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For the detailed understanding of transient combustion processes, in particular, of auto-ignition, quantitative measurements with high spatio-temporal resolution are desirable. These can, for instance, serve as validation data for time-resolved numerical simulations and in particular for the combustion models used in those simulations. In the current study, a jet-in-hot-coflow (JHC) burner, developed at the German Aerospace Center (DLR), the DLR JHC, was used to inject a turbulent methane jet into the hot exhaust gas of a lean hydrogen/air flame, and a steady state jet flame was established. In addition, fuel could be injected in a transient manner. Here, an auto-igniting jet was observed. The flame stabilization of the steady state jet flame and the auto-ignition during transient fuel injection were studied using high-speed laser-based and optical measurements. A strategy for quantifying high-speed OH planar laser-induced fluorescence is presented, and the measurement uncertainties are evaluated. The flame stabilization mechanism in steady state jet flames was assessed using probability density functions of the OH concentration at different axial and radial locations. The formation of auto-ignition kernels during transient fuel injection is evaluated based on time series of the OH concentration. It is shown how the OH concentration levels and PDF shapes can be used to characterize the chemical state of the reacting flow and to distinguish between auto-ignition and flame propagation.

Quantitative Analysen zur Entwicklung des Sozialstaats kämpfen mit dem „dependent variable problem“, da Untersuchungen, die Sozialausgaben analysieren, zu anderen Ergebnissen kommen als Analysen von individuellen Lohnersatzraten. Der vorliegende Artikel schlägt einen dritten Weg vor und präsentiert Ergebnisse einer quantitativen Gesetzgebungsanalyse zur Renten- und zur Arbeitslosenversicherung in Deutschland zwischen 1974 und 2014. Dabei zeigt sich, dass ausbauende und rückbauende Ereignisse in allen untersuchten Jahrzehnten und in unterschiedlichen Mischungsverhältnissen auftreten. Zudem weist eine Regressionsanalyse darauf hin, dass die parteipolitische Ausrichtung in Deutschland entlang der „Nixon-goes-to-China“-These relevant ist, da Unionsregierungen die Wahrscheinlichkeit des Ausbaus erhöhen, während unter sozialdemokratischen Kanzlern – und unter budgetärem Druck – zurückgebaut wird. Quantitative analyses on welfare state dynamics have to cope with the “dependent variable problem”, as studies on social spending reach different conclusions than analyses of replacement rate data. This article suggests a way around this problem by presenting results from a fine-grained analysis of welfare state legislation in Germany between 1974 and 2014. We show that the German welfare state has seen both cuts and expansions occur in all decades. Moreover, we show by means of a regression analysis that partisan politics play a role. Supporting the “Nixon-in-China”-thesis, social democratic governments are associated with a higher probability of cutbacks—especially in times of budgetary pressure—whereas expansions are more likely under Christian democratic governments.

Recent theoretical advances in the welfare state literature have outlined the differences between labour market- and life course-related schemes as centre-right parties have difficulties in enacting retrenchment on life course-related schemes because these concern every voter. In contrast, the textbook risk profile of centre-right parties’ electorates allows them to cutback on labour market-related schemes as these parties get negligible support from workers and low-income voters. Conducting a comparative case study of recent Danish and Swedish centre-right governments, this article analyses the stylized assumptions on the party level by comparing two similar centre-right governments, which differed in their voter coalitions’ risk profile. I first argue that centre-right governments are generally constrained by the popular entrenchment of the universal welfare state when it comes to life course-related welfare schemes. Second, I argue that the leeway on labour market-related schemes is contingent on the actual risk profile of the centre-right’s electorate, and thereby move beyond the stylized assumptions from recent literature. In this respect, the Danish centre-right did, in contrast to its Swedish counterpart, gain power with an unusual high support among working-class voters which constrained its latitude on labour market-related schemes. I find that the Danish centre-right governments after 2001 acted with bound hands thanks to its high working-class backing, and refrained from outright cutbacks on both labour market- and life course-related schemes until 2010 except for labour market outsiders. In contrast, the Swedish centre-right had a much lower working-class backing and therefore engaged in some outright cutbacks of labour market-related schemes such as unemployment benefits directly after taking office 2006. The centre-right’s actual voter coalition’s risk profile is thus an important determinant for its public policies and its leeway for policy-seeking.

Cross-clamping of the descending aorta immediately below the subclavian artery may result in damage to the spinal cord. Despite various protective procedures, the risk of such damage cannot be entirely eliminated. In an experimental study with 47 pigs, the influence of various factors on the genesis of spinal cord damage was examined. The pigs were divided into five groups: Groups I to IV—occlusion of the descending aorta for 45 minutes; Group I—no reduction in arterial blood pressure proximal to the site of occlusion; Group II—like Group I, plus drainage of the cerebrospinal fluid; Group III—reduction in arterial blood pressure; Group IV—like Group III, plus drainage of the cerebrospinal fluid; Group V—permanent ligation of the artery of Adamkiewicz. The degree of permanent spinal cord damage was 85.7% (Groups I to IV, six animals) and 71.4% (Group V, five animals). Thus there were no significant differences among the various groups. The frequency of spinal cord damage was independent of arterial blood pressure, intracranial pressure, and intraspinal pressure. The intracranial pressure and the intraspinal pressure were significantly dependent upon the central venous pressure but were independent of the arterial blood pressure.

Spinal cord injury is the most dreaded complication of operative procedures on the descending aorta. Our previous experimental study on pigs indicated that an increase in the cerebrospinal fluid pressure after aortic cross-clamping did not influence the occurrence of spinal cord injury. We therefore concluded that the cause of spinal cord injury after aortic cross-clamping is due to primary oxygen deficiency in the spinal cord distal to the occlusion site, especially in the area supplied by the artery of Adamkiewicz. The aim of the present study is to examine the primary ischemic cause of spinal cord injury after aortic cross-clamping by directly measuring the oxygen tension on the spinal cord surface in pigs. During the occlusion phase, oxygen tension decreased significantly distal to the clamping site and especially in the areas supplied by the artery of Adamkiewicz both after occlusion of the high thoracic (Group I) and the lumbar aorta (Group II). The marked decrease in oxygen tension proves that hypoxia is the primary reason for spinal cord injury. The presence of a “steal phenomenon” should be discussed.

Ischemic spinal cord injury after cross-clamping of the descending aorta can occur independently of aortic disease. In a previous study we had shown a precipitous uniform fall of spinal surface oxygen tension downstream to the clamping site irrespective of level In the present paper, the hemodynamic changes in the spinal and aortic collateral circulation were investigated. Pressures were measured in the proximal, distal, and excluded aortic segments (descending thoracic and lumbar aorta) as well as in the intercostal and the lumbar arterial beds. Before high aortic occlusion, pressures in the intercostal and lumbar arterial beds were lower than aortic pressure. Along with the postclamping fall in distal arterial pressure, intercostal and lumbar arterial bed pressure decreased further but remained above aortic pressure. Exclusion of the thoracic aorta by double clamping restored intercostal bed pressure almost to control, whereas exclusion of the abdominal aorta hardly affected lumbar bed pressure. We conclude that spinal collateral circulation is more highly developed in the thoracic than in the lumbar region. After aortic cross-clamping, blood tends to drain away from the spinal cord rather than supplying it longitudinally. Under clinical conditions, therefore, retrograde bleeding into the opened aorta as well as into the aorta downstream to the distal clamp should be minimized and larger vessels originating from the aorta should promptly be anastomosed to the graft.

Wall temperature measurements with fiber coupled online phosphor thermometry were, for the first time, successfully performed in a full-scale H-class Siemens gas turbine combustor. Online wall temperatures were obtained during high-pressure combustion tests up to 8 bar at the Siemens Clean Energy Center (CEC) test facility. Since optical access to the combustion chamber with fibers being able to provide high laser energies is extremely challenging, we developed a custom-built measurement system consisting of a water-cooled fiber optic probe and a mobile measurement container. A suitable combination of chemical binder and thermographic phosphor was identified for temperatures up to 1800 K on combustor walls coated with a thermal barrier coating (TBC). To our knowledge, these are the first measurements reported with fiber coupled online phosphor thermometry in a full-scale high-pressure gas turbine combustor. Details of the setup and the measurement procedures will be presented. The measured signals were influenced by strong background emissions probably from CO*2 chemiluminescence. Strategies for correcting background emissions and data evaluation procedures are discussed. The presented measurement technique enables the detailed study of combustor wall temperatures and using this information an optimization of the gas turbine cooling design.