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Objectives  To evaluate the long‐term effects of different types of urinary diversion on skeletal bone density and whole‐body potassium content in patients with an early correction of base excess (<−2.5). Patients and methods  The early correction of base excess (<−2.5) is one of the principles of the treatment of patients undergoing urinary diversion at our institution. In 27 patients with urinary diversion, bone mineral density (assessed by dual‐photon absorptiometry), whole‐body potassium, electrolyte and creatinine levels were determined, and capillary blood gas analysed. The mean time since surgery was 16.8 years in 16 patients with a rectal reservoir, 20.5 years in six patients with a colonic conduit, 7.8 years in four patients with an ileocaecal pouch and 5 years in one adolescent with an ileal bladder augmentation. Results  Bone mineral density was normal in 25 of the 27 patients; no exact measurement was possible in the remaining two. The whole‐body potassium content was reduced in eight of the 27 patients (three with a conduit, two with a rectal reservoir, two with an ileocaecal pouch and one with ileal augmentation). In four of these eight patients the base excess was <−2.5 (−2.7 to −5). Of the other four, two had no regular testing of their base balance and two were obese. The electrolytes were within the normal ranges. None of the patients had hyperchloraemic metabolic acidosis. Conclusion  With early correction of the base excess (<−2.5), there was no decrease in bone mineral density and no hyperchloraemic acidosis. There was no significant difference between the different types of urinary diversion. There seems to be a relationship between low base excess and decreased whole‐body potassium.

Conventional annular Hall thrusters become inefficient when scaled to low power. Cylindrical Hall thrusters, which have lower surface-to-volume ratio, are more promising for scaling down. They presently exhibit performance comparable with conventional annular Hall thrusters. The present paper gives a review of the experimental and numerical investigations of electron crossfield transport in the 2.6 cm miniaturized cylindrical Hall thruster (100 W power level). We show that, in order to explain the discharge current observed for the typical operating conditions, the electron anomalous collision frequency ν B has to be on the order of the Bohm value, ν B ≈ω c /16. The contribution of electron-wall collisions to cross-field transport is found to be insignificant. The optimal regimes of thruster operation at low background pressure (below 10-5 Torr) in the vacuum tank appear to be different from those at higher pressure (~10-4 Torr).

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