Dissipation and Rheology of Sheared Soft-Core Frictionless Disks

We use numerical simulations to investigate the effect of different dissipative models on the shearing rheology of massive soft-core frictionless disks in two dimensions. We show that the presence of Newtonian (overdamped) vs Bagnoldian (inertial) rheology is related to the formation of large connected clusters of disks, and that sharp transitions may exist between the two as system parameters vary. In the limit of strongly inelastic collisions, we find that rheological curves collapse to a well-defined limit when plotted against an appropriate dimensionless strain rate.Comment: 6 pages, 5 figures, revised to published versio

Glassiness, Rigidity and Jamming of Frictionless Soft Core Disks

The jamming of bi-disperse soft core disks is considered, using a variety of different protocols to produce the jammed state. In agreement with other works, we find that cooling and compression can lead to a broad range of jamming packing fractions $\phi_J$, depending on cooling rate and initial configuration; the larger the degree of big particle clustering in the initial configuration, the larger will be the value of $\phi_J$. In contrast, we find that shearing disrupts particle clustering, leading to a much narrower range of $\phi_J$ as the shear strain rate varies. In the limit of vanishingly small shear strain rate, we find a unique non-trivial value for the jamming density that is independent of the initial system configuration. We conclude that shear driven jamming is a unique and well defined critical point in the space of shear driven steady states. We clarify the relation between glassy behavior, rigidity and jamming in such systems and relate our results to recent experiments.Comment: 10 pages, 11 figures, significantly expanded version as accepted for publication in PR

Finite-Size-Scaling at the Jamming Transition: Corrections to Scaling and the Correlation Length Critical Exponent

We carry out a finite size scaling analysis of the jamming transition in frictionless bi-disperse soft core disks in two dimensions. We consider two different jamming protocols: (i) quench from random initial positions, and (ii) quasistatic shearing. By considering the fraction of jammed states as a function of packing fraction for systems with different numbers of particles, we determine the spatial correlation length critical exponent $\nu\approx 1$, and show that corrections to scaling are crucial for analyzing the data. We show that earlier numerical results yielding $\nu<1$ are due to the improper neglect of these corrections.Comment: 5 pages, 4 figures -- slightly revised version as accepted for Phys. Rev. E Rapid Communication

Heavy and Toxic Metals and Nutrients in Separate Places in the River Bregalnica (Eastern Macedonia)

Through a small scale of geochemical and geoecological research through the flow of the river Bregalnica, this paper will present the information about the character of the waters of the river, the level of presence of hard and toxic metals, nutrients and the amount of organic contamination. These researches will define the condition and the presence of Fe, Mn, Pb, Zn, Cd, Cr, Co, Cu, cyanides, detergents, organic contaminators in separate measurement locations through the flow of the river Bregalnica. During the realization of these researches, the first thing was the approach to determine the required geochemical monitoring through the flow of the river Bregalnica. When the conditions of the waters of the river Bregalnica are considered from the aspect of presence of hard and toxic metals, it can be stated that all the measured parameters are under the allowed concentrations with the exception of Arsenic and Manganum which showed higher concentrations in separate measurement locations. key words : Heavy and toxic metals, Cyanides, Nutrients, Organic contaminators, River Bregalnica

The underpinning biology relating to multiple sclerosis disease modifying treatments during the COVID-19 pandemic

Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre - including this research content - immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active