The study addresses a contact problem of a thin elastic (isotropic, incompressible and homogeneous) layer bonded to a rigid plane foundation and indented by a rigid frictionless punch in the form of an elliptical paraboloid. Given the total load, approximate analytical results for the contact ellipse, penetration depth and contact pressure distribution are presented. and Obsahuje seznam literatury
O tom jak se rodily první přístupy k udržení horkého fúzního plazmatu pomocí silných elektrických a magnetických polí., Through his whole scientific career, carried out mainly at FTI Kharkov in the Soviet Union, O. A. Lavrentev (1926-2011) studied thermonuclear plasma confinement. Initially an electrostatic confinement and later a magnetic electrostatic plasma confinement was proposed by him. However, he did not describe the transition from the first to the second type of confinement, e. g., from the spherical concentric purely electrostatic trap to the magnetic trap formed by spindle cusp fields with its slits plugged by electrostatic fields, which represents the simplest type of an electromagnetic trap. This article offers a hypothesis of how O. A. Lavrentev transformed the earlier concept into the later one., Milan Řípa, Miroslav Šos., and Obsahuje bibliografii
Duodenal, jejunal, ileal and caecal morphometries were determined in chickens from hatching to the age of 15 weeks. The ratios of fresh weight/surface area and dry weight/surface area showed age- dependent changes in all the intestinal segments studied. The percentage of mucosa in each segment was also age-dependent in the first three weeks of life with a higher participation in the proximal intestine. Transport of 3-oxy-methyl-D-glucose was determined in the jejunum and ileum using a perfusion technique in vivo and expressed as a function of fresh weight, dry weight and surface area. The age- dependent differences observed in weight and mucosa composition of the intestine make it difficult to interpret the results of transport capacity during development. The optimum expression of results in the field of intestinal absorption may be the surface area, since it involves the smallest errors.
Pheophytin (Pheo) is structurally constituted as to make possible certain reactions, previously given very little attention, which appear to play crucial roles in the initial electron transfer (ET) processes. The transformations involve enolisation with subsequent formation of mono- and di-iminium cations at the Pheo core. The important impact of these ions on ET from chlorophyll (Chl) to Pheo and then to quinone are evaluated. These insights rationalise the long-standing enigmas of fast transfer, across gap ET, activation-less aspect, and essential lack of reversibility. Comparisons are made to other important areas of iminium involvement, e.g. chemistry of vision, polyaniline doping, and DNA alkylation.
Screening of nuclear genome size was carried out on ca 2400 plants from over 120 mainly Central- European localities of the Juncus bufonius group. Besides the diploid level, corresponding to known diploid species (in this case J. ranarius, J. hybridus and J. sorrentini), two polyploid cytotypes were detected, conforming with the tetraploid and hexaploid levels treated by some authors as separate species: J. minutulus and J. bufonius s. str. The relationship between nuclear DNA content and the number of chromosomes was verified by chromosome counting. Polyploidy, as opposed to agmatoploidy can, therefore, account for the karyological variation. The 2C values of diploid, tetraploid and hexaploid individuals were ca 0.65, 1.18±2.8% and 1.84±1.6% pg 2C DNA, respectively. No other cytotype or statistically significant variation in nuclear genome size was found. To asses the utility of hitherto published morphological characters distinguishing J. minutulus from J. bufonius s. str., measurements of seven floral and three vegetative quantitative characters were obtained (no less than 10 measurements per flower, 30 per plant) for 358 mature plants of known ploidy level from 47 localities. Diverse ordination and clustering techniques did not indicate the presence of any grouping in the dataset. Canonical discriminant analysis and stepwise variable selection indicated that inner tepal length followed by mean capsule width and mean capsule length were the most useful characters for identifying the two ploidy levels; however, the estimated 10-fold cross-validation error rate of a simple k nearest neighbour classification analysis was 0.45. Other analyses corroborated this result. No new morphological character that would allow successful separation of tetraploids from hexaploids was discovered. This provides independent support for the opinion of some previous authors that J. bufonius L. is best treated as a single variable species comprising two cytotypes that are inseparable using hitherto suggested diagnostic characters until convincing proof to the contrary is available.
Kolorované ilustrace a dekor., Na titulní straně signet., Na titulní straně vlastnický přípisek Simon Retter Hembavensis. Na zadní předsádce rukopisné přípisky., and Na předním přídeští viditelná makulatura rukopisu.