Pop-up Langmuir probe diagnostic in the water cooled divertor of Wendelstein 7-X.

The design, development, and successful implementation of pop-up Langmuir probes installed in the water-cooled divertor of W7-X are described. The probes are controlled by drive coils (actuators) installed behind the divertor plates. These drive coils make use of the magnetic field in W7-X to move the probe tips into and out of the plasma. The drive coils were installed in the vacuum vessel after extensively testing the durability of the coils and analyzing the criteria for safe operation. The probe design is carefully tailored for each of the 36 probe tips in order to be suitable for the different magnetic field configurations used in W7-X and ensure that the probes do not present leading edges to the magnetic flux tubes. An electronic bridge circuit is used for measurement to compensate for the effects of signal propagation time on the long cable lengths used. The diagnostic is integrated with the segment control of W7-X for automated operation and control of the diagnostic. The evaluation of the results from the plasma operation is presented after accounting for appropriate sheath expansion for negative bias voltage on the probes.

Rapid metabolism fosters microbial survival in the deep, hot subseafloor biosphere.

A fourth of the global seabed sediment volume is buried at depths where temperatures exceed 80 °C, a previously proposed thermal barrier for life in the subsurface. Here, we demonstrate, utilizing an extensive suite of radiotracer experiments, the prevalence of active methanogenic and sulfate-reducing populations in deeply buried marine sediment from the Nankai Trough subduction zone, heated to extreme temperature (up to ~120 °C). The small microbial community subsisted with high potential cell-specific rates of energy metabolism, which approach the rates of active surface sediments and laboratory cultures. Our discovery is in stark contrast to the extremely low metabolic rates otherwise observed in the deep subseafloor. As cells appear to invest most of their energy to repair thermal cell damage in the hot sediment, they are forced to balance delicately between subsistence near the upper temperature limit for life and a rich supply of substrates and energy from thermally driven reactions of the sedimentary organic matter.

Development of the ion cyclotron emission diagnostic for the W7-X stellarator.

An ion cyclotron emission (ICE) diagnostic is prepared for installation into the W7-X stellarator, with the aim to be operated in the 2022 experimental campaign. The design is based on the successful ICE diagnostic on the ASDEX Upgrade tokamak. The new diagnostic consists of four B-dot probes, mounted about 72° toroidally away (one module) from the neutral beam injector, with an unobstructed plasma view. Two of the B-dot probes are oriented parallel to the local magnetic field, aimed to detect fast magnetosonic waves. The remaining two probes are oriented poloidally, with the aim to detect slow waves. The radio frequency (RF) signals picked up by the probes are transferred via 50 Ω vacuum-compatible coaxial cables to RF detectors. Narrow band notch filters are used to protect the detectors from possible RF waves launched by the W7-X antenna. The signal will be sampled with a four-channel fast analog-to-digital converter with 14 bit depth and 1 GSample/s sampling rate. The diagnostic's phase-frequency characteristic is properly measured in order to allow measuring the wave vectors of the picked up waves.

The Langmuir probe system in the Wendelstein 7-X test divertor.

The design and evaluation of the Langmuir probe system used in the first divertor operation phase of Wendelstein 7-X is described. The probes are integrated into the target plates and have individually facetted surfaces to keep the angle of incidence of the magnetic field within an appropriate range for different magnetic configurations. Multiple models for the derivation of plasma parameters from current-voltage characteristics are introduced. These are analyzed with regard to their assumptions and limitations, generalized, and adapted to our use case. A detailed comparison is made to determine the most suitable model. It is found that the choice of model has a large impact, for example, resulting in a change in the inferred temperatures of up to a factor two. This evaluation is implemented in a Bayesian modeling framework and automated to allow for joint analysis with other diagnostics and a replacement of ad hoc assumptions. We rigorously treat parameter uncertainties, revealing strong correlations between them. General and flexible model formulations permit an expansion to additional effects.

Contamination Control for Scientific Drilling Operations.

Drilling is an integral part of subsurface exploration. Because almost all drilling operations require the use of a drill fluid, contamination by infiltration of drill fluid into the recovered core material cannot be avoided. Because it is impossible to maintain sterile conditions during drilling the drill fluid will contain surface microbes and other contaminants. As contamination cannot be avoided, it has to be tracked to identify those parts of the drill core that were not infiltrated by the drill fluid. This is done by the addition of tracer compounds. A great variety of tracers is available, and the choice depends on many factors. This review will first explain the basic principles of drilling before presenting the most common tracers and discussing their strengths and weaknesses. The final part of this review presents a number of key questions that have to be addressed in order to find the right tracer for a particular drilling operation.

Active sulfur cycling by diverse mesophilic and thermophilic microorganisms in terrestrial mud volcanoes of Azerbaijan.

Terrestrial mud volcanoes (TMVs) represent geochemically diverse habitats with varying sulfur sources and yet sulfur cycling in these environments remains largely unexplored. Here we characterized the sulfur-metabolizing microorganisms and activity in four TMVs in Azerbaijan. A combination of geochemical analyses, biological rate measurements and molecular diversity surveys (targeting metabolic genes aprA and dsrA and SSU ribosomal RNA) supported the presence of active sulfur-oxidizing and sulfate-reducing guilds in all four TMVs across a range of physiochemical conditions, with diversity of these guilds being unique to each TMV. The TMVs varied in potential sulfate reduction rates (SRR) by up to four orders of magnitude with highest SRR observed in sediments where in situ sulfate concentrations were highest. Maximum temperatures at which SRR were measured was 60°C in two TMVs. Corresponding with these trends in SRR, members of the potentially thermophilic, spore-forming, Desulfotomaculum were detected in these TMVs by targeted 16S rRNA analysis. Additional sulfate-reducing bacterial lineages included members of the Desulfobacteraceae and Desulfobulbaceae detected by aprA and dsrA analyses and likely contributing to the mesophilic SRR measured. Phylotypes affiliated with sulfide-oxidizing Gamma- and Betaproteobacteria were abundant in aprA libraries from low sulfate TMVs, while the highest sulfate TMV harboured 16S rRNA phylotypes associated with sulfur-oxidizing Epsilonproteobacteria. Altogether, the biogeochemical and microbiological data indicate these unique terrestrial habitats support diverse active sulfur-cycling microorganisms reflecting the in situ geochemical environment.

Urinary changes in ultra long-distance marathon runners.

The urine of 45 athletes, male and female, were studied after completing an ultra long-distance marathon race. Of these athletes, 24.4% were found on screening to have red blood cells in the urine. The urinary mean corpuscular volume (MCV) of red cells was used in an attempt to differentiate between lower and upper urinary tract haematuria. With the exception of 1 athlete, the red cells were not dysmorphic and had an MCV greater than 72 fl. This suggested that the haematuria had an origin from the lower urinary tract. The urinary changes disappeared within 7 days. No definite residual renal damage could be established.

Spontaneous regression of metastases in a case of bilateral renal cell carcinoma.

A patient is described who had undergone bilateral nephrectomy for renal cell carcinoma and who had been maintained on hemodialysis for the last 2 years. A total of 3 months after acceptance into the program he was found histologically to have metastatic pleural lesions, which had regressed spontaneously 1 1/2 years ago. Repeat clinical and radiological assessment has shown no tumor recurrence.

Vocal cord paralysis associated with subacute thyroiditis. A case report.

A 44-year-old man was treated for subacute de Quervain's thyroiditis. This was complicated by the development of vocal cord paralysis, which persisted after recovery from the thyroiditis.

The milk-alkali syndrome. A case report.

A case of the milk-alkali syndrome is described. The patient presented with a raised serum calcium level without hypercalciuria, nephrocalcinosis and azotaemia. The alkali used was an antacid preparation containing calcium carbonate.

Psychological effects of in-centre haemodialysis on the dialysand's adolescent children.

A perusal of the literature on the psychological aspects of haemodialysis reveals that the patient, his spouse and his children are affected. Most studies have dealt with patients on home dialysis. This study was designed to ascertain in psychological terms the effect that the in-centre 'dialysing parent' has on his adolescent children. The results indicate that the children of parents on hospital-based haemodialysis appeared to react to the parents' altered state of health. They were more self-sufficient and less well-adjusted as regarded home and social relations than were controls. The results are discussed in terms of the psychological management of the patient and his family.

An interracial study of continuous ambulatory peritoneal dialysis (CAPD) in Natal.

This study analyses our experience with continuous ambulatory peritoneal dialysis (CAPD) over a period of 2 1/2 years. Twenty-six patients are continuing on CAPD. Of the 31 Whites, 19 Asians, 5 Coloureds and 3 Blacks who began treatment, 15 Whites, 8 Asians, and 3 Coloureds but no Black patients are continuing treatment. Peritonitis was the most important limiting factor and occurred once in every 28,5 weeks in Coloureds, once in 19,5 weeks in Whites, once every 16 weeks in Asiatics and once every 11 weeks in Blacks. Twenty-eight per cent of the patients had 70% of the episodes of peritonitis. Advantages of CAPD were personal freedom, control of blood pressure and fluid balance, and a greater latitude in acceptance of more patients into a chronic renal dialysis programme. The value of CAPD should be assessed further in time and should not be regarded as the final solution to the management of patients with chronic renal failure.

Changes in calcium levels associated with rhabdomyolysis-induced acute renal failure.

Two patients with acute renal failure (ARF) following marathon running are discussed. The association between rhabdomyolysis and calcium changes in these cases is stressed and a short review of pertinent literature is discussed. It is felt that the calcium changes in ARF are multifactorial. They include parathyroid hormone changes, calcium deposition in muscle, and changes in 1,25-dihydroxycholecalciferol and serum phosphorus levels.

Acute renal failure in marathon runners.

The Comrades Marathon is a gruelling test of man's stamina and only trained athletes participate. It is surprising that of over 2,000 contestants each year on a 90-km (56.25-mile) course, severe cardiac and renal damage does not occur more often. We are able, however, to report 10 cases over 9 years when renal damage did occur. 3 cases required haemodialysis; 1 had peritoneal dialysis; 2 patients had renal biopsies. Possible idiosyncratic factors are discussed as is the pathogenesis of acute tubular necrosis.

The effect of thyrocalcitonin therapy and phosphate deprivation on tumoral calcinosis.

Six siblings were screened for clinical and biochemical evidence of tumoral calcinosis. The 3 brothers showed all the characteristic manifestations of this entity. Two of them were treated for an initial period of 6 months with large doses of thyrocalcitonin, with virtually no response. After a 9-month equilibration period they were treated by phosphate depletion, and at the end of 6 months they were re-investigated. There was no appreciable objective or radiological difference in the extent of the masses. It was concluded that, in these 2 patients, surgical excision of the tumours was the only feasible form of therapy.