Novel concept suppressing plasma heat pulses in a tokamak by fast divertor sweeping

One of the remaining challenges in magnetic thermonuclear fusion is survival of the heat shield protecting the tokamak reactor vessel against excessive plasma heat fluxes. Unmitigated high confinement edge localized mode (ELM) is a regular heat pulse damaging the heat shield. We suggest a novel concept of magnetic sweeping of the plasma contact strike point fast and far enough in order to spread this heat pulse. We demonstrate feasibility of a dedicated copper coil in a resonant circuit, including the induced currents and power electronics. We predict the DEMO ELM properties, simulate heat conduction, 3D particles motion and magnetic fields of the plasma and coil in COMSOL Multiphysics and Matlab. The dominant system parameter is voltage, feasible 18 kV yields 1 kHz sweeping frequency, suppressing the ELM-induced surface temperature rise by a factor of 3. Multiplied by other known mitigation concepts, ELMs might be mitigated enough to ensure safe operation of DEMO.

Rapid microarray-based assay for detection of pyrazinamide resistant Mycobacterium tuberculosis

Pyrazinamide (PZA) is a key antibiotic for the treatment of drug susceptible tuberculosis. PZA-resistance is mainly mediated by mutations in the pncA gene; however the current gold standard is a phenotypic drug susceptibility test requiring a well-adjusted pH-value for reliable results. Our melting curve assay detects a non-wild type genotype in selected pncA regions in at least 3750 gene copies/mL within 2.5 hours. The prototype assay was further evaluated by analyzing 271 Mycobacterium tuberculosis complex isolates from Swaziland originating from a previously published drug resistance survey and including 118 isolates with pncA mutations. Sensitivity was 83% (95% CI 75-89%) and specificity was 100% (95% CI 98-100%). Under consideration of further improvements with regard to the target range our melting curve assay has the potential as a rapid rule-in test for PZA susceptibility (wild type pncA), however false resistant results (mutant pncA, but PZA susceptible) cannot be ruled out completely.

Edge Thomson scattering diagnostic on COMPASS tokamak: installation, calibration, operation, improvements

The core Thomson scattering diagnostic (TS) on the COMPASS tokamak was put in operation and reported earlier. Implementation of edge TS, with spatial resolution along the laser beam up to ∼1/100 of the tokamak minor radius, is presented now. The procedure for spatial calibration and alignment of both core and edge systems is described. Several further upgrades of the TS system, like a triggering unit and piezo motor driven vacuum window shutter, are introduced as well. The edge TS system, together with the core TS, is now in routine operation and provides electron temperature and density profiles.

Introducing minimum Fisher regularisation tomography to AXUV and soft x-ray diagnostic systems of the COMPASS tokamak

The contribution focuses on plasma tomography via the minimum Fisher regularisation (MFR) algorithm applied on data from the recently commissioned tomographic diagnostics on the COMPASS tokamak. The MFR expertise is based on previous applications at Joint European Torus (JET), as exemplified in a new case study of the plasma position analyses based on JET soft x-ray (SXR) tomographic reconstruction. Subsequent application of the MFR algorithm on COMPASS data from cameras with absolute extreme ultraviolet (AXUV) photodiodes disclosed a peaked radiating region near the limiter. Moreover, its time evolution indicates transient plasma edge cooling following a radial plasma shift. In the SXR data, MFR demonstrated that a high resolution plasma positioning independent of the magnetic diagnostics would be possible provided that a proper calibration of the cameras on an x-ray source is undertaken.

Bedside percutaneous dilational tracheostomy with endoscopic guidance: experience with 71 ICU patients

OBJECTIVE

To assess the value of endoscopic guidance in bedside percutaneous dilational tracheostomy.

DESIGN

The medical critical care unit of a large community hospital.

SETTING

71 consecutive adult patients who required prolonged mechanical ventilation.

INTERVENTIONS

72 elective percutaneous dilational tracheostomies using the Ciaglia technique were performed under view of a flexible fiberoptic bronchoscope.

MEASUREMENTS AND RESULTS

Patients were examined during tracheostomy and on days 2 and 7 after the procedure, at discharge and after half a year if they were still alive. A correct median puncture was observed by endoscopic control in 59 interventions. An initial paramedian puncture was detected in 13/72 (18%) procedures and was corrected by renewed insertion in all cases. No severe complications related to percutaneous dilational tracheostomy were noticed. Minor complications occurred in 4/71 (5.6%) patients including minor bleeding in 2, inflammatory infiltration in 1 and one superficial lesion of the posterior tracheal mucosa. Long-term follow-up revealed stomal granulation in 3 patients including one at the tracheal site. At the end of the observation period the tracheostomy still was in use in 14/71 (20%) patients and 12/71 (17%) patients were decannulated. Due to their severe underlying diseases 45/71 (63%) patients had died. To facilitate weaning from the tracheostomy a minitracheostomy tube was used in 3 patients.

CONCLUSION

Percutaneous dilational tracheostomy is a simple bedside procedure associated with a low complication rate. We recommend the use of endoscopic guidance to increase the safety of tracheal puncture and dilation procedure.

Type 1 and 3 M-proteins of Streptococcus pyogenes: peptic extraction and fibrinogen binding properties

The pepsin extraction of group A type 1 streptococci for the isolation of M protein fragments was studied at different pH values and at different time intervals. The extracts were compared by SDS PAGE and fused rocket immunoelectrophoresis. Type 1 M protein fragments were prepared in preparative scale by pepsin extraction of type 1 streptococci at pH 5.5 for 60 min. The fragments were separated by affinity chromatography on immobilized fibrinogen and finally purified for sequence studies by gel chromatography. Pepsin extraction of group A type 3 streptococci was also studied at different pH values. In contrast to type 1, the SDS PAGE pattern changed drastically in dependence on the pH. Affinity chromatography on immobilized fibrinogen is also effective in the separation of the pH 5.5 type 3 streptococcal pepsin extract.

Interaction of group A type 1 streptococcal M protein with fibrinogen

Adsorption chromatography of streptococcal extracts on immobilized fibrinogen allows isolation of components that are linked to the corresponding receptors. In this study it is shown by an indirect bactericidal test that fibrinogen binds the M proteins of the streptococcal strains used. Phage-associated lysin extracts of group A type 1 streptococci precipitated with fibrinogen in a double-diffusion test. Fibrinogen reactive components of other streptococcal types inhibited this precipitation reaction. This suggests that the fibrinogen receptors in different types of group A streptococci have identical activity. The interaction between M protein and fibrinogen does not interfere with the interaction between M protein and the corresponding type specific antibodies. The streptococcal antigen components isolated by immobilized fibrinogen showed mitogenic activity in a lymphocyte transformation test.

[Changes in the non-neoplastic thymus in myasthenia gravis]

Non-neoplastic thymuses were examined in 63 patients suffering from myasthenia gravis. Germinal centres were found in 61 patients, minute capsular and septal foci consisting of histiocytes and eosinophilic leucocytes were in 27 cases. An opinion was discussed that lesion close to germinal centres could be related to immune reaction after myogenic induction in thymuses from cases of myasthenia gravis.

M antigens of group A streptococci isolated by means of immunochromatography. Biochemical and serological properties

M proteins of Streptococcus pyogenes types 1 and 12 were purified by immunochromatography on immobilized type-specific opsonizing antibodies. The M proteins were characterized serologically and biochemically. They absorb after immobilization opsonizing antibodies and only precipitate with homologous antisera in immunodiffusion. In SDS PAGE they show one main band, corresponding to mol. weights of 5 X 104 (type 1) and 5.4 X 104 (type 12), accompanied by faint lines, which form with the main band a precipitation line of identity in SDS-crossed immunoelectrophoresis. Both M proteins aggregate blood platelets and clot fibrinogen.

Type-specific and non-type-specific reactions of purified M protein preparations

M proteins of type 1 and type 12 Streptococcus pyogenes were extracted by means of phage-associated lysin and purified by ion-exchange chromatography on CM and DEAE cellulose. Molecular weight distributions were studied by gel chromatography on Biogel A 0.5 m in a 6 molar urea solution and by SDS electrophresis. Serological activities were studied by the complement-fixation reaction and immunodiffusion and were compared with the estimated molecular weights. Type-specific and non-specific activity was found to be located on the same polypeptide chain of a size of 2 X 10(4) daltons (type 1) and 1.5 X 10(4) daltons (type 12). These serologically active chains are in preparations purified by chromatographic methods accompanied by polypeptides of different sizes which are held together by noncovalent bonds thus forming molecules above 4 X 10(4) daltons.