Seed selection for information cascade in multilayer networks

Information spreading is an interesting field in the domain of online social media. In this work, we are investigating how well different seed selection strategies affect the spreading processes simulated using independent cascade model on eighteen multilayer social networks. Fifteen networks are built based on the user interaction data extracted from Facebook public pages and tree of them are multilayer networks downloaded from public repository (two of them being Twitter networks). The results indicate that various state of the art seed selection strategies for single-layer networks like K-Shell or VoteRank do not perform so well on multilayer networks and are outperformed by Degree Centrality

Retraction Note: An apoptosis-enhancing drug overcomes platinum resistance in a tumour-initiating subpopulation of ovarian cancer.

This Article has been retracted; see accompanying Retraction Note

Peach witches’-broom, an emerging disease associated with ‘Candidatus Phytoplasma phoenicium’ and ‘Candidatus Phytoplasma aurantifolia’ in Iran

During field surveys carried out from 2013 to 2017 in the eight main peach producing provinces of Iran, symptoms of a phytoplasma-like peach witches'-broom disease (PWIB), inducing severe yellowing, little leaf, internode shortening, crown and stem witches\u2019-broom, decline, and death, were observed. The aim of this work was to identify and characterize the agent(s) associated with PWIB by biological assays and molecular analyses. PWIB agents were successfully transmitted under controlled conditions from scions of in field-affected peach trees, exhibiting severe or mild symptoms, to peach and bitter almond seedlings inducing phytoplasma-like symptoms. A 16S rDNA fragment of 1250 bp was amplified by nested-PCR from all PWIB-affected trees and grafted seedlings. Nucleotide sequence identity, presence of species-specific signature sequences, in silico RFLP, single nucleotide polymorphisms, and phylogenetic analyses of 16S rDNA allowed the assignation of the phytoplasma strains identified in seven Iranian provinces in peach trees with severe PWIB symptoms to four SNP genetic lineages of \u2018Ca. P. phoenicium\u2019 (subgroup 16SrIX-B and its variant). PWIB phytoplasma strains identified in Abarkooh (Yazd province) in peach trees with mild symptoms were attributed to the species \u2018Ca. P. aurantifolia\u2019 (subgroup 16SrII-C). This report of a wide spread of \u2018Ca. P. phoenicium\u2019 in association with PWIB in Iran supported its capability of adaptation to a broad range of fruit tree species, such as peach, nectarine, and apricot. As \u2018Ca. P. phoenicium\u2019 and \u2018Ca. P. aurantifolia\u2019 are the etiological agents of other important plant diseases in Iran and neighbouring countries, further investigations are needed to determine the role played by peach in their epidemiological pathways

Shadow Implications: What does measuring the photon ring imply for gravity?

With the imaging and characterization of the horizon-scale images of M87* and Sgr A* by the Event Horizon Telescope (EHT), it has become possible to resolve the near-horizon region of astrophysical black holes. As a result, there has been considerable interest in the implications of the measurement of the shadow size, i.e., the asymptotic photon ring. We explore the general implications of such a measurement, identifying what is and, more importantly, is not constrained by such measurements, with applications to EHT and future instruments. We consider a general spherically symmetric metric, which effectively applies for a polar observer (appropriate for M87*) in the slow rotation limit. We propose a nonperturbative, nonparametric spacetime-domain characterization of shadow size and related measurements that makes explicit the nature and power (or lack thereof) of shadow-size-based constraints, and facilitates comparisons among observations and targets.Comment: Submitted to ApJ, 16 pages, 5 figure