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

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 $\leq 2.5$ nm over a period of a day or more. The portable electronics system presented here has a displacement sensitivity $\leq 10$ nm$/\sqrt{\textrm{Hz}}$ ($\leq 0.6$ nm at $1000$ s). The battery power system used a modulated LED for measurements and required temperature control of the system to $\pm$ 2 mK, monitoring of the tilt to $\pm$ 2 $\mu$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

Fermion Helicity Flip Induced by Torsion Field

We show that in theories of gravitation with torsion the helicity of fermion particles is not conserved and we calculate the probability of spin flip, which is related to the anti-symmetric part of affine connection. Some cosmological consequences are discussed.Comment: 6 pages, to appear in Europhysics Letter

Field tests of a portable MEMS gravimeter

Gravimeters are used to measure density anomalies under the ground. They are applied in many different fields from volcanology to oil and gas exploration, but present commercial systems are costly and massive. A new type of gravity sensor has been developed that utilises the same fabrication methods as those used to make mobile phone accelerometers. In this study, we describe the first results of a field-portable microelectromechanical system (MEMS) gravimeter. The stability of the gravimeter is demonstrated through undertaking a multi-day measurement with a standard deviation of 5.58 × 10−6 ms−2 . It is then demonstrated that a change in gravitational acceleration of 4.5 × 10−5 ms−2 can be measured as the device is moved between the top and the bottom of a 20.7 m lift shaft with a signal-to-noise ratio (SNR) of 14.25. Finally, the device is demonstrated to be stable in a more harsh environment: a 4.5 × 10−4 ms−2 gravity variation is measured between the top and bottom of a 275-m hill with an SNR of 15.88. These initial field-tests are an important step towards a chip-sized gravity senso

A measurement of noise created by fluctuating electrostatic charges on dielectric surfaces using a torsion balance

Future gravitational wave detectors could have their sensitivity significantly limited, at frequencies below 10 Hz, by the presence of fluctuating electrostatic charges on the dielectric surfaces of the detector optics. A confirmed observation of the effect of fluctuating charges, or charging noise, in a gravitational wave detector has still to be made and it has never been experimentally verified by any other means. This paper presents a direct measurement of the fluctuating force noise created by moving charges on a dielectric surface using a servo controlled torsion balance. The results confirm that the fluctuating force noise caused by excess charges can be best described by a Markov process with a single correlation time and has a frequency dependence of f<sup>-1</sup&gt

Morality, responsibility and risk: Gay men and proximity to HIV

No abstract available

Effects of a torsion field on Big Bang nucleosynthesis

In this paper it is investigated whether torsion, which arises naturally in most theories of quantum gravity, has observable implications for the Big Bang nucleosynthesis. Torsion can lead to spin flips amongst neutrinos thus turning them into sterile neutrinos. In the early Universe they can alter the helium abundance which is tightly constrained by observations. Here I calculate to what extent torsion of the string theory type leads to a disagreement with the Big Bang nucleosynthesis predictions.Comment: accepted by General Relativity and Gravitatio

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