14,283 research outputs found
Establishing a support service for educational technology within a university
This paper covers some of the issues associated with the support of learning technology within an institution. It describes the activities of a working support service, and highlights approaches to some of the academic, technological, political and management issues that have helped it perform effectively over a fourâyear period
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Precision placement of fertiliser for optimising the early nutrition of vegetable crops : a review of the implications for the yield and quality of crops, and their nutrient use efficiency
The research outlined in this paper highlights the importance of the early nutrition of vegetable crops, and its long-term effects on their subsequent growth and development. Results are also presented to demonstrate how the nutrient supply during the establishment stages of young seedlings and transplants can be enhanced by targeting fertiliser to a zone close to their developing roots. Three different precision fertiliser placement techniques are compared for this purpose: starter, band or side-injected fertiliser. The use of each of these methods consistently produced the same (or greater) yields at lower application rates than those from conventional broadcast applications, increasing the apparent recovery of N, P and K, and the overall efficiency of nutrient use, while reducing the levels of residual nutrients in the soil. Starter fertilisers also advanced the maturity of some crops, and enhanced produce quality by increasing the proportions of the larger and/or more desirable marketable grades. The benefits of the different placement techniques are illustrated with selected examples from research at Warwick HRI using different vegetable crops, including lettuce, onion and carrot
Strings in gravity with torsion
A theory of gravitation in 4D is presented with strings used in the material
action in spacetime. It is shown that the string naturally gives rise to
torsion. It is also shown that the equation of motion a string follows from the
Bianchi identity, gives the identical result as the Noether conservation laws,
and follows a geodesic only in the lowest order approximation. In addition, the
conservation laws show that strings naturally have spin, which arises not from
their motion but from their one dimensional structure.Comment: 16 page
A High Stability Optical Shadow Sensor with Applications for Precision Accelerometers
Gravimeters are devices which measure changes in the value of the
gravitational acceleration, \textit{g}. This information is used to infer
changes in density under the ground allowing the detection of subsurface voids;
mineral, oil and gas reserves; and even the detection of the precursors of
volcanic eruptions. A micro-electro mechanical system (MEMS) gravimeter has
been fabricated completely in silicon allowing the possibility of cost
e-effective, lightweight and small gravimeters. To obtain a measurement of
gravity, a highly stable displacement measurement of the MEMS is required. This
requires the development of a portable electronics system that has a
displacement sensitivity of nm over a period of a day or more. The
portable electronics system presented here has a displacement sensitivity nm ( nm at s). The battery power
system used a modulated LED for measurements and required temperature control
of the system to 2 mK, monitoring of the tilt to 2 radians,
the storage of measured data and the transmission of the data to an external
server.Comment: 8 Pages, 12 figures, 5 equations, currently submitted and under
review at IEEE Sensors SIE
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Evidence of neutral transcriptome evolution in plants
The transcriptome of an organism is its set of gene transcripts (mRNAs) at a defined spatial and temporal locus. Because gene expression is affected markedly by
environmental and developmental perturbations, it is widely assumed that transcriptome divergence among taxa represents adaptive phenotypic selection. This assumption has been challenged by neutral theories which propose that stochastic
processes drive transcriptome evolution. To test for evidence of neutral transcriptome evolution in plants, we quantified 18 494 gene transcripts in nonsenescent leaves of 14 taxa of Brassicaceae using robust cross-species transcriptomics which includes a two-step physical and in silicobased normalization procedure based on DNA similarity among taxa. Transcriptome divergence correlates positively with evolutionary distance between taxa and with variation in gene expression among samples. Results are similar for pseudogenes and chloroplast genes evolving at different rates. Remarkably, variation in transcript abundance among root-cell samples correlates positively with
transcriptome divergence among root tissues and among taxa.
Because neutral processes affect transcriptome evolution in plants, many differences in gene expression among or within taxa may be nonfunctional, reflecting ancestral
plasticity and founder effects. Appropriate null models are required when comparing transcriptomes in space and time
Design of a digital ride quality augmentation system for commuter aircraft
Commuter aircraft typically have low wing loadings, and fly at low altitudes, and so they are susceptible to undesirable accelerations caused by random atmospheric turbulence. Larger commercial aircraft typically have higher wing loadings and fly at altitudes where the turbulence level is lower, and so they provide smoother rides. This project was initiated based on the goal of making the ride of the commuter aircraft as smooth as the ride experienced on the major commercial airliners. The objectives of this project were to design a digital, longitudinal mode ride quality augmentation system (RQAS) for a commuter aircraft, and to investigate the effect of selected parameters on those designs
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Optimising the analysis of transcript data using high density oligonucleotide arrays and genomic DNA-based probe selection
Background: Affymetrix GeneChip arrays are widely used for transcriptomic studies in a diverse range of species. Each gene is represented on a GeneChip array by a probe-set, consisting of up to 16 probe-pairs. Signal intensities across probe-pairs within a probe-set vary in part due to different physical hybridisation characteristics of individual probes with their target labelled transcripts. We
have previously developed a technique to study the transcriptomes of heterologous species based
on hybridising genomic DNA (gDNA) to a GeneChip array designed for a different species, and subsequently using only those probes with good homology.
Results: Here we have investigated the effects of hybridising homologous species gDNA to study the transcriptomes of species for which the arrays have been designed. Genomic DNA from Arabidopsis thaliana and rice (Oryza sativa) were hybridised to the Affymetrix Arabidopsis ATH1 and Rice Genome GeneChip arrays respectively. Probe selection based on gDNA hybridisation
intensity increased the number of genes identified as significantly differentially expressed in two
published studies of Arabidopsis development, and optimised the analysis of technical replicates obtained from pooled samples of RNA from rice.
Conclusion: This mixed physical and bioinformatics approach can be used to optimise estimates of gene expression when using GeneChip arrays
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