Hybrid approaches to heavy ion collisions and future perspectives

We present the current status of hybrid approaches to describe heavy ion collisions and their future challenges and perspectives. First we present a hybrid model combining a Boltzmann transport model of hadronic degrees of freedom in the initial and final state with an optional hydrodynamic evolution during the dense and hot phase. Second, we present a recent extension of the hydrodynamical model to include fluctuations near the phase transition by coupling a chiral field to the hydrodynamic evolution

Handlungsspielräume im europäischen Gleichgewichtssystem

Die hier vorliegende Diplomarbeit beschäftigt sich mit den Handlungsspielräumen im europäischen Gleichgewichtssystem in der Mitte des 18. Jahrhunderts und stellt dabei Kaunitz und das Renversement des alliances in den Mittelpunkt. Im ersten Teil dieser Arbeit geht es darum, die Ursprünge des europäischen Gleichgewichtssystems nachzuzeichnen, es in seinen unterschiedlichen Varianten im Laufe der Jahrhunderte zu skizzieren und es in seiner Ausgestaltung im 18. Jahrhundert zu charakterisieren. Nach den eher theoretischen Ausführungen über mögliche Gleichgewichtsmodelle und deren Entwicklung werden die einzelnen Akteure, also Staaten, vorgestellt, die einen bedeutenden Einfluss auf das europäische Gleichgewicht im 18. Jahrhundert hatten. Dazu bedarf es einer eingehenden Analyse der beteiligten Staaten, die der demographischen Entwicklung, den territorialen Gegebenheiten, der Finanzgebarung, der Wirtschaft, den militärischen Kapazitäten sowie spezifischen Besonderheiten jedes einzelnen Staates Platz einräumt. Anschließend werden deren jeweilige außenpolitische Strukturen unter die Lupe genommen und ein Einblick in die Entscheidungsabläufe, die wichtigsten handelnden Personen, diplomatische Entwicklungen und ihre außenpolitischen Zielsetzungen gewährt. Ambitionierte Außenpolitik führte zumeist zu Konflikten mit anderen europäischen Großmächten, daher dürfen die wichtigsten Konfliktfelder hier nicht außer Acht gelassen werden. Ein zweiter Teil beschäftigt sich mit der Person des österreichischen Staatskanzlers Wenzel Anton von Kaunitz, um einen der Hauptprotagonisten des europäischen Gleichgewichtssystems in den Mittelpunkt zu rücken. Der Beschäftigung mit seiner Person und der Betrachtung seines politischen Werdegangs folgt eine Analyse seiner Sicht auf jede einzelne der europäischen Großmächte, „die Gesinnung, und Absichten der auswärtigen Höfen“, um zu zeigen, was man sich „von einem jeden Hof zu hoffen, oder zu beförchten haben dürfften.“ An diese Kaunitz’sche Beurteilung Frankreichs, Preußens, Russlands und der Seemächte schließt sich eine Untersuchung seiner außenpolitischen Ziele an, um in dieser Gesamtheit der Überlegungen das europäische Gleichgewichtssystem aus der Sicht der Zeit zeigen und darüber hinaus einen Blick aus der Innenperspektive einer der handelnden Personen ermöglichen zu können. Den Handlungsspielräumen ist ein dritter und abschließender Teil gewidmet, um einerseits die Einschränkung der Handlungsspielräume der einzelnen Akteure durch das Gleichgewichtssystems darzustellen, andererseits die Freiräume aufzuzeigen, die sich für die handelnden Personen ergeben konnten und anhand des Beispiels des „Renversement des alliances“ sowohl Erfolge als auch Ernüchterungen in den internationalen Beziehungen des 18. Jahrhunderts nachzeichnen zu können

Measurement of compartment pressure of the rectus sheath during intra-abdominal hypertension in rats

Objective: To investigate whether the compartment pressure of the rectus sheath (CPRS) reflects the intra-abdominal pressure (IAP) under various conditions of intra-abdominal hypertension (IAH). Design and setting: Prospective experimental study with in vivo pressure measurements at the Institute for Clinical and Experimental Surgery, University of Saarland. Animals: Sprague-Dawley rats. Interventions: Stepwise increase and decrease in IAP with continuous measurement of the correspondent CPRS. Measurements and results: Physiological IAP (2 mmHg) and CPRS (6 mmHg) showed astatistically significant difference. Stepwise elevation in IAP was associated with asimultaneous increase in CPRS. Accordingly, stepwise decompression of IAP resulted in astepwise decrease in CPRS. Under both conditions Bland-Altman analysis comparing IAP to correspondent CPRS showed avery good agreement for IAP at or above 12 mmHg. In addition, closure of the overlaying subcutaneous tissue and skin did not affect CPRS or its correlation with IAP. Conclusions: CPRS accurately reflects IAP for IAP of 12 mmHg or higher. Thus CPRS measurements may represent anovel approach for diagnosis and monitoring of IA

Percutaneous aortic valve replacement: valvuloplasty studies in vitro

Objective: Valvuloplasty of the aortic valve is currently used in selected patients for severe calcified aortic valve disease, but clinical effectiveness is low and complication rate remains high. In this study, the total particle load after valvuloplasty and the embolization risk of calcific debris into the coronary arteries was analyzed in an in vitro model. Methods: Three highly calcified human aortic leaflets have been sutured into a porcine annulus (N=9). Both coronary arteries were separated and each was anastomized to a silicon line, which was drained off into a measuring beaker. Then valvuloplasty was performed (Thyshak II, 20mm, 1.5atm). After removal of the balloon, 100ml of sodium chloride solution irrigated the ascending aorta. After passing through the separated coronary arteries, the solution was filtered (filter size 0.45μm), dried, and the total amount of particles was analyzed microscopically. Results: Nine experiments were analyzed. After valvuloplasty, all hearts showed a median of 18 particles larger than 1mm in the coronary arteries (range 0-307). The amount of particles smaller than 1mm was 6574 (median, range 2207-14200). In five cases, coronary arteries were completely occluded by bulky particles. Conclusion: This study demonstrated a large amount of calcific particles after valvuloplasty with a consequently high risk for coronary embolic events in case of highly calcified aortic valves. In times of valvuloplasty rediscovering as part of transcatheter valve implantation, the risk of embolization should be taken into consideration and filtering techniques have to be develope

HVEM and CD160: Regulators of Immunopathology During Malaria Blood-Stage

CD8+ T cells are key players during infection with the malaria parasite Plasmodium berghei ANKA (PbA). While they cannot provide protection against blood-stage parasites, they can cause immunopathology, thus leading to the severe manifestation of cerebral malaria. Hence, the tight control of CD8+ T cell function is key in order to prevent fatal outcomes. One major mechanism to control CD8+ T cell activation, proliferation and effector function is the integration of co-inhibitory and co-stimulatory signals. In this study, we show that one such pathway, the HVEM-CD160 axis, significantly impacts CD8+ T cell regulation and thereby the incidence of cerebral malaria. Here, we show that the co-stimulatory molecule HVEM is indeed required to maintain CD8+ T effector populations during infection. Additionally, by generating a CD160−/− mouse line, we observe that the HVEM ligand CD160 counterbalances stimulatory signals in highly activated and cytotoxic CD8+ T effector cells, thereby restricting immunopathology. Importantly, CD160 is also induced on cytotoxic CD8+ T cells during acute Plasmodium falciparum malaria in humans. In conclusion, CD160 is specifically expressed on highly activated CD8+ T effector cells that are harmful during the blood-stage of malaria

Susceptibility to collagen-induced arthritis is modulated by TGFβ responsiveness of T cells

The objective of our study was to determine the regulatory effects that endogenous transforming growth factor β (TGFβ) exerts on T cells in the pathogenesis of collagen-induced arthritis (CIA). CIA was induced in transgenic mice expressing a dominant negative TGFβ type II receptor in T cells under the control of the human CD2 promoter. Clinical and histological arthritis scores were determined and experiments on disease induction and the healing phase of disease were performed. The proliferation and cytokine production of draining lymph node cells in vitro were analyzed. Transgenic mice were more susceptible to induction of CIA. The overall incidence was higher in transgenic mice than in wild-type mice (57% vs 35%, P < 0.05). Affected transgenic animals displayed a significantly higher clinical (4.5 ± 0.6 vs 1.67 ± 0.19, P = 0.001) and histological arthritis score (8.01 ± 0.9 vs 4.06 ± 1.1, P < 0.05). Draining lymph node cells of transgenic mice secreted more tumor necrosis factor α and IFNγ and proliferated more vigorously in response to collagen type II and upon CD3/CD28 costimulation in vitro. Therefore, the regulation of T cells by endogenous TGFβ is important for the maintenance of joint integrity after arthritis induction. Defects in TGFβ-signalling as a susceptibility factor for rheumatoid arthritis may warrant further investigation

Microdialysis of the rectus abdominis muscle for early detection of impending abdominal compartment syndrome

Objective: To investigate whether microdialysis is capable of assessing metabolic derangements during intra-abdominal hypertension (IAH), and whether monitoring of the rectus abdominis muscle (RAM) by microdialysis represents areliable approach in the early detection of organ dysfunctions in abdominal compartment syndrome (ACS). Design: Prospective, randomized, controlled animal study. Setting: University animal research facility. Subjects: Fifteen isoflurane-anesthetized and mechanically ventilated Sprague-Dawley rats. Interventions: IAH of 20 mmHg was induced for 3 h and followed by decompression and reperfusion for another 3-h period (n = 10). Five sham-operated animals served as controls. Microdialysis was performed in the anterior gastric wall, liver, kidney, and RAM. The anterior cervical muscles served as distant reference. Glucose, lactate, pyruvate, and glycerol was analyzed throughout the 6-h experiment. Measurements and main results: Prolonged IAH induced significant cardiopulmonary dysfunction and persistent abdominal organ injury. Microdialysis revealed asignificant increase of lactate/pyruvate and glycerol in kidney, intestine and liver, indicating ischemia, energy failure, and cell membrane damage. In addition, at 3 h IAH glucose was significantly decreased in all organs studied. The distant reference did not show any alteration of lactate/pyruvate, glycerol, and glucose over the entire 6-h observation period. In contrast to the other organs, microdialysis of the RAM showed an early and more pronounced increase of lactate, lactate/pyruvate and glycerol already at 1 h IAH. It is noteworthy that lactate, glycerol, and glucose did not completely recover upon decompression of IAH. Conclusions: Our data suggest that continuous microdialysis in the RAM may represent apromising tool for early detecting IAH-induced metabolic derangement

The Coronary Microcirculation in Hamster-to-Rat Cardiac Xenografts

BACKGROUND The aim of this study was to establish a new experimental model to directly analyse the coronary microcirculation in cardiac xenografts. METHODS Intravital fluorescence microscopy (IVM) of the subepicardial microcirculation in heterotopically transplanted hamster-to-rat cardiac xenografts was performed at 30 and 90 min of reperfusion. We quantitatively assessed the microcirculatory perfusion characteristics as well as the interactions of leukocytes and platelets with the endothelium of postcapillary coronary venules in non-sensitised as well as sensitised recipients. RESULTS In this first experimental IVM study of cardiac xenografts, we successfully visualised the subepicardial microcirculation, i.e. feeding arterioles, nutritive capillaries and draining postcapillary venules, during reperfusion. Leukocyte-endothelial and platelet-endothelial cell interactions could be quantified. In the non-sensitised group, the myocardial microcirculation remained stable during the observation period of 90 min, whereas in the sensitised group, xenografts were rejected immediately. CONCLUSIONS We established a model for the assessment of the microcirculatory dysfunction and inflammation during ischaemia/reperfusion injury in hamster-to-rat cardiac xenografts

Physics opportunities at RHIC and LHC

Nonequilibrium models (three-fluid hydrodynamics, UrQMD, and quark molecular dynamics) are used to discuss the uniqueness of often proposed experimental signatures for quark matter formation in relativistic heavy ion collisions from the SPS via RHIC to LHC. It is demonstrated that these models - although they do treat the most interesting early phase of the collisions quite differently (thermalizing QGP vs. coherent color fields with virtual particles) -- all yield a reasonable agreement with a large variety of the available heavy ion data. Hadron/hyperon yields, including J/Psi meson production/suppression, strange matter formation, dileptons, and directed flow (bounce-off and squeeze-out) are investigated. Observations of interesting phenomena in dense matter are reported. However, we emphasize the need for systematic future measurements to search for simultaneous irregularities in the excitation functions of several observables in order to come close to pinning the properties of hot, dense QCD matter from data. The role of future experiments with the STAR and ALICE detectors is pointed out

The likelihood of GODs' existence: Improving the SN1987a constraint on the size of large compact dimensions

The existence of compact dimensions which are accessible only to gravity represents an intriguing possible solution to the hierarchy problem. At present the strongest constraint on the existence of such compact Gravity-Only Dimensions (GODs) comes from SN1987a. Here we report on the first self-consistent simulations of the early, neutrino-emitting phase of a proto-neutron star which include energy losses due to the coupling of the Kaluza-Klein modes of the graviton which arise in a world with GODs. We compare the neutrino signals from these simulations to that from SN1987a and use a rigorous probabilistic analysis to derive improved bounds for the radii of such GODs. We find that the possibility that there are two compact extra dimensions with radii larger than 0.66 $\mu$m is excluded at the 95% confidence level---as is the possibility that there are three compact extra dimensions larger than 0.8 nm.Comment: 14 pages including 2 figure