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Quantitative analysis of the household's expenditure for food
No full textAbstract. The paper deals with the dependence of the share of households' food expenditure on the total expenditure and the household's size. This problem is important in applied welfare economics. According to the Engel's law, the poorer household, the greater proportion of its total expenditure is devoted to the food consumption. In the study, the Working-Leser model was applied to Polish households microeconomic data from 2000, 2005 and 2009
Physiologically structured populations with diffusion and dynamic boundary conditions
No full textAbstract. We consider a linear size-structured population model with diffusion in the size-space. Individuals are recruited into the population at arbitrary sizes. We equip the model with generalized Wentzell-Robin (or dynamic) boundary conditions. This approach allows the modelling of populations in which individuals may have distinguished physiological states. We establish existence and positivity of solutions by showing that solutions are governed by a positive quasicontractive semigroup of linear operators on the biologically relevant state space. These results are obtained by establishing dissipativity of a suitably perturbed semigroup generator. We also show that solutions of the model exhibit balanced exponential growth, that is, our model admits a finitedimensional global attractor. In case of strictly positive fertility we are able to establish that solutions in fact exhibit asynchronous exponential growth. 1. Introduction. A significant amount of interest has been devoted to the analysis of mathematical models arising in structured population dynamics (see e.g. In a recent paper, Hadeler [18] introduced size-structured population models with diffusion in the size-space. The biological motivation is that diffusion allows for "stochastic noise" to be incorporated in the model equations in a deterministic fashion. The main question addressed i
Proinflammatory mediators of toxic shock and their correlation to lethality.Mediators Inflamm.;2010:517594
No full textBacterial exotoxins and endotoxins both stimulate proinflammatory mediators but the contribution of each individual toxin in the release of mediators causing lethal shock is incompletely understood. This study examines the cytokine response and lethality of mice exposed to varying doses of staphylococcal enterotoxin B (SEB) or lipopolysaccharide (LPS) and their combinations. In vivo, SEB alone induced moderate levels of IL-2 and MCP-1 and all mice survived even with a high dose of SEB (100 μg/mouse). LPS (80 μg/mouse) caused 48% lethality and induced high levels of IL-6 and MCP-1. SEB induced low levels of TNFα, IL-1, IFNγ, MIP-2, and LPS synergized with SEB in the expression of these cytokines and that of IL-6 and MCP-1. Importantly, the synergistic action of SEB and LPS resulted in lethal shock and hypothermia. ANOVA of cytokine levels by survival status of SEB-plus-LPS groups revealed significantly higher levels of TNFα, IL-6, MIP-2, and MCP-1 in nonsurvivors measured at 8 hours. Significantly higher levels of IFNγ and IL-2 were observed at 21 hours in nonsurvivors of toxic shock compared to those in survivors. Overall, synergistic action of SEB and LPS resulted in higher and prolonged levels of these key cytokines leading to toxic shock
Qualitative Crosstalk Analysis of Wnt and Notch Signaling in Mammalian Skin
No full textAbstract. The Qualitative networks framework allows to construct discrete executable models of biological systems. An efficient symbolic algorithm can be used to verify that all stable states of such a model are consistent with a set of requirements derived from the laboratory experimental data. Here we consider the crosstalk between the Notch and Wnt pathways that play a key role in the regulation of cell proliferation and differentiation. We extend the analysis of our model of interaction between these pathways in mammalian skin. By further constraining the requirements from the model, we formulate a hypothesis that the ligand Jagged, which is part of the Notch pathway, is a downstream target of Wnt signaling. This prediction has been recently validated experimentally by Estrach et al.
Mediators of Inflammation in Polycystic Ovary Syndrome in Relation to Adiposity
No full textPolycystic ovary syndrome (PCOS) is a common endocrine disorder in women of reproductive age group and is associated with a higher cardiovascular risk. Obesity, mainly visceral adiposity, is prevalent in patients with PCOS. Obesity is associated with lowgrade inflammation and raised inflammatory cytokines, both of which are also described in patients with PCOS. In this paper, the potential relationships between fat distribution, adipocyte dysfunction and, altered inflammatory markers in patients with PCOS have been discussed
METABOLISM OF A NEW CARDIOTONIC AGENT, (-)-a-(3,4-.DIMETHOXYPHENETHYLAMINOMETHYL)-4-HYDROXYBENZYL ALCOHOL (TA-064), IN MAN 0-Demethylatlon and Ring Hydroxylation
No full textConceptualizing the emerging field of smart learning environments
No full textAbstract Learning environments have changed dramatically in the last 50 years, in large part due to information and communications technologies. From the introduction of personal computing and the Internet, there has been a continuing explosion of innovations in support of learning and instruction. Much has been written about new learning approaches and instructional paradigms, but relatively little has been implemented on a large scale with any significant learning outcomes. What has tended to happen when a new learning technology is introduced is that it is tried out on a small-scale in a privileged context (e.g., highly experienced and motivated teachers, on-site researchers, etc.), and when results show promise, the technology is broadly disseminated and used to replace a previous activity or resource, often without adequate training and support. Given the power and potential of new and emerging technologies, it is time to conceptualize how learning environments can be made more effective, efficient and engaging (i.e., smarter) on a large and sustainable scale. This article attempts to provide a small step in that direction
