An intercomparison of meteorological data taken by aircraft, radiosondes and a Laser-Doppler-anemometer

This paper describes an intercomparison experiment between airborne measurement Systems, radiosondes and laser-Doppler-Anemometer. [more of abstract in uploaded pdf-file

The wake vortex prediction and monitoring system WSVBS Part I: design

The design of the Wake Vortex Prediction and Monitoring System WSVBS is described with all its components and their interaction. The WSVBS has been developed to tactically increase airport capacity for approach and landing on closely-spaced parallel runways. It is thought to dynamically adjust aircraft separations dependent on weather conditions and the resulting wake vortex behaviour without compromising safety. Dedicated meteorological instrumentation and short-term numerical terminal weather prediction provide the input to the prediction of wake-vortex behaviour and respective safety areas. The prediction tools employ a number of conservative aircraft parameter combinations that represent the aircraft weight categories medium and heavy. Predictions of the time when all approach corridors along the final approach do not overlap with safety areas determine aircraft separations for follower aircraft of categories medium and heavy. As a safety net a LIDAR monitors the correctness of WSVBS predictions in the most critical gates at low altitude

Comparison of wake-vortex parameters measured by pulsed and continuous-wave lidars

Field trials carried out at Tarbes airfield in the summer of 2002 offered the unique opportunity to compare the results of simultaneous wake-vortex measurements by the 2-μm pulsed Doppler lidar from DLR, German Aerospace Research Center, and the 10-μm continuous wave (cw) Doppler lidars from ONERA and QinetiQ. The discrepancies in vortex core position obtained from the data of the pulsed lidar and the cw lidars are 9 m for the vertical and 13 m for the horizontal co-ordinates. The accuracies of the vortex circulation measurements with the DLR and ONERA lidars are almost the same and equal 13 m2/s. This accuracy and the long-range capability of the pulsed lidar allows precise measurements over long periods from the moment of wake generation to a progressed state of vortex decay. Moreover, the influence of different atmospheric turbulence conditions and aircraft configurations on the wake-vortex circulation can be analyzed. This has been demonstrated out of ground effect under conditions of weak to moderate levels of turbulence

Overexpression of protein phosphatase 5 in the mouse heart: Reduced contractility but increased stress tolerance - Two sides of the same coin?

The pathophysiological mechanisms of sepsis-induced cardiac dysfunction are largely unknown. The Toll-like receptor 4 (TLR4) is expressed in cardiac myocytes and is involved in bacterial endotoxin-mediated inflammatory disorders. TLR4 signaling leads to activation of the nuclear factor kappa B followed by increased expression of cytokines. Several protein phosphatases including PP2Cβ, PP2A or PP1 are known to act as regulators of this signaling pathway. Here, we examined the role of PP5 for the inflammatory response to the bacterial endotoxin lipopolysaccharide in the heart using a transgenic mouse model with cardiac myocyte directed overexpression of PP5. In these transgenic mice, basal cardiac contractility was reduced, in vivo as well as in vitro, but LPS-induced cardiac dysfunction was less pronounced compared to wild type mice. Quantitative RT-PCR suggested an attenuated NF-κB signaling in the heart and cardiac expression of heat shock protein 25 (HSP25) was increased in PP5 transgenic mice. From our data we assume that PP5 increases stress tolerance of cardiac myocytes by downregulation of NF-κB signaling and upregulation of HSP25 expression

Research towards a wake-vortex advisory system for optimal aircraft spacing

Wake turbulence is a major concern for busy airports as it limits capacity. Solutions for new aircraft staggering procedures are sought which relax the current separations but keep safety on a high level. Systems which advice air-traffic control on wake-vortex behaviour under present and expected weather conditions will hopefully contribute to such a solution. Knowledge on transport and decay of wake vortices in the atmosphere is presented. Concepts and designs of wake-vortex advisory systems in Europe and the USA are outlined. European wake-vortex measurement and prediction campaigns are described where the components of such systems have been tested successfully

Mechanisms of Systolic Cardiac Dysfunction in PP2A, PP5 and PP2AxPP5 Double Transgenic Mice

As part of our ongoing studies on the potential pathophysiological role of serine/threonine phosphatases (PP) in the mammalian heart, we have generated transgenic mice with cardiac muscle cell-specific overexpression of PP2Acα (PP2A) and PP5 (PP5). For further studies we crossbred PP2A and PP5 mice to obtain PP2AxPP5 double transgenic mice (PP2AxPP5, DT) and compared them with littermate wild-type mice (WT) serving as a control. The mortality of DT mice was greatly enhanced vs. other genotypes. Cardiac fibrosis was noted histologically and mRNA levels of collagen 1α, collagen 3α and fibronectin 1 were augmented in DT. DT and PP2A mice exhibited an increase in relative heart weight. The ejection fraction (EF) was reduced in PP2A and DT but while the EF of PP2A was nearly normalized after β-adrenergic stimulation by isoproterenol, it was almost unchanged in DT. Moreover, left atrial preparations from DT were less sensitive to isoproterenol treatment both under normoxic conditions and after hypoxia. In addition, levels of the hypertrophy markers atrial natriuretic peptide and B-type natriuretic peptide as well as the inflammation markers interleukin 6 and nuclear factor kappa B were increased in DT. PP2A enzyme activity was enhanced in PP2A vs. WT but similar to DT. This was accompanied by a reduced phosphorylation state of phospholamban at serine-16. Fittingly, the relaxation times in left atria from DT were prolonged. In summary, cardiac co-overexpression of PP2A and PP5 were detrimental to animal survival and cardiac function, and the mechanism may involve dephosphorylation of important regulatory proteins but also fibrosis and inflammation