High current lightning test of space shuttle external tank lightning protection system

During lift-off, the shuttle launch vehicle (external tank, solid rocket booster and orbiter) may be subjected to a lightning strike. Tests of a proposed lightning protection method for the external tank and development materials which were subjected to simulated lightning strikes are described. Results show that certain of the high resistant paint strips performed remarkably well in diverting the 50 kA lightning strikes

Dacron Patch Infection After Carotid Angioplasty. A Report of 6 Cases

ObjectiveWe describe our experience with Dacron patch infections after carotid endarterectomy (CEA).ReportFrom 633 patients undergoing carotid endarterectomy with Dacron patching, six re-presented with prosthetic infections. In 3 of the 6 cases a neck haematoma had necessitated surgical revision after the original carotid surgery. Five patients underwent interposition vein grafting and 1 vein patch angioplasty. Postoperatively, 2 patients developed a repeat infection including the 1 patient with patch angioplasty. All patients were free of infection and neurological symptoms after a maximum follow-up of 56.5 months.ConclusionFollowing the development of haemorrhage or wound complications careful clinical surveillance should be carried out after carotid reconstruction

Cluster Observations of a Cusp Diamagnetic Cavity: Structure, Size, and Dynamics

We have analyzed Cluster magnetic field and plasma data during high‐altitude cusp crossing and compared them with high‐resolution MHD simulations. Cluster encountered a diamagnetic cavity (DMC) during northward interplanetary magnetic field (IMF) conditions, and as the IMF rotated southward, the spacecraft reencountered the cavity more at the sunward side of the cusp because the reconnection site had changed location. We found evidence of magnetic reconnection both during northward and southward IMF conditions. The Cluster separation was ∼5000 km, enabling for the first time measurements both inside the DMC and surrounding boundaries that allowed us to construct the structure of the DMC and put the observations of ion pitch angle distributions in context of local reconnection topology and gradients of the boundaries. The cavity is characterized by strong magnetic field fluctuations and high‐energy particles. At the magnetosheath boundary the high‐energy particle fluxes reduced by several orders of magnitude. Throughout the magnetosheath, the high‐energy proton fluxes remained low except during brief intervals when sc4 and sc1 dropped back into the cavity due to changes in solar wind dynamic pressure. However, the high‐energy O+ fluxes did not drop as much in the magnetosheath and were mostly at 60°–120° pitch angles, indicative of a trapped population in the DMC which is observed in the magnetosheath due to a large gyroradius. Significant fluxes of protons and ionized oxygen were also observed escaping from the diamagnetic cavity antiparallel to the magnetic field in a time scale more consistent with the local DMC source than with a reflected bow shock source

Micron- to nano-scale intergrowths among members of the cuprobismutite series and paderaite: HRTEM and microanalytical evidence

Copyright © 2004 The Mineralogical SocietyCoherent intergrowths, at the lattice scale, between cuprobismutite (N = 2) and structurally related padraite along both major axes (15 Åand 17 Årepeats) of the two minerals are reported within skarn from Ocna de Fier, Romania. The structural subunit, DTD, 3 layers of padraite, is involved at interfaces of the two minerals along the 15 Årepeat, as well as in transposition of 1 padraite unit to 2 cuprobismutite units along the 17 Årepeat in slip defects. Lattice images obtained by HRTEM across intervals of 200 -400 nm show short- to long-range stacking sequences of cuprobismutite and padraite ribbons. Such nanoscale slabs mimic µm-scale intergrowths observed in back-scattered electron images at three orders of magnitude greater. These slabs are compositionally equivalent to intermediaries in the cuprobismutite-padraite range encountered during microanalysis. Hodrushite (N = 1.5) is identified in the µm-scale intergrowths, but its absence in the lattice images indicates that, in this case, formation of polysomes between structurally related phases is favoured instead of stacking disorder among cuprobismutite homologues. The tendency for short-range ordering and semi-periodic occurrence of polysomes suggests they are the result of an oscillatory chemical signal with periodicity varying from one to three repeats of 15 Å, rather than simple 'accidents' or irregular structural defects. Lead distribution along the polysomes is modelled as an output signal modulated by the periodicity of stacking sequences, with Pb carried within the D units of padraite. This type of modulator acts as a patterning operator activated by chemical waves with amplitudes that encompass the chemical difference between the minerals. Conversion of the padraite structural subunit DTD to the C unit of cuprobismutite, conserving interval width, emphasizes that polysomatic modularity also assists interference of chemical signals with opposite amplitudes. Observed coarsening of lattice-scale intergrowths up to the µm-scale implies coupling between diffusion-controlled structural modulation, and rhythmic precipitation at the skarn front during crystallization.C.L. Ciobanu, A. Pring and N.J. Coo

State Capacity and the Environmental Investment Gap in Authoritarian States

We construct an n-period, constrained optimization model where the authoritarian ruler maximizes expected rents subject to budget constraint of available surplus. We show that the larger state capacity is in the previous period, the worse environmental quality will be in the next period: while infrastructural investment and environmental protection increase with state capacity, the former increases at a faster rate which enlarges the gap between the two?the environmental investment gap. Given infrastructural public goods typically damage the environment, the larger this gap is the worse the environmental quality would be. This follows from rulers? optimizing logic of equating marginal returns once we assume the declining marginal productivity of factors of production of surplus. We model three types of air and water pollutants in autocracies as a function of state capacity and other relevant variables. State capacity is associated with higher levels of all three types of pollutants

A Real-Time Contouring Feedback Tool for Consensus-Based Contour Training

PURPOSE: Variability in contouring structures of interest for radiotherapy continues to be challenging. Although training can reduce such variability, having radiation oncologists provide feedback can be impractical. We developed a contour training tool to provide real-time feedback to trainees, thereby reducing variability in contouring. METHODS: We developed a novel metric termed localized signed square distance (LSSD) to provide feedback to the trainee on how their contour compares with a reference contour, which is generated real-time by combining trainee contour and multiple expert radiation oncologist contours. Nine trainees performed contour training by using six randomly assigned training cases that included one test case of the heart and left ventricle (LV). The test case was repeated 30 days later to assess retention. The distribution of LSSD maps of the initial contour for the training cases was combined and compared with the distribution of LSSD maps of the final contours for all training cases. The difference in standard deviations from the initial to final LSSD maps, ΔLSSD, was computed both on a per-case basis and for the entire group. RESULTS: For every training case, statistically significant ΔLSSD were observed for both the heart and LV. When all initial and final LSSD maps were aggregated for the training cases, before training, the mean LSSD ([range], standard deviation) was -0.8 mm ([-37.9, 34.9], 4.2) and 0.3 mm ([-25.1, 32.7], 4.8) for heart and LV, respectively. These were reduced to -0.1 mm ([-16.2, 7.3], 0.8) and 0.1 mm ([-6.6, 8.3], 0.7) for the final LSSD maps during the contour training sessions. For the retention case, the initial and final LSSD maps of the retention case were aggregated and were -1.5 mm ([-22.9, 19.9], 3.4) and -0.2 mm ([-4.5, 1.5], 0.7) for the heart and 1.8 mm ([-16.7, 34.5], 5.1) and 0.2 mm ([-3.9, 1.6],0.7) for the LV. CONCLUSIONS: A tool that uses real-time contouring feedback was developed and successfully used for contour training of nine trainees. In all cases, the utility was able to guide the trainee and ultimately reduce the variability of the trainee\u27s contouring