71%) of 16287 patients enrolled in RECOVERY were eligible to receive convalescent plasma and were assigned to either the convalescent plasma group or the usual care group. There was no significant difference in 28-day mortality between the two groups: 1399 (24%) of 5795 patients in the convalescent plasma group and 1408 (24%) of 5763 patients in the usual care group died within 28 days (rate ratio 1·00, 95% CI 0·93–1·07; p=0·95). The 28-day mortality rate ratio was similar in all prespecified subgroups of patients, including in those patients without detectable SARS-CoV-2 antibodies at randomisation. Allocation to convalescent plasma had no significant effect on the proportion of patients discharged from hospital within 28 days (3832 [66%] patients in the convalescent plasma group vs 3822 [66%] patients in the usual care group; rate ratio 0·99, 95% CI 0·94–1·03; p=0·57). Among those not on invasive mechanical ventilation at randomisation, there was no significant difference in the proportion of patients meeting the composite endpoint of progression to invasive mechanical ventilation or death (1568 [29%] of 5493 patients in the convalescent plasma group vs 1568 [29%] of 5448 patients in the usual care group; rate ratio 0·99, 95% CI 0·93–1·05; p=0·79). Interpretation: In patients hospitalised with COVID-19, high-titre convalescent plasma did not improve survival or other prespecified clinical outcomes. Funding: UK Research and Innovation (Medical Research Council) and National Institute of Health Research

Preliminary investigation into the rheology of dairy shed waste

With the introduction of stricter control on the final disposal of all forms of farm waste, its transportation is becoming an everyday component of farm management. In the past and at present the design of such transportation systems has been and is being based on criteria for transportation of fresh water with little appreciation of the differences that may or may not exist. Certain research workers have found this difference to be quite significant (13, 15, 31). Estep (36) has suggested that manure pump installations should be designed for a friction loss 10% higher than for water. Grimm et ale (12) found that with total solids (T.S) less than 35,000ppm pressure loss was less than for water. Thus it might be concluded that a considerable amount of work is required before accurate flow characteristics of manure slurries can be understood

Tourism, water, wastewater and waste services in small towns

This is a two-part report on research completed during 2003/2004 in Hanmer Springs and Kaikoura. The research was conducted by the Tourism Recreation Research and Education Centre (TRREC) at Lincoln University. Hanmer Springs and Kaikoura are small towns and cater for steadily increasing numbers of tourists each year - now in excess of one million visits per year to Kaikoura. The research, funded by the Ministry of Economic Development and Canterbury Development Corporation, included four seven-day snapshot studies (in July 2003, October 2003 and December/January 2004) of water, wastewater and waste services in the townships. Tourists directly and indirectly use the water, wastewater and solid waste services provided by the District Councils in those townships. The research also examines the funding of the water, wastewater and solid waste systems in the township. A particular focus is tourism demand for these services.Part One of the report studies the rates and charges used at present in each of the townships to fund these services. Part Two of the report provides a Toolkit to aid Territorial Local Authorities (TLAs) in the management of water, wastewater and solid wastes in small townships. The Toolkit developed is the culmination of four intensive seven-day snapshot studies completed in Hanmer Springs and Kaikoura during 2003-2004.Research Project Funded by the Ministry of Economic Development and the Canterbury Development Corporatio

Risk assessment, costs and benefits for community effluent reuse and disposal schemes: contrasting experiences from Victoria and New Zealand

Specific challenges to the provision of a sustainable wastewater service for existing towns with poorly performing on-site systems are being identified through both domestic wastewater management planning and the Victorian Government Country Town Water Supply and Sewerage Program. A key challenge is the development of economically and socially viable effluent reuse and disposal schemes for community wastewater systems that also meet regulatory requirements for the protection of human health and ecosystems.This paper presents the outcomes of a risk assessment and cost benefit analysis for a proposed community wastewater system for a small town in central Gippsland, Victoria. Preliminary modelling suggests that very limited improvement in environmental/human health performance can be expected with the provision of large storage facilities (i.e. wet weather dam) and restriction of deep drainage. Recent experiences from New Zealand support the outcomes of this assessment. Current Victorian guidelines, however, discourage deep drainage in effluent irrigation and therefore the benefits that such schemes can deliver in the future. The outcomes illustrate the need for case by case risk analysis and triple bottom line assessment of wastewater servicing options