1,322 research outputs found
Simulated Altitude Performance of Combustors for the Westinghouse 24C Jet Engine I-24C-2 Combustor
A Westinghouse 24C-2 combustor was investigated at conditions simulating operation of the 24C Jet engine at zero ram over ranges of altitude and engine speed. The investigation was conducted to determine the altitude operational limits, that is, the maximum altitude for various engine speeds at which an average combustor-outlet gas temperature sufficient for operation of the jet engine could be obtained. Information was also obtained regarding the character of the flames, the combustion efficiency, the combustor-outlet gas temperature and velocity distributions, the extent of afterburning, the flow characteristics of the fuel manifolds, the combustor inlet-to-outlet total-pressure drop, and the durability of the combustor basket. The results of the investigation indicated that the altitude operational limits for zero ram decreased from 12,000 feet at an engine speed of 4000 rpm to a minimum of 9000 feet at 6000 rpm, and thence increased to 49,000 feet at 12,000 rpm.. At altitudes below the operational limits, flames were essentially steady, but, at altitudes above the operational limits, flames were often cycling and either blew out or caused violent explosions and vibrations. At conditions on the altitude operational limits the type of combustion varied from steady to cycling with increasing fuel-air ratio and the reverse occurred with decreasing fuel-air ratio. In the region of operation investigated, the combustion efficiency ranged from 75 to 95 percent at altitudes below the operational limits and dropped to 55 percent or less at some altitudes above the operational limits. The deviations in the local combustor-outlet gas temperatures were within +20 to -30 percent of the mean combustor temperature rise for inlet-air temperatures at the low end of the range investigated, but became more uneven (up to +/-100 percent) with increasing inlet-air temperatures. The distribution of the combustor-outlet gas velocity followed a similar trend. Practically no afterburning downstream of the combustor outlet occurred. At conditions of high inlet-air temperature several factors indicated that fuel vapor or air formed in the fuel manifolds and adversely affected combustion. The combustor inlet-to-outlet total-pressure drop can be correlated as a function of the ratio of the combustion-air inlet density to outlet density and of the inlet dynamic pressure. The walls of the combustor basket were warped and burned during 29 hours of operation
Simulated Altitude Performance of Combustors for the 24C Jet Engine
The performance of a 24C-4 combustor was investigated with three different combustor baskets and five modifications of these baskets at conditions simulating static (zero-ram) operation of the 24C jet engine over ranges of altitude and engine speed to determine and improve the altitude operational limits of the 24C combustor. Information was also obtained regarding combustion characteristics, the fuel-flow characteristics of the fuel manifolds, and the combustor total-pressure drop. NACA modifications, which consisted of blocking rows of holes on the baskets, increased the minimum point on the altitude-operational-limit curve, which occurs at low engine speeds, for a narrow-upstream-end basket by 8000 feet (from 23, 000 to 31,000 ft_ and for a wide-upstream-end basket by 21,000 feet (from 12, 000 to 34,000 ft). These improvements were approximately maintained over the entire range of engine speeds investigated
"Low-dose"-Droperidol-Gabe bei Kindern: "Rescue"-Therapie gegen persistierende postoperative Ãœbelkeit und Erbrechen
Zusammenfassung: Hintergrund: Persistierende postoperative Übelkeit und Erbrechen ("postoperative nausea and vomiting", PONV) trotz Prophylaxe ist in der Kinderanästhesie ein wichtiges Problem. In der vorgestellten Studie wurde untersucht, ob die "Low-dose"-Droperidol-Gabe (10µg/kgKG) als Rescue-Therapie bei persistierender PONV effektiv ist. Patienten und Methoden: Im elektronischen Archiv der Anästhesieabteilung der Universitäts-Kinderkliniken Zürich wurden von 2004 bis 2009 alle Patienten herausgefiltert, die im Aufwachraum Droperidol erhalten hatten. Es wurde überprüft, ob Low-dose-Droperidol gegen persistierende PONV wirksam ist und ob unerwünschte Nebenwirkungen aufgetreten sind. Ergebnisse: Daten von 144Patienten im Alter von 12,3Jahren [Interquartilabstand (IQR) 9,5 bis 15,2Jahre] konnten für die Untersuchung verwendet werden. Bei 128Patienten (89%) war die Rescue-Therapie mit Low-dose-Droperidol effektiv. Bei 16Patienten (11%) erfolgte keine Besserung. Sedation war die einzige beobachtete Nebenwirkung bei 39Patienten (27%). Schlussfolgerung: Die Gabe von Low-dose-Droperidol erwies sich als effektive Rescue-Therapie bei Kindern, bei denen trotz prophylaktischer antiemetischer Therapie PONV persistiert
Immorality and Irrationality
Does immorality necessarily involve irrationality? The question is often taken to be among the deepest in moral philosophy. But apparently deep questions sometimes admit of deflationary answers. In this case we can make way for a deflationary answer by appealing to dualism about rationality, according to which there are two fundamentally distinct notions of rationality: structural rationality and substantive rationality. I have defended dualism elsewhere. Here, I’ll argue that it allows us to embrace a sensible – I will not say boring – moderate view about the relationship between immorality and irrationality: roughly, that immorality involves substantive irrationality, but not structural irrationality. I defend this moderate view, and argue that many of the arguments for less moderate views turn either on missing the distinction between substantive and structural rationality, or on misconstruing it
Near-infrared spectroscopy can detect brain activity during a color-word matching Stroop task in an event-related design
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Correlation of cognitive status, MRI- and SPECT-imaging in CADASIL patients
Although there is evidence for correlations between disability and magnetic resonance imaging (MRI) total lesion volume in autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), the significance of structural MRI abnormalities for cognitive dysfunction remains controversial. We performed detailed neuropsychological testing, high resolution MRI, and Tc-99m-ethyl cysteinate-dimer SPECT in three CADASIL patients. MR-images were rated independently by two investigators for the presence of white matter lesions, lacunar infarcts, microbleeds, and ventricular enlargement. Cortical atrophy was quantified by the use of automatic morphometric assessment of the cortical thickness. In addition, laboratory and patients' history data were collected in order to assess the individual vascular risk factor profile. The differences in cognitive performance between the three patients are neither explained by structural-, or functional neuroimaging, nor by the patient-specific vascular risk factor profiles. The neuroradiologically least affected patient met criteria for dementia, whereas the most severely affected patient was in the best clinical and cognitive state. Conventional structural and functional neuroimaging is important for the diagnosis of CADASIL, but it is no sufficient surrogate marker for the associated cognitive decline. Detailed neuropsychological assessment seems to be more useful, particularly with respect to the implementation of reliable outcome parameters in possible therapeutic trials
Emergence of rich-club topology and coordinated dynamics in development of hippocampal functional networks in vitro.
Recent studies demonstrated that the anatomical network of the human brain shows a "rich-club" organization. This complex topological feature implies that highly connected regions, hubs of the large-scale brain network, are more densely interconnected with each other than expected by chance. Rich-club nodes were traversed by a majority of short paths between peripheral regions, underlining their potential importance for efficient global exchange of information between functionally specialized areas of the brain. Network hubs have also been described at the microscale of brain connectivity (so-called "hub neurons"). Their role in shaping synchronous dynamics and forming microcircuit wiring during development, however, is not yet fully understood. The present study aimed to investigate the role of hubs during network development, using multi-electrode arrays and functional connectivity analysis during spontaneous multi-unit activity (MUA) of dissociated primary mouse hippocampal neurons. Over the first 4 weeks in vitro, functional connectivity significantly increased in strength, density, and size, with mature networks demonstrating a robust modular and small-world topology. As expected by a "rich-get-richer" growth rule of network evolution, MUA graphs were found to form rich-clubs at an early stage in development (14 DIV). Later on, rich-club nodes were a consistent topological feature of MUA graphs, demonstrating high nodal strength, efficiency, and centrality. Rich-club nodes were also found to be crucial for MUA dynamics. They often served as broker of spontaneous activity flow, confirming that hub nodes and rich-clubs may play an important role in coordinating functional dynamics at the microcircuit level.M.S.S. is supported by a PhD studentship funded by a Core Award from the Medical Research Council and the
Wellcome Trust to the Behavioural and Clinical Neuroscience Institute (MRC Ref G1000183; WT Ref 093875/Z/10/Z)
and by the Studienstiftung des deutschen Volkes. Additional support for this study from the Biotechnology and
Biological Sciences Research Council (BBSRC Ref BB/H008608/1) is gratefully acknowledged.This is the final published version. It first appeared at http://www.jneurosci.org/content/35/14/5459.full
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