Constraining the dark matter-vacuum energy interaction using the EDGES 21-cm absorption signal

The recent measurement of the global 21-cm absorption signal reported by the Experiment to Detect the Global Epoch of Reionization Signature (EDGES) Collaboration is in tension with the prediction of the $\Lambda$CDM model at a $3.8\,\sigma$ significance level. In this work, we report that this tension can be released by introducing an interaction between dark matter and vacuum energy. We perform a model parameter estimation using a combined dataset including EDGES and other recent cosmological observations, and find that the EDGES measurement can marginally improve the constraint on parameters that quantify the interacting vacuum, and that the combined dataset favours the $\Lambda$CDM at 68\% CL. This proof-of-the-concept study demonstrates the potential power of future 21-cm experiments to constrain the interacting dark energy models.Comment: 6 pages, 5 figures, 1 table; accepted for publication in Ap

A measurement of the Hubble constant using galaxy redshift surveys

We perform a measurement of the Hubble constant, $H_0$, using the latest baryonic acoustic oscillations (BAO) measurements from galaxy surveys of 6dFGS, SDSS DR7 Main Galaxy Sample, BOSS DR12 sample, and eBOSS DR14 quasar sample, in the framework of a flat $\Lambda$CDM model. Based on the Kullback-Leibler (KL) divergence, we examine the consistency of $H_0$ values derived from various data sets. We find that our measurement is consistent with that derived from Planck and with the local measurement of $H_0$ using the Cepheids and type Ia supernovae. We perform forecasts on $H_0$ from future BAO measurements, and find that the uncertainty of $H_0$ determined by future BAO data alone, including complete eBOSS, DESI and Euclid-like, is comparable with that from local measurements.Comment: 5 pages, 2 figures, 2 tables; accepted for publication in Ap

Tractable approximate deduction for OWL

Acknowledgements This work has been partially supported by the European project Marrying Ontologies and Software Technologies (EU ICT2008-216691), the European project Knowledge Driven Data Exploitation (EU FP7/IAPP2011-286348), the UK EPSRC project WhatIf (EP/J014354/1). The authors thank Prof. Ian Horrocks and Dr. Giorgos Stoilos for their helpful discussion on role subsumptions. The authors thank Rafael S. Gonçalves et al. for providing their hotspots ontologies. The authors also thank BoC-group for providing their ADOxx Metamodelling ontologies.Peer reviewedPostprin

The Role of the Exocyst in Membrane Deformation, Cell Migration and Exocytosis

Dynamic shape changes of the plasma membrane are fundamental to many processes ranging from morphogenesis and cell migration to phagocytosis and viral propagation. In this study, I showed that Exo70, a component of the exocyst complex, induces tubular membrane invaginations towards the lumen of synthetic vesicles in vitro and generates actin-free protrusions on the surface of cells. Analyses using Exo70 mutants suggest that Exo70 generates negative membrane curvature through an oligomerization-based mechanism. The membrane-deformation function of Exo70 is likely to be independent of the other exocyst subunits. Exo70 thus represents a novel membrane-deforming protein for plasma membrane remodeling. Directional cell migration requires the coordination of actin assembly and membrane remodeling. Exo70 directly interacts with and activates the Arp2/3 complex, a central nucleating factor for the generation of branched actin networks for cell morphogenesis and migration. Here I found that both the stimulatory effect of Exo70 on Arp2/3 and the membrane-deformation function of Exo70 are required for lamellipodia formation and maintaining directional persistence of cell migration. Exo70 thus may couple actin dynamics and plasma membrane remodeling during cell migration. The late stage of exocytosis is regulated by the exocyst and SNARE complexes. The secretory vesicles are first tethered to the plasma membrane by the exocyst and then docked and fused to the plasma membrane by SNARE complex. Here I showed that the exocyst component Sec3, based on its sequence similarity to a SNARE-binding protein amisyn, directly binds to the plasma membrane SNARE Syntaxin4. Both Sec3 and amisyn binds to PI(4,5)P2 through basic residues on the N-terminus. Sec3 may regulate MMP and VSV-G exocytosis in cells. These results reveal a novel direct interaction between the exocyst and the plasma membrane SNARE and suggest that Sec3 may regulate the SNARE activity during exocytosis

EASTWEB: building an integrated leading Euro-Asian higher education and research community in the field of the Semantic WEB

Based on the experience of the EC funded project EASTWEB, a project involving Universities from Italy (main partner), Austria, Ireland, Poland, China, India and Thailand, we describe a set of on going and planned collaboration activities. We highlight what we see the major advantages but also the difficulties in carrying out such a program

Post-PlanckPlanck constraints on interacting vacuum energy

We present improved constraints on an interacting vacuum model using updated astronomical observations including the first data release from Planck. We consider a model with one dimensionless parameter, $\alpha$, describing the interaction between dark matter and vacuum energy (with fixed equation of state $w=-1$). The background dynamics correspond to a generalised Chaplygin gas cosmology, but the perturbations have a zero sound speed. The tension between the value of the Hubble constant, $H_0$, determined by Planck data plus WMAP polarisation (Planck+WP) and that determined by the Hubble Space Telescope (HST) can be alleviated by energy transfer from dark matter to vacuum ($\alpha>0$). A positive $\alpha$ increases the allowed values of $H_0$ due to parameter degeneracy within the model using only CMB data. Combining with additional datasets of including supernova type Ia (SN Ia) and baryon acoustic oscillation (BAO), we can significantly tighten the bounds on $\alpha$. Redshift-space distortions (RSD), which constrain the linear growth of structure, provide the tightest constraints on vacuum interaction when combined with Planck+WP, and prefer energy transfer from vacuum to dark matter ($\alpha<0$) which suppresses the growth of structure. Using the combined datasets of Planck+WP+Union2.1+BAO+RSD, we obtain the constraint on $\alpha$ to be $-0.083<\alpha<-0.006$ (95% C.L.), allowing low $H_0$ consistent with the measurement from 6dF Galaxy survey. This interacting vacuum model can alleviate the tension between RSD and Planck+WP in the $\Lambda$CDM model for $\alpha<0$, or between HST measurements of $H_0$ and Planck+WP for $\alpha>0$, but not both at the same time.Comment: 15 pages, 12 figures, 3 tables; accepted for publication in Phys. Rev.

Evolution of dark energy reconstructed from the latest observations

We reconstruct evolution of the dark energy (DE) density using a nonparametric Bayesian approach from a combination of latest observational data. We caution against parameterizing DE in terms of its equation of state as it can be singular in modified gravity models, and using it introduces a bias preventing negative effective DE densities. We find a $3.7\sigma$ preference for an evolving effective DE density with interesting features. For example, it oscillates around the $\Lambda$CDM prediction at $z\lesssim0.7$, and could be negative at $z\gtrsim2.3$; dark energy can be pressure-less at multiple redshifts, and a short period of cosmic deceleration is allowed at $0.1 \lesssim z\lesssim 0.2$. We perform the reconstruction for several choices of the prior, as well as a evidence-weighted reconstruction. We find that some of the dynamical features, such as the oscillatory behaviour of the DE density, are supported by the Bayesian evidence, which is a first detection of a dynamical DE with a positive Bayesian evidence. The evidence-weighted reconstruction prefers a dynamical DE at a $(2.5\pm0.06)\sigma$ significance level.Comment: 10 pages, 6 figures, 2 tables; accepted for publication in ApJ Letter

Neighborhood Matching Network for Entity Alignment

Structural heterogeneity between knowledge graphs is an outstanding challenge for entity alignment. This paper presents Neighborhood Matching Network (NMN), a novel entity alignment framework for tackling the structural heterogeneity challenge. NMN estimates the similarities between entities to capture both the topological structure and the neighborhood difference. It provides two innovative components for better learning representations for entity alignment. It first uses a novel graph sampling method to distill a discriminative neighborhood for each entity. It then adopts a cross-graph neighborhood matching module to jointly encode the neighborhood difference for a given entity pair. Such strategies allow NMN to effectively construct matching-oriented entity representations while ignoring noisy neighbors that have a negative impact on the alignment task. Extensive experiments performed on three entity alignment datasets show that NMN can well estimate the neighborhood similarity in more tough cases and significantly outperforms 12 previous state-of-the-art methods.Comment: 11 pages, accepted by ACL 202