A comparison of Li + transport in dimethoxyethane, poly(ethylene oxide) and poly(tetramethylene oxide) by molecular dynamics simulations.

Pure dimethoxyethane (DME), poly(ethylene oxide) (PEO) and poly(tetramethylene oxide) (PTME) and their binary mixtures with LiI were investigated by molecular dynamics simulations (Li/O proportion equal to 1:8). The properties analyzed included the relative occurrence of trans and gauche population for selected torsions, radial distribution functions, mean square fluctuations and mobilities. We studied the relation between the ionic transport process of Li + and the conformational behavior in DME, PEO and PTME systems. We investigated the solvation shell around Li + in those systems. The gauche effect of DME and PEO (OCCO torsion) is strongly related to salt addition. This effect is more pronounced in DME-based systems. Li + /O co-ordination occurs in all considered systems. The mobility of the ionic species is larger in DME than in the polymers. In PTME, it is only slightly smaller than in PEO

Business networks and their effects on tourism.

O presente artigo tem como objetivo propor um modelo de alinhamento competitivo para a rede de atores do turismo, visando aumentar sua coes?o e facilitar a busca de objetivos comuns. Tal proposta foi definida com base na expertise dos autores na analise de redes de turismo, aliada a resultados obtidos na pesquisa em Ouro Preto (MG). Dessa forma, foi poss?vel perceber o peso dos atores envolvidos em fun??o dos crit?rios de escolha utilizados pelos visitantes para configurar seu caminho dentro da regi?o tur?stica analisada e, assim, refor?ar os relacionamentos existentes.The relationships between firms, to be successful, demand high levels of transparency, information and physical flows of goods and services, in order to provide free access for all people involved in doing business together. The same can be said regarding flow of money resources and talents needed by the processes and operations performed by the network. Thus, the main idea involves reaching balance conditions in terms of sharing the results obtained by all participants, considering their objectives and goals, to keep the network form of organization as being an adequate strategy. This proposal was defined from the authors? expertise in analysis of tourism networks, together with results obtained on research in Ouro Preto. Thus it was possible to realize the weight of the players involved depending on the selection criteria used by visitors to configure their way into of the tourist region analyzed and thereby strengthen existing relationships

The first 80 days of the COVID-19 pandemic in the city of Belo Horizonte : from containment to reopening.

Este artigo examina o contexto e as implica??es da pandemia por Covid-19 na cidade de Belo Horizonte (BH) nos primeiros 80 dias da doen?a. Utilizamos um recorte anal?tico descritivo para mensurar a evolu??o dos casos, o excesso de ?bitos, a taxa de transmissibilidade do v?rus e a press?o da doen?a sobre o sistema de sa?de de BH e regi?o, atrav?s da taxa de ocupa??o hospitalar nos leitos p?blicos. Al?m disso, identificamos as principais pol?ticas de conten??o adotadas pelas autoridades locais, bem como as implica??es da redu??o do distanciamento social. Nossos resultados demonstram que o Sistema ?nico de Sa?de (SUS), bem gerido, ? fundamental para o enfrentamento da pandemia e a mitiga??o de suas consequ?ncias para a popula??o. O processo de flexibiliza??o que se inicia tem imposto novos desafios que requerer?o monitoramento atento das autoridades e da sociedade.The paper examines the implications of Co vid-19 pandemic for the city of Belo Horizonte (BH), during the fi rst 80 days of the disease. We use a descriptive-analytical approach to estimate the growth of Covid-19 cases over time, the excess of deaths, the virus? rate of transmissibility, and the consequent burden on the municipal the health system, measured by the rate of occupancy of public hospital beds. Also, we identify the main containment policies adopted by local authorities, and the implications of reopen ing measures and the following reduction of social distancing. Our fi ndings reveal that a well-managed Unifi ed Health System (SUS) is paramount to effectively tackle the pan demic and its consequences for the population. The reopening process has imposed new challenges that will require close monitoring by the authorities and by the Society

Scale-free fuse network and its robustness.

The robustness and reliability of scale-free networks are tested as a fuse network. The idea is to examine the robustness of a scale-free network when links are irreversibly removed after failing. Due to inherent characteristics of the fuse network model, the sequence of links removal is deterministic and conditioned to fuse tolerance and connectivity of its ends. It is a different situation from classical robustness analysis of complex networks, when they are usually tested under random fails and deliberate attacks of nodes. The use of this system to study the fracture of elastic material brought some interesting results

A model for fracture in fibrous materials.

A fiber bundle model in (1 + 1)-dimensions for the breaking of fibrous composite matrix is introduced. The model consists of N parallel fibers fixed in two plates. When one of the plates is pulled in the direction parallel to the fibers, these can be broken with a probability that depends on their elastic energy. The mechanism of rupture is simulated by the breaking of neighbouring fibers that can generate random crack spreading up through the system. Due to the simplicity of the model we have virtually no computational limitation. The model is sensitive to external conditions as temperature and traction time-rate. The energy vs. temperature behaviour, the diagrams of stress vs. strain and the histograms of the frequency vs. size of cracks are obtained

The stable-chaotic transition on cellular automata used to model the immune repertoire.

In this paper we study a simplified version of the cellular automata approximation introduced by De Boer, Segel and Perelson to model the immune repertoire. The automaton rule defines an activation window based on the idea of the proliferation function (biphasic dose-response function), which is used to describe the receptor crosslinking involved in the B cell activation. This proliferation function is very sensitive to the activation threshold and activation interval definitions. Here we investigate the influence of these parameters on the automaton rule proposed by Stauffer and Weisbuch. Using a fixed window they obtained the stable-"chaofic" transition only for d > 4. We find, contrary to their results, that this transition is always present for d > 2 until a certain critical value of the activation threshold is attained, above which this transition disappears and the system will always evolve towards a stable configuration. The shorter the activation interval the faster the system undergoes to the "chaotic" behaviour. Increasing the activation interval there is a certain critical size from which the system will always exhibit the same behaviour no matter the activation interval size. We also investigate the influence of the initial distribution on the results. Since we defined the relevant parameters of the model, we obtained the phase diagrams exhibiting the regions of stable and "chaotic" behavior. Such diagrams are not easily found in the literature

Theoretical study of solvent and temperature effects on the behaviour of poly(ethylene oxide) (PEO).

Molecular mechanics and molecular dynamics simulations were applied in order to study the behaviour of poly ethylene. oxide PEO in different temperatures and solvents. It was found that over the temperature range of 50?500 K the equilibrium structure of PEO is folded. Both kinetic and potential energies increase with temperature. The behaviour of PEO . in two different solvents ? CHCl ? s5 and H O ? s80 ? was found to be similar, with the folded structure observed 32 in equilibrium. The solvation energy calculated using the GBrSA model yielded essentially the same value in CHCl and H2O