The modular structure of an ontology: Atomic decomposition

Extracting a subset of a given ontology that captures all the ontology’s knowledge about a specified set of terms is a well-understood task. This task can be based, for instance, on locality-based modules. However, a single module does not allow us to understand neither topicality, connectedness, structure, or superfluous parts of an ontology, nor agreement between actual and intended modeling. The strong logical properties of locality-based modules suggest that the family of all such modules of an ontology can support comprehension of the ontology as a whole. However, extracting that family is not feasible, since the number of localitybased modules of an ontology can be exponential w.r.t. its size. In this paper we report on a new approach that enables us to efficiently extract a polynomial representation of the family of all locality-based modules of an ontology. We also describe the fundamental algorithm to pursue this task, and report on experiments carried out and results obtained.

Molecular mechanisms of hepatitis C virus–induced hepatocellular carcinoma

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Glutamate induces autophagy via the two-pore channels in neural cells

NAADP (nicotinic acid adenine dinucleotide phosphate) has been proposed as a second messenger for glutamate in neuronal and glial cells via the activation of the lysosomal Ca2+ channels TPC1 and TPC2. However, the activities of glutamate that are mediated by NAADP remain unclear. In this study, we evaluated the effect of glutamate on autophagy in astrocytes at physiological, non-toxic concentration. We found that glutamate induces autophagy at similar extent as NAADP. By contrast, the NAADP antagonist NED-19 or SiRNA-mediated inhibition of TPC1/2 decreases autophagy induced by glutamate, confirming a role for NAADP in this pathway. The involvement of TPC1/2 in glutamate-induced autophagy was also confirmed in SHSY5Y neuroblastoma cells. Finally, we show that glutamate leads to a NAADP-dependent activation of AMPK, which is required for autophagy induction, while mTOR activity is not affected by this treatment. Taken together, our results indicate that glutamate stimulates autophagy via NAADP/TPC/AMPK axis, providing new insights of how Ca2+ signalling glutamate-mediated can control the cell metabolism in the central nervous system

phase coexistence in two dimensional fe 0 70 ni 0 30 films on w 110

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Electronic Structure of the Topological Insulator Bi2Se3 Using Angle-Resolved Photoemission Spectroscopy: Evidence for a Nearly Full Surface Spin Polarization

We performed high-resolution spin- and angle-resolved photoemission spectroscopy studies of the electronic structure and the spin texture on the surface of Bi$_2$Se$_3$, a model topological insulator. By tuning the photon energy, we found that the topological surface state is well separated from the bulk states in the vicinity of $k_z=Z$ plane of the bulk Brillouin zone. The spin-resolved measurements in that region indicate a very high degree of spin polarization of the surface state, $\sim 0.75$, much higher than previously reported. Our results demonstrate that the topological surface state on Bi$_2$Se$_3$ is highly spin polarized and that the dominant factors limiting the polarization are mainly extrinsic.Comment: published version, 4 pages, 4 figure

Spin Configuration and Scattering Rates on the Heavily Electron-doped Surface of Topological Insulator Bi2_2Se3_3

Heavily electron-doped surfaces of Bi$_2$Se$_3$ have been studied by spin and angle resolved photoemission spectroscopy. Upon doping, electrons occupy a series of {\bf k}-split pairs of states above the topological surface state. The {\bf k}-splitting originates from the large spin-orbit coupling and results in a Rashba-type behavior, unequivocally demonstrated here via the spin analysis. The spin helicities of the lowest laying Rashba doublet and the adjacent topological surface state alternate in a left-right-left sequence. This spin configuration sets constraints to inter-band scattering channels opened by electron doping. A detailed analysis of the scattering rates suggests that intra-band scattering dominates with the largest effect coming from warping of the Fermi surface

Electronic and magnetic properties of the topological semimetal SmMg2_2Bi2_2

Dirac semimetals show nontrivial physical properties and can host exotic quantum states like Weyl semimetals and topological insulators under suitable external conditions. Here, by combining angle-resolved photoemission spectroscopy measurements (ARPES) and first-principle calculations, we demonstrate that Zintl-phase compound SmMg$_2$Bi$_2$ belongs to the close proximity to a topological Dirac semimetallic state. ARPES results show a Dirac-like band crossing at the zone-center near the Fermi level ($E_\mathrm {F}$) which is further confirmed by first-principle calculations. Theoretical studies also reveal that SmMg$_2$Bi$_2$ belongs to a $Z_2$ topological class and hosts spin-polarized states around the $E_\mathrm {F}$. Zintl's theory predicts that the valence state of Sm in this material should be Sm$^{2+}$, however we detect many Sm-4$f$ multiplet states (flat-bands) whose energy positions suggest the presence of both Sm$^{2+}$ and Sm$^{3+}$. It is also evident that these flat-bands and other dispersive states are strongly hybridized when they cross each other. Due to the presence of Sm$^{3+}$ ions, the temperature dependence of magnetic susceptibility $\chi(T)$ shows Curie-Weiss-like contribution in the low temperature region, in addition to the Van Vleck-like behaviour expected for the Sm$^{2+}$ ions. The present study will help in better understanding of the electronic structure, magnetism and transport properties of related materials.Comment: 10 pages, 7 figure