Contribution of poor blood pressure control to strokes

No abstract available

Coherent Amplification of Optical Pulses in Metamaterials

In this paper we theoretically study propagation of steady state ultrashort pulse in dissipative medium. We considered two cases (i) medium consists of lossy metallic nanostructures embedded into a gain material and (ii) the gain material is embedded directly into the nanostructures. We found the shape and velocity of an optical pulse coupled with the polarization wave.Comment: 9 pages, 5 figures, submitted to IEEE Tran

Development and preliminary evaluation of a clinical guidance programme for the decision about prophylactic oophorectomy in women undergoing a hysterectomy

Objectives: To develop a decision analysis based and computerised clinical guidance programme (CGP) that provides patient specific guidance on the decision whether or not to undergo a prophylactic oophorectomy to reduce the risk of subsequent ovarian cancer and to undertake a preliminary pilot and evaluation. Subjects: Women who had already agreed to have a hysterectomy who otherwise had no ovarian pathology. Setting: Oophorectomy decision consultation at the outpatient or pre-admission clinic. Methods: A CGP was developed with advice from gynaecologists and patient groups, incorporating a set of Markov models within a decision analytical framework to evaluate the benefits of undergoing a prophylactic oophorectomy or not on the basis of quality adjusted life expectancy, life expectancy, and for varying durations of hormone replacement therapy. Sensitivity analysis and preliminary testing of the CGP were undertaken to compare its overall performance with established guidelines and practice. A small convenience sample of women invited to use the CGP were interviewed, the interviews were taped and transcribed, and a thematic analysis was undertaken. Results: The run time of the programme was 20 minutes, depending on the use of opt outs to default values. The CGP functioned well in preliminary testing. Women were able to use the programme and expressed overall satisfaction with it. Some had reservations about the computerised format and some were surprised at the specificity of the guidance given. Conclusions: A CGP can be developed for a complex healthcare decision. It can give evidence-based health guidance which can be adjusted to account for individual risk factors and reflects a patient’s own values and preferences concerning health outcomes. Future decision aids and support systems need to be developed and evaluated in a way which takes account of the variation in patients’ preferences for inclusion in the decision making process

Study of 42 and 85 GHz coupled cavity traveling-wave tubes for space use

Designs were formulated for four CW, millimeter wavelength traveling-wave tubes having high efficiency and long life. Three of these tubes, in the 42 to 44 GHz frequency region, develop power outputs of 100 to 300 watts with overall efficiencies of typically 45 percent. Another tube, which covers the frequency range of 84 to 86 GHz, provides a power output of 200 watts at 25 percent efficiency. The cathode current density in each design was 1A/sq cm. Each tube includes: metal-ceramic construction, periodic permanent magnet focusing, a two step velocity taper, an electron beam refocusing section, and a radiation cooled three-stage depressed collector. The electrical and mechanical design for each tube type is discussed in detail. The results of thermal and mechanical analyses are presented

Effect of a Spin-1/2 Impurity on the Spin-1 Antiferromagnetic Heisenberg Chain

Low-lying excited states as well as the ground state of the spin-1 antiferro- magnetic Heisenberg chain with a spin-1/2 impurity are investigated by means of a variational method and a method of numerical diagonalization. It is shown that 1) the impurity spin brings about massive modes in the Haldane gap, 2) when the the impurity-host coupling is sufficiently weak, the phenomenological Hamiltonian used by Hagiwara {\it et al.} in the analysis of ESR experimental results for NENP containing a small amount of spin-1/2 Cu impurities is equivalent to a more realistic Hamiltonian, as far as the energies of the low-lying states are concerned, 3) the results obtained by the variational method are in semi-quantitatively good agreement with those obtained by the numerical diagonalization.Comment: 11 pages, plain TeX (Postscript figures are included), KU-CCS-93-00

Methyl 2-amino-5-iso­propyl-1,3-thia­zole-4-carboxyl­ate

The title compound, C8H12N2O2S, forms a supramolecular network based on N-HN hydrogen-bonded centrosymmetric dimers that are linked in turn by N-HO contacts

Electrotransport in metals electroluminescence in zinc telluride

(i) ELECTROTRANSPORT IN METALS The effects of an applied electric field on diffusion in metals is discussed. Frequently, under high current densities, and for temperatures in the diffusion range, a directed displacement of the diffusion species results. This mass transport is described by the term electrotransport. The major theoretical considerations relevant to the development of this topic are described, with particular emphasis on derivations which have been applied to the interpretation of experimental results. Previous experimental investigations of electrotransport in metals are reviewed.The results of experiments on electrotransport of indium, using a radioactive isotope technique, are presented. The investigations are concerned with the electrotransport of the isotope In114m in solid gold, thin gold films and thin indium films. Electrotransport phenomena in thin films have not previously been investigated in any detail. The results are amenable to interpretation in terms of the interaction of electrons with an activated complex associated with the diffusing species.(ii) ELECTROLUMINESCENCE IN ZINC TELLURIDE This section reports on the electroluminescent properties of the II VI semiconducting compound zinc telluride. Previous investigations into the preparation of zinc telluride crystals and the optical, electrical and electroluminescent properties of the material are reviewed. The results of an experimental programme concerned with the preparation of zinc telluride crystals and the electroluminescent properties of devices fabricated from several forms of the material are presented. Relatively simple contacting and processing techniques are utilised and the electroluminescence is primarily associated with metal :semiconductor junctions and contact barrier regions. Particular emphasis is placed on the observation of room- temperature electroluminescence in zinc telluride as this has not been the subject of previous detailed investigation. The incorporation of oxygen in the crystals results in radiative recombinations in which temperature quenching of the emission is not pro- nounced. This results in considerable improvement in room- tempera- ture emission efficiencies; the associated emission is located in the red region of the visible spectrum. Other forms of zinc telluride investigated include nominally undoped and semi -insulating single crystals and also polycrystalline material. The potential of electroluminescent devices based on these various forms of zinc telluride as room -temperature visible emitters is evaluated. Possible mechanisms of electroluminescence are discussed