TY - JOUR A1 - Kotliar, Konstantin A1 - Nagel, Edgar A1 - Vilser, Walthard A1 - Lanzl, Ines M. T1 - Functional in vivo assessment of retinal artery microirregularities in glaucoma / Kotliar, Konstantin E. ; Nagel, Edgar ; Vilser, Walthard ; Lanzl, Ines M. JF - Acta Ophthalmologica. 86 (2008), H. 4 Y1 - 2008 SN - 1755-3768 SP - 424 EP - 433 PB - - ER - TY - JOUR A1 - Kotliar, Konstantin A1 - Lanzl, Ines M. A1 - Hanssen, Henner A1 - Eberhardt, Karla A1 - Vilser, Walthard A1 - Halle, Martin A1 - Heemann, Uwe A1 - Schmidt-Trucksäss, Arno A1 - Baumann, Marcus T1 - Does increased blood pressure rather than aging influence retinal pulse wave velocity? JF - Investigative Ophthalmology & Visual Science, IOVS N2 - Purpose: It was demonstrated previously that retinal pulse wave velocity (rPWV) as a measure of retinal arterial stiffness is increased in aged anamnestically healthy volunteers compared with young healthy subjects. Using novel methodology of rPWV assessment this finding was confirmed and investigated whether it might relate to the increased blood pressure usually accompanying the aging process, rather than to the aging itself. Methods: A total of 12 young 25.5-year-old (24.0–28.8) [median(1st quartile–3rd quartile)] and 12 senior 68.5-year-old (63.8–71.8) anamnestically healthy volunteers; and 12 senior 63.0-year-old (60.8–65.0) validated healthy volunteers and 12 young 33.0-year-old (29.5–35.0) hypertensive patients were examined. Time-dependent alterations of vessel diameter were assessed by the Dynamic Vessel Analyzer in a retinal artery of each subject. The data were filtered and processed using mathematical signal analysis and rPWVs were calculated. Results: rPWV amounted to 1200 (990-1470) RU (relative units)/s in the hypertensive group and to 1040 (700-2230) RU/s in anamnestically healthy seniors. These differed significantly from rPWVs in young healthy group (410 [280–500] RU/s) and in validated healthy seniors (400 [320–510] RU/s). rPWV associated with age and mean arterial pressure (MAP) in the pooled cohort excluded validated healthy seniors. In a regression model these associations remain when alternately adjusted for MAP and age. When including validated healthy seniors in the pooled cohort only association with MAP remains. Conclusions: Both aging (with not excluded cardiovascular risk factors) and mild hypertension are associated with elevated rPWV. rPWV increases to a similar extent both in young mildly hypertensive subjects and in aged anamnestically healthy persons. Healthy aging is not associated with increased rPWV. Y1 - 2012 U6 - http://dx.doi.org/10.1167/iovs.11-8815 SN - 0146-0404 VL - 53 IS - 4 SP - 2119 EP - 2126 PB - ARVO CY - Rockville, Md. ER - TY - JOUR A1 - Kotliar, Konstantin A1 - Nagel, Edgar A1 - Vilser, Walthard A1 - Seidova, Seid-Fatima A1 - Lanzl, Ines T1 - Microstructural alterations of retinal arterial blood column along the vessel axis in systemic hypertension JF - Investigative Ophthalmology & Visual Science, IOVS N2 - Purpose: Image analysis by the retinal vessel analyzer (RVA) observes retinal vessels in their dynamic state online noninvasively along a chosen vessel segment. It has been found that high-frequency diameter changes in the retinal artery blood column along the vessel increase significantly in anamnestically healthy volunteers with increasing age and in patients with glaucoma during vascular dilation. This study was undertaken to investigate whether longitudinal sections of the retinal artery blood column are altered in systemic hypertension. Methods: Retinal arteries of 15 untreated patients with essential arterial hypertension (age, 50.9 ± 11.9 years) and of 15 age-matched anamnestically healthy volunteers were examined by RVA. After baseline assessment, a monochromatic luminance flicker (530–600 nm; 12.5 Hz; 20 s) was applied to evoke retinal vasodilation. Differences in amplitude and frequency of spatial artery blood column diameter change along segments (longitudinal arterial profiles) of 1 mm in length were measured and analyzed using Fourier transformation. Results: In the control group, average reduced power spectra (ARPS) of longitudinal arterial profiles did not differ when arteries changed from constriction to dilation. In the systemic hypertension group, ARPS during constriction, baseline, and restoration were identical and differed from ARPS during dilation (P < 0.05). Longitudinal arterial profiles in both groups showed significant dissimilitude at baseline and restoration (P < 0.05). Conclusions: The retinal artery blood column demonstrates microstructural alterations in systemic hypertension and is less irregular along the vessel axis during vessel dilation. These microstructural changes may be an indication of alterations in vessel wall rigidity, vascular endothelial function, and smooth muscle cells in this disease, leading to impaired perfusion and regulation. Y1 - 2010 U6 - http://dx.doi.org/10.1167/iovs.09-3649 SN - 0146-0404 VL - 51 IS - 4 SP - 2165 EP - 2172 PB - ARVO CY - Rockville, Md. ER - TY - JOUR A1 - Kotliar, Konstantin A1 - Lanzl, Ines M. T1 - Can vascular function be assessed by the interpretation of retinal vascular diameter changes? JF - Investigative Ophthalmology & Visual Science, IOVS. 52 (2011), H. 1 Y1 - 2011 SN - 0146-0404 SP - 635 EP - 636 PB - ARVO CY - Rockville, Md. ER - TY - JOUR A1 - Kotliar, Konstantin A1 - Mücke, Bruno A1 - Vilser, Walthard A1 - Schilling, Rudolf T1 - Effect of aging on retinal artery blood column diameter measured along the vessel axis / Kotliar, Konstantin E. ; Mücke, Bruno ; Vilser, Walthard ; Schilling, Rudolf ; Lanzl, Ines M. JF - Investigative Ophthalmology & Visual Science, IOVS. 49 (2008), H. 5 Y1 - 2008 SN - 0146-0404 SP - 2094 EP - 2102 PB - - ER - TY - CHAP A1 - Gerhards, Michael A1 - Sander, Volker A1 - Belloum, Adam ED - Zimmermann, Wolf ED - Lee, Yong Woo ED - Demchenko, Yuri T1 - About the flexible Migration of Workflow Tasks to Clouds : Combining on- and off-premise Executions of Applications T2 - CLOUD COMPUTING 2012 : The Third International Conference on Cloud Computing, GRIDs, and Virtualization ; July 22-27, 2012 - Nice, France N2 - An increasing number of applications target their executions on specific hardware like general purpose Graphics Processing Units. Some Cloud Computing providers offer this specific hardware so that organizations can rent such resources. However, outsourcing the whole application to the Cloud causes avoidable costs if only some parts of the application benefit from the specific expensive hardware. A partial execution of applications in the Cloud is a tradeoff between costs and efficiency. This paper addresses the demand for a consistent framework that allows for a mixture of on- and off-premise calculations by migrating only specific parts to a Cloud. It uses the concept of workflows to present how individual workflow tasks can be migrated to the Cloud whereas the remaining tasks are executed on-premise. KW - Workflow Orchestration KW - Workflow KW - Grid Computing KW - Cloud Service Broker KW - Cloud Computing Y1 - 2012 SN - 978-1-61208-216-5 SP - 82 EP - 87 PB - IARIA Journals ER - TY - JOUR A1 - Novacek, V. A1 - Tran, Thanh Ngoc A1 - Klinge, U. A1 - Tolba, R. H. A1 - Staat, Manfred A1 - Bronson, D. G. A1 - Miesse, A. M. A1 - Whiffen, J. A1 - Turquier, F. T1 - Finite element modelling of stapled colorectal end-to-end anastomosis : Advantages of variable height stapler design JF - Journal of Biomechanics N2 - The impact of surgical staplers on tissues has been studied mostly in an empirical manner. In this paper, finite element method was used to clarify the mechanics of tissue stapling and associated phenomena. Various stapling modalities and several designs of circular staplers were investigated to evaluate the impact of the device on tissues and mechanical performance of the end-to-end colorectal anastomosis. Numerical simulations demonstrated that a single row of staples is not adequate to resist leakage due to non-linear buckling and opening of the tissue layers between two adjacent staples. Compared to the single staple row configuration, significant increase in stress experienced by the tissue at the inner staple rows was observed in two and three rows designs. On the other hand, adding second and/or third staple row had no effect on strain in the tissue inside the staples. Variable height design with higher staples in outer rows significantly reduced the stresses and strains in outer rows when compared to the same configuration with flat cartridge. KW - Variable height stapler design KW - Anastomotic leakage KW - Finite element modelling KW - End-to-end colorectal anastomosis KW - Surgical staplers Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.jbiomech.2012.07.021 SN - 1873-2380 VL - 45 IS - 115 SP - 2693 EP - 2697 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Nguyen, Nhu Huynh A1 - Duong, Minh Tuan A1 - Tran, Thanh Ngoc A1 - Pham, Phu Tinh A1 - Grottke, O. A1 - Tolba, R. A1 - Staat, Manfred T1 - Influence of a freeze–thaw cycle on the stress–stretch curves of tissues of porcine abdominal organs JF - Journal of Biomechanics N2 - The paper investigates both fresh porcine spleen and liver and the possible decomposition of these organs under a freeze–thaw cycle. The effect of tissue preservation condition is an important factor which should be taken into account for protracted biomechanical tests. In this work, tension tests were conducted for a large number of tissue specimens from twenty pigs divided into two groups of 10. Concretely, the first group was tested in fresh state; the other one was tested after a freeze-thaw cycle which simulates the conservation conditions before biomechanical experiments. A modified Fung model for isotropic behavior was adopted for the curve fitting of each kind of tissues. Experimental results show strong effects of the realistic freeze–thaw cycle on the capsule of elastin-rich spleen but negligible effects on the liver which virtually contains no elastin. This different behavior could be explained by the autolysis of elastin by elastolytic enzymes during the warmer period after thawing. Realistic biomechanical properties of elastin-rich organs can only be expected if really fresh tissue is tested. The observations are supported by tests of intestines. KW - Autolysis KW - Decomposition KW - Freeze–thaw process KW - Spleen KW - Liver Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.jbiomech.2012.07.008 SN - 1873-2380 VL - 45 IS - 14 SP - 2382 EP - 2386 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Spelthahn, Heiko A1 - Schubert, Jürgen A1 - Schöning, Michael Josef T1 - Dünnschichtsensoren für die Schwermetallanalytik JF - GIT : Labor-Fachzeitschrift N2 - Die Detektion von Schadstoffen repräsentiert in der Umweltanalytik eine wichtige Aufgabenstellung. Gerade die Abwasser- bzw. Brauchwasseranalytik sowie die Prozesskontrolle haben einen hohen Stellenwert. Siliziumbasierte Dünnschichtsensoren bieten eine kostengünstige Möglichkeit, „online“-Messungen bzw. Vor-Ort-Messungen zeitnah durchzuführen. In dieser Arbeit wird ein potentiometrisches Sensorarray auf der Basis von Chalkogenidgläsern zur Detektion von Schwermetallen in wässrigen Medien vorgestellt. Y1 - 2012 SN - 0016-3538 VL - 56 IS - 4 SP - 285 EP - 287 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Hillen, Walter A1 - Alper Selver, M. A1 - Fischer, Felix A1 - Kuntalp, Mehmet T1 - A software tool for interactive generation, representation, and systematical storage of transfer functions for 3D medical images / Alper Selver, M. ; Fischer, Felix ; Kuntalp, Mehmet ; Hillen, Walter JF - Computer Methods and Programs in Biomedicine. 86 (2007), H. 3 Y1 - 2007 SN - 0169-2607 SP - 270 EP - 280 PB - - ER -