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Search Results: 1 - 10 of 1435 matches for " Ewa Siucinska "
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Fear Learning Increases the Number of Polyribosomes Associated with Excitatory and Inhibitory Synapses in the Barrel Cortex
Malgorzata Jasinska, Ewa Siucinska, Ewa Jasek, Jan A. Litwin, Elzbieta Pyza, Malgorzata Kossut
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0054301
Abstract: Associative fear learning, resulting from whisker stimulation paired with application of a mild electric shock to the tail in a classical conditioning paradigm, changes the motor behavior of mice and modifies the cortical functional representation of sensory receptors involved in the conditioning. It also induces the formation of new inhibitory synapses on double-synapse spines of the cognate barrel hollows. We studied density and distribution of polyribosomes, the putative structural markers of enhanced synaptic activation, following conditioning. By analyzing serial sections of the barrel cortex by electron microscopy and stereology, we found that the density of polyribosomes was significantly increased in dendrites of the barrel activated during conditioning. The results revealed fear learning-induced increase in the density of polyribosomes associated with both excitatory and inhibitory synapses located on dendritic spines (in both single- and double-synapse spines) and only with the inhibitory synapses located on dendritic shafts. This effect was accompanied by a significant increase in the postsynaptic density area of the excitatory synapses on single-synapse spines and of the inhibitory synapses on double-synapse spines containing polyribosomes. The present results show that associative fear learning not only induces inhibitory synaptogenesis, as demonstrated in the previous studies, but also stimulates local protein synthesis and produces modifications of the synapses that indicate their potentiation.
ALICE as a tool for programming at schools  [PDF]
Ewa Graczyńska
Natural Science (NS) , 2010, DOI: 10.4236/ns.2010.22021
Abstract: We present some possible application of ALICE in the context of a possible attraction of pupils (especially girls) in early programming course. Our examples presented in the paper are fully explained on the base of [1].
Rational Choice Theory: Toward a Psychological, Social, and Material Contextualization of Human Choice Behavior  [PDF]
Tom Burns, Ewa Roszkowska
Theoretical Economics Letters (TEL) , 2016, DOI: 10.4236/tel.2016.62022
Abstract: The main purpose of this paper is to provide a brief overview of the rational choice approach, followed by an identification of several of the major criticisms of RCT and its conceptual and empirical limitations. It goes on to present a few key initiatives to develop alternative, more realistic approaches which transcend some of the limitations of Rational Choice Theory (RCT). Finally, the article presents a few concluding reflections and a table comparing similarities and differences between the mainstream RCT and some of the initial components of an emerging choice theory. Our method has been to conduct a brief selective review of rational choice theoretical formulations and applications as well as a review of diverse critical literature in the social sciences where rational choice has been systematically criticized. We have focused on a number of leading contributors (among others, several Nobel Prize Recipients in economics, who have addressed rational choice issues). So this article makes no claim for completeness. The review maps a few key concepts and assumptions underpinning the conceptual model and empirical applications of RCT. It reviews also a range of critical arguments and evidence of limitations. It identifies selected emerging concepts and theoretical revisions and adaptations to choice theory and what they entail. The results obtained, based on our literature reviews and analyses, are the identification of several major limitations of RCT as well as selected modifications and adaptations of choice theory which overcome or promise to overcome some of the RCT limitations. Thus, the article with Table 1 in hand provides a point of departure for follow-up systematic reviews and more precise questions for future theory development. The criticisms and adaptations of RCT have contributed to greater realism, empirical relevance, and increased moral considerations. The developments entail, among other things: the now well-known cognitive limitations (“bounded rationality”) and, for instance, the role of satisficing rather than maximizing in decision-making to deal with cognitive complexity and the uncertainties of multiple values; choice situations are re-contextualized with psychology, sociology, economic, and material conditions and factors which are taken into account explicitly and insightfully in empirical and theoretical work. Part of the contextualization concerns the place of multiple values, role and norm contradictions, and moral dilemmas in much choice behavior. In conclusion, the article suggests that the adaptations and
Topological Classification of Conformal Actions on -Hyperelliptic Riemann Surfaces
Ewa Tyszkowska
International Journal of Mathematics and Mathematical Sciences , 2007, DOI: 10.1155/2007/47839
Abstract: A compact Riemann surface X of genus g>1 is said to be p-hyperelliptic if X admits a conformal involution ρ, for which X/ρ is an orbifold of genus p. If in addition X is q-hyperelliptic, then we say that X is pq-hyperelliptic. Here we study conformal actions on pq-hyperelliptic Riemann surfaces with central p- and q-hyperelliptic involutions.
The chromatic sum of a graph: history and recent developments
Ewa Kubicka
International Journal of Mathematics and Mathematical Sciences , 2004, DOI: 10.1155/s0161171204306216
Abstract: The chromatic sum of a graph is the smallest sum of colors among all proper colorings with natural numbers. The strength of a graph is the minimum number of colors necessary to obtain its chromatic sum. A natural generalization of chromatic sum is optimum cost chromatic partition (OCCP) problem, where the costs of colors can be arbitrary positive numbers. Existing results about chromatic sum, strength of a graph, and OCCP problem are presented together with some recent developments. The focus is on polynomial algorithms for some families of graphs and NP-completeness issues.
Performance Analysis of a Photovoltaic-Thermal Integrated System
Ewa Radziemska
International Journal of Photoenergy , 2009, DOI: 10.1155/2009/732093
Abstract: The present commercial photovoltaic solar cells (PV) converts solar energy into electricity with a relatively low efficiency, less than 20%. More than 80% of the absorbed solar energy is dumped to the surroundings again after photovoltaic conversion. Hybrid PV/T systems consist of PV modules coupled with the heat extraction devices. The PV/T collectors generate electric power and heat simultaneously. Stabilizing temperature of photovoltaic modules at low level is higly desirable to obtain efficiency increase. The total efficiency of 60–80% can be achieved with the whole PV/T system provided that the T system is operated near ambient temperature. The value of the low-T heat energy is typically much smaller than the value of the PV electricity. The PV/T systems can exist in many designs, but the most common models are with the use of water or air as a working fuid. Efficiency is the most valuable parameter for the economic analysis. It has substantial meaning in the case of installations with great nominal power, as air-cooled Building Integrated Photovoltaic Systems (BIPV). In this paper the performance analysis of a hybrid PV/T system is presented: an energetic analysis as well as an exergetic analysis. Exergy is always destroyed when a process involves a temperature change. This destruction is proportional to the entropy increase of the system together with its surroundings—the destroyed exergy has been called anergy. Exergy analysis identifies the location, the magnitude, and the sources of thermodynamic inefficiences in a system. This information, which cannot be provided by other means (e.g., an energy analysis), is very useful for the improvement and cost-effictiveness of the system. Calculations were carried out for the tested water-cooled ASE-100-DGL-SM Solarwatt module.
Hypoxia: not merely a regulator of angiogenesis?
Ewa Paleolog
Arthritis Research & Therapy , 2004, DOI: 10.1186/ar1160
Abstract: The way in which cells 'sense' and respond to changes in oxygen concentration in their environment has attracted considerable interest. An important and well-characterised master regulator of the adaptive response to alterations in oxygen tension is hypoxia-inducible factor (HIF), a transcriptional complex containing two (α and β) members of the basic-helix-loop-helix PAS (period-aryl hydrocarbon nuclear receptor translocator-single minded) family. Several HIF-α isoforms exist, including HIF-1α and HIF-2α. HIF molecules bind specifically to hypoxia-responsive elements in the promoter or enhancer regions of various genes, which include erythropoietin, vascular endothelial growth factor (VEGF), glycolytic enzymes and genes involved in iron metabolism [2].Oxygen levels regulate HIF primarily through a mechanism involving oxygen-dependent proteolysis of HIF-α [3]. Under normoxic conditions, HIF-α subunits have a very short half-life. This is because prolyl 4-hydroxylase domain enzymes, that require oxygen as an obligatory cosubstrate, hydroxylate conserved proline residues in the HIF-α subunit, which allows the von Hippel-Lindau E3 ubiquitin ligase complex to bind to HIF-α and target it for proteasomal destruction [2,4]. In addition, the recruitment of transcriptional coactivators by HIF-α is regulated by oxygen-dependent hydroxylation of asparaginyl residues within the subunit [5]. The critical dependence of prolyl and asparaginyl hydroxylation on oxygen means that, under conditions of hypoxia, HIF-α accumulates in the nucleus where, upon binding to constitutively expressed HIF-1β and recruitment of coactivators, it recognizes hypoxia-responsive elements within promoters of target genes, leading to their transcriptional activation.Hypoxia has been postulated to contribute to a number of pathologies, including tumour growth and metastasis, and, of relevance to this article, rheumatoid arthritis (RA). The main features of RA are an inflamed, heavily infiltrated and thick
Nonlinear models describing the difference in growth curves of cattle strains
Ewa Ptak
Genetics Selection Evolution , 1980, DOI: 10.1186/1297-9686-12-4-425b
Abstract:
It's all in the blood: circulating endothelial progenitor cells link synovial vascularity with cardiovascular mortality in rheumatoid arthritis?
Ewa Paleolog
Arthritis Research & Therapy , 2005, DOI: 10.1186/ar1850
Abstract: The notion that angiogenesis – the formation of new blood vessels from pre-existing vasculature – is important in the perpetuation of RA synovitis is no longer novel. There is ample evidence supporting this idea, ranging from expression of proangiogenic factors such as vascular endothelial growth factor (VEGF) to studies in which inhibition of angiogenesis reduced the disease severity in animal models of arthritis [1]. However, while the rheumatologic and scientific community is in all probability now quite familiar with angiogenesis and its role in RA pathogenesis, the contribution made by EPC to blood vessel formation is less well understood. The distinct processes that result in the formation of the vasculature are vasculogenesis, which is the coalescence of endothelial cells, angiogenesis, and arteriogenesis, when the lumen of vessels increases to form collateral arteries. In the embryo, development of the vascular system occurs via a combination of vasculogenesis and angiogenesis. Formation of the primordial vascular network results from the commitment by precursor cells (haemangioblasts) to form endothelial cells, rather than haematopoietic stem cells. Following in situ differentiation of these EPC to form clusters of endothelial cells (or blood islands), these cells then multiply and interconnect to give rise to the yolk sac capillary network. Mature vessels then form by budding and re-modelling of pre-existing vessels. VEGF and its receptors are intimately involved in the regulation of both embryonic vasculogenesis and angiogenesis.Vasculogenesis has now been shown to be recapitulated in adults postnatally. EPC were first isolated from human peripheral blood by selection for cells expressing the haematopoietic maker CD34 [2]. These cells were found to differentiate into endothelial cells and to express both haematopoietic markers such as CD133 and endothelial cell markers, including CD31 and VEGF receptor type 2. Crucially, these cells also incorporated into
ON SYMMETRIES OF PQ-HYPERELLIPTIC RIEMANN SURFACES
TYSZKOWSKA,EWA;
Proyecciones (Antofagasta) , 2006, DOI: 10.4067/S0716-09172006000200004
Abstract: a symmetry of a riemann surface x is an antiholomorphic involution f. the species of f is the integer ek, where k is the number of connected components in the set fix(f) of fixed points of f and e = -1 if x \ fix(f) is connected and e = 1 otherwise. a compact riemann surface x of genus g > 1 is said to be p-hyperelliptic if it admits a conformal involution ?, called a p-hyperelliptic involution, for which x/? is an orbifold of genus p. symmetries of p-hyperelliptic riemann surfaces has been studied by klein for p = 0 and by bujalance and costa for p > 0. here we study the species of symmetries of so called pq-hyperelliptic surface defined as a riemann surface which is p- and q-hyperelliptic simultaneously
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