H. Griffiths

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The cultivated potato (Solanum tuberosum) shares similar biology with other members of the Solanaceae, yet has features unique within the family, such as modified stems (stolons) that develop into edible tubers. To better understand potato biology, we have undertaken a survey of the potato transcriptome using expressed sequence tags (ESTs) from diverse(More)
A single-channel magnetic induction system operating at 10 MHz has been constructed. The system consists of an excitation coil and a sensing coil, between which different objects can be scanned. The eddy currents induced in the object cause perturbations in the sensed magnetic field, which are measured with a phase-sensitive detector with backing off of the(More)
A dominant allele at the D locus (also known as I in diploid potato) is required for the synthesis of red and purple anthocyanin pigments in tuber skin. It has previously been reported that D maps to a region of chromosome 10 that harbors one or more homologs of Petunia an2, an R2R3 MYB transcription factor that coordinately regulates the expression of(More)
  • H Griffiths
  • Clinical physics and physiological measurement…
  • 1988
A method has been developed for constructing phantoms for electrical impedance tomography (EIT). A mesh of resistors is soldered to pins in a matrix board and forms a physical realisation of a finite element numerical model. To simulate different body tissues, changes in the apparent electrical conductivity and permittivity can be introduced at a particular(More)
In this study the performance of a planar array for magnetic induction tomography (MIT) was investigated and the results of measurements to determine the precision and sensitivity of the sensor were undertaken. A planar-array MIT system utilizing flux-linkage minimization for the primary field has been constructed and evaluated. The system comprises 4(More)
For a magnetic induction tomography (MIT) system operating at 10 MHz, the signals produced by a haemorrhagic cerebral stroke were computed using an anatomically realistic, multi-layer, finite element (FE) head model comprising 12 tissues. The eddy-current problem was approximated using the commercial FE package, Comsol Multiphysics, and the numerical(More)
In biomedical magnetic induction tomography (MIT), measurement precision may be improved by incorporating some form of primary field compensation/cancellation scheme. Schemes which have been described previously include gradiometric approaches and the use of 'back-off' coils. In each of these methods, however, the primary field cancellation was achieved(More)
Normative visual field area, feasibility and repeatability using (Octopus) semi-automated kinetic perimetry are reported in 221 healthy volunteers aged 5-22 years. I4e and I2e stimuli assessed the visual field at 5°/second (°/s) or 3°/s. Blind spot was assessed with I2e at 2°/s. Reliable visual fields were plotted in 23% of participants <10 years, 64% of(More)
In an ideal magnetic induction tomography (MIT) system, the coupling between the coils and the sample is entirely by the magnetic field. In a practical system, unwanted electric-field (capacitive) coupling can also exist and cause large errors in the MIT measurements unless the hardware is designed carefully. A series of tests was carried out to assess the(More)
Possum (the physiological and operative severity score for the enumeration of mortality) is used in many surgical specialities for comparative audit. We investigated its validity in relation to head and neck surgery by retrospectively scoring 301 operative interventions. We also applied the P-Possum (Portsmouth Possum) equation for mortality. We compared(More)