1,759 research outputs found

    Prospects for Detecting Neutrino Signals from Annihilating/Decaying Dark Matter to Account for the PAMELA and ATIC results

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    Recent PAMELA data show that positron fraction has an excess above several GeV while anti-proton one is not. Moreover ATIC data indicates that electron/positron flux have a bump from 300 GeV to 800 GeV. Both annihilating dark matter (DM) with large boost factor and decaying DM with the life around 1026s 10^{26} s can account for the PAMELA and ATIC observations if their main final products are charged leptons (ee, μ\mu and τ\tau). In this work, we calculated the neutrino flux arising from μ\mu and τ\tau which originate from annihilating/decaying DM, and estimated the final muon rate in the neutrino telescopes, namely Antares and IceCube. Given the excellent angular resolution, Antares and IceCube are promising to discover the neutrino signals from Galactic center and/or large DM subhalo in annihilating DM scenario, but very challenging in decaying DM scenario.Comment: 21 pages, 7 figures, 2 tables. V2: references added. V3: the number density of massive subhalo has been discussed in the appendix; accepted by PR

    Structural Deep Embedding for Hyper-Networks

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    Network embedding has recently attracted lots of attentions in data mining. Existing network embedding methods mainly focus on networks with pairwise relationships. In real world, however, the relationships among data points could go beyond pairwise, i.e., three or more objects are involved in each relationship represented by a hyperedge, thus forming hyper-networks. These hyper-networks pose great challenges to existing network embedding methods when the hyperedges are indecomposable, that is to say, any subset of nodes in a hyperedge cannot form another hyperedge. These indecomposable hyperedges are especially common in heterogeneous networks. In this paper, we propose a novel Deep Hyper-Network Embedding (DHNE) model to embed hyper-networks with indecomposable hyperedges. More specifically, we theoretically prove that any linear similarity metric in embedding space commonly used in existing methods cannot maintain the indecomposibility property in hyper-networks, and thus propose a new deep model to realize a non-linear tuplewise similarity function while preserving both local and global proximities in the formed embedding space. We conduct extensive experiments on four different types of hyper-networks, including a GPS network, an online social network, a drug network and a semantic network. The empirical results demonstrate that our method can significantly and consistently outperform the state-of-the-art algorithms.Comment: Accepted by AAAI 1

    Neutrino Constraints on Inelastic Dark Matter after CDMS II

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    We discuss the neutrino constraints from solar and terrestrial dark matter (DM) annihilations in the inelastic dark matter (iDM) scenario after the recent CDMS II results. To reconcile the DAMA/LIBRA data with constraints from all other direct experiments, the iDM needs to be light (mχ<100m_\chi < 100 GeV) and have a large DM-nucleon cross section (σn∼\sigma_n \sim 10−4^{-4} pb in the spin-independent (SI) scattering and σn∼\sigma_n \sim 10 pb in the spin-dependent (SD) scattering). The dominant contribution to the iDM capture in the Sun is from scattering off Fe/Al in the SI/SD case. Current bounds from Super-Kamiokande exclude the hard DM annihilation channels, such as W+W−W^+W^-, ZZZZ, ttˉt\bar{t} and τ+τ−\tau^+ \tau^-. For soft channels such as bbˉb\bar{b} and ccˉc \bar{c}, the limits are loose, but could be tested or further constrained by future IceCube plus DeepCore. For neutrino constraints from the DM annihilation in the Earth, due to the weaker gravitational effect of the Earth and inelastic capture condition, the constraint exists only for small mass splitting δ<\delta < 40 keV and mχ∼(10,50)m_\chi \sim (10, 50) GeV even in the τ+τ−\tau^+ \tau^- channel.Comment: 11 pages, 8 figure

    Harmony in diversity:Can One Belt One Road initiative promote China’s OFDI?

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    This paper investigates the effect of the One Belt One Road (OBOR) initiative on China&rsquo;s outward foreign direct investment (OFDI) using a dataset of all host countries for the period of 2010&ndash;2015. The employed econometric technique combines a difference-in-differences estimator with matching techniques. The results show that China&rsquo;s OFDI in OBOR countries is about 40% higher than in non-OBOR countries. After the initiative, the OFDI from China increases by 46.2% in OBOR countries. However, after controlling for the heterogeneity across OBOR and non-OBOR countries using the matching approach, the significance of the increasing effect caused by the OBOR initiative disappears. We also find the OBOR initiative diminishes the resource-seeking motivation and improves the market-seeking motivation of China&rsquo;s OFDI. Our results cast doubts on the infrastructure-led and institution-based strategy of the OBOR initiative, but support the boosting effect of the OBOR initiative on institutional cooperation and cultural convergence. Thus, the OBOR initiative is a sustainable continuation and development of the long tradition of economic, institutional, and cultural convergence with the OBOR countries, rather than a temporary policy shock

    Optimization-Based Motion Planning for Autonomous Agricultural Vehicles Turning in Constrained Headlands

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    Headland maneuvering is a crucial aspect of unmanned field operations for autonomous agricultural vehicles (AAVs). While motion planning for headland turning in open fields has been extensively studied and integrated into commercial auto-guidance systems, the existing methods primarily address scenarios with ample headland space and thus may not work in more constrained headland geometries. Commercial orchards often contain narrow and irregularly shaped headlands, which may include static obstacles,rendering the task of planning a smooth and collision-free turning trajectory difficult. To address this challenge, we propose an optimization-based motion planning algorithm for headland turning under geometrical constraints imposed by field geometry and obstacles

    Characterizations and representations of left and right hybrid (b, c)-inverses in rings

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    Let R be an associative ring with unity 1 and let a, b ,c is an element of R. In this paper, several characterizations for left and right hybrid (b, c)-inverses of a are derived. Moreover, their formulae are given by regularities of certain elements. Then, we give characterizations of right (b, c)-inverses and right annihilator (b, c)-inverses of the product of three elements. Finally, relations among the right hybrid (b, c)-inverse of paq, the right (qb, c)-inverse of aq and the right annihilator (b, cp)-inverse of aq are given.This research is supported by the National Natural Science Foundation of China (No. 11801124), the Natural Science Foundation of Anhui Province (No. 1808085QA16), the Fundamental Research Funds for the Central Universities (No. JZ2018HGTB0233) and was partially financed by Portuguese Funds through FCT (Fundação para a Ciência e a Tecnologia) within the Projects UIDB/00013/2020 and UIDP/00013/2020

    Transition of stoichiometricSr2VO3FeAs to a superconducting state at 37.2 K

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    The superconductor Sr4V2O6Fe2As2 with transition temperature at 37.2 K has been fabricated. It has a layered structure with the space group of p4/nmm, and with the lattice constants a = 3.9296Aand c = 15.6732A. The observed large diamagnetization signal and zero-resistance demonstrated the bulk superconductivity. The broadening of resistive transition was measured under different magnetic fields leading to the discovery of a rather high upper critical field. The results also suggest a large vortex liquid region which reflects high anisotropy of the system. The Hall effect measurements revealed dominantly electron-like charge carriers in this material. The superconductivity in the present system may be induced by oxygen deficiency or the multiple valence states of vanadium.Comment: 5 pages, 4 figure
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