Biography:

In the past G.P. Thomas has collaborated on articles with R.L. Soulsby and L. Thais. One of their most recent publications is Low energy K− −p elastic interaction. Which was published in journal Physics Letters B.

More information about G.P. Thomas research including statistics on their citations can be found on their Copernicus Academic profile page.

G.P. Thomas's Articles: (6)

Low energy K− −p elastic interaction

AbstractForty-four K− −p low momentum elastic scattering events between 0 and 250 MeV/c have been found by following 265. 12 meters of K− meson tracks, backward from their capture points in nuclear emulsion. The total scattering cross-section is plotted as a function of kaon momentum and this is fitted with the s-wave zro-effective-range theory with the scattering lenghts A0 = −1.1 + 0.55 i, A1 = −0.20 + 0.44 i for the isotopic spin T = 0 and T = 1 channel respectively. Further evidence for s-wave interaction is discussed through the angular distribution in the center-of-mass system for the elastic events.

Wave-current interaction within and outside the bottom boundary layer

AbstractThis paper reviews the state-of-the-art as perceived by the Wave-Current Interaction (WCI) group which forms part of the MAST G6M Coastal Morphodynamics project, and includes some new results arising out of that project. Those processes which affect the vertical profiles of current and wave kinematics, and the bed shear-stresses, are discussed, but “horizontal” processes such as refraction of waves by currents, and generation of longshore currents, are not included. Among the group's conclusions are recommendations for the calculation of wave-induced bottom orbital velocities with and without WCI, and direct parameterisations of the bed shear-stresses produced by WCI. The latter is the results of a comprehensive intercomparison of WCI boundary-layer models and data. The results are aimed at aiding the formulation of numerical models of coastal morphodynamics.

Regular ArticleSpecies-Divergent Regulation of Human and Mouse Osteocalcin Genes by Calciotropic Hormones

AbstractAlthough osteocalcin is the most abundant noncollagenous protein in bone, its role remains undefined. Recent studies have reported diametrically opposing responses in the vitamin D regulation of the mouse vs the human and rat osteocalcin genes. The aim of this study was to increase the understanding of these differences and further elucidate the physiological function and regulation of osteocalcin. Direct comparison of the regulation of both the endogenous mouse osteocalcin gene (mOC) and a human osteocalcin promoter–chloramphenicol acetyl transferase (hOC-CAT) reporter as integrated templates was undertaken in primary osteoblastic cultures from OSCAT transgenic mice. Expression of both genes was up-regulated with the onset of mineralization. Long-term chronic 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) treatment and acute (2 day) PTH treatment inhibited both mOC and hOC-CAT expression. At all stages of osteoblastic development studied, hOC-CAT was up-regulated by acute 1,25-(OH)2D3, whereas mOC was unaffected or inhibited. Mouse osteopontin was strongly up-regulated by acute 1,25-(OH)2D3 treatment. Thus, the divergence of the osteocalcin responses to 1,25-(OH)2D3 is specific for the osteocalcin gene and for an acute 1,25-(OH)2D3 treatment regime. Elucidation of this unique aspect of bone physiology will provide valuable insights into the still incompletely understood roles of osteocalcin and 1,25-(OH)2D3 in bone.

Estimates of wave decay rates in the presence of turbulent currents

AbstractA full-depth numerical model solving the free surface flow induced by linear water waves propagating with collinear vertically sheared turbulent currents is presented. The model is used to estimate the wave amplitude decay rate in combined wave current flows. The decay rates are compared with data collected in wave flumes by Kemp and Simons [J Fluid Mech, 116 (1982) 227; 130 (1983) 73] and Mathisen and Madsen [J Geophys Res, 101 (C7) (1996) 16,533]. We confirm the main experimental finding of Kemp and Simons that waves propagating downstream are less damped, and waves propagating upstream significantly more damped than waves on fluid at rest. A satisfactory quantitative agreement is found for the decay rates of waves propagating upstream, whereas not more than a qualitative agreement has been observed for waves propagating downstream. Finally, some wave decay rates in the presence of favourable and adverse currents are provided in typical field conditions.

Regular ArticleEffect of Flutonidine on Ouabain-Induced Arrhythmias and Lethality in Guinea-Pig

AbstractFlutonidine (10, 20 and 40 μg/kg) was studied for its efficacy against the cardiotoxic effects induced by slow intravenous infusion of ouabain in guineapigs. Flutonidine increased the dose of ouabain required to cause ventricular premature beats, ventricular tachyarrhythmias and lethality. Flutonidine further inhibited the rate of ouabain-induced rise in blood pressure. Alpha1 adrenoceptor antagonist, corynanthine (1 mg/kg), could not alter the protective action of flutonidine, whereas idazoxan (100 μg/kg), the alpha2 adrenoceptor blocker, showed significant inhibition of this effect. It is suggested that the reduction in the arrhythmogenic and lethal effects of ouabain by flutonidine may be due to its ability to reduce sympathetic tone by interfering with the neural components of ouabain action mediated through alpha2 adrenoceptors.

An Application of Model Predictive Control to a Wave Energy Point Absorber

AbstractOptimal performance of wave energy converters requires appropriate control strategies. This is especially true of wave energy point absorbers, which are relatively small oscillators excited by waves. The two control methods for point absorbers which are most studied in the literature are reactive control and latching, which have major deficiencies. This article outlines a time-domain control method based on Model Predictive Control, which can be applied to any wave energy point absorber whose behaviour can be described by a linear state-space model. The control method is applied here to a semi-immersed vertical cylinder in deep water, excited by regular or irregular waves and oscillating in heave only; the motion may be either free or subject to amplitude constraints. Preliminary results from numerical simulations are presented and discussed. This control approach aims to obviate some of the limitations of already existing control strategies and to pave the way towards better control methods for point absorbers.

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