Development of combustion engines can be characterized by continuous increase in the number of computational simulations being applied in all areas. There is a clear trend to use chain or belt drives for the design of timing drives. Computational simulation of these drives has not been developing too long due to high demands on the computational technology. The paper focuses on simulation of dynamics of the timing chain drive with the use of a multi-body system. A mass-produced four cylinder in-line engine with two camshafts and two valves per cylinder has been used as a computational model. and Obsahuje seznam literatury
The Leishmania metalloproteinase GP63 has been reported to play important roles mainly in resistance of promastigotes to complement-mediated lysis and in interaction with macrophage receptors. On the other hand, its function in insect vectors is still unclear. We compared the structure and dosage of gp63 genes and the activity of GP63 in Leishmania major Yakimoff et Schokhor strains and lines differing in virulence for mice and ability to develop in sand flies. The results demonstrate considerable variability in amount and proteolytical activity of GP63 among L. major strains although genomic changes in the gp63 locus were not found. Attenuated LV561/AV line showed low amount and low enzymatic activity of GP63. Serial passages of attenuated parasites through either Phlebotomus duboscqi Neveu-Lemaire or through mice led to a recovery of GP63 proteolytical activity to the level present in virulent LV561/V line. Overexpression of GP63 was found in two L. major strains (L119, Neal) with defective lipophosphoglycan (LPG); both these strains were capable to cause mice infection but unable to survive and multiply in sand flies. Differences were found also in karyotypes and in amount of minichromosomes amplified in some lines of the LV561 strain. The results suggest that parasite virulence is not simply correlated with the activity of GP63; however, this enzyme plays a significant role in association with other surface molecules, especially LPG. Overexpression of GP63 can compensate LPG defect in the vertebrate host but in sand flies both molecules fulfil quite different functions and the defect in LPG is lethal for the parasite. On the other hand, linear minichromosomes of about 200 kb found in some lines of the LV561 strain are associated with development in vitro and in the vector but they are not essential for the infection of the vertebrate host.
V tomto přehledovém sdělení je stručně nastíněna problematika fyziologie přenosu vzruchu senzitivními a viscerálními nervovými vlákny a patofyziologie viscerální bolesti přenášené z útrobních orgánů do Haedových zón na kůži. Text pojednává o viscerálních receptorech, o aferentních dráhách a centrálních strukturách, o mediátorech i o možnostech ovlivnění viscerální bolesti. Pozornost je věnována i nebolestivým formám neuropatie. Jsou zmíněny základní otázky diagnostiky a léčby neuropatie se zvláštním zřetelem na neuropatii diabetickou., Rudolf Chlup, Jiří Podivínský, Dana Masnikosová, and Lit.: 32
Bolest u onkologicky nemocných je závažným a kvalitu života zhoršujícím symptomem, který vyžaduje zájem lékařů a ošetřovatelského personálu. Velmi problematickým typem bolesti pro její obtížnou lokalizaci a definici je bolest viscerální. Problematika tohoto typu bolesti je nastíněna v přehledném sdělení včetně strategie její léčby., Cancer pain is a serious and quality of life deteriorating quality of life symptom requiring the interest of doctors and nursing staff. Visceral pain is a very complicated type of pain for its difficult localization and definition. Problems of this type of pain is briefly outlined in a clear communication strategy, including its treatment., Ladislav Slováček, and Literatura 19
Mechanical behavior of biological structures under dynamic loading generally depends on elastic as well as viscous properties of biological materials. The significance of “viscous” parameters in real situations remains to be elucidated. Behavior of rheological models consisting of a combination of inertial body and two Voigt’s bodies were described mathematically with respect to inverse problem solution, and behavior in impulse and harmonic loadings was analyzed. Samples of walls of porcine and human aorta thoracica in transverse direction and samples of human bone (caput femoris, substantia compacta) were measured. Deformation responses of human skin in vivo were also measured. Values of elastic moduli of porcine aorta walls were in the interval from 102 kPa to 103 kPa, values of viscous coefficients were in the interval from 102 Pa.s to 103 Pa.s. The value of shear stress moduli of human caput femoris, substantia compacta range from 52.7 to 161.1 MPa, and viscous coefficients were in the interval from 27.3 to 98.9 kPa.s. The role of viscous coefficients is significant for relatively high loading frequencies - in our materials above 8 Hz in aorta walls and 5 Hz for bones. In bones, the viscosity reduced maximum deformation corresponding to short rectangular stress., M. Kuchařová, S. Ďoubal, P. Klemera, P. Rejchrt, M. Navrátil., and Obsahuje bibliografii