Adjuvant chemotherapy for stage I non-seminomatous testicular cancer

Developments in the treatment of stage I testicular nonseminomatous germ cell tumours have aimed primarily at reducing morbidity since the introduction of retroperitoneal lymph node dissection. Surveillance after orchidectomy, i.e. follow-up alone with chemotherapy only for relapsed disease, was found to be logistically and psychologically taxing for patients. Risk factors for relapse were, however, identified from analyses of tumour histology of the orchidectomy specimen.Between September 1988 and April 1992, 20 patients with clinical stage I testicular non-seminomatous germ cell tumours and a relatively high risk of relapse were entered into a prospective study of adjuvant chemotherapy. The chemotherapy regimen consisted of 2 cycles of cisplatin, etoposide and bleomycin. Each cycle of chemotherapy lasted 3 days.There have been no relapses at a median follow-up of 31 months (range 12 - 53 months). Acute and late toxicity have been modest. We have found adjuvant chemotherapy to be effective after orchidectomy in patients with stage I disease with adverse prognostic factors for relapse

The first 100 kidney transplants from living related donors at Groote Schuur Hospital

Improved results with cadaver kidney transplantation and the increase in the number of cadaver organs have caused the continued use of donor kidneys from living relatives to be questioned. In this analysis of our first 100 renal transplants involving a living related donor, the 5-year graft survival rate was 70%. The 5-year graft survival rate for recipients of grafts from HLA-identical donors was 81%, as opposed to the 64% survival rate for grafts from one-haplotype donors. Recipients of grafts from one-haplotype-matched donors who received donor-specific blood transfusions demonstrated better graft survival than those who were not transfused. This analysis demonstrates that the results of living related kidney transplantation are good, and suggests that donor-specific blood transfusions may be beneficial

Estimating the Rate of Field Line Braiding in the Solar Corona by Photospheric Flows

In this paper, we seek to understand the timescale in which the photospheric motions on the Sun braid coronal magnetic field lines. This is a crucial ingredient for determining the viability of the braiding mechanism for explaining the high temperatures observed in the corona. We study the topological complexity induced in the coronal magnetic field, primarily using plasma motions extracted from magneto-convection simulations. This topological complexity is quantified using the field line winding, finite time topological entropy (FTTE), and passive scalar mixing. With these measures, we contrast mixing efficiencies of the magneto-convection simulation, a benchmark flow known as a "blinking vortex", and finally photospheric flows inferred from sequences of observed magnetograms using local correlation tracking. While the highly resolved magneto-convection simulations induce a strong degree of field line winding and FTTE, the values obtained from the observations from the plage region are around an order of magnitude smaller. This behavior is carried over to the FTTE. Nevertheless, the results suggest that the photospheric motions induce complex tangling of the coronal field on a timescale of hours

Review article: MHD wave propagation near coronal null points of magnetic fields

We present a comprehensive review of MHD wave behaviour in the neighbourhood of coronal null points: locations where the magnetic field, and hence the local Alfven speed, is zero. The behaviour of all three MHD wave modes, i.e. the Alfven wave and the fast and slow magnetoacoustic waves, has been investigated in the neighbourhood of 2D, 2.5D and (to a certain extent) 3D magnetic null points, for a variety of assumptions, configurations and geometries. In general, it is found that the fast magnetoacoustic wave behaviour is dictated by the Alfven-speed profile. In a $\beta=0$ plasma, the fast wave is focused towards the null point by a refraction effect and all the wave energy, and thus current density, accumulates close to the null point. Thus, null points will be locations for preferential heating by fast waves. Independently, the Alfven wave is found to propagate along magnetic fieldlines and is confined to the fieldlines it is generated on. As the wave approaches the null point, it spreads out due to the diverging fieldlines. Eventually, the Alfven wave accumulates along the separatrices (in 2D) or along the spine or fan-plane (in 3D). Hence, Alfven wave energy will be preferentially dissipated at these locations. It is clear that the magnetic field plays a fundamental role in the propagation and properties of MHD waves in the neighbourhood of coronal null points. This topic is a fundamental plasma process and results so far have also lead to critical insights into reconnection, mode-coupling, quasi-periodic pulsations and phase-mixing.Comment: 34 pages, 5 figures, invited review in Space Science Reviews => Note this is a 2011 paper, not a 2010 pape

Heating of Braided Coronal Loops

Aims. We investigate the relaxation of braided magnetic loops in order to find out how the type of braiding via footpoint motions affects resultant heating of the loop. Methods. Two magnetic loops, braided in different ways, are used as initial conditions in resistive MHD simulations and their subsequent evolution is studied. Results. The fields both undergo a resistive relaxation in which current sheets form and fragment and the system evolves towards a state of lower energy. In one case this relaxation is very efficient with current sheets filling the volume and homogeneous heating of the loop occurring. In the other case fewer current sheets develop, less magnetic energy is released in the process and a patchy heating of the loop results. The two cases, although very similar in their setup, can be distinguished by the mixing properties of the photospheric driver. The mixing can be measured by the topological entropy of the plasma flow, an observable quantity