Will the Paris Accord Accelerate Climate Change?

The 2015 Paris climate accord (Paris Agreement) is meant to control our planet’s rising temperature to limit climate change. But it may be doing the opposite in permitting a slow phase-in of CO2 emission mitigation. The accord asks its 195 national signatories to specify their emission reductions and to raise those contributions over time. However, there is no mechanism to enforce these pledges. This said, the accord puts dirty energy producers on notice that their days are numbered. Unfortunately, this “use it or lose it” message may accelerate the extraction and sale of fossil fuels and, thereby, permanently worsen climate change. Our paper uses a simple OLG model to illustrate this long-noted, highly troubling Green Paradox. Its framework properly treats climate damage as a negative externality imposed by today’s generations on tomorrow’s—an externality that is, in part, irreversible and, if large enough, can tip the climate to a permanently bad state. Our paper shows that delaying abatement can be worse than doing nothing. Indeed, it can make all generations worse off. In contrast, immediate policy action can make all generations better off. Finally, we question the standard use of infinitely lived, single-agent models to determine optimal abatement policy. Intergenerational altruism underlies such models. But its assumption lacks empirical support. Moreover, were such altruism widespread, effective limits on CO2 emissions would, presumably, already be in place. Unfortunately, optimal abatement prescriptions derived from such models can differ, potentially dramatically, from those actually needed to correct the negative climate externality that today’s generations are imposing on tomorrow’

Persistent random walk of cells involving anomalous effects and random death

The purpose of this paper is to implement a random death process into a persistent random walk model which produces subballistic superdiffusion (L\'{e}vy walk). We develop a Markovian model of cell motility with the extra residence variable $\tau .$ The model involves a switching mechanism for cell velocity with dependence of switching rates on $\tau$. This dependence generates intermediate subballistic superdiffusion. We derive master equations for the cell densities with the generalized switching terms involving the tempered fractional material derivatives. We show that the random death of cells has an important implication for the transport process through tempering of superdiffusive process. In the long-time limit we write stationary master equations in terms of exponentially truncated fractional derivatives in which the rate of death plays the role of tempering of a L\'{e}vy jump distribution. We find the upper and lower bounds for the stationary profiles corresponding to the ballistic transport and diffusion with the death rate dependent diffusion coefficient. Monte Carlo simulations confirm these bounds.Comment: 20 pages, 1 figur

KINETICS AGGREGATION OF MAGNETIC SUSPENSIONS

International audienceWe present results of theoretical and computer study of the kinetics of chain-like aggregate formation in suspensions of non-Brownian magnetizable particles. An analytical model for calculation of the time-dependent function of distribution over chain size is suggested. This model describes the evolution of the chain structure due to the chain-chain aggregation. In order to verify this model we have compared it with the results of computer simulations of two-dimensional model of this suspension. Results of computer simulations and of the analytical model are in reasonable agreement up to 5% of the surface concentration of the particles

Effect of drop-like aggregates on the viscous stress in magnetic suspensions

We present results of theoretical and experimental study of effect of dense drop-like aggregates on the magnetoviscous effects in suspensions of non-Brownian magnetizable particles. Unlike the previous works on this subject, we do not restrict ourselves by the limiting case of highly elongated drops. This allows us to reproduce the experimental rheological curve in wide region of the shear rate of the suspension flow.This work has been supported by the Russian Fund of Fundamental Investigations, Grants 12-01-00132, 13-02-91052, 13-01-96047 and 14-08-00283; by the Act 211 Government of the Russian Federation No. 02.A03.21.0006; by the Junta de Andalucía (Spain), Project P09-FQM-4787; and by the University of Granada (Acción Integrada con Russia; Plan Propio 2011); and CNRS PICS No. 6102 is also acknowledged

Shear elasticity of isotropic magnetic gels

The paper deals with a theoretical study of the effective shear modulus of a magnetic gel, consisting of magnetizable particles randomly and isotropically distributed in an elastic matrix. The effect of an external magnetic field on the composite modulus is the focus of our consideration. We take into account that magnetic interaction between the particles can induce their spatial rearrangement and lead to internal anisotropy of the system. Our results show that, if this magnetically induced anisotropy is insignificant, the applied field reduces the total shear modulus of the composite. Strong anisotropy can qualitatively change the magnetomechanic effect and induce an increase of this modulus with the field.A.Y.Z. is grateful for financial support from the Russian Fund for Basic Research, through Grant No. 16-58-12003, the Program of Russian Federation Ministry of Science and Education, Project No. 3.1438.2017/4.6. M.T.L.-L. was supported by Project No. FIS2013-41821-R of Plan Nacional de Investigación Científica, Desarrollo e Innovación Tecnológica, Ministerio de Economía y Competitividad, Spain, co-funded by ERDF, European Union. D.Y.B. would like to acknowledge support of from Deutsche Forschungsgemeinschaft under Grant No. Bo 3343/1-1

Microdynamics of magnetic particles in complex fluids

International audienceThe agregation of magnetic particles in the presence of a magnetic field is the basic phenomenon which underlies all the physcis of magnetorheological (MR) fluids.Although these interactions are well understood when the suspending fluid is a simple liquid, new MR fluids based on dispersions of magnetic microparticles in a ferrofluid or MR elastomers based on dispersion of magnetic paryticles in a rubber matrix, present some unsusual properties which are not well described by conventional theories We analyse in this work, the motion of magnetic particles dispersed in a ferrofluid and submitted to a magnetic field and discuss the possible application

Эконометрический анализ факторов банкротств российских компаний в обрабатывающем секторе

This work is devoted to the analysis of the factors influencing the bankruptcy of the Russian manufacturing industry companies for the period from 2012 to 2020. Logistic regression was used as an econometric tool for the modelling the probability of companies’ default. According to the results, financial indicators of profitability, liquidity and business activity play a significant role in explaining the probability of default of Russian manufacturing companies. Special attention was paid to the impact on the probability of bankruptcy of corporate governance and ownership structure factors. First, including these indicators into the model led to an increase in its predictive power. Secondly, CEO-duality increases the stability of the company, and too high maximum share of ownership increases the likelihood of bankruptcy

Факторы риска, прибыльности и вероятности дефолта в российском банковском секторе

Banks, acting as intermediaries in conducting settlements and providing liquidity to economic agents, play an important role in modern economic systems. At the same time, banking activity is associated with many risks that necessitates control from the regulator. Over the past 9 years, the Russian banking sector has experienced a transformation that resulted in a more than halving of the number of players in the banking system. However, a revoking a bank's license is not always associated with financial difficulties. In this paper, based on quarterly data on the financial statements of Russian banks for the period from mid-2013 to early 2022, using econometric methods of analysis, we estimated the factors that affect both the probability of bank default as well as other indicators of its activity – the risk of insolvency and profitability. The Z-score was used as an indicator of insolvency risk and the return on assets was used as an indicator of profitability. The results obtained showed that balance sheet ratios are significantly correlated with the probability of bank default, its risk of insolvency and profitability. The results support the “too-big-to-fail” hypothesis for the Russian banking sector, since larger banks have a lower probability of default, but a higher risk of insolvency. The insolvency risk is significantly negatively correlated with the probability of default and profitability

Макроэкономические факторы банкротства компаний обрабатывающей отрасли в Российской Федерации

The paper presents the results of an econometric assessment of probabilistic default models on a sample of medium-sized manufacturing companies in Russia for the period from 2012 to 2020. Characteristics of the macroeconomic environment were included in the models. The inclusion of the real effective exchange rate, the growth rate of the exchange rate, the key interest rate or the price of Brent oil in real terms lead to an increase in the forecast power of the base model with internal factors only. The growth in the key interest rate and the price of oil increases the probability of a corporate default

Behavior of nanoparticle clouds around a magnetized microsphere under magnetic and flow fields

When a micron-sized magnetizable particle is introduced into a suspension of nanosized magnetic particles, the nanoparticles accumulate around the microparticle and form thick anisotropic clouds extended in the direction of the applied magnetic field. This phenomenon promotes colloidal stabilization of bimodal magnetic suspensions and allows efficient magnetic separation of nanoparticles used in bioanalysis and water purification. In the present work, size and shape of nanoparticle clouds under the simultaneous action of an external uniform magnetic field and the flow have been studied in details. In experiments, dilute suspension of iron oxide nanoclusters (of a mean diameter of 60 nm) was pushed through a thin slit channel with the nickel microspheres (of a mean diameter of 50$\mu$m) attached to the channel wall. The behavior of nanocluster clouds was observed in the steady state using an optical microscope. In the presence of strong enough flow, the size of the clouds monotonically decreases with increasing flow speed in both longitudinal and transverse magnetic fields. This is qualitatively explained by enhancement of hydrodynamic forces washing the nanoclusters away from the clouds. In the longitudinal field, the flow induces asymmetry of the front and the back clouds. To explain the flow and the field effects on the clouds, we have developed a simple model based on the balance of the stresses and particle fluxes on the cloud surface. This model, applied to the case of the magnetic field parallel to the flow, captures reasonably well the flow effect on the size and shape of the cloud and reveals that the only dimensionless parameter governing the cloud size is the ratio of hydrodynamic-to-magnetic forces - the Mason number. At strong magnetic interactions considered in the present work (dipolar coupling parameter $\alpha \geq 2$), the Brownian motion seems not to affect the cloud behavior