1,337 research outputs found

    Malignant glioma after ependymoma: an unusual secondary malignancy

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    Purpose : Secondary malignancies (SM) are a known long-­‐term problem in children surviving brain tumors. We report on two unusual cases of SM observed after treatment of ependymoma. Case reports : 1. The first case is a female survivor of a low-­‐grade ependymoma (Grade II). She had been treated at the age of 3 months with surgery and chemotherapy. A relapse of the primary tumor happened two years later, which was completely removed and treated with local radiotherapy to the posterior fossa. Fifteen years after the first cancer, she developed a pontine glioma near the location of the previous radiotherapy. 2. The second case is a femal survivor of an ependymoma (Grade III) which was removed and irradiated when she was 4 years old. The child developed a pontine glioma near the location of the previous radiotherapy ten years after the diagnosis of the first cancer. Further extension of the disease showed after biopsy PNET-­‐ like features. Both patients passed away. Discussion and Conclusion : Second malignant neoplasia is a rare phenomenon and this risk should not overshadow the great success in treating cancer of childhood. Among the studied risk factors, young age and radiotherapy are well established. The reported patients were followed annually to ensure their remission and both developed symptoms and an unusual unreported secondary cancer a few months after the annual monitoring that was considered as normal. This issue highlights the complexity of monitoring cancer survivors and raises the question of the best way for their long-­‐term follow-­‐up

    Spatiotemporal evolution of runaway electrons from synchrotron images in Alcator C-Mod

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    In the Alcator C-Mod tokamak, relativistic runaway electron (RE) generation can occur during the flattop current phase of low density, diverted plasma discharges. Due to the high toroidal magnetic field (B = 5.4 T), RE synchrotron radiation is measured by a wide-view camera in the visible wavelength range (~400-900 nm). In this paper, a statistical analysis of over one thousand camera images is performed to investigate the plasma conditions under which synchrotron emission is observed in C-Mod. In addition, the spatiotemporal evolution of REs during one particular discharge is explored in detail via a thorough analysis of the distortion-corrected synchrotron images. To accurately predict RE energies, the kinetic solver CODE [Landreman et al 2014 Comput. Phys. Commun. 185 847-855] is used to evolve the electron momentum-space distribution at six locations throughout the plasma: the magnetic axis and flux surfaces q = 1, 4/3, 3/2, 2, and 3. These results, along with the experimentally-measured magnetic topology and camera geometry, are input into the synthetic diagnostic SOFT [Hoppe et al 2018 Nucl. Fusion 58 026032] to simulate synchrotron emission and detection. Interesting spatial structure near the surface q = 2 is found to coincide with the onset of a locked mode and increased MHD activity. Furthermore, the RE density profile evolution is fit by comparing experimental to synthetic images, providing important insight into RE spatiotemporal dynamics

    Rolle der Zytologie in der hämatopathologischen Diagnostik

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    Zusammenfassung: Die Zytologie stellt ein wichtiges diagnostisches Instrument in der täglichen Praxis der Hämatopathologie dar. Durch den zytologisch erfolgten Nachweis nichthämatologischer Ursachen einer Knotenbildung (z.B. Speicheldrüsenneoplasien, Tuberkulose, Melanom- oder Karzinommetastasen) besteht seltener die Notwendigkeit einer chirurgischen Exzision. Die kombinierte Anwendung morphologischer, immunphänotypischer sowie molekularer Analysen und der fachliche Austausch machen diese Untersuchungstechnik sicher. Somit stellt die zytologische Untersuchung in verschiedensten Situationen eine Alternative zur Exzisionsbiopsie dar - auch bei primären hämatologischen Erkrankungen und insbesondere bei Rezidive

    Scaling laws for jets of single cavitation bubbles

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    Fast liquid jets, called micro-jets, are produced within cavitation bubbles experiencing an aspherical collapse. Here we review micro-jets of different origins, scales and appearances, and propose a unified framework to describe their dynamics by using an anisotropy parameter ζ\zeta, representing a dimensionless measure of the liquid momentum at the collapse point (Kelvin impulse). This parameter is rigorously defined for various jet drivers, including gravity and nearby boundaries. Combining theoretical considerations with hundreds of high-speed visualisations of bubbles collapsing near a rigid surface, near a free surface or in variable gravity, we classify the jets into three distinct regimes: weak, intermediate and strong. Weak jets (ζ<103\zeta<10^{-3}) hardly pierce the bubble, but remain within it throughout the collapse and rebound. Intermediate jets (103<ζ<0.110^{-3}<\zeta<0.1) pierce the opposite bubble wall close to the last collapse phase and clearly emerge during the rebound. Strong jets (ζ>0.1\zeta>0.1) pierce the bubble early during the collapse. The dynamics of the jets is analysed through key observables, such as the jet impact time, jet speed, bubble displacement, bubble volume at jet impact and vapour-jet volume. We find that, upon normalising these observables to dimensionless jet parameters, they all reduce to straightforward functions of ζ\zeta, which we can reproduce numerically using potential flow theory. An interesting consequence of this result is that a measurement of a single observable, such as the bubble displacement, suffices to estimate any other parameter, such as the jet speed. Remarkably, the dimensionless parameters of intermediate and weak jets only depend on ζ\zeta, not on the jet driver. In the same regime, the jet parameters are found to be well approximated by power-laws of ζ\zeta, which we explain through analytical arguments
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