The reactivity of a char depends very on the parent coal. Much information about correlation between properties of coal and reactivity of chars is lost by using only standard methods for a large dataset evaluation. In this research a set of 8 coals has been investigated by thermal analysis and reactivity of obtained chars was analyzed as a function of properties of parent coal properties using Canonical correlation analysis. The reactivity of chars was determined by thermogravimetric analysis of nonisothermal combustion in oxygen. It can be stated that methods of multivariate data analysis are useful tools for the interpretation of coal chars reactivity data., Mariusz Minkina, Elwira Zajusz-Zubek and Andrzej Mianowski., and Obsahuje bibliografii
The response of selected photosynthetic and morphological parameters of plants to drought was examined in 5 inbred lines of maize (Zea mays L.) and their 10 F1 hybrids. The aim of the study was to establish whether the photosynthetic performance of parental genotypes under drought conditions correlates with the performance of their progeny and whether the net photosynthetic rate, the chlorophyll fluorescence parameters or the content of photosynthetic pigments could be used as reliable physiological markers for early breeding generations. The relative importance of the additive and the nonadditive (dominance, maternal) genetic effects in the inheritance of these parameters was also assessed by means of the quantitative genetics analysis. The results showed that the nonadditive genetic effects associated with a particular combination of genotypes or a particular direction of crossing are at least equally and often even more important as the additivity and that these genetic effects almost totally change with the exposure of plants to drought conditions. This was reflected in the inability to predict the response of F1 hybrids to drought on the basis of the photosynthetic performance of their parents, which indicates that the practical usability of such parameters in maize breeding programs is rather limited. and D. Holá ... [et al.].
The paper discusses a problem of salt structures recent vertical movements that are observed by geodetic surveys on the example of salt dome in Inowroclaw. Presented survey results were carried by several years with use of precise levelling and GPS survey techniques. The new surveys were involved in 2002 that are carried on established network points and benchmarks of former existed country levelling network. Comp arative analysis of obtained displacement results derived by different methods is discussed as well. The effects of the an alysis are conclusions providing the usefulness of GPS techniques in the presented research. Other conclusions derived from carried observation deal with feat ures of determined vertical displacements., Zbigniew Szczerbowski., and Obsahuje bibliografické odkazy
The presented text attempts to assess the possibilities and limitations of processing Great Moravian currency bars (by domestic archaeologists traditionally called axe-shaped hryvnias) into the form of an end product – a tool in the form of an axe – using an archaeological experiment. In this manner, it is also testing the possibilities of the axe-shaped bars to remain in circulation as tokens of general-purpose money. The present experiment shows that the processing of these bars is considerably loss-making, which means that in the case of their circulation as tokens, their withdrawal from circulation for the purpose of their practical utilization would be unlikely. The text also attempts to model the genesis of axe-shaped currency, seeing their roots in Moravian social currency, which probably originally had the form of real axes. During the social and political changes of the Great Moravian period, this currency acquired the form of stylised semi-finished products and were probably also integrated in anonymous market transactions at least in part of Great Moravian territory.
The formation of ring species might provide an explanation of how speciation can occur despite ongoing gene flow. However, few species fit all of the criteria of a classic ring species that formed via isolation by distance around a barrier. Population genetic analyses and ecological niche models were used to examine a ring of song sparrow (Melospiza melodia) subspecies that surround the Sierra Nevada in North America. Eight models were compared that included both geography-based and ecology-based scenarios of ring formation. Song sparrows do fit some aspects of a classic ring species that formed via expansion around a barrier; however, admixture rather than complete reproductive isolation occurred when populations met at the terminus of the ring in southern California. Nichemodels show that variation among subspecies is likely to reflect adaptation to local conditions coupled with current limitations to gene flow across ecotones and that birds are likely to have expanded from a refugium in the southwestern United States. Given that simple isolation-based models often fail to explain many ring species patterns, alternative models that incorporate ecological factors might provide a better explanation of how most ring species formed. Isolation and subsequent partitioning of populations by ecotones can be important drivers of geographic variability in ring species.
Modern studies on the Be star population of young open clusters point towards the presence of an evolutionary enhancement of the Be phenomenon in the second half of the B stars main sequence lifetime. However, in the galactic field, Be stars are equally present in luminosity classes V to III, indicating that there is no evolutionary trend. To investigate these diverging results we have studied samples of main sequence B stars in the galactic field and in theh and ¬ Per clusters. From the analysis of the HR diagrams it is shown that there is no segregation between class V and class III stars, both groups being evenly distributed along the whole main sequence. We conclude that luminosity classes of main sequence B stars are not related to the evolutionary status of the stars. We propose a scenario of evolutionary enhancement of the rotational velocity to explain both the lack of relation between the evolutionary status and the luminosity classes and the evolutionary enhancement of the Be phenomenon.
This paper deals with an experimental study of lubricant film in an experimental device (tribometer). Lubricating film is formed between a glass disc and steel ball on which modification for friction surfaces have been made. The experiment is aimed at both fully flooded EHL lubrication regime as well as the starved. This document also deals with a comparison of micro dents passage through a contact at different degrees of slip. and Obsahuje seznam literatury
This paper considers an exponential cost optimality problem for finite horizon semi-Markov decision processes (SMDPs). The objective is to calculate an optimal policy with minimal exponential costs over the full set of policies in a finite horizon. First, under the standard regular and compact-continuity conditions, we establish the optimality equation, prove that the value function is the unique solution of the optimality equation and the existence of an optimal policy by using the minimum nonnegative solution approach. Second, we establish a new value iteration algorithm to calculate both the value function and the ϵ-optimal policy. Finally, we give a computable machine maintenance system to illustrate the convergence of the algorithm.
In the present study we investigated the effect of a two-stage bilateral lesion of the olfactory bulb (OB) in rats on the regeneration ability of peripheral olfactory neurons and their reinnervation capacity in the spared OB. The outgrowth of newly-generated olfactory axons as well as the maturation of their terminal synaptic field was detected by immunohistochemistry of the growth-associated phosphoprotein B-50/GAP-43. In addition, the glial response to the surgery was monitored by an immunohistochemical marker for astrocytes, glial fibrillary acidic protein (GFAP). In neonatal rats (P3-P5), the right OB was removed, then three months later the contralateral side was ablated. Six days after the second operation the animals were transcardially perfused. Their brains were embedded in paraplast, serially sectioned and processed for histological and immunohistochemical observations. After neonatal OB ablation, homogeneous B-50-immunoreactivity (BIR) was found in the forebrain, olfactory axons and ectopic glomeruli localized in the small OB remnant-like structures and in the regenerated neuroepithelium. A strong GFAP response was revealed in the brain cortex as well as in the newly-formed olfactory axons and glomeruli-like structures of the OB remnants. After adult OB ablation strong BIR was observed in olfactory axons, while remaining glomerular structures were only faintly stained. The neuroepithelium revealed signs of massive degenerative processes with a substantial decrease in BIR. The GFAP-positive astrocytes were scattered throughout the entire OB remnant and were prominent in the glomeruli-like structures and adjacent frontal cortex. In the present study, we applied GAP-43 and GFAP immunohistochemistry to characterize the responses of individual olfactory components after two-stage olfactory bulbectomy. Furthermore, this model of OB ablation characterized by two immunohistochemical markers could elucidate certain molecular mechanisms involved in the regeneration and/or plasticity of the olfactory system.