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61.
Historically, an important role informing the Czech cultural landscape was played by the strong middle class of farmers. The period of collectivization which occurred progressively between 1950 and 1989 meant liquidation of the rural community. Whereas in 1950 there were 1,404,225 private farmers, this number had decreased to only 2,000 in 1988. This paper focuses on the problems of stewardship and responsibility towards landscape associated with this social group, which recently has started a new period of growth. The research uses a variety of qualitative and quantitative methods. Dialogues with interviewees have enabled us to interpret stewardship and responsibility into a coherent story about the relationship between people and landscape. Similarities and differences have been related to variables such as farmer's age and length of time in farming. The results show that patterns of stewardship and responsibility are not related to economic variables, but rather to common features of ‘timeless’ rural culture.  相似文献   
62.
63.
A single‐ and multi‐objective optimization package is presented and described in detail. It contains an ensemble of local and global optimization routines. Procedures controlling variable number of dimensions are implemented as well, which is a rare feature among optimization oriented packages. The package is provided as a MATLAB toolbox. It excels in versatility and extensibility, which is demonstrated on a series of examples covering classical electromagnetism and antenna design. It is taken for granted that defining parameters of the optimization method can be set prior to the simulation run. However, its effective performance can be changed during the optimization run thanks to the full control feature. Moreover, it opens new possibilities in merging various algorithms into hybrids, performing complex dynamic programming tasks, or exploiting third party software. These advantages render the package as a perfect tool to deal with nowadays challenging engineering tasks.  相似文献   
64.
Praseodymium-, samarium-, and dysprosium-doped chalcogenide glasses from Ga–Ge–(Sb)–Se system were prepared. The Slater electrostatic Fk (k = 2,4,6), spin-orbit (ζ4f), and configuration–interaction (α) parameters of Pr3+, Sm3+, and Dy3+ ions, calculated on the basis of transmittance spectra, were studied. The dependences of all mentioned parameters on the chemical composition of the glassy matrix are discussed.  相似文献   
65.
Published data of impact sensitivity of 33 polynitro compounds detected by sound were expressed as the drop energy, Edr, required for 50 percent initiation probability. A logarithmic relationship has been found between the Edr values and heats of fusion of the said compounds. The relationship has been found to be in accordance with the idea concerning the role of plastic deformations of crystal played in the initiation of energetic materials by impact and shock. An analogous application of heats of sublimation has not given convincing results.  相似文献   
66.
The purpose of this work was to improve the resistance of hydrogen-induced cracking in API 5L X70 steel by engineering the crystallographic texture and grain boundary distributions via different rolling temperatures. Hydrogen-induced cracking and electrochemical hydrogen charging tests were carried out in two different conditions: commercially produced and isothermally rolled at 850 °C in laboratory. The results showed that the development of dominant {011} grains parallel to the normal direction, and a small number of {001}//ND grains obtained by isothermal rolling at 850 °C, increased the hydrogen-induced crack resistance; while the hot rolled sample with sharp {001}//ND textures was highly susceptible to cracking.  相似文献   
67.
High-contrast visual stimulation promotes retinal regeneration and visual function, but the underlying mechanism is not fully understood. Here, we hypothesized that Müller cells (MCs), which express neurotrophins such as brain-derived neurotrophic factor (BDNF), could be key players in this retinal plasticity process. This hypothesis was tested by conducting in vivo and in vitro high-contrast stimulation of adult mice and MCs. Following stimulation, we examined the expression of BDNF and its inducible factor, VGF, in the retina and MCs. We also investigated the alterations in the expression of VGF, nuclear factor kappa B (NF-κB) and pro-inflammatory mediators in MCs, as well as their capacity to proliferate and develop a neurogenic or reactive gliosis phenotype after high-contrast stimulation and treatment with BDNF. Our results showed that high-contrast stimulation upregulated BDNF levels in MCs in vivo and in vitro. The additional BDNF treatment significantly augmented VGF production in MCs and their neuroprotective features, as evidenced by increased MC proliferation, neurodifferentiation, and decreased expression of the pro-inflammatory factors and the reactive gliosis marker GFAP. These results demonstrate that high-contrast stimulation activates the neurotrophic and neuroprotective properties of MCs, suggesting their possible direct involvement in retinal neuronal survival and improved functional outcomes in response to visual stimulation.  相似文献   
68.
Monofilaments possessing various degrees of birefringence were obtained by changing the drawing rate, the molten polymer temperature, and the molecular weight of polystyrene (PS) and poly(methyl methacrylate) (PMMA). The “brittle-toductile” transition point of optically pure PS was found in the range of birefringences of ?0.6 · 10?3 to ?2.6 · 10?3. Both the height and position of this point are influenced by M?w, molecular weight distribution, and polymer melt temperature. The birefringence of PS is higher by two orders of magnitude than that of PMMA in which this transition point has not been observed. The mechanical and optical properties depend not only on the average amount of orientation characterized by the birefringence but on what portion of the relaxation spectrum of the polymer is preferentially oriented. During the drawing of PS and PMMA monofilaments crazes are formed in the centre of the fibers and do not reach the surface.  相似文献   
69.
Herstellen von Kurbelwellen aus unlegiertem Stahl. Auswertung von Betriebsschmelzen, erzeugt in einem 25-t-Elektrolichtbogenofen mit Spülbehandlungen außerhalb des Ofens. Vakuumbehandlung des Stahls in der Pfanne ohne und mit Einblasen von Argon. Spülbehandlung des Stahles mit Argon bei Luftzutritt. Untersuchung des Einflusses des feuerfesten Materials auf die Reinheit des Stahles mit Neutronenaktivierungsanalyse.  相似文献   
70.
This paper reports the development and using of ICP-MS and ICP-OES methods for determination of major, minor and trace elements in multivitamin preparations and dietary supplements and, based on results, their classification using multivariate statistical methods.The method was optimised and evaluated with the use of “in-house” reference material, commercial reference materials and spiked samples. Macroelements (Na, K, Ca, Mg, P), microelements (Cu, Fe, Mn, Zn, Se, Cr), toxic elements (As, Cd, Pb, Ni, V) and a whole series of other elements (e.g. REEs, Ti, Au, Pt, Pd, etc.) were detected with excellent limits of detection as well as other procedure parameters suitable for the purpose of the elemental analysis.As for physiologically significant elements, contents were found as follows (mg kg−1): Ca 560-196,000, Mg 308-70,300, Na 289-74,000, K from undetectable to 28,200, Cu 28-1460, P from undetectable to 217,000, Zn 2.1-25,000, Fe 115-39,400, Mn 28-1860, Cr 0.486-26.6, Mo 0.0418-9.88, and Se 0.395-161. It was found out, if compared with recommended daily intakes, that maximally 50% Ca, 37% Mg, 3% K, 20% P, 14% Na, 100% Cu, 160% Mn, 190% Fe, 120% Zn, 24% Cr, 29% Mo and 79% Se can be obtained from one dose. Extreme samples presenting a possible health risk (Ni content nearly 200 mg kg−1) were indicated. Most of the remaining elements (e.g. REEs) were analysed in order to get reference values for nutritional preparation.  相似文献   
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