The affiliation with various social groups can be a critical factor when it comes to quality of life of each individual, making such groups an essential element of every society. The group dynamics, ...longevity and effectiveness strongly depend on group's ability to attract new members and keep them engaged in group activities. It was shown that high heterogeneity of scientist's engagement in conference activities of the specific scientific community depends on the balance between the numbers of previous attendances and non-attendances and is directly related to scientist's association with that community. Here we show that the same holds for leisure groups of the Meetup website and further quantify individual members' association with the group. We examine how structure of personal social networks is evolving with the event attendance. Our results show that member's increasing engagement in the group activities is primarily associated with the strengthening of already existing ties and increase in the bonding social capital. We also show that Meetup social networks mostly grow trough big events, while small events contribute to the groups cohesiveness.
The communication processes of knowledge creation represent a particular class of human dynamics where the expertise of individuals plays a substantial role, thus offering a unique possibility to ...study the structure of knowledge networks from online data. Here, we use the empirical evidence from questions-and-answers in mathematics to analyse the emergence of the network of knowledge contents (or tags) as the individual experts use them in the process. After removing extra edges from the network-associated graph, we apply the methods of algebraic topology of graphs to examine the structure of higher-order combinatorial spaces in networks for four consecutive time intervals. We find that the ranking distributions of the suitably scaled topological dimensions of nodes fall into a unique curve for all time intervals and filtering levels, suggesting a robust architecture of knowledge networks. Moreover, these networks preserve the logical structure of knowledge within emergent communities of nodes, labeled according to a standard mathematical classification scheme. Further, we investigate the appearance of new contents over time and their innovative combinations, which expand the knowledge network. In each network, we identify an innovation channel as a subgraph of triangles and larger simplices to which new tags attach. Our results show that the increasing topological complexity of the innovation channels contributes to network's architecture over different time periods, and is consistent with temporal correlations of the occurrence of new tags. The methodology applies to a wide class of data with the suitable temporal resolution and clearly identified knowledge-content units.
Participation in conferences is an important part of every scientific career. Conferences provide an opportunity for a fast dissemination of latest results, discussion and exchange of ideas, and ...broadening of scientists' collaboration network. The decision to participate in a conference depends on several factors like the location, cost, popularity of keynote speakers, and the scientist's association with the community. Here we discuss and formulate the problem of discovering how a scientist's previous participation affects her/his future participations in the same conference series. We develop a stochastic model to examine scientists' participation patterns in conferences and compare our model with data from six conferences across various scientific fields and communities. Our model shows that the probability for a scientist to participate in a given conference series strongly depends on the balance between the number of participations and non-participations during his/her early connections with the community. An active participation in a conference series strengthens the scientist's association with that particular conference community and thus increases the probability of future participations.
The aim of this paper is considering a brief historical perspective and overview of recent ideas and directions in electrochemistry in Bosnia and Herzegovina. Since the 1950s, dozens of researchers ...worked and are still working on the study of electrochemistry. The research evolved from polarography in the beginning to electrochemical deposition and/or dissolution of metals, alloys, polymers, nanocomposites and deposition of metal powders, corrosion mechanisms and corrosion protection, different catalysts and energy storage and conversion. Since the electrochemical and chemical industry was developed on the territory of today’s Bosnia and Herzegovina in the period from 1950 to the 1980s, researchers and professors were focused on the problems and challenges in the industry, not on publications. The industry was destroyed after the breakup of Yugoslavia, and names of the important researchers are very difficult to find today. That is why only a few individuals can be found on scientific databases in this period. The important validations of electrochemistry schools in Bosnia and Herzegovina are former students who are successful people in the industry or academia worldwide.
The environmental performance of various aspects of animal origin food supply chains has been the focus of research in recent years, and has provided useful information. However, there were no ...studies that covered the entire egg supply chain from different perspectives. The aim of this study was to analyze the majority of environmental impacts in the table egg supply chain comprising of three subsystems: farms, retail outlets and households, with quantification of each individual subsystem and the entire supply chain. All data were gathered from 30 farms, 50 retail stores and 300 households in Serbia. In parallel, the perception and ranking of environmental impacts along the supply chain were also evaluated. Finally, the quality function deployment for the environment was used to determine the degree of correlation between the set of environmental requirements and the identified environmental impacts. Results revealed that the greatest environmental impacts come from the production of feed for laying hens and the use of natural resources, and they contribute the most to the pollution of each individual environmental indicator. Additionally, the results show the differences in the environmental impacts of each individual subsystem and identify opportunities to mitigate them through the optimization of animal feed, energy consumption and household food waste management. The overall perspective of the egg supply chain points to climate change effects as the most important. The differences in the perceptions of environmental impacts along the entire egg supply chain suggest the need for promotion of mitigation strategies to all stakeholders that would encourage them to achieve sustainable development goals.
The aim of this paper is electrodeposition of Zn/CeO
2
and Zn-Mn/CeO
2
nanocomposite coatings. Four plating solutions were used (R1–R4). Solution R1 was without manganese ions, whereas solutions R2, ...R3, and R4 had Mn
2+
/Zn
2+
ratios of 1:1, 1:2, and 2:1, respectively. Electrodeposition is performed galvanostatically at 1 A dm
−2
, 2 A dm
−2
, and 4 A dm
−2
current densities with ultrasonic bath assisted mixing. The morphology of the coatings was observed using optical and scanning electron microscopy, the chemical compositions were determined using energy dispersive x-ray spectroscopy, whereas electrochemical impedance spectroscopy and potentiodynamic polarization method were used to determine the corrosion resistance of the coatings. All the solutions yield compact coatings with a small grain size and surface roughness ranging from 0.6 to 1.47 μm at all current densities. The results suggest that with the increase in current density, the content of manganese in the coating decrease, whereas the content of CeO
2
particles increases in Zn-Mn/CeO
2
coatings. Corrosion resistance of the coatings obtained from R2, R3, and R4 solutions deposited at lower current densities is higher compared to the coatings deposited from solution R1. The coating with the highest corrosion resistance was obtained from solution R2 at 1 A dm
−2
current density.
Graphical Abstract
Election data represent a precious source of information to study human behavior at a large scale. In proportional elections with open lists, the number of votes received by a candidate, rescaled by ...the average performance of all competitors in the same party list, has the same distribution regardless of the country and the year of the election. Here we provide the first thorough assessment of this claim. We analyzed election datasets of 15 countries with proportional systems. We confirm that a class of nations with similar election rules fulfill the universality claim. Discrepancies from this trend in other countries with open-lists elections are always associated with peculiar differences in the election rules, which matter more than differences between countries and historical periods. Our analysis shows that the role of parties in the electoral performance of candidates is crucial: alternative scalings not taking into account party affiliations lead to poor results.
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