Network centrality: an introduction

Centrality is a key property of complex networks that influences the behavior of dynamical processes, like synchronization and epidemic spreading, and can bring important information about the organization of complex systems, like our brain and society. There are many metrics to quantify the node centrality in networks. Here, we review the main centrality measures and discuss their main features and limitations. The influence of network centrality on epidemic spreading and synchronization is also pointed out in this chapter. Moreover, we present the application of centrality measures to understand the function of complex systems, including biological and cortical networks. Finally, we discuss some perspectives and challenges to generalize centrality measures for multilayer and temporal networks.Comment: Book Chapter in "From nonlinear dynamics to complex systems: A Mathematical modeling approach" by Springe

Modification of Oligomers and Reinforced Polymeric Composites by Carbon Nanotubes and Ultrasonic

An abridged version of the book chapter is presented in the archive. Full version on the publisher's site: https://link.springer.com/chapter/10.1007/978-3-030-26672-1_3Розглядається широке коло питань щодо розроблених напрямів модифікації епоксидних олігомерів і армованих полімерних композитів на їх основі вуглецевими нанотрубками і ультразвуком. Аналізується перспективність створення гібридних полімерних композитів функціонального призначення.This chapter analyzes the physical (in the form of ultrasound) and chemical modification of liquid polymer media and reinforced polymeric composites. The main emphasis is made on the analysis of ultrasonic cavitation processing as the most effective one for solving one of the main technological problems in the production of nanomodified polymer composites

Bioinspired approaches for toughening of fibre reinforced polymer composites

In Nature, there are a large range of tough, strong, lightweight and multifunctional structures that can be an inspiration to better performingmaterials. Thiswork presents a review of structures found in Nature, frombiological ceramics and ceramics composites, biological polymers and polymers composites, biological cellular materials, biological elastomers to functional biological materials, and their main tougheningmechanisms, envisaging potential mimicking approaches that can be applied in advanced continuous fibre reinforced polymer (FRP) composite structures. For this, themost common engineering compositemanufacturing processes and current composite damage mitigation approaches are analysed. This aims at establishing the constraints of biomimetic approaches development as these bioinspired structures are to be manufactured by composite technologies. Combining both Nature approaches and engineering composites developments is a route for the design and manufacturing of high mechanical performance and multifunctional composite structures, therefore new bioinspired solutions are proposed.This research was funded by the project “IAMAT—Introduction of advanced materials technologies into new product development for the mobility industries”, with reference MITP-TB/PFM/0005/2013, under the MIT-Portugal program and in the scope of projects with references UIDB/05256/2020 and UIDP/05256/2020, exclusively financed by FCT - Fundação para a Ciência e Tecnologia

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

Modelling flow and filtration in liquid composite moulding of nanoparticle loaded thermosets

This paper presents analytical and numerical models of liquid moulding of hybrid composites. An 1-D analytical solution of Darcy's problem, accompanied by nanoparticle filtration kinetics and conservation, has been developed. A non-linear finite difference model incorporating variations in permeability, porosity and viscosity as a function of local nanoparticle loading was formulated. Comparison of the two models allowed verification of their validity, whilst a mesh sensitivity study demonstrated the convergence of the numerical scheme. The limits of validity of the analytical solution were established over a range of infiltration lengths and filtration rates for different nanoparticle loadings. The analytical model provides an accurate and efficient approximation of through thickness infusion of hybrid composites, whereas use of the numerical scheme is necessary for accurate simulation of in-plane filling processes. The models developed here can serve as the basis of process design/optimisation for the production of hybrid composites with controlled distribution of nano-reinforcement

Liquid moulding of carbon nanoparticle filled composites

This thesis focuses on the incorporation of carbon nanoparticles within continuous fibre reinforcements by liquid composite moulding processes, in order to provide enhanced electrical and delamination properties to the multiscale composites. The mechanisms controlling the flow and filtration of these nanoparticles during liquid composite moulding are studied, in order to develop a predictive 1-D model which allows design of the processing of these composite materials. Five different carbon nanoparticles at 0.25 wt% loading, three unmodified and one surface modified carbon nanotube systems and one carbon nanofibre system, were utilised to modify a commercial two-component epoxy resin utilised to impregnate carbon and glass reinforcements at high fibre volume fraction by resin transfer moulding. The dispersion of the nanofillers in the prepolymer was carried out by ultrasonication, high shear mixing or triple roll milling or a combination of the three. Electrical conductivity measurements of the carbon nanoparticle liquid suspensions during dispersion, alongside optical microscopy imaging and rheological analysis of these allowed the selection of the concentration of nanofiller and the appropriate dispersion technique for each nanoparticle system. The resin transfer moulding process required adaptation to incorporate the dispersion and modify degassing steps, especially when utilising unmodified carbon nanoparticles suspensions, due to their higher viscosity and tendency to be filtered. Nanoparticle filtration was identified by electrical conductivity measurements and microscopy of specimens cut at increasing distances from the inlet. Cake filtration was observed for some of the unmodified systems, whereas deep bed filtration occurred for the surface modified CNT material. Property graded composites were obtained due to filtration, where the average electrical conductivity of the carbon and glass composites produced increased by a factor of two or one order of magnitude respectively. The effect of filler on the delamination properties of the carbon fibre composites was tested under mode I. The results do not show a statistically significant improvement of delamination resistance with the presence of nanoparticles, although localised toughening mechanisms such as nanoparticle pull-out and crack bridging as well as inelastic deformation have been observed on fracture surfaces. Particle filtration and gradients in concentration resulted in non-linear flow behaviour. An 1-D analytical and a finite difference model, based on Darcy’s law accompanied by particle mass conservation and filtration kinetics were developed to describe the flow and filtration of carbon nanoparticle filled thermosets. The numerical model describes the non-linear problem by incorporating material property update laws, i.e. permeability, porosity and viscosity variations on concentration of retained and suspended particles with location and time. The finite difference model is consistent and converges to the analytical solution. The range of applicability of the analytical model is limited to lower filtration coefficients and shorter filling lengths, providing an approximate solution for through thickness infusion; whereas the numerical model presents a solution outside this range, i.e. in-plane filling processes. These models allow process design, with specified carbon nanoparticle concentration distributions achieved via modifying the nanofiller loading at the inlet as a function of time

RTM processing and electrical performance of carbon nanotube modified epoxy/ fibre composites

This investigation focuses on nanoparticle filtration in the processing of multiscale carbon and glass fibre composites via resin transfer moulding. Surface modified and unmodified carbon nanotubes (CNTs) were incorporated into a commercial epoxy resin. The dispersion quality was evaluated using electrical measurements of the liquid suspensions. The manufacturing process was adapted to the challenges posed by the modified rheological behaviour of the CNT loaded resin. Nanoparticle filtration was observed; with some of the unmodified systems following so called ‘cake filtration' behaviour. This resulted in nonlinear flow behaviour that deviated from the ideal response observed in RTM filling in conventional composites. The electrical conductivity of relatively high fibre volume fraction multiscale carbon and glass laminates increased by less than an order of magnitude with the addition of the nanotub

Ichthyofauna of the ribeirão Sucuri, tributary of rio Tietê, upper rio Paraná basin, southeastern Brazil

The ribeirão Sucuri, a tributary of the rio Tietê, and part of the upper rio Paraná basin, is located in the municipality of Pongaí, São Paulo state. The ichthyofauna of ribeirão Sucuri was sampled at nine collection sites in May 2018. Our study captured 408 specimens representing five orders, 11 families, and 35 species. Among the species collected, two have not been previously reported from the rio Tietê basin: Eigenmannia guairaca Peixoto, Dutra & Wosiacki, 2015 and Hoplias misionera Rosso, Mabragaña, González-Castro, Delpiani, Avigliano, Schenone & Días de Astarloa, 2016. Additionally, four species were found that are non-native: Hoplias misionera, Poecilia reticulata Peters, 1859, Roeboides descalvadensis Fowler, 1932, and Satanoperca sp. This study represents the first fish inventory of a tributary on the left margin of the Tietê-Batalha sub-basin and only the second for this portion of the rio Tietê. Our results increase to 55 the number of species recorded from this sub-basin and add data on the putative morphological variation in several species

Ein viruzides Phthalocyanin-basiertes Mundspül-/Gurgelprotokoll zur Reduzierung des Erkrankungsrisikos durch COVID-19: eine Bevölkerungsstudie

Aim: In this community trial, the objective was to evaluate the incidence of coronavirus disease-2019 (COVID-19) cases in two similar communities in three distinct phases: 1 (before the intervention), 2 (during the intervention), and 3 (after the intervention). Methods: The test community received the oral antiseptic intervention (experimental), while the control community did not. The official information agency ("Statewise System for Data Analysis") provided the number of confirmed COVID-19 cases. Data were analyzed according to the three phases per epidemiological week (epi) using the R Core Team (2021) program. The relative risk and 95% confidence intervals between the cumulative incidence values of the test and control communities were calculated for each period. In the test community, a total of 995 residents over 10 years of age received two bottles containing 600 ml of mouthwash containing antiviral phthalocyanine derivative (APD). The participants were asked to gargle/rinse with of 5 mL of the mouthwash containing ADP 3 to 5 times a day, for 1 min, until the bottles were empty. Results: In phases 1 and 3, the disease risk between the two communities did not differ significantly (p>0.05), while in phase 2, the disease risk was 54% lower in the test community than in the control community. Conclusion: The use of the APD mouthwash protocol seems to reduce the COVID-19 incidence at the population level, and further studies are needed to confirm its protective effect under more precisely controlled conditions.Zielsetzung: In einer Bevölkerungsstudie sollte das Auftreten von COVID-19 in zwei vergleichbaren Gemeinden in drei verschiedenen Phasen untersucht werden: Phase 1 vor, Phase 2 während und Phase 3 nach der Intervention.Methode: Die Testpopulation erhielt die orale antiseptische Intervention, die Kontrollpopulation dagegen nicht. Die amtliche Informationsstelle lieferte die Zahl der bestätigten COVID-19 Fälle. Die Daten wurden entsprechend den drei Phasen pro epidemiologischer Woche (epi) mit dem Programm R Core Team (2021) analysiert. Das relative Risiko und die 95%-Konfidenzintervalle zwischen den kumulativen Inzidenzwerten der Test- und Kontrollpopulation wurden für jeden Zeitraum berechnet. In der Testpopulation erhielten 995 Einwohner im Alter >10 Jahre zwei Flaschen mit je 600 ml Mundwasser mit Gehalt an dem antiviralen Phthalocyanin-Derivat (APD). Die Teilnehmer wurden gebeten, 3 bis 5 Mal täglich 1 min lang mit 5 ml des Mundwassers zu gurgeln/zu spülen, bis die Flaschen aufgebraucht sind. Ergebnisse: In den Phasen 1 und 3 unterschied sich das Erkrankungsrisiko zwischen den beiden Bevölkerungsstichproben nicht signifikant (p>0,05), während in Phase 2 das Erkrankungsrisiko in der Testpopulation 54% niedriger war als in der Kontrollpopulation.Schlussfolgerung: Das viruzide APD-Mundspülprotokoll scheint die COVID-19-Inzidenz auf Bevölkerungsebene zu verringern, jedoch sind weitere Studien erforderlich, um die Schutzwirkung unter genauer kontrollierten Bedingungen zu bestätigen