Higher-Order Aggregate Networks in the Analysis of Temporal Networks: Path structures and centralities

Recent research on temporal networks has highlighted the limitations of a static network perspective for our understanding of complex systems with dynamic topologies. In particular, recent works have shown that i) the specific order in which links occur in real-world temporal networks affects causality structures and thus the evolution of dynamical processes, and ii) higher-order aggregate representations of temporal networks can be used to analytically study the effect of these order correlations on dynamical processes. In this article we analyze the effect of order correlations on path-based centrality measures in real-world temporal networks. Analyzing temporal equivalents of betweenness, closeness and reach centrality in six empirical temporal networks, we first show that an analysis of the commonly used static, time-aggregated representation can give misleading results about the actual importance of nodes. We further study higher-order time-aggregated networks, a recently proposed generalization of the commonly applied static, time-aggregated representation of temporal networks. Here, we particularly define path-based centrality measures based on second-order aggregate networks, empirically validating that node centralities calculated in this way better capture the true temporal centralities of nodes than node centralities calculated based on the commonly used static (first-order) representation. Apart from providing a simple and practical method for the approximation of path-based centralities in temporal networks, our results highlight interesting perspectives for the use of higher-order aggregate networks in the analysis of time-stamped network data.Comment: 27 pages, 13 figures, 3 table

An ensemble perspective on multi-layer networks

We study properties of multi-layered, interconnected networks from an ensemble perspective, i.e. we analyze ensembles of multi-layer networks that share similar aggregate characteristics. Using a diffusive process that evolves on a multi-layer network, we analyze how the speed of diffusion depends on the aggregate characteristics of both intra- and inter-layer connectivity. Through a block-matrix model representing the distinct layers, we construct transition matrices of random walkers on multi-layer networks, and estimate expected properties of multi-layer networks using a mean-field approach. In addition, we quantify and explore conditions on the link topology that allow to estimate the ensemble average by only considering aggregate statistics of the layers. Our approach can be used when only partial information is available, like it is usually the case for real-world multi-layer complex systems

GOALS survey: P6 pupils and further and higher education

The Quality in Education Centre (QIE) at the University of Strathclyde was commissioned bythe GOALS Project team to provide baseline data from pupils who had not, as yet,participated in the GOALS programme for the purpose of contributing to a larger evaluation ofthe impact of the GOALS Project, and to make recommendations on the future developmentof the project. This report summarises and discusses data from surveys of a sample of P6pupils and interview data from a smaller sample of their parents

Dry Bulk Tanker Material Sampling Device

The purpose of this project is to provide an easy to manufacture solution to sampling material from dry bulk tankers. A device was developed using basic design requirements. Once a design was created a CAD design was drawn to illustrate and prototype the device. This prototype was placed under rigorous testing to determine effectiveness. The end result provides a dry bulk sampling device for plant workers and/or truck drivers to sample the material in their tankers and send to the laboratory when unloading at a facility

Remote Preconditioning: Evaluating The Efficacy Of Cardioprotection In Type-2 Diabetes And Exploring The Mechanistic Role Of Exosomes

Remote preconditioning is a promising and robust treatment for myocardial ischemia/reperfusion injury that evokes cardioprotection through endogenous neural and/or humoral signaling. A recent study has reported that protective signaling is mediated by exosomes through the circulation; however this concept is supported by limited and inconsistent evidence. Despite overwhelming success in preclinical studies, the efficacy of remote preconditioning in human studies is inconclusive. Importantly, the majority of remote preconditioning studies use healthy animal models despite growing evidence that comorbidities, such as type-2 diabetes, may negatively influence outcomes. Nonetheless, the efficacy of remote preconditioning in the setting of type-2 diabetes has not been investigated. Using an established model of myocardial ischemia/reperfusion in the Zucker model of type-2 diabetes and a model of hypoxia/reoxygenation in cultured HL-1 cardiomyocytes we tested four hypotheses: i. remote preconditioning is ineffective in early-stage type-2 diabetes in vivo; ii. the traditional ultracentrifugation technique for exosomes isolating is inadequate to isolate protective factor(s) from remote preconditioning; iii. enhanced ultracentrifugation technique for exosome isolation sequesters a protective fraction of serum; iv. the humoral component of remote preconditioning is defective in type-2 diabetes. In support of Hypothesis I, we demonstrate that remote preconditioning failed to reduce infarct size caused by ischemia/reperfusion in the Zucker model of early-stage type-2 diabetes. Our results illustrate that the loss in efficacy is not the result of hyperglycemia per se nor sensitization of the myocardium to ischemia/reperfusion. Subsequently, we sought to isolate a subfraction of serum from remote preconditioned rats which contained exosomes that could communicate protection and render HL-1 cardiomyocytes resistant to hypoxia/reoxygenation-induced cell death. In agreement with Hypothesis II, we report that the traditional ultracentrifugation isolation technique (100,000 xg for 2 hr) did not isolate the protective component with the exosome-rich pellet from serum, suggesting that the protective component remained in the supernatant. In accordance with these observations, we enhanced the ultracentrifugation technique to improve exosome sedimentation and obtain a protective sub-fraction of serum. In agreement with Hypothesis III, the enhanced ultracentrifugation technique (300,000 xg for 12 hr) isolated a protective exosome-rich supernatant fraction from remote preconditioned serum. However, our enhanced ultracentrifugation technique also yielded an additional, exosome-rich pellet and an exosome-depleted fraction, neither of which evoked protection. Lastly, in support of Hypothesis IV, we demonstrate that unfractionated serum and the exosome-rich supernatant fraction obtained from remote preconditioned diabetic Zucker Fatty rats did not protect HL-1 cardiomyocytes from hypoxia/reoxygenation. In conclusion, our results illustrate for the first time that the infarct-sparing efficacy of remote preconditioning is abolished in the setting of early-stage type-2 diabetes. We demonstrate that exosomes, although not sufficient for protection, may be requisite in the humoral component of remote preconditioning. Finally, we report that the humoral component of remote preconditioning is defective in the setting of type-2 diabetes – a defect that may contribute to the failure of remote conditioning to limit infarct size in this comorbid model

Politicians on the board : a driving force for Corporate Social Responsibility performance of german DAX 30 firms?

This paper aims to explore the following question: Do political directors on supervisory boards affect the corporate social responsibility (CSR) performance of firms? Based on identity theory, this paper predicts that politicians incorporate their political identity and social interests into their role as directors and consequently increase the CSR performance of the firm. Furthermore, this study explores whether gender diversity on the board of directors and the power of CEOs intensify this relationship. The empirical setting includes all 41 firms listed in the German DAX 30 between 2009 und 2020. In order to analyze the panel data set regression analyses are conducted. The results of the study indicate a non-significant result on the influence of political directors on CSR performance in the sample. A potential reason could be the often extremely high number of board members in German DAX 30 firms and the comparatively low influence of each individual or the low regional linkages of firms with politicians of this scale. Furthermore, additional post hoc analyses suggest that there are significant positive correlations between conservative as well as national politicians on CSR performance. This effect weakens under the influence of the moderating factors gender diversity and CEO power. Thus, these results indicate that the differentiation of political orientation, jurisdiction scope and other characteristics can contribute decisively to the understanding of the effect of political directors on CSR performance.Este documento pretende explorar a seguinte questão: Os directores políticos dos conselhos de supervisão afectam o desempenho das empresas em matéria de responsabilidade social empresarial (RSE)? Baseado na teoria da identidade, este documento prevê que os políticos incorporem a sua identidade política e interesses sociais no seu papel de directores e consequentemente aumentem o desempenho da empresa em termos de RSE. Além disso, este estudo explora se a diversidade de género no conselho de administração e o poder dos CEOs intensificam esta relação. A amostra inclui todas as 41 empresas listadas no DAX 30 alemão entre 2009 e 2020. A fim de analisar o conjunto de dados do painel, são efectuadas análises de regressão. Os resultados do estudo indicam um resultado não significativo sobre a influência dos directores políticos no desempenho da RSE na amostra. Uma razão potencial poderia ser o número frequentemente extremamente elevado de membros do conselho de administração nas empresas do DAX 30 alemão e a influência comparativamente baixa de cada indivíduo ou a baixa ligação regional das empresas com políticos desta escala. Além disso, análises post hoc adicionais sugerem que existem correlações positivas significativas entre políticos conservadores e políticos nacionais sobre o desempenho em termos de RSE. Este efeito enfraquece sob a influência dos factores moderadores diversidade de género e poder de direcção. Estes resultados indicam que a diferenciação da orientação política e do âmbito de jurisdição pode contribuir decisivamente para compreender o efeito dos directores políticos no desempenho da RSE