7 research outputs found
Parallel and I/O-efficient randomisation of massive networks using global curveball trades
Graph randomisation is a crucial task in the analysis and synthesis of networks. It is typically implemented as an edge switching process (ESMC) repeatedly swapping the nodes of random edge pairs while maintaining the degrees involved [23]. Curveball is a novel approach that instead considers the whole neighbourhoods of randomly drawn node pairs. Its Markov chain converges to a uniform distribution, and experiments suggest that it requires less steps than the established ESMC [6]. Since trades however are more expensive, we study Curveball’s practical runtime by introducing the first efficient Curveball algorithms: the I/O-efficient EM-CB for simple undirected graphs and its internal memory pendant IM-CB. Further, we investigate global trades [6] processing every node in a single super step, and show that undirected global trades converge to a uniform distribution and perform superior in practice. We then discuss EM-GCB and EMPGCB for global trades and give experimental evidence that EM-PGCB achieves the quality of the state-of-the-art ESMC algorithm EM-ES [15] nearly one order of magnitude faster
Elucidation of time-dependent systems biology cell response patterns with time course network enrichment
Advances in OMICS technologies emerged both massive expression data sets and
huge networks modelling the molecular interplay of genes, RNAs, proteins and
metabolites. Network enrichment methods combine these two data types to extract
subnetwork responses from case/control setups. However, no methods exist to
integrate time series data with networks, thus preventing the identification of
time-dependent systems biology responses. We close this gap with Time Course
Network Enrichment (TiCoNE). It combines a new kind of human-augmented
clustering with a novel approach to network enrichment. It finds temporal
expression prototypes that are mapped to a network and investigated for
enriched prototype pairs interacting more often than expected by chance. Such
patterns of temporal subnetwork co-enrichment can be compared between different
conditions. With TiCoNE, we identified the first distinguishing temporal
systems biology profiles in time series gene expression data of human lung
cells after infection with Influenza and Rhino virus. TiCoNE is available
online (https://ticone.compbio.sdu.dk) and as Cytoscape app in the Cytoscape
App Store (http://apps.cytoscape.org/)