The Effect of Modified Control Limits on the Performance of a Generic Commercial Aircraft Engine

This paper studies the effect of modifying the control limits of an aircraft engine to obtain additional performance. In an emergency situation, the ability to operate an engine above its normal operating limits and thereby gain additional performance may aid in the recovery of a distressed aircraft. However, the modification of an engine s limits is complex due to the risk of an engine failure. This paper focuses on the tradeoff between enhanced performance and risk of either incurring a mechanical engine failure or compromising engine operability. The ultimate goal is to increase the engine performance, without a large increase in risk of an engine failure, in order to increase the probability of recovering the distressed aircraft. The control limit modifications proposed are to extend the rotor speeds, temperatures, and pressures to allow more thrust to be produced by the engine, or to increase the rotor accelerations and allow the engine to follow a fast transient. These modifications do result in increased performance; however this study indicates that these modifications also lead to an increased risk of engine failure

Understanding correlates of neighborhood aesthetic ratings: A European-based Four City comparison

Evidence of associations between nature and health behaviors and health status is mounting. However, there is a need to deconstruct “natural space” to capture the qualities of green and blue space and the various ways people experience these natural outdoor environments. These experiences influence and sustain changes in health and social behaviors such as physical activity, diet, and social connectedness. In this paper, we examine the social, cultural, and emotional factors that influence people´s perceptions of natural outdoor environments, also referred to as neighborhood aesthetics. Using a population-based sample of 2948 adults in four European cities who participated in the PHENOTYPE study, we developed a quality-based aesthetics index of nearby nature to represent our study outcome. The scale had high internal consistency (Cronbach’s alpha 0.86). We assessed its association with common measures of the natural environment (Normalized Difference Vegetation Index (NDVI)), and examined factors that may influence aesthetic ratings. Hypothesized correlates of neighborhood aesthetics including presence of and time in neighborhood nature, perceived environmental stressors and neighborhood social cohesion and attachment were generally confirmed. Contrary to our expectations, respondents born in the country of current residence rated neighborhood aesthetics lower than those born elsewhere and associations with length of residence were not consistent across countries. Interventions designed to influence social, cultural, and emotional processes could improve aesthetics ratings and potentially contribute to better health and wellbeing

13C NMR Metabolomic Evaluation of Immediate and Delayed Mild Hypothermia in Cerebrocortical Slices after Oxygen–Glucose Deprivation

BACKGROUND: Mild brain hypothermia (32°C–34°C) after human neonatal asphyxia improves neurodevelopmental outcomes. Astrocytes but not neurons have pyruvate carboxylase (PC) and an acetate uptake transporter. (13)C NMR spectroscopy of rodent brain extracts after administering [1-(13)C]glucose and [1,2-(13)C]acetate can distinguish metabolic differences between glia and neurons, and tricarboxylic acid cycle (TCA cycle) entry via pyruvate dehydrogenase (PDH) and PC. METHODS: Neonatal rat cerebrocortical slices receiving a (13)C-acetate/glucose mixture underwent a 45-min asphyxia simulation via oxygen-glucose-deprivation (OGD) followed by 6 h of recovery. Protocols in three groups of N = 3 experiments were identical except for temperature management. The three temperature groups were: normothermia (37°C), hypothermia (32°C for 3.75 h beginning at OGD start), and delayed hypothermia (32°C for 3.75 h, beginning 15 min after OGD start). Multivariate analysis of nuclear magnetic resonance metabolite quantifications included principal component analyses and the L1-Penalized Regularized Regression algorithm known as the Least Absolute Shrinkage and Selection Operator (LASSO). RESULTS: The most significant metabolite difference (p < 0.0056) was [2-(13)C]glutamine’s higher final/control ratio for the Hypothermia group (1.75 ± 0.12) compared to ratios for the Delayed (1.12 ± 0.12) and Normothermia group (0.94 ± 0.06), implying a higher PC/PDH ratio for glutamine formation. LASSO found the most important metabolites associated with adenosine triphosphate preservation: [3,4-(13)C]glutamate—produced via PDH entry, [2-(13)C]taurine--an important osmolyte, and phosphocreatine. Final principal component analyses scores plots suggested separate cluster formation for the hypothermia group, but with insufficient data for statistical significance. CONCLUSIONS: Starting mild hypothermia simultaneously with OGD, compared with delayed starting or no hypothermia, has higher PC throughput, suggesting that better glial integrity is one important neuroprotection mechanism of earlier hypothermia

Understanding correlates of neighborhood aesthetic ratings: a European-based Four City comparison

Article Number: 126523Evidence of associations between nature and health behaviors and health status is mounting. However, there is a need to deconstruct “natural space” to capture the qualities of green and blue space and the various ways people experience these natural outdoor environments. These experiences influence and sustain changes in health and social behaviors such as physical activity, diet, and social connectedness. In this paper, we examine the social, cultural, and emotional factors that influence people´s perceptions of natural outdoor environments, also referred to as neighborhood aesthetics. Using a population-based sample of 2948 adults in four European cities who participated in the PHENOTYPE study, we developed a quality-based aesthetics index of nearby nature to represent our study outcome. The scale had high internal consistency (Cronbach’s alpha 0.86). We assessed its association with common measures of the natural environment (Normalized Difference Vegetation Index (NDVI)), and examined factors that may influence aesthetic ratings. Hypothesized correlates of neighborhood aesthetics including presence of and time in neighborhood nature, perceived environmental stressors and neighborhood social cohesion and attachment were generally confirmed. Contrary to our expectations, respondents born in the country of current residence rated neighborhood aesthetics lower than those born elsewhere and associations with length of residence were not consistent across countries. Interventions designed to influence social, cultural, and emotional processes could improve aesthetics ratings and potentially contribute to better health and wellbeingAplinkotyros katedraVytauto Didžiojo universiteta