A prospective clinical comparison of two intravenous polyurethane cannulae

Publisher's copy made available with the permission of the publisher © 1997 Australian Society of Anaesthetists "Because of a printer's error in the December 1996 issue of Anaesthesia and Intensive Care (Vol. 24, No. 6, p. 708, Figure 4) this paper is reprinted here in its entirety and in its correct form"--cf. p.42Tissue irritation, as evidenced by phlebitis, associated with Optiva™ (Johnson & Johnson Medical) and Insyte™ (Becton Dickinson) polyurethane cannulae was studied. The integrity of the cannulae on removal, the incidence of infection at the cannula site and the factors which influence phlebitis were also examined. One thousand and eight patients had a polyurethane cannula placed for induction of anaesthesia for cardiac surgery. After surgery, the cannula was examined every 24 hours. If evidence of phlebitis occurred, the cannula was removed and sent for culture. All remaining cannulae were removed at 72 hours and the site examined daily for a further three days. There were 503 Optiva™ and 505 Insyte™ cannulae studied. The distributions between the two cannulae with respect to patient characteristics, gauge of cannula, number of attempts and difficulty of insertion, cannula site and anaesthetist inserting were similar. The early removal rate for both groups was 47%. Overall phlebitis rate with Optiva™ was 31% and Insyte™ 33%. This difference is not statistically significant. The cumulative phlebitis rate increased with time but did not differ between the two types of cannulae. Minor tip distortion or shaft kinking of the cannulae occurred in 16.2% of Optiva™ and 23.5% of Insyte™. This difference is statistically significant and may relate to the slightly more acute taper at the Optiva™ cannula tip. Both cannulae were similar in clinical performance.W.J. Russell, S. Micik, S. Gourd, H. Mackay, S. Wrigh

Multivariable control theory applied to hierarchial attitude control for planetary spacecraft

Multivariable control theory is applied to the design of a hierarchial attitude control system for the CARD space vehicle. The system selected uses reaction control jets (RCJ) and control moment gyros (CMG). The RCJ system uses linear signal mixing and a no-fire region similar to that used on the Skylab program; the y-axis and z-axis systems which are coupled use a sum and difference feedback scheme. The CMG system uses the optimum steering law and the same feedback signals as the RCJ system. When both systems are active the design is such that the torques from each system are never in opposition. A state-space analysis was made of the CMG system to determine the general structure of the input matrices (steering law) and feedback matrices that will decouple the axes. It is shown that the optimum steering law and proportional-plus-rate feedback are special cases. A derivation of the disturbing torques on the space vehicle due to the motion of the on-board television camera is presented. A procedure for computing an upper bound on these torques (given the system parameters) is included

Assessment of Variable-cycle Engines for Mach 2.7 Supersonic Transports

Three proposed SCAR propulsion systems in terms of aircraft range for a fixed payload and take-off gross weight with a design cruise Mach number 2.7 are evaluated. The effects of various noise and operational restraints are determined and sensitivities to some of the more important performance variables are presented for the most probable design noise and operational restraint case. Critical areas requiring new or improved technology for each cycle are delineated

Stabilization of colloidal suspensions by means of highly-charged nanoparticles

We employ a novel Monte Carlo simulation scheme to elucidate the stabilization of neutral colloidal microspheres by means of highly-charged nanoparticles [V. Tohver et al., Proc. Natl. Acad. Sci. U.S.A. 98, 8950 (2001)]. In accordance with the experimental observations, we find that small nanoparticle concentrations induce an effective repulsion that prevents gelation caused by the intrinsic van der Waals attraction between colloids. Higher nanoparticle concentrations induce an attractive potential which is, however, qualitatively different from the regular depletion attraction. We also show how colloid-nanoparticle size asymmetry and nanoparticle charge can be used to manipulate the effective interactions.Comment: Accepted for publication in Physical Review Letters. See also S. Karanikas and A.A. Louis, cond-mat/0411279. Updated to synchronize with published versio

Results of the Mariner 6 and 7 Mars occultation experiments

Final profiles of temperature, pressure, and electron density on Mars were obtained for the Mariner 6 and 7 entry and exit cases, and results are presented for both the lower atmosphere and ionosphere. The results of an analysis of the systematic and formal errors introduced at each stage of the data-reduction process are also included. At all four occulation points, the lapse rate of temperature was subdadiabatic up to altitudes in excess of 20 km. A pronounced temperature inversion was present above the surface at the Mariner 6 exit point. All four profiles exhibit a sharp, superadiabatic drop in temperature at high altitudes, with temperatures falling below the frost point of CO2. These results give a strong indication of frozen CO2 in the middle atmosphere of Mars

Estimating the diameter of the left main bronchus

Publisher's copy made available with the permission of the publisherTwo hundred and six standard PA chest X-rays were measured. The mean diameter of the left main bronchus (LMB) was 12.6±1.9 mm. The mean diameter of the 92 male LMB was 13.0±2.6, and for females 11.8±1.6. These data correspond closely to that reported by others. The correlation between the diameter of the LMB and that of the trachea was 0.74 but was not precise enough to be useful as an estimate for clinical use. Similarly there was good correlation between the diameter of the right main bronchus and that of the left (r=0.75) but not precise enough to be clinically useful. In contrast to previous claims, only direct measurement of the left main bronchus has sufficient precision to define the appropriate size of left double-lumen tube to be selected for lung separation.T. Hampton, S. Armstrong, W.J. Russellhttp://www.aaic.net.au/Article.asp?D=200003

The interaction between transpolar arcs and cusp spots

Transpolar arcs and cusp spots are both auroral phenomena which occur when the interplanetary magnetic field is northward. Transpolar arcs are associated with magnetic reconnection in the magnetotail, which closes magnetic flux and results in a "wedge" of closed flux which remains trapped, embedded in the magnetotail lobe. The cusp spot is an indicator of lobe reconnection at the high-latitude magnetopause; in its simplest case, lobe reconnection redistributes open flux without resulting in any net change in the open flux content of the magnetosphere. We present observations of the two phenomena interacting--i.e., a transpolar arc intersecting a cusp spot during part of its lifetime. The significance of this observation is that lobe reconnection can have the effect of opening closed magnetotail flux. We argue that such events should not be rare

VIRTUAL TEACHING CASES?AN EXPLORATORY STUDY

This research, when complete, will represent a prototype of the development of a virtual teaching case and the use and assessment of the initial versions of research instruments whose aim is the assessment of this new form of teaching case, or any type of teaching case, with regards to learning efficacy, gains, satisfaction, and environment. The purpose of this virtual teaching case (that is, a teaching case, embedded within a virtual world) is to leverage the rich heritage of casebased teaching while helping today’s students to learn by providing a more engaging environment where these students (experienced with multiplayer computer games and the Internet) can collaboratively practice project management skills such as planning scopes of work, schedules, and budgets—skills they have already learnt in class. In a virtual teaching case, students can experience the challenges of discovering problems; collaboratively creating, judging, and transforming resolutions; and reacting to changing circumstances