The aim of this article is to show how a tumor can modify energy substrates fluxes in the brain to support its own growth. To address this question we use a modeling approach to explain brain nutrient kinetics. In particular we set up a system of 17 equations for oxygen, lactate, glucose concentrations and cells number in the brain. We prove the existence and uniqueness of nonnegative solutions and give bounds on the solutions. We also provide numerical simulations.

A tight control of intracellular [Ca2+\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{2+}$$\end{document}] is essential for the survival and normal function of cells. In this study we investigate key mechanistic steps by which calcium is regulated and calcium oscillations could occur using in silico modeling of membrane transporters. To do so we give a deterministic description of intracellular Ca2+\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{2+}$$\end{document} dynamics using nonlinear dynamics in order to understand Ca2+\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} (...) \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{2+}$$\end{document} signaling. We first present the ordinary differential equations system for cell calcium kinetics and make a preliminary work on Sobol indices. We then describe and analyze complex transporters action. Besides, we analyze the whole system. We finally perform numerical simulations and compare our results to real data. (shrink)

Mechanistic models are built using knowledge as the primary information source, with well-established biological and physical laws determining the causal relationships within the model. Once the causal structure of the model is determined, parameters must be defined in order to accurately reproduce relevant data. Determining parameters and their values is particularly challenging in the case of models of pathophysiology, for which data for calibration is sparse. Multiple data sources might be required, and data may not be in a uniform or (...) desirable format. We describe a calibration strategy to address the challenges of scarcity and heterogeneity of calibration data. Our strategy focuses on parameters whose initial values cannot be easily derived from the literature, and our goal is to determine the values of these parameters via calibration with constraints set by relevant data. When combined with a covariance matrix adaptation evolution strategy, this step-by-step approach can be applied to a wide range of biological models. We describe a stepwise, integrative and iterative approach to multiscale mechanistic model calibration, and provide an example of calibrating a pathophysiological lung adenocarcinoma model. Using the approach described here we illustrate the successful calibration of a complex knowledge-based mechanistic model using only the limited heterogeneous datasets publicly available in the literature. (shrink)

It is hypothesized that iron from biological tissues, liberated during decay, may have played a role in inhibiting loss of anatomical information during fossilization of extinct organisms. Most tissues in the animal kingdom contain iron in different forms. A widely distributed iron‐bearing molecule is ferritin, a globular protein that contains iron crystallites in the form of ferrihydrite minerals. Iron concentrations in ferritin are high and ferrihydrites are extremely reactive. When ancient animals are decaying on the sea floor under anoxic environmental (...) conditions, ferrihydrites may initialize the selective replication of some tissues in pyrite FeS2. This model explains why some labile tissues are preserved, while other more resistant structures decay and are absent in many fossils. A major implication of this hypothesis is that structures described as brains in Cambrian arthropods are not fossilization artifacts, but are instead a source of information on anatomical evolution at the dawn of complex animal life. (shrink)

This article examines the technique and legality of induced abortion of one or more fetuses in a multiple pregnancy, where the aim is the destruction of some but not all of the fetuses present (selective reduction of pregnancy). It concludes that since the legal status of the procedure in English law is unclear, it may be a criminal offence to perform selective reduction even where there is an ostensible clinical need. Moreover if the procedure is carried out negligently, and any (...) infant damaged as a result is subsequently born alive, he or she may have a civil claim against the practitioner who carried out the procedure. (shrink)

Tom 1. Rannekhristianskiĭ gnosticheskiĭ tekst v rossiĭskoĭ kulʹture (21 i︠a︡nvari︠a︡ 2011 g.) -- Tom 2. Sudʹby religiozno-filosofskikh iskaniĭ Nikolai︠a︡ Novikova i ego kruga (15-17 okti︠a︡bri︠a︡ 2012 g.).

v. 1. Edinyĭ i︠a︡zyk chelovechestva. --.

Russell’s distinction between knowledge by acquaintance and knowledge by description has been recently re-examined in frequently controversial epistemo-logical contributions. The present essay reflects upon the pertinent papers by D. F. Pears, J. Hintikka, R. Chisholm, W. Sellars, A. J. Ayer, and others, but is pri-marily founded on Russell’s significant formulations from his writings published between 1910 and 1918. By employing an auxiliary device of a late-Wittgen-steinian language game, I explore at first the situation in which human subject is “experiencing” and (...) naming particular objects and later the subject’s acquaintance with universals. The reconstruction of such situations shows that, contrary to Russell’s assumptions, even the “purest” acquaintance cannot function without knowledge by description, i.e. without sta-ting propositions about the object of acquaintance . Then the only “descriptionless” alternative would be a kind of intuitive knowledge of such objects which is difficult to reconcile with the position held by Russell in the 1910s. Whatever the consequences, this topic retains its fundamental epistemological significance. (shrink)

The paper proves that a historical method in Marxism is not identified to a dialectical method. The logic of history and the logic of its analysis in Marxism do not always coincide. The Logical coincides with the Historical only in eternity as it actually occurs in the works by G.V.F. Hegel. Eternity which has already witnessed everything does not know history any more. In the same way, history also begins there where the eternity comes to an end. Therefore, artificial identification (...) of the Logical with the Historical in Marxism led sometimes to actual mistakes. It is no wonder that it has always caused discussions in Marxism. They are mainly explained by the fact that the deductive, abstract-to-concrete method in which the “General” appears before the “Concrete” is an anti-historical method in its Nature. In real human history the “General” which is generalization of many “Concrete” could not appear before the latter in any way. For this reason, the real historical materialism needs an inductive method of knowledge. Only in that case historical materialism will cease to remain the soviet “histmat” and becomes the real form of a new world outlook. The author is of the opinion that the Party spirit of the Soviet philosophy promoted preservation of the anomalies mentioned in Marxism. The open discussion could help to find valid but not inherited from Hegel relation of historical and logical methods in Marxism. (shrink)

We investigate to what extent theorems about quantum mechanical or classical entropy can be generalized to functionals of the type ρ→Tr f(ρ), or ψ→∫f(ψ)dμ, respectively, wheref is an arbitrary concave function.