Interview with Colin Kirkland

[Colin J. Kirkland has been involved in the design and construction of underground works for more than thirty years. His experience encompasses work in both the consulting and contracting arenas of the tunnelling industry. For most of his professional life, he has worked for the international consulting firm Sir William Halcrow & Partners, London, and he currently holds directorships in three Halcrow companies. He served as Head of Halcrow's Tunnel Department from 1982 until July 1985, when he was named Technical Director of EuroTunnel, the joint venture group responsible for building the Channel Tunnel between England and France, Mr Kirkland has had wide experience in the planning, design, administration and construction of tunnel projects throughout the world, ranging from small-diameter service tunnels, to railway and metro tunnels, to large-diameter road tunnels, constructed in many different conditions. Since 1985, Mr Kirkland has served as Chairman of the British Tunnelling Society; he is currently serving as a Vice-President of the International Tunnelling Association as well. In June, when he appeared as the keynote speaker at the Rapid Excavation Tunnelling Conference in New Orleans, Louisiana (U.S.A.), Mr Kirkland was interviewed by Tunnelling and Underground Space Technology.]     

Acute and chronic inhibition of nitric oxide synthase in conscious rabbits: role of nitric oxide in the control of vascular tone

Acute and chronic effects of Nw-nitro-L-arginine (L-NNA), an inhibitor of nitric oxide synthase, were examined on the hindquarter hemodynamics of conscious rabbits. After pharmacological autonomic reflex blockade on four experimental days (days 0, 1, 2, and 7), responses to aortic occlusion (balloon cuff, 5-80 s inflation), intra-aortic infusion of acetylcholine, adenosine, and sodium nitroprusside (SNP) were measured before and after vehicle (day 0) or L-NNA (16 mg/kg/h i.v., days 1, 2, and 7). On day 1, L-NNA raised the mean arterial pressure (MAP), and lowered the heart rate (HR) and hindquarter vascular conductance (HVC = abdominal aortic Doppler blood flow/MAP). On days 2 and 7, L-NNA only slowly raised the MAP. The dilator response to acetylcholine was inhibited by L-NNA on day 1 and before and after L-NNA on days 2 and 7. The responses to aortic occlusion, adenosine, or SNP infusion were unaffected by L-NNA treatment on any day. Thus, if nitric oxide synthase inhibition by L-NNA abolishes NO release, then (i) reactive hyperaemia is independent of NO, (ii) basal NO release normalises the arterial pressure in the short term but other factors become important in the long term, and (iii) the blockade by L-NNA of receptor-stimulated NO release by acetylcholine is only very slowly reversible.     

Lower confidence bound on the percentage improvement in comparingtwo failure rates

It is often necessary to determine whether a design change in a product has actually improved its failure rate, and to compute a lower confidence bound on the percentage of failure rate improvement affected by the change. It is shown that such a bound can be computed based on certain test data. The main result is a special case on an equivalent result derived in Lehmann (1959) for hypothesis testing and used extensively in applied statistics. However, it is not well known in its confidence interval form, nor is it extensively reported in reliability methods books, and its derivation is important in reliability testing     

Acute adrenal insufficiency: a new presentation of Castleman''s disease

On the 19-21 September 1994 an international meeting of experts was convened at the World Health Organization office in Geneva. The result of this meeting was the formation of the PACE working group. PACE stands for "Prevention And Control Exchange". It is programme designed to stimulate the sharing of solutions and control measures in order to reduce occupational hazards. Internationally there is wide agreement on the need for sharing of knowledge and a realisation that a collaborate effort is required.     

Response of PUVA-induced keratoses to etretinate

Maximal, reproducible, and thus "standardized" dilation of epicardial coronary arteries can be easily achieved with intracoronary bolus administration of 0.1 mg nitroglycerin without considerable decrease in blood pressure. The addition of other nitrocompounds or calcium antagonists cannot increase coronary dilation after nitroglycerin, but may be hampered by adverse effects.     

Three-dimensional imaging in double aberration-corrected scanning confocal electron microscopy, part II: inelastic scattering

The implementation of spherical aberration-corrected pre- and post-specimen lenses in the same instrument has facilitated the creation of sub-Angstrom electron probes and has made aberration-corrected scanning confocal electron microscopy (SCEM) possible. Further to the discussion of elastic SCEM imaging in our previous paper, we show that by performing a 3D raster scan through a crystalline sample using inelastic SCEM imaging it will be possible to determine the location of isolated impurity atoms embedded within a bulk matrix. In particular, the use of electron energy loss spectroscopy based on inner-shell ionization to uniquely identify these atoms is explored. Comparisons with scanning transmission electron microscopy (STEM) are made showing that SCEM will improve both the lateral and depth resolution relative to STEM. In particular, the expected poor resolution of STEM depth sectioning for extended objects is overcome in the SCEM geometry.     

A composite method for the determination of the chirality of single walled carbon nanotubes

An approach to the unambiguous determination of the conformation of individual single walled nanotubes utilizing high‐resolution transmission electron microscopy and digital image processing is described. The exit plane wave of single walled nanotubes restored from a focal series of images is used in a stepwise characterization procedure utilizing both the phase of the real space restoration and its Fourier transform. A combination of these complementary characterization steps yields an accurate measurement of the chiral vector for an individual nanotube.