1,228 research outputs found

    Dynamical robustness of biological networks with hierarchical distribution of time scales

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    We propose the concepts of distributed robustness and r-robustness, well adapted to functional genetics. Then we discuss the robustness of the relaxation time using a chemical reaction description of genetic and signalling networks. First, we obtain the following result for linear networks: for large multiscale systems with hierarchical distribution of time scales the variance of the inverse relaxation time (as well as the variance of the stationary rate) is much lower than the variance of the separate constants. Moreover, it can tend to 0 faster than 1/n, where n is the number of reactions. We argue that similar phenomena are valid in the nonlinear case as well. As a numerical illustration we use a model of signalling network that can be applied to important transcription factors such as NFkB

    Ways of Transition to Clean Energy Use: Two Methodological Approaches

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    The combustion of fossil fuels for the production of energy has already resulted in significant modifications of the earth's environment, primarily through the emissions of carbon dioxide, sulfur dioxide, nitrogen oxides, and particulates. The modern world primary energy consumption patterns and its trends lead to the utilization of dirtier and more expensive fossil fuels. The desire to protect the environment is contradictory Lo such structural changes in energy like the broader use of coal as substitution for liquid fuels, taking into account the depletion of coal deposits with low sulfur contents. Previous studies carried out at IIASA, in the FRG, the US, the USSR and other countries, formulate one long-term technological strategy that might limit pollutant emissions sufficiently to permit an efficient and ecologically sustainable development of the world's energy consumption patterns. This technological strategy is based on the implementation of the so-called Integrated Energy Systems (IES) or Integrated Energy-Chemical Systems (IECS). The basic idea of IES incorporates the decomposition and purification of primary fossil energy inputs before combustion, the integration of these decomposed (clean) products and the allocation of them in line with the requirements for final energy. Thus, Integrated Energy Systems represent a concept for providing a flexible range of final energy forms from varying inputs of different primary energy sources. Other potential advantages include improved performance of the whole energy system, such as higher efficiencies and lower environmental impacts. The joint report of the Kernforschungsanlage Julich (KFA), Julich, FRG and the Siberian Energy Institute (SEI), Irkutsk, USSR describes the concepts, methodological approaches, and preliminary results of the analysis of technological options and technoeconomic properties of the different types of integrated energy systems. The study of KFA and SEI, based on the cooperation with the International Institute for Applied Systems Analysis, emphasizes the common viewpoint that the idea of integrated energy systems constitutes an essential basis for new studies on energy systems with a high degree of utilizing primary energy sources and with low emissions

    Scale invariance in coarsening of binary and ternary fluids

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    Phase separation in binary and ternary fluids is studied using a two dimensional Lattice Gas Automata. The lengths, given by the the first zero crossing point of the correlation function and the total interface length is shown to exhibit power law dependence on time. In binary mixtures, our data clearly indicate the existence of a regime having more than one length scale where the coarsening process proceeds through the rupture and reassociation of domains. In ternary fluids; in the case of symmetric mixtures there exists a regime with a single length scale having dynamic exponent 1/2, while in asymmetric mixtures our data establish the break down of scale invariance.Comment: 20 pages, 13 figure

    Current limiting and negative differential resistance in indium oxide based ceramics

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    Indium oxide based ceramics with bismuth oxide addition were sintered in air in the temperature range 800-1300 ÂşC. Current-voltage characteristics of In2O3-Bi2O3 ceramics sintered at different temperatures are weakly nonlinear. After an additional heat treatment in air at about 200 ÂşC samples sintered at a temperature within the narrow range of about 1050-1100 ÂşC exhibit a current-limiting effect accompanied by low-frequency current oscillations. It is shown that the observed electrical properties are controlled by the grain-boundary barriers and the heat treatment in air at 200 ÂşC leads to the decrease in the barrier height. Electrical measurements, scanning electron microscopy and X-ray photoelectron spectroscopy results suggest that the current-limiting effect observed in In2O3-Bi2O3 may be explained in terms of a modified barrier model; the observed current-limiting effect is the result of an increase of barrier height with increasing electric field, due to additional oxygen absorption. It is found that In2O3-Bi2O3-Co3O4-Cr2O3 ceramic exhibits current-voltage characteristics with negative differential resistance due to Joule micro heating.This study was performed in part in the frames of the project SEP-2003-C02-42821, CONACYT, MĂ©xico. Funding from the Royal Society, United Kingdom (2007R1/R26999) is gratefully acknowledged

    Alterations of Homocysteine Serum Levels during Alcohol Withdrawal Are Influenced by Folate and Riboflavin: Results from the German Investigation on Neurobiology in Alcoholism (GINA)

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    Aims: Various studies have shown that plasma homocysteine (HCY) serum levels are elevated in actively drinking alcohol-dependent patients a during alcohol withdrawal, while rapidly declining during abstinence. Hyperhomocysteinemia has been associated not only with blood alcohol concentration (BAC), but also with deficiency of different B-vitamins, particularly folate, pyridoxine and cobalamin. Methods: Our study included 168 inpatients (110 men, 58 women) after admission for detoxification treatment. BAC, folate, cobalamin, pyridoxine, thiamine and riboflavin were obtained on admission (Day 1). HCY was assessed on Days 1, 7 and 11. Results: HCY levels significantly declined during withdrawal. General linear models and linear regression analysis showed an influence of BAC, folate and riboflavin on the HCY levels on admission as well as on HCY changes occurring during alcohol withdrawal. No significant influence was found for thiamine, cobalamin and pyridoxine. Conclusions: These findings show that not only BAC and plasma folate levels, but also plasma levels of riboflavin influence HCY plasma levels in alcohol-dependent patient

    Methodology to prospect electronics compositions and flows, illustrated by material trends in printed circuit boards

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    Raw Materials are crucial in the development, production, and improvement of modern-day technology. Reliable access to critical, scarce, and valuable materials used in electronics is becoming a worldwide concern. Therefore, the quantification of material recovery from the urban mine is currently pursued worldwide. Commonly, data on (Waste) Electrical and Electronic Equipment is scattered, not harmo-nized, and uses different types of classifications and terminology. This provides a big challenge of a structured mapping of secondary raw materials in the urban mine. To address these issues, a state-of -the-art methodology has been developed and is presented by analyzing and tracking printed circuit boards in different key Electrical and Electronic Equipment over time. A total of 4051 composition data records where analyzed to extract the concentration of 19 elements in printed circuit boards between 1990 until 2020. The methodology harmonizes urban mine data, provides structured information that can be used to analyze and monitor the impact of product trends on their components and concentration of the elements in electronics. The resulting database and harmonization protocols are made freely available at the urban mine platform. (c) 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Thrombosis and Hemostasi

    Phase separating binary fluids under oscillatory shear

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    We apply lattice Boltzmann methods to study the segregation of binary fluid mixtures under oscillatory shear flow in two dimensions. The algorithm allows to simulate systems whose dynamics is described by the Navier-Stokes and the convection-diffusion equations. The interplay between several time scales produces a rich and complex phenomenology. We investigate the effects of different oscillation frequencies and viscosities on the morphology of the phase separating domains. We find that at high frequencies the evolution is almost isotropic with growth exponents 2/3 and 1/3 in the inertial (low viscosity) and diffusive (high viscosity) regimes, respectively. When the period of the applied shear flow becomes of the same order of the relaxation time TRT_R of the shear velocity profile, anisotropic effects are clearly observable. In correspondence with non-linear patterns for the velocity profiles, we find configurations where lamellar order close to the walls coexists with isotropic domains in the middle of the system. For particular values of frequency and viscosity it can also happen that the convective effects induced by the oscillations cause an interruption or a slowing of the segregation process, as found in some experiments. Finally, at very low frequencies, the morphology of domains is characterized by lamellar order everywhere in the system resembling what happens in the case with steady shear.Comment: 1 table and 12 figures in .gif forma

    Three-dimensional lattice-Boltzmann simulations of critical spinodal decomposition in binary immiscible fluids

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    We use a modified Shan-Chen, noiseless lattice-BGK model for binary immiscible, incompressible, athermal fluids in three dimensions to simulate the coarsening of domains following a deep quench below the spinodal point from a symmetric and homogeneous mixture into a two-phase configuration. We find the average domain size growing with time as tÎłt^\gamma, where Îł\gamma increases in the range 0.545<Îł<0.7170.545 < \gamma < 0.717, consistent with a crossover between diffusive t1/3t^{1/3} and hydrodynamic viscous, t1.0t^{1.0}, behaviour. We find good collapse onto a single scaling function, yet the domain growth exponents differ from others' works' for similar values of the unique characteristic length and time that can be constructed out of the fluid's parameters. This rebuts claims of universality for the dynamical scaling hypothesis. At early times, we also find a crossover from q2q^2 to q4q^4 in the scaled structure function, which disappears when the dynamical scaling reasonably improves at later times. This excludes noise as the cause for a q2q^2 behaviour, as proposed by others. We also observe exponential temporal growth of the structure function during the initial stages of the dynamics and for wavenumbers less than a threshold value.Comment: 45 pages, 18 figures. Accepted for publication in Physical Review

    Innovation highway Breakthrough milestones amp; key developments in chalcopyrite photovoltaics from a retrospective viewpoint

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    The present contribution is a summary of an event that was organized as a special evening session in Symposium V Chalcogenide Thin Film Solar Cells at the E MRS 2016 Spring Meeting, Lille, France. The presentations in this session were given by the coauthors of this paper. These authors present retrospectives of key developments in the amp; 64257;eld of Cu In,Ga S,Se 2 solar cells as they themselves had witnessed in their laboratories or companies. Also, anecdotes are brought up, which captured interesting circumstances in that evolutionary phase of the amp; 64257;eld. Be cause the focus was on historical perspectives rather than a comprehensive review of the amp; 64257;eld, recent develop ments intentionally were not addresse

    Gluon polarization in the nucleon from quasi-real photoproduction of high-pT hadron pairs

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    We present a determination of the gluon polarization Delta G/G in the nucleon, based on the helicity asymmetry of quasi-real photoproduction events, Q^2<1(GeV/c)^2, with a pair of large transverse-momentum hadrons in the final state. The data were obtained by the COMPASS experiment at CERN using a 160 GeV polarized muon beam scattered on a polarized 6-LiD target. The helicity asymmetry for the selected events is = 0.002 +- 0.019(stat.) +- 0.003(syst.). From this value, we obtain in a leading-order QCD analysis Delta G/G=0.024 +- 0.089(stat.) +- 0.057(syst.) at x_g = 0.095 and mu^2 =~ 3 (GeV}/c)^2.Comment: 10 pages, 3 figure
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