Self-similar variables and the problem of nonlocal electron heat conductivity

Self-similar solutions of the collisional electron kinetic equation are obtained for the plasmas with one (1D) and three (3D) dimensional plasma parameter inhomogeneities and arbitrary Z{sub eff}. For the plasma parameter profiles characterized by the ratio of the mean free path of thermal electrons with respect to electron-electron collisions, {gamma}{sub T}, to the scale length of electron temperature variation, L, one obtains a criterion for determining the effect that tail particles with motion of the non-diffusive type have on the electron heat conductivity. For these conditions it is shown that the use of a {open_quotes}symmetrized{close_quotes} kinetic equation for the investigation of the strong nonlocal effect of suprathermal electrons on the electron heat conductivity is only possible at sufficiently high Z{sub eff} (Z{sub eff} {ge} (L/{gamma}{sub T}){sup 1/2}). In the case of 3D inhomogeneous plasma (spherical symmetry), the effect of the tail electrons on the heat transport is less pronounced since they are spread across the radius r

Early-time velocity autocorrelation for charged particles diffusion and drift in static magnetic turbulence

Using test-particle simulations, we investigate the temporal dependence of the two-point velocity correlation function for charged particles scattering in a time-independent spatially fluctuating magnetic field derived from a three-dimensional isotropic turbulence power spectrum. Such a correlation function allowed us to compute the spatial coefficients of diffusion both parallel and perpendicular to the average magnetic field. Our simulations confirm the dependence of the perpendicular diffusion coefficient on turbulence energy density and particle energy predicted previously by a model for early-time charged particle transport. Using the computed diffusion coefficients, we exploit the particle velocity autocorrelation to investigate the time-scale over which the particles "decorrelate" from the solution to the unperturbed equation of motion. Decorrelation time-scales are evaluated for parallel and perpendicular motions, including the drift of the particles from the local magnetic field line. The regimes of strong and weak magnetic turbulence are compared for various values of the ratio of the particle gyroradius to the correlation length of the magnetic turbulence. Our simulation parameters can be applied to energetic particles in the interplanetary space, cosmic rays at the supernova shocks, and cosmic-rays transport in the intergalactic medium.Comment: 10 pages, 11 figures, The Astrophyical Journal in pres

Anomalous Heat Diffusion

Consider anomalous energy spread in solid phases, i.e., $MSD= \int (x -{\langle x \rangle}_E)^2 \rho_E(x,t)dx \propto t^{\beta}$, as induced by a small initial excess energy perturbation distribution $\rho_{E}(x,t=0)$ away from equilibrium. The associated total thermal equilibrium heat flux autocorrelation function $C_{JJ}(t)$ is shown to obey rigorously the intriguing relation, $d^2 MSD/dt^2 = 2C_{JJ}(t)/(k_BT^2c)$, where $c$ is the specific volumetric heat capacity. Its integral assumes a time-local Helfand-moment relation; i.e. $dMSD/dt|_{t=t_s} = 2/(k_BT^2c)\int_0^{t_s} C_{JJ}(s)ds$, where the chosen cut-off time $t_s$ is determined by the maximal signal velocity for heat transfer. Given the premise that the averaged nonequilibrium heat flux is governed by an anomalous heat conductivity, energy diffusion scaling determines a corresponding anomalous thermal conductivity scaling behaviour

Anarchism and Health

This article looks at what anarchism has to offer in debates concerning health and healthcare. I present the case that anarchism’s interest in supporting the poor, sick, and marginalized, and rejection of state and corporate power, places it in a good position to offer creative ways to address health problems. I maintain that anarchistic values of autonomy, responsibility, solidarity, and community are central to this endeavor. Rather than presenting a case that follows one particular anarchist theory, my main goal is to raise issues and initiate debate in this underresearched field in mainstream bioethics

Application and development of IT technologies in Russian education: problems and solutions

Lately the role of information technology in education has grown significantly. One of the most important reasons for the use of information and communication technologies in the education system is undoubtedly a global tendency, which finds its expression in a huge number of online courses, trainings, individual consultations, applied through the use of various technical devices, which have become usual and quite common phenomenon in recent two or three decades. Another important reason for the transition to the online education system is associated with the COVID pandemic, since it is very logical to use online technologies for studies to prevent increased infection rates. It should also be noted that, in addition to the above obvious reasons for the use of information technology in the field of education, it is necessary to include such as the inability of the student to attend the teacher, or if the student does not want to attend an educational institution full-time for any reason, it can also be any psychological complexes of being in a large classroom, or lack of discipline in the student. All of the above strongly pushes and warms up society to the introduction and use of online technologies in education. This work is devoted to the study of the development and formation of information and communication technologies in the Russian education system, as well as the detailed analysis and discussion of the problems of the implementation and application of IT in Russia and ways of solving various kinds of problems arising in this area

Thermal diffusion in the IGM of clusters of galaxies

We revisit the phenomenon of elements diffusion in the intergalactic medium (IGM) in clusters of galaxies. The diffusion is driven by gravity, concentration and temperature gradients. The latter cause thermal diffusion, which has been so far ignored in IGM studies. We consider the full problem based on the Burgers' equations and demonstrate that the temperature gradients present in clusters of galaxies may successfully compete with gravity, evacuating metals from cooler regions. Under the combined action of gravity and temperature gradients, complicated metallicity profiles with several peaks and depressions may be formed. For a typical cool core cluster, the thermal diffusion may significantly reduce and even reverse the gravitational sedimentation of metals, resulting in the depression in their abundance in the core. This may have implications for diagnostics of the low temperature plasma in the centers of clusters of galaxies.Comment: 10 pages, 8 figures; accepted to MNRA

Signatures of non-Markovian turbulent transport in Reversed Field Pinch plasmas

Transport of field lines is studied for a realistic model of magnetic field configuration in a Reversed Field Pinch. It is shown that transport is anomalous, i.e., it cannot be described within the standard diffusive paradigm. To fit numerical results we present a transport model based upon the Continuous Time Random Walk formalism. Fairly good quantitative agreement appears for exponential memory functions.Comment: 20 pages. Submitte

Anarchist education and the paradox of pedagogical authority

This paper interrogates a key feature of anarchist education; focusing on a problem with implications not only for anarchist conceptions of education, but for anarchist philosophy and practice more broadly. The problem is this: if anarchism consists in the principled opposition to all forms of coercive authority, then how is this to be reconciled with situations where justice demands the use of coercion in order to protect some particular good? It seems that anarchist educators are forced to deny coercive authority in principle, whilst at the same time affirming it in practice. This is the paradox of pedagogical authority in anarchist education. Coercive authority is simultaneously impossible and indispensable. Exploring this paradox through a reading of Jacques Derrida’s later work, and, in particular, his conception of justice as requiring openness to the singular situation (Derrida, 1990), I argue that in exercising their authority anarchist educators encounter the aporetic moment in anarchism, experiencing what Derrida calls ‘the ordeal of the undecidable’ (Ibid.). Understood this way, the paradox becomes less an indication of anarchism’s limitations than it does its value. For it is here that the problem of pedagogical authority is treated with the gravity that all questions of justice deserve

What is an Insurrection? Destituent Power and Ontological Anarchy in Agamben and Stirner

The aim of this article is to develop a theoretical understanding of the insurrection as a central concept in radical politics in order to account for contemporary movements and forms of mobilisation that seek to withdraw from governing institutions and affirm autonomous practices and forms of life. I will develop a theory of insurrection by investigating the parallel thinking of Giorgio Agamben and Max Stirner. Starting with Stirner’s central distinction between revolution and insurrection, and linking this with Agamben’s theory of destituent power, I show how both thinkers develop an ontologically anarchic approach to ethics, subjectivity and life that is designed to destitute and profane governing institutions and established categories of politics. However, I will argue that Stirner’s ‘egoistic’ and voluntarist approach to insurrection provides a more tangible and positive way of thinking about political action and agency than Agamben’s at times vague, albeit suggestive, notion of inoperativity