Bench-to-bedside review: Mechanisms and management of hyperthermia due to toxicity

Body temperature can be severely disturbed by drugs capable of altering the balance between heat production and dissipation. If not treated aggressively, these events may become rapidly fatal. Several toxins can induce such non-infection-based temperature disturbances through different underlying mechanisms. The drugs involved in the eruption of these syndromes include sympathomimetics and monoamine oxidase inhibitors, antidopaminergic agents, anticholinergic compounds, serotonergic agents, medicaments with the capability of uncoupling oxidative phosphorylation, inhalation anesthetics, and unspecific agents causing drug fever. Besides centrally disturbed regulation disorders, hyperthermia often results as a consequence of intense skeletal muscle hypermetabolic reaction. This leads mostly to rapidly evolving muscle rigidity, extensive rhabdomyolysis, electrolyte disorders, and renal failure and may be fatal. The goal of treatment is to reduce body core temperature with both symptomatic supportive care, including active cooling, and specific treatment options

Quantisierung der Randbedingung für isolierte Horizonte. Flächen-Holonomien in der Schleifenquantengravitation

The aim of this thesis is to investigate an approach to the description of black holes from within loop quantum gravity first proposed in [1]. In contrast to the first works on black holes in loop quantum gravity, the distinguishing feature of this approach is that the existence of a black hole is not already imposed in the classical theory. Also, the approach considered here does not restrict itself to a symmetry reduced sector of the full theory. Instead, the full Hilbert space of loop quantum gravity will be examined for solutions that could possibly describe black holes in the sense that they fulfill a certain boundary condition on a 2-dimensional surface. Therefore, the boundary condition for spherically symmetric isolated horizons is central to this approach. It will be quantised in this thesis for the case of full SU(2) gauge freedom on the horizon. This boundary condition is also of interest in contexts not related to black holes: it is very similar to the self-duality condition for Yang-Mills fields and it is also relevant to Chern-Simons theory. Since it is not straightforward to formulate this boundary condition in the quantum theory, the first part of this thesis will start with addressing classical aspects of the isolated horizon boundary condition. This includes a reformulation into an equivalent condition in which the concept of surface holonomies plays a crucial role. Surface holonomies will be introduced in the context of higher gauge theory, where they naturally arise. The second part of this thesis then deals with the quantisation of the reformulated boundary condition. After a short introduction to the Duflo-Kirillov map, we will present a detailed calculation determining the action of a quantum operator associated to surface holonomies on so-called single puncture states. The action of this operator on generic spin network states can be expressed as a product of surface holonomy operators acting on single puncture states. We then proceed to the analysis of the properties of this quantum operator, which can be viewed as an operator-valued 2x2 matrix. This includes, for example, its determinant and the commutators between its matrix elements. The results indicate that the quantum surface holonomies take values in some new quantum deformation of SU(2). Finally, we search for solutions to the quantised isolated horizon boundary condition. Since, for technical reasons, such solutions cannot exist in the Ashtekar-Lewandowski Hilbert space of loop quantum gravity, we redefine (path) holonomies via the quantised isolated horizon boundary condition. In the U(1) case we show that solutions are describing U(1) Chern-Simons theory with punctures, ruled by the quantum group U_q(1), as in previous works that start with Chern-Simons theory on the boundary. It proves to be a lot more complicated to find such explicit results also for the SU(2) case. Using some further assumptions to simplify the computations, we analyse the quantised isolated horizon boundary condition on states with up to two punctures. While the cases with zero and one puncture can be quickly dismissed, the two puncture case is at least in principle capable of providing a solution to the quantised isolated horizon boundary condition. However, in the explicit calculations, we see that solutions only exist asymptotically in the limit of large spins j. After a summary of the results of this thesis, including a brief discussion of these, we thus end the final chapter with an outlook of possible research directions following up on the results of this thesis.Gegenstand dieser Arbeit ist die Untersuchung eines Ansatzes zur Beschreibung schwarzer Löcher in der Schleifenquantengravitation, der erstmals in [1] vorgeschlagen wurde. Das Besondere an diesem Zugang ist, dass die Existenz des schwarzen Loches nicht bereits in der klassischen Theorie vorausgesetzt wird, wie dies in den ersten Arbeiten zu schwarzen Löchern in der Schleifenquantengravitation der Fall war. Auch wird nicht von vornherein nur ein symmetriereduzierter Sektor der vollen Theorie betrachtet. Vielmehr wird direkt in der vollen Quantentheorie nach Lösungen gesucht, die möglicherweise schwarze Löcher beschreiben könnten, da sie auf einer 2-dimensionalen Fläche eine bestimmte Randbedingung erfüllen. Die Randbedingung für sphärisch symmetrische isolierte Horizonte, welche in dieser Arbeit für den Fall mit SU(2) als Eichgruppe quantisiert wird, ist daher ein zentrales Element dieses Zugangs. Sie ist zudem auch unabhängig von der Betrachtung schwarzer Löcher von Interesse: Sie besitzt große Ähnlichkeit mit der Selbstdualitätsbedingung für Yang-Mills Felder und ist zudem auch für die Chern-Simons Theorie relevant. Da die Übertragung der Randbedingung in die Quantentheorie nicht direkt möglich ist, wird im ersten Teil der Arbeit zunächst auf klassische Aspekte der Randbedingung für isolierte Horizonte eingegangen. Dies schließt eine Umformulierung in eine äquivalente Bedingung ein, wobei dem Konzept der Flächen-Holonomien eine wesentliche Bedeutung zukommt. Diese werden in ihrem natürlichen Kontext - der höheren Eichtheorie - eingeführt. Der zweite Teil der Arbeit befasst sich anschließend mit der Quantisierung dieser umformulierten Randbedingung. Hierzu folgt nach einer kurzen Einführung der Duflo- Kirillov-Abbildung eine ausführliche Rechnung zur Bestimmung der Wirkung eines den Flächen-Holonomien zugeordneten Quantenoperators auf sogenannten Single-Puncture- States. Die Wirkung des Operators auf allgemeinen Spinnetzwerk-Zuständen lässt sich durch ein Produkt von Flächen-Holonomie-Operatoren, die auf Single-Puncture-States wirken, ausdrücken. Anschließend folgt die Analyse der Eigenschaften dieses Quantenoperators, welchen man als operatorwertige 2x2 Matrix betrachten kann. Diese schließt zum Beispiel dessen Determinante sowie die Kommutatoren zwischen dessen Matrixelementen ein. Die Ergebnisse deuten darauf hin, dass die quantisierten Flächen-Holonomien Werte in einer neuen Quantendeformation von SU(2) annehmen. Schließlich kommen wir dann zur Suche nach Lösungen der quantisierten Randbedingung für isolierte Horizonte. Da es solche Lösungen im Ashtekar-Lewandowski Hilbertraum der Schleifenquantengravitation aus technischen Gründen nicht geben kann, nehmen wir die quantisierte Randbedingung für isolierte Horizonte stattdessen als Definition für neue (Pfad-)Holonomie-Operatoren. Im U(1) Fall zeigen wir, dass die Lösungen, wie in früheren Arbeiten die mit Chern-Simons Theorie auf dem Rand beginnen, U(1) Chern-Simons Theorie mit Defekten beschreiben und somit die Quantengruppe U_q(1) eine zentrale Rolle spielt. Im SU(2) Fall stellt es sich als deutlich komplizierter heraus ähnlich konkrete Ergebnisse zu erzielen. Unter Verwendung weiterer Annahmen zur Vereinfachung der Rechnungen analysieren wir die quantisierte Randbedingung für isolierte Horizonte auf Quantenzuständen mit bis zu zwei Punctures. Während die Quantenzustände mit keiner bzw. einer Puncture zügig ausgeschlossen werden können, besteht bei den Quantenzuständen mit zwei Punctures zumindest grundsätzlich die Chance, dass diese die quantisierte Randbedingung für isolierte Horizonte lösen. Die expliziten Rechnungen, die wiederum von einigen Vereinfachungen Gebrauch machen, zeigen jedoch, dass Lösungen nur asymptotisch im Grenzwert großer Spins j existieren. Auf eine Zusammenfassung der Ergebnisse dieser Arbeit – einschließlich einer kurzen Diskussion derselben – folgt daher im letzten Kapitel ein Ausblick auf mögliche, auf den Ergebnissen dieser Arbeit aufbauende, Forschungsprojekte

Towards a new image processing system at Wendelstein 7-X: From spatial calibration to characterization of thermal events

Wendelstein 7-X (W7-X) is the most advanced fusion experiment in the stellarator line and is aimed at proving that the stellarator concept is suitable for a fusion reactor. One of the most important issues for fusion reactors is the monitoring of plasma facing components when exposed to very high heat loads, through the use of visible and infrared (IR) cameras. In this paper, a new image processing system for the analysis of the strike lines on the inboard limiters from the first W7-X experimental campaign is presented. This system builds a model of the IR cameras through the use of spatial calibration techniques, helping to characterize the strike lines by using the information given by real spatial coordinates of each pixel. The characterization of the strike lines is made in terms of position, size, and shape, after projecting the camera image in a 2D grid which tries to preserve the curvilinear surface distances between points. The description of the strike-line shape is made by means of the Fourier Descriptors

Forward modeling of collective Thomson scattering for Wendelstein 7-X plasmas: Electrostatic approximation

In this paper, we present a method for numerical computation of collective Thomson scattering (CTS). We developed a forward model, eCTS, in the electrostatic approximation and benchmarked it against a full electromagnetic model. Differences between the electrostatic and the electromagnetic models are discussed. The sensitivity of the results to the ion temperature and the plasma composition is demonstrated. We integrated the model into the Bayesian data analysis framework Minerva and used it for the analysis of noisy synthetic data sets produced by a full electromagnetic model. It is shown that eCTS can be used for the inference of the bulk ion temperature. The model has been used to infer the bulk ion temperature from the first CTS measurements on Wendelstein 7-X

Demonstration of reduced neoclassical energy transport in Wendelstein 7-X

Research on magnetic confinement of high-temperature plasmas has the ultimate goal of harnessing nuclear fusion for the production of electricity. Although the tokamak(1) is the leading toroidal magnetic-confinement concept, it is not without shortcomings and the fusion community has therefore also pursued alternative concepts such as the stellarator. Unlike axisymmetric tokamaks, stellarators possess a three-dimensional (3D) magnetic field geometry. The availability of this additional dimension opens up an extensive configuration space for computational optimization of both the field geometry itself and the current-carrying coils that produce it. Such an optimization was undertaken in designing Wendelstein 7-X (W7-X)(2), a large helical-axis advanced stellarator (HELIAS), which began operation in 2015 at Greifswald, Germany. A major drawback of 3D magnetic field geometry, however, is that it introduces a strong temperature dependence into the stellarator's non-turbulent 'neoclassical' energy transport. Indeed, such energy losses will become prohibitive in high-temperature reactor plasmas unless a strong reduction of the geometrical factor associated with this transport can be achieved; such a reduction was therefore a principal goal of the design of W7-X. In spite of the modest heating power currently available, W7-X has already been able to achieve high-temperature plasma conditions during its 2017 and 2018 experimental campaigns, producing record values of the fusion triple product for such stellarator plasmas(3,4). The triple product of plasma density, ion temperature and energy confinement time is used in fusion research as a figure of merit, as it must attain a certain threshold value before net-energy-producing operation of a reactor becomes possible(1,5). Here we demonstrate that such record values provide evidence for reduced neoclassical energy transport in W7-X, as the plasma profiles that produced these results could not have been obtained in stellarators lacking a comparably high level of neoclassical optimization.Previously documented record values of the fusion triple product in the stellarator Wendelstein 7-X are shown to be evidence for reduced neoclassical energy transport in this optimized device