Vascular Remodeling in Health and Disease

The term vascular remodeling is commonly used to define the structural changes in blood vessel geometry that occur in response to long-term physiologic alterations in blood flow or in response to vessel wall injury brought about by trauma or underlying cardiovascular diseases.1, 2, 3, 4 The process of remodeling, which begins as an adaptive response to long-term hemodynamic alterations such as elevated shear stress or increased intravascular pressure, may eventually become maladaptive, leading to impaired vascular function. The vascular endothelium, owing to its location lining the lumen of blood vessels, plays a pivotal role in regulation of all aspects of vascular function and homeostasis.5 Thus, not surprisingly, endothelial dysfunction has been recognized as the harbinger of all major cardiovascular diseases such as hypertension, atherosclerosis, and diabetes.6, 7, 8 The endothelium elaborates a variety of substances that influence vascular tone and protect the vessel wall against inflammatory cell adhesion, thrombus formation, and vascular cell proliferation.8, 9, 10 Among the primary biologic mediators emanating from the endothelium is nitric oxide (NO) and the arachidonic acid metabolite prostacyclin [prostaglandin I2 (PGI2)], which exert powerful vasodilatory, antiadhesive, and antiproliferative effects in the vessel wall

Ein lernfaehiger Fuzzy-Verteilungsschaetzer zur adaptiven Analyse von Radardaten

Presented is a new learning fuzzy distribution estimator (LFVS). It estimates similarities between pattern distributions and the distribution of a signal which is to be analysed. Learning capability gives a high flexibility to the system. Its application is not restricted to SAR data analysis. Compared to conventional estimation algorithms, there are two significant advantages of the fuzzy approach: One is that the gradual similarity between density distributions can be established, and the other is the estimation of reliability without additional computations. The fuzzy distribution estimator is applied to compress SAR raw data and it is a main modul of a new fuzzy classification system. This system allows a user adaptive classification of SAR image data. In addition to the classification itself, the user gets pixel by pixel classification reliability. Pixels belonging to several classes - a typical problem of low resolution radar images - are well detected. (orig.)Available from TIB Hannover: RN 437(99-03) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Practicability of investigating artifically forced instabilities in planar laminar boundary layers at Mach 5 in the Ludwieg-tube Goettingen (RWG)

SIGLEAvailable from TIB Hannover: RR 6926(98A18) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Experimental investigation of artificially generated disturbances in laminar hypersonic boundary layers

Experiments to study artificially generated disturbances in flat plate boundary layers were conducted in the Ludwieg-tube wind tunnel of the DLR in Goettingen at a free-stream Mach number of M_1=5. For the investigations, a 500 mm long and 20 mm thick flat plate model was used which spanned the test section 400 mm in width. As disturbance source a spark device flush mounted to the model surface close to its leading edge was utilized. The hot wire measurements in the boundary layer of the flat plate were conducted at different streamwise positions for natural and forced disturbances. The charge conditions used were almost constant at p_c_h_a_r_g_e=5 bar and T_c_h_a_r_g_e=393 K. This resulted in a unit Reynolds number of Re_1=8.45 x 10"6 1/m and a mass flow rate of #rho#_1 u_1=43.5 kg/m"2s. To check the flow quality of the tunnel and the laminar characteristic of the boundary layer optically, Schlieren pictures and high-speed shadowgraphs were taken prior to each measurement campaign. The artificially inserted wave packets were successfully measured at different distances and spanwise locations downstream of the park source. The main wave parameters, e.g. wave numbers and wave inclination angle were deduced from the obtained results. (orig.)SIGLEAvailable from TIB Hannover: RR 6926(98A29) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman