Node similarity as a basic principle behind connectivity in complex networks

How are people linked in a highly connected society? Since in many networks a power-law (scale-free) node-degree distribution can be observed, power-law might be seen as a universal characteristics of networks. But this study of communication in the Flickr social online network reveals that power-law node-degree distributions are restricted to only sparsely connected networks. More densely connected networks, by contrast, show an increasing divergence from power-law. This work shows that this observation is consistent with the classic idea from social sciences that similarity is the driving factor behind communication in social networks. The strong relation between communication strength and node similarity could be confirmed by analyzing the Flickr network. It also is shown that node similarity as a network formation model can reproduce the characteristics of different network densities and hence can be used as a model for describing the topological transition from weakly to strongly connected societies.Comment: 6 pages in Journal of Data Mining & Digital Humanities (2015) jdmdh:3

The eDAL Suite: Tools and Concepts for Primary Data Citation

Retrieval and citation of primary data is the important factor in the approaching age of “data science”. Digital data are easily shared, and just as easily wiped or lost. The problem of keeping on-line data accessible and
retrievable is especially difficult for SME like plant breeders plant biotech companies as well as research projects in this domain.
Intension of eDAL is the provisioning of an information retrieval and data citation infrastructure that meets the requirements of the “data science” age and implements a re-usable platform for data retrieval, data
citation, and data publication. Like a shopping cart, the idea is to combine a search engine and a data cart, which retrieves, rank and collect query relevant data from crop plant data centers

Single-photon generation and simultaneous observation of wave and particle properties

We describe an experiment that generates single photons on demand and measures properties accounted to both particle- and wave-like features of light. The measurement is performed by exploiting data that are sampled simultaneously in a single experimental run.Comment: The following article has been submitted to Proceedings of "Foundations of probability and physics-3", Vaxjo, Sweden 2004. After it is published, it will be found at http://proceedings.aip.org/ . 1 Reference was added in version

Studying the course of Covid-19 by a recursive delay approach

In an earlier paper we proposed a recursive model for epidemics; in the present paper we generalize this model to include the asymptomatic or unrecorded symptomatic people, which we call {\em dark people} (dark sector). We call this the SEPAR$_d$-model. A delay differential equation version of the model is added; it allows a better comparison to other models. We carry this out by a comparison with the classical SIR model and indicate why we believe that the SEPAR$_d$ model may work better for Covid-19 than other approaches. In the second part of the paper we explain how to deal with the data provided by the JHU, in particular we explain how to derive central model parameters from the data. Other parameters, like the size of the dark sector, are less accessible and have to be estimated more roughly, at best by results of representative serological studies which are accessible, however, only for a few countries. We start our country studies with Switzerland where such data are available. Then we apply the model to a collection of other countries, three European ones (Germany, France, Sweden), the three most stricken countries from three other continents (USA, Brazil, India). Finally we show that even the aggregated world data can be well represented by our approach. At the end of the paper we discuss the use of the model. Perhaps the most striking application is that it allows a quantitative analysis of the influence of the time until people are sent to quarantine or hospital. This suggests that imposing means to shorten this time is a powerful tool to flatten the curvesComment: 66 pages, 67 figures Changes in v2:Correction of formulas pp. 5, 6, 7, 20, general case of dark model, p_c \neq p_d included, tautological model for eta_7 adde

Paired Sr isotope (⁸⁷Sr/⁸⁶Sr, δ^88/86Sr) systematic of pore water profiles: A new perspective in marine weathering and seepage studies

The simultaneous and independent determination of the radiogenic (87Sr/86Sr) and the fractionation reflecting stable (!88/86Sr) Sr isotope ratio on pore waters, sediments and precipitates (e.g. carbonates and sulfates) opens a new perspective in the field of submarine weathering and Sr contribution to the ocean chemistry. Four initial case studies covering (1.) CO2 seeps of the Okinawa Trough (OT), (2.) mud volcanoes (MV) and mounds in the Gulf of Cadiz (GoC) and the (3.) Central American Fore Arc as well as first results from the (4.) Black Sea are conducted and reflect a stable Sr perspective on seeps from a broad range of geological settings. Referred to NIST-SRM-987, in this study the IAPSO seawater (SW) standard has a !88/86Sr of 0.39 ‰ (±0.03, 2SD). As a prominent systematic deviation the OT pore water (PW) data from a site with CO2 hydrate and liquid CO2 occurence show values ranging from 0.27 to 0.59 ‰ (286 to 64 cm sediment depth), accompanied by a weak inversely correlated trend from 0.2 to 0.15 ‰ for the corresponding bulk sediment (286 to 36 cm). In contradiction to a simple fluid/SW-mixing approach as driving mechanism for the PW stable Sr trend the 87Sr/86Sr signature stays within analytical uncertainty constant with depth (0.70980 (1)) and differs significantly from SW (0.70917 (1)) and the more radiogenic, slightly heterogeneous sediment (0.71892-0.71731). Potential explanation for the observed !88/86Sr trend and PW signatures heavier than SW are (a) strong fractionation processes enriching light isotopes in secondary precipitates and remineralisation products and heavier signatures in the remaining fluid and/or (b) preferential dissolution of heavier mineral phases. Examples for the latter kind of sediment component are determined in a detailed study of the Mercator MV (GoC) by high !88/86Sr ratios of 0.72 for authigenic and 0.92 ‰ for potentially extruded gypsum crystals. Combined with PW data from the other seep settings (0.2 to 0.52 ‰) a broad range of Sr contribution and fractionation processes becomes evident

A computational model of gene expression reveals early transcriptional events at the subtelomeric regions of the malaria parasite, Plasmodium falciparum

A mathematical model of the intraerythrocytic developmental cycle identifies a delay between subtelomeric and central chromosomal gene activities in the malaria parasite, Plasmodium falciparum