18,907 research outputs found

    The three different phases in the dynamics of chemical reaction networks and their relationship to cancer

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    We investigate the catalytic reactions model used in cell modeling. The reaction kinetic is defined through the energies of different species of molecules following random independent distribution. The related statistical physics model has three phases and these three phases emerged in the dynamics: fast dynamics phase, slow dynamic phase and ultra-slow dynamic phase. The phenomenon we found is a rather general, does not depend on the details of the model. We assume as a hypothesis that the transition between these phases (glassiness degrees) is related to cancer. The imbalance in the rate of processes between key aspects of the cell (gene regulation, protein-protein interaction, metabolical networks) creates a change in the fine tuning between these key aspects, affects the logics of the cell and initiates cancer. It is probable that cancer is a change of phase resulting from increased and deregulated metabolic reactions.Comment: 5 pages, 2 figures, EPL, in pres

    Characterization of radially symmetric finite time blowup in multidimensional aggregation equations,

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    This paper studies the transport of a mass μ\mu in ℜd,d≥2,\real^d, d \geq 2, by a flow field v=−∇K∗μv= -\nabla K*\mu. We focus on kernels K=∣x∣α/αK=|x|^\alpha/ \alpha for 2−d≤α<22-d\leq \alpha<2 for which the smooth densities are known to develop singularities in finite time. For this range This paper studies the transport of a mass μ\mu in ℜd,d≥2,\real^d, d \geq 2, by a flow field v=−∇K∗μv= -\nabla K*\mu. We focus on kernels K=∣x∣α/αK=|x|^\alpha/ \alpha for 2−d≤α<22-d\leq \alpha<2 for which the smooth densities are known to develop singularities in finite time. For this range we prove the existence for all time of radially symmetric measure solutions that are monotone decreasing as a function of the radius, thus allowing for continuation of the solution past the blowup time. The monotone constraint on the data is consistent with the typical blowup profiles observed in recent numerical studies of these singularities. We prove monotonicity is preserved for all time, even after blowup, in contrast to the case α>2\alpha >2 where radially symmetric solutions are known to lose monotonicity. In the case of the Newtonian potential (α=2−d\alpha=2-d), under the assumption of radial symmetry the equation can be transformed into the inviscid Burgers equation on a half line. This enables us to prove preservation of monotonicity using the classical theory of conservation laws. In the case 2−d<α<22 -d < \alpha < 2 and at the critical exponent pp we exhibit initial data in LpL^p for which the solution immediately develops a Dirac mass singularity. This extends recent work on the local ill-posedness of solutions at the critical exponent.Comment: 30 page

    On Generalized Self-Duality Equations Towards Supersymmetric Quantum Field Theories Of Forms

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    We classify possible `self-duality' equations for p-form gauge fields in space-time dimension up to D=16, generalizing the pioneering work of Corrigan et al. (1982) on Yang-Mills fields (p=1) for D from 5 to 8. We impose two crucial requirements. First, there should exist a 2(p+1)-form T invariant under a sub-group H of SO(D). Second, the representation for the SO(D) curvature of the gauge field must decompose under H in a relevant way. When these criteria are fulfilled, the `self-duality' equations can be candidates as gauge functions for SO(D)-covariant and H-invariant topological quantum field theories. Intriguing possibilities occur for dimensions greater than 9, for various p-form gauge fields.Comment: 20 pages, Late

    Volatility Comovement: A Multifrequency Approach

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    We implement a multifrequency volatility decomposition of three exchange rates and show that components with similar durations are strongly correlated across series. This motivates a bivariate extension of the Markov-Switching Multifractal (MSM) introduced in Calvet and Fisher (2001, 2004). Bivariate MSM is a stochastic volatility model with a closed-form likelihood. Estimation can proceed by ML for state spaces of moderate size, and by simulated likelihood via a particle filter in high-dimensional cases. We estimate the model and confirm its main assumptions in likelihood ratio tests. Bivariate MSM compares favorably to a standard multivariate GARCH both in- and out-of-sample. We extend the model to multivariate settings with a potentially large number of assets by proposing a parsimonious multifrequency factor structure.

    Environment Energy Assessment of Trips (EEAT): An updated approach to assess the environmental impacts of urban mobility, The case of Lille Region

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    This paper deals with sustainable mobility in an urban context. We investigate the assessment of the impacts of the evolution of travel behaviour (travelled distance and modal choice) in terms of energy consumption and greenhouse gases (GHG) emissions at the local level. Indeed, today, the control of exhausts generated by the mobility within the urban areas is at the core of the environmental policies and the stabilisation of GHG emissions is one of the main goals of 'sustainable development'. To face this challenge in the transport sector, the national government and local authorities need a better understanding of the link between urban development choices, the operation of the different modes of transport systems, and residents and non residents' attitude, and mobility patterns at the local level.MOBILITE ; ZONE URBAINE ; POLLUTION ATMOSPHERIQUE ; ENERGIE ; CONSOMMATION DE CARBURANT

    Measurement-based Run-to-run Optimization of a Batch Reaction-distillation System

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    Measurement-based optimization schemes have been developed to deal with uncertainty and process variations. One of the methods therein, labeled NCO tracking, relies on appropriate parameterization of the input profiles and adjusts the corresponding input parameters using measurements so as to satisfy the necessary conditions of optimality (NCO). The applicability of NCO-tracking schemes has been demonstrated on several academic-size examples. The goal of this paper is to show that it can be applied with similar ease to more complex real-life systems. Run-to-run optimization of a batch reaction-separation system with propylene glycol is used for illustration
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