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Search Results: 1 - 10 of 13735 matches for " Anna Bednarska "
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Canonical vector valued 1-forms on higher order adapted frame bundles over category of fibered squares
Anna Bednarska
Annales UMCS, Mathematica , 2008, DOI: 10.2478/v10062-008-0003-5
Abstract: Let Y be a fibered square of dimension (m1, m2, n1, n2). Let V be a finite dimensional vector space over. We describe all 21,m2,n1,n2 - canonical V -valued 1-form Θ TPrA (Y) → V on the r-th order adapted frame bundle PrA(Y).
Almost symplectic structures on the linear frame bundle from linear connection
Anna Bednarska
Annales UMCS, Mathematica , 2009, DOI: 10.2478/v10062-009-0005-y
Abstract: We describe all M fm-natural operators S: Q Symp P1 transforming classical linear connections on m-dimensional manifolds M into almost symplectic structures S( ) on the linear frame bundle P1M over M.
Temperature-dependent effect of filamentous cyanobacteria on Daphnia magna life history traits
Anna BEDNARSKA,Joanna ?O?,Piotr DAWIDOWICZ
Journal of Limnology , 2011, DOI: 10.4081/jlimnol.2011.353
Abstract: Filamentous cyanobacteria are unsuitable food for Daphnia due to their poor manageability, poor nutritional value and, in some cases, toxicity. As the strength of harmful effects of cyanobacteria on filter-feeding zooplankton is temperature dependent, the global warming scenarios for eutrophic lakes in temperate zone might include an escalated suppression of Daphnia populations caused by the presence of cyanobacterial filaments. To test this assumption, we conducted life-table experiments with four clones of Daphnia magna fed either a green alga Scenedesmus obliquus or a non-toxic strain of filamentous cyanobacteria Cylindrospermopsis raciborskii in two temperatures (20 °C and 24 °C). Key life history parameters of Daphnia, i.e., age and size at first reproduction, fecundity, and individual growth rate, were measured. Both food and temperature significantly affected Daphnia performance, however, the effect of interaction of these two factors was ambiguous and highly genotype-dependent. We conclude that the temperature increase within the studied range will not necessarily strengthen the suppression of Daphnia growth by filamentous cyanobacteria, but may affect clonal selection within population of Daphnia, thus possibly triggering microevolutionary changes within affected populations.
WP YW MALARSTWA SURREALISTYCZNEGO NA REKLAM WSPó CZESN
Sonia Bednarska
Studia Humanistyczne AGH , 2012,
Abstract:
snRNP: Rich Nuclear Bodies in Hyacinthus orientalis L. Microspores and Developing Pollen Cells
K. Zienkiewicz,E. Bednarska
International Journal of Cell Biology , 2009, DOI: 10.1155/2009/209303
Abstract: The aim of the present work was the characterization of nuclear bodies in the microspore and developing pollen cells of Hyacinthus orientalis L.. The combination of Ag-NOR, immunofluorescence and immunogold techniques was used in this study. The obtained results showed the presence of highly agyrophylic extranucleolar bodies in microspore and developing pollen cells, which were finally identified as Cajal bodies. In all cases, a strong accumulation of snRNP-indicating molecules including TMG cap, Sm proteins and U2 snRNA, was observed in the examined nuclear bodies. In contrast to their number the size of the identified structures did not change significantly during pollen development. In the microspore and the vegetative cell of pollen grains CBs were more numerous than in the generative cell. At later stages of pollen development, a drastic decrease in CB number was observed and, just before anthesis, a complete lack of these structures was indicated in both pollen nuclei. On the basis of these results, as well as our previous studies, we postulate a strong relationship between Cajal body numbers and the levels of RNA synthesis and splicing machinery elements in microspore and developing pollen cells.
THE ROLE OF FLEXIBLE FORMS OF EMPLOYMENT IN POLAND
IZABELA BEDNARSKA-WNUK
Ad Alta : Journal of Interdisciplinary Research , 2011,
Abstract: Modern organizations are increasingly eager to hire workers on the basis offlexible forms of employment. For the past few years Poland has also noticed increasein the share of temporary workers in the general structure of employment inorganizations that increasingly use these solutions within the personnel function. Thisarticle aims to present the flexible forms of employment as a modern trend in thelabour market based on the Polish example. In addition, it presents opportunities andrisks of flexible forms of work from the perspective of the employee and theorganization.
Localization of membrane-associated calcium in unpollinated and pollinated pistil of Petunia hybrida Hort.
El?bieta Bednarska
Acta Societatis Botanicorum Poloniae , 1995, DOI: 10.5586/asbp.1995.003
Abstract: In the pistil of Petunia hybrida, the transmitting tract and the ovules are the sites which give Ca2+-CTC fluorescence. In unpollinated pistil the level of membrane-associated Ca2+ decreases from the stigma to the base of the style. The renewed strong rise of Ca2+-CTC fluorescence appears on the placenta surface and in the ovule integuments. Following pollination, when the pollen tubes have grown through the pistil, the pattern of membrane-associated Ca2+ on the path stigma - ovary is reversed. The highest fluorescence is found in the base of the style. In pollinated ovules the Ca2+-CTC fluorescence increases markedly. In the transmitting cells membrane-associated Ca2+ occurs mainly in the polar regions of the cell. During cell degeneration following pollination the cytoplasmic clusters show Ca2+-CTC fluorescence. The used P. hybrida cultivar is self-fertile. The selection of pollen tubes occurs mainly in the upper part of the style. The rejected pollen tubes show a steady high level of membrane-associated calcium.
The effect of intracellular calcium level regulators on the synthesis of pollen tube callose in Oenothera biennis L.
El?bieta Bednarska
Acta Societatis Botanicorum Poloniae , 1989, DOI: 10.5586/asbp.1989.016
Abstract: It is shown that callose synthesis in the Oenothera biennis pollen tube is regulated by the endogenous Ca2+ level. Calcium antagonists reduced the amount of callose in the wall above the tip of the pollen tube (Verapamil - calcium channels blocker) and at the tube tip after stopping tube growth (La3+ - a Ca2+ substitute). Ruthenium red and ionophore A 23187, which raise the Ca 21 level in the cytoplasm, induced callose synthesis at the tip of pollen tube.
Localization of Ca2+ and Ca-ATPase on wet (Ruscus aculeatus) and dry (Primula officinalis) stigma surface
El?bieta Bednarska
Acta Societatis Botanicorum Poloniae , 1991, DOI: 10.5586/asbp.1991.021
Abstract: Calcium is present in the surface cells of both types of stigma. The chlorotetracycline method was used to show that the papillae of the dry stigma of Primula officinalis are the source of fluorescence of the CTC-Ca2+ complex. The precipitation method (NHA) localized calcium ions mainly in the pellicula surrounding these papillae. The NHA-Ca2+ precipitates were localized on the plasma membrane in the papillae of the wet stigma of Ruscus aculeatus. Ca-ATPase activity was found in both types of stigma in sites where the presence of Ca2+ had been determined.
Application of Intracellular Alkaline Phosphatase Activity Measurement in Detection of Neutrophil Adherence In Vitro
Katarzyna Bednarska,Magdalena Klink,Zofia Sulowska
Mediators of Inflammation , 2006, DOI: 10.1155/mi/2006/19307
Abstract: We have proposed the use of the fluorimetric method with 4-methylumbelliferyl phosphate (4-MUP) specific substrate for the alkaline phosphatase determination in the neutrophil adhesion assay. We provide evidence that the endogenous neutrophil alkaline phosphatase (NAP) activity evaluation is reliable to quantify neutrophil adhesion at a wide range of cell numbers (104–106). The results obtained by fluorimetric NAP activity test correlate to the results of adherence evaluated using the MTT reduction assay. The fluorimetric NAP activity test may be applied for resting as well as activated neutrophils without the risk of the activators interferences into the test. The alkaline phosphatase survey with the use of 4-MUP substrate is recommended herein as a sensitive, repeatable, simple, and reliable method of the neutrophil adherence determination in vitro.
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