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  • 1
    Electronic Resource
    Electronic Resource
    Production of large-area plasmas by electron beams : The 39th annual meeting of division of plasma physics of APS (1998)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 5 (1998), S. 2137-2143 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An analysis is presented for the production of weakly ionized plasmas by electron beams, with an emphasis on the production of broad, planar plasmas capable of reflecting X-band microwaves. Considered first in the analysis is the ability of weakly ionized plasmas to absorb, emit and reflect electromagnetic radiation. Following that is a determination of the electron beam parameters needed to produce plasmas, based on considerations of beam ionization, range, and stability. The results of the analysis are then compared with a series of experiments performed using a sheet electron beam to produce plasmas up to 0.6 m square by 2 cm thick. The electron beam in the experiments was generated using a long hollow-cathode discharge operating in an enhanced-glow mode. That mode has only recently been recognized, and a brief analysis of it is given for completeness. The conclusion of the study is that electron beams can produce large-area, planar plasmas with high efficiency, minimal gas heating, low electron temperature, high uniformity, and high microwave reflectivity, as compared with plasmas produced by other sources. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.872886
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  • 2
    Electronic Resource
    Electronic Resource
    The mortality and morbidity associated with umbilical cord prolapse (1995)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 102 (1995), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Objective To examine the management of cord prolapse and its morbidity and mortality.Design Retrospective study of consecutive babies born after cord prolapse, identified using the Oxford Obstetric Data System, and those with registered handicap, identified by the Oxford Region Register of Early Childhood Impairments.Setting District maternity hospital managing more than 6000 deliveries annually.Subjects One hundred and thirty–two babies born after the identification of cord prolapse in the John Radcliffe Hospital between January 1984 and December 1992.Main outcome measures Survival rates, condition at birth assessed by Apgar scores at 1 and 5 minutes and blood gas values on cord blood samples, and incidence of major handicap at three years of age.Results The incidence of cord prolapse was 1 in 426 total births. There were six stillbirths and six neonatal deaths. One baby died as a result of birth asphyxia. The uncorrected perinatal mortality rate was 91 per 1000. Of 120 survivors, only one baby was known to suffer a major neurological handicap. Electronic cardiotocographs aided the diagnosis of cord prolapse in 41 % of cases. Apgar scores were better with a shorter diagnosis to delivery interval, but cord gas results did not correlate well with Apgar scores or the diagnosis to delivery interval.Conclusions Cord prolapse occurs with a relatively stable incidence in this population irrespective of changes in obstetric practices. Despite the high incidence of ominous cardiotocographs, low Apgar scores and acidaemia on blood gas analysis, the fetal outcome is not as poor as might be expected and mortality is predominantly attributable to congenital anomalies and prematurity rather than birth asphyxia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1995.tb10850.x
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  • 3
    Electronic Resource
    Electronic Resource
    Tetracycline-Regulated Transgene Expression in Hippocampal Neurones Following Transfection with Adenoviral Vectors (1997)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 69 (1997), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: A transfer system that enabled the efficient introduction of transgenes into neurones and the quantitative control of the expressed transgene would greatly facilitate studies into neuronal gene function. To develop such a system we incorporated the tetracycline (Tet)-responsive On/Off regulatory elements into type-5 adenoviral (Ad) vectors. Regulation of transgene expression following transfection was measured by placing the enhanced green fluorescent protein (EGFP) gene upstream of the Tet regulatory element. The results showed that cultures of primary hippocampal cells could be transfected with very high efficiency (〈70%) by the AdTet-On and AdTet-Off systems. Following transfection with the AdTet-On system no EGFP-fluorescent cells could be detected until doxycycline was added. The AdTet-Off system showed the reverse transcriptional regulation, in that the addition of Tet caused EGFP fluorescence to be abolished.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1997.69062620.x
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  • 4
    Electronic Resource
    Electronic Resource
    Emittance tailoring of electron beams for propagation in dense gas (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 4258-4267 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An intense relativistic electron beam injected into dense gas characteristically propagates in a self-pinched mode but is susceptible to the resistive hose instability. This convective instability typically leads to large amplitude beam motion and the disruption of propagation. Theory and computation suggest that, although resistive hose cannot be completely suppressed, its convective growth can be reduced by varying the average betatron oscillation frequency from head to tail in the beam pulse. We report here on experiments designed to implement this variation by tailoring the beam emittance using an ion-focused regime "conditioning'' cell. Conditioning effectiveness is assessed by using measured beam quantities to evaluate a detuning parameter η(t). This information is correlated with beam propagation measurements to determine the optimum conditioning for resistive hose suppression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363385
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  • 5
    Electronic Resource
    Electronic Resource
    Use of an active wire Bθ cell for electron beam conditioning (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 4249-4257 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The propagation of intense, relativistic electron beams in air is subject to the resistive hose instability. Conditioning the beam prior to injecting it into the air can extend its range by reducing the hose growth rate and by reducing the initial spatial perturbations that seed the hose instability. Experiments have been performed using the SuperIBEX accelerator (Ipeak=10–30 kA, E=4.5 MeV, 40 ns full width at half-maximum) to develop conditioning cells that suppress the hose. This paper describes the performance of an active wire Bθ cell that is used in conjunction with an ion focused regime (IFR) cell. The IFR cell detunes the instability by producing a head-to-tail radius taper on the beam. The wire cell maintains this radius taper while producing an emittance taper that is necessary to suppress the hose growth. In addition, the wire cell reduces the initial beam perturbations through the anharmonic centering force associated with the wire current and its azimuthal magnetic field Bθ. The ability of the Bθ cell to reduce the beam offset with a minimal increase in the beam radius gives it several advantages over the use of a simple, thick scattering foil to perform the radius taper to emittance taper conversion. The SuperIBEX beam propagation distance, in terms of the betatron oscillation scale length, was extended to ∼10λβ using these cells. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363384
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  • 6
    Electronic Resource
    Electronic Resource
    Transport and centering of high current electron beams in neutral gas filled cells (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 3580-3591 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Conducting tubes filled with neutral gas at pressures between 0.001 and 0.1 Torr can be used to transport, to center, and to reduce the transverse oscillations of high current ((approximately-greater-than)10 kA) electron beams. Electron impact ionization of the gas leads to partial neutralization of the beam space charge allowing self-focused beam transport and phase-mix damping of injected beam oscillations. In addition, the presence of conducting walls helps center the beam in the transport tube. High current beams, transported through a 1.3 m long tube, were centered to within one-tenth of the beam radius and input transverse oscillations were damped to submillimeter values without significant current loss or emittance growth. Beam transport properties are examined as a function of injected current, gas pressure, and cell geometry. Experimental results are compared with a theoretical model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359933
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  • 7
    Electronic Resource
    Electronic Resource
    Passivation of GaAs using (Ga2O3)1−x(Gd2O3)x, 0≤x≤1.0 films (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 1116-1118 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The Ga2O3(Gd2O3) dielectric film was previously discovered to passivate the GaAs surface effectively. We have investigated the systematic dependence of the dielectric properties of (Ga2O3)1−x(Gd2O3)x on the Gd (x) content. Our results show that pure Ga2O3 does not passivate GaAs. Films with x≥14% are electrically insulating with low leakage current and high electrical breakdown strength. Furthermore, a low interfacial density of states was attained in films with x≥14%. The results show the important role of Gd2O3 in the (Ga2O3)1−x(Gd2O3)x dielectric films for effective passivation of GaAs. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.124614
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  • 8
    Electronic Resource
    Electronic Resource
    Impact of MHC Class I Gene on Resistance to Murine AIDS (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of immunology 42 (1995), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Development of murine AIDS in mice following infection with LP-BM5 murine leukaemia virus (MuLV) is highly strain dependent, with strain differences determind by genes within and outside H-2. Among H-2 genes, the Dd gene is the most closely associated with resistance to LP-BM5 MuLV infection. However, the Dd-mediated resistance is highly influenced by outside H-2 genes, i. e. A lineage strains are more resistant than mice strains of B6/B10 lineage. In this study, the mice having BALB background were analysed and, similarly to A lineage mice, only Dd gene products were found to be required to provide resistance to LP-BM5 MuLV infection. Furthermore, BALB/c Kh mice bearing both Dd and Ld genes clearly showed obviously higher resistance than BALB/c-H-2dm2 mice solely having the Dd gene. In addition, in the long-term observation of the effect of the Dd gene on B6/B10 background mice, D8 mice having the Dd gene as a transgene and expressing a high level Dd gene product showed higher resistance than naturally recombinant B10. A(18R) mice. These results suggest that the MAIDS resistance associated with the D end loci is dependent on the level of expression of an MHC class I gene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3083.1995.tb03669.x
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  • 9
    Electronic Resource
    Electronic Resource
    A comparison of the effects of tramadol and morphine on gastric emptying in man (1997)
    Oxford, UK : Blackwell Science Ltd
    Anaesthesia 52 (1997), S. 0 
    Details
    ISSN: 1365-2044
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In a previous study using an electrical bioimpedance technique and the paracetamol absorption test, we demonstrated that 0.09 mgkg−1 of morphine delayed gastric emptying in healthy human volunteers. The aim of this study was to investigate whether analgesic doses of tramadol would cause a delay in gastric emptying similar to conventional opioids. Using the same volunteers and techniques as in our previous study, placebo or tramadol (1 mgkg−1) was given in a randomised, double-blinded, cross-over placebo-controlled study. Gastric emptying was measured concurrently by a noninvasive epigastric bioimpedance technique and by the paracetamol absorption test. After the ingestion of 500 ml of deionised water plus paracetamol 1.5 g, the mean (SEM) time taken for gastric volume to decrease to 50% (t0.5) was recorded. No difference in gastric emptying rates (t0.5) between placebo, 7.7 (1 min), and tramadol, 9.5 (2 min), was noted. In our previous study, morphine prolonged t0.5 to 21 (3) min (p 〈 0.03). The maximum concentration and area under the curve of serum paracetamol concentrations following morphine were significantly different from placebo (p 〈 0.05) and tramadol (p 〈 0.05). We conclude that tramadol at a dose of 1 mgkg−1 does not delay gastric emptying in humans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2044.1997.214-az0349.x
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  • 10
    Electronic Resource
    Electronic Resource
    Pseudotuberculous pyelonephritis: a rare entity and a diagnostic pitfall (1999)
    Oxford, U.K. and Cambridge, USA : Blackwell Science Ltd
    Histopathology 35 (1999), S. 0 
    Details
    ISSN: 1365-2559
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2559.1999.0744b.x
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