2,580 research outputs found
Existence of positive ground state solutions of critical nonlinear Klein-Gordon-Maxwell systems
In this paper we study the following nonlinear Klein–Gordon–Maxwell system −∆u + [m2 0 − (ω + φ) 2 ]u = f(u) in R3 ∆φ = (ω + φ)u in R3 where 0 < ω < m0. Based on an abstract critical point theorem established by Jeanjean, the existence of positive ground state solutions is proved, when the nonlinear term f(u) exhibits linear near zero and a general critical growth near infinity. Compared with other recent literature, some different arguments have been introduced and some results are extended
RSA: Byzantine-Robust Stochastic Aggregation Methods for Distributed Learning from Heterogeneous Datasets
In this paper, we propose a class of robust stochastic subgradient methods
for distributed learning from heterogeneous datasets at presence of an unknown
number of Byzantine workers. The Byzantine workers, during the learning
process, may send arbitrary incorrect messages to the master due to data
corruptions, communication failures or malicious attacks, and consequently bias
the learned model. The key to the proposed methods is a regularization term
incorporated with the objective function so as to robustify the learning task
and mitigate the negative effects of Byzantine attacks. The resultant
subgradient-based algorithms are termed Byzantine-Robust Stochastic Aggregation
methods, justifying our acronym RSA used henceforth. In contrast to most of the
existing algorithms, RSA does not rely on the assumption that the data are
independent and identically distributed (i.i.d.) on the workers, and hence fits
for a wider class of applications. Theoretically, we show that: i) RSA
converges to a near-optimal solution with the learning error dependent on the
number of Byzantine workers; ii) the convergence rate of RSA under Byzantine
attacks is the same as that of the stochastic gradient descent method, which is
free of Byzantine attacks. Numerically, experiments on real dataset corroborate
the competitive performance of RSA and a complexity reduction compared to the
state-of-the-art alternatives.Comment: To appear in AAAI 201
catena-Poly[dipropylÂammonium [[bisÂ(benzotriazolato-κN 1)zinc(II)]-μ-benzotriazolato-κ2 N 1:N 3]]
In the title compound, {(C6H16N)[Zn(C6H4N3)3]}n, the ZnII atom has a distorted tetraÂhedral geometry defined by four N atoms from four benzotriazolate (BTA) ligands. The compound is composed of extended polymeric chains in which two BTA N atoms bridge [Zn(BTA)2] fragments along [001]. Cations and anions are linked by N—H⋯N hydrogen-bond interÂactions along [010]
Government Control, Uncertainty, and Investment Decisions in China's Listed Companies
AbstractThis paper empirically investigates the relation between uncertainty and investment among China's listed companies, and analyzes the influence of government control on the investment-uncertainty relation. We find that there is a negative relation between total firm uncertainty and investment in China's listed companies. However, this holds only for privately controlled firms. Among privately controlled listed firms, investment is negatively related to firm-specific uncertainty, whereas among government-controlled ones, investment is positively related to market uncertainty. We also find that the risk-taking preference of government-controlled listed companies is greater among those firms with fewer investment opportunities. Finally, among financially distressed firms, the negative relation between investment and uncertainty becomes nonsignificant because of risk shifting, which is more serious among government-controlled listed companies. We conclude that government control leads to state interference and weak corporate governance, which, in turn, distorts investment decision making among listed companies
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