Nearly Optimal Stochastic Approximation for Online Principal Subspace Estimation

Processing streaming data as they arrive is often necessary for high dimensional data analysis. In this paper, we analyse the convergence of a subspace online PCA iteration, as a followup of the recent work of Li, Wang, Liu, and Zhang [Math. Program., Ser. B, DOI 10.1007/s10107-017-1182-z] who considered the case for the most significant principal component only, i.e., a single vector. Under the sub-Gaussian assumption, we obtain a finite-sample error bound that closely matches the minimax information lower bound of Vu and Lei [Ann. Statist. 41:6 (2013), 2905-2947].Comment: 37 page

Optimal Resource Allocation for Multi-UAV Assisted Visible Light Communication

In this paper, the optimization of deploying unmanned aerial vehicles (UAVs) over a reconfigurable intelligent surfaces (RISs)-assisted visible light communication (VLC) system is studied. In the considered model, UAVs are required to simultaneously provide wireless services as well as illumination for ground users. To meet the traffic and illumination demands of the ground users while minimizing the energy consumption of the UAVs, one must optimize UAV deployment, phase shift of RISs, user association and RIS association. This problem is formulated as an optimization problem whose goal is to minimize the transmit power of UAVs via adjusting UAV deployment, phase shift of RISs, user association and RIS association. To solve this problem, the original optimization problem is divided into four subproblems and an alternating algorithm is proposed. Specifically, phases alignment method and semidefinite program (SDP) algorithm are proposed to optimize the phase shift of RISs. Then, the UAV deployment optimization is solved by the successive convex approximation (SCA) algorithm. Since the problems of user association and RIS association are integer programming, the fraction relaxation method is adopted before using dual method to find the optimal solution. For simplicity, a greedy algorithm is proposed as an alternative to optimize RIS association. The proposed two schemes demonstrate the superior performance of 34:85% and 32:11% energy consumption reduction over the case without RIS, respectively, through extensive numerical study

Evolution of sanctioning systems and opting out of games of life

In explaining altruistic cooperation and punishment, the challenging riddle is how transcendental rules can emerge within the empirical world. Recent game-theoretical studies show that pool punishment, in particular second-order punishment, plays a key role in understanding the evolution of cooperation. Second-order pool punishment, however, is tautological in nature: the punishment system itself is caused by its own effects. The emergence of pool punishment poses a logical conundrum that to date has been overlooked in the study of the evolution of social norms and institutions. Here we tackle the issue by considering the interplay of (a) cognitive biases in reasoning and (b) Agamben's notion of homo sacer (Agamben, G. 1998. Homo Sacer: Sovereign Power and Bare Life. Stanford Univ. Press), that is, a person who may be killed without legal consequence. Based on cognitive disposition of reversing the cause-and-effect relationship, then we propose a new system: preemptive punishment of homo sacers. This action can lead to retrospectively forming moral assessment in particular for second-order pool punishment.Comment: 6 pages, 1 figur

Role of ERK/MAPK in endothelin receptor signaling in human aortic smooth muscle cells

<p>Abstract</p> <p>Background</p> <p>Endothelin-1 (ET-1) is a potent vasoactive peptide, which induces vasoconstriction and proliferation in vascular smooth muscle cells (VSMCs) through activation of endothelin type A (ET_A) and type B (ET_B) receptors. The extracellular signal-regulated kinase 1 and 2 (ERK1/2) mitogen-activated protein kinases (MAPK) are involved in ET-1-induced VSMC contraction and proliferation. This study was designed to investigate the ET_Aand ET_Breceptor intracellular signaling in human VSMCs and used phosphorylation (activation) of ERK1/2 as a functional signal molecule for endothelin receptor activity.</p> <p>Results</p> <p>Subconfluent human VSMCs were stimulated by ET-1 at different concentrations (1 nM-1 μM). The activation of ERK1/2 was examined by immunofluorescence, Western blot and phosphoELISA using specific antibody against phosphorylated ERK1/2 protein. ET-1 induced a concentration- and time- dependent activation of ERK1/2 with a maximal effect at 10 min. It declined to baseline level at 30 min. The ET-1-induced activation of ERK1/2 was completely abolished by MEK1/2 inhibitors U0126 and SL327, and partially inhibited by the MEK1 inhibitor PD98059. A dual endothelin receptor antagonist bosentan or the ET_Aantagonist BQ123 blocked the ET-1 effect, while the ET_Bantagonist BQ788 had no significant effect. However, a selective ET_Breceptor agonist, Sarafotoxin 6c (S6c) caused a time-dependent ERK1/2 activation with a maximal effect by less than 20% of the ET-1-induced activation of ERK1/2. Increase in bosentan concentration up to 10 μM further inhibited ET-1-induced activation of ERK1/2 and had a stronger inhibitory effect than BQ123 or the combined use of BQ123 and BQ788. To further explore ET-1 intracellular signaling, PKC inhibitors (staurosporin and GF109203X), PKC-delta inhibitor (rottlerin), PKA inhibitor (H-89), and phosphatidylinositol 3-kinase (PI3K) inhibitor (wortmannin) were applied. The inhibitors showed significant inhibitory effects on ET-1-induced activation of ERK1/2. However, blockage of L-type Ca²⁺channels or calcium/calmodulin-dependent protein kinase II, chelating extracellular Ca²⁺or emptying internal Ca²⁺stores, did not affect ET-1-induced activation of ERK1/2.</p> <p>Conclusion</p> <p>The ET_Areceptors predominate in the ET-1-induced activation of ERK1/2 in human VSMCs, which associates with increments in intracellular PKC, PKA and PI3K activities, but not Ca²⁺signalling.</p

Drag force and heavy quark potential in a rotating background

We explored the gravity dual of the rotating quark-gluon plasma by transforming the boundary coordinates of the Schwarzschild-$AdS_5$ metric. The Euler-Lagrange equation of the Nambu-Goto action and its solution become more complex than those without rotation. For small angular velocity, we obtained an analytical form of the drag force acting on a quark moving in the direction of the rotation axis and found it stronger than that without rotation. We also calculated the heavy quark potential under the same approximation. For the quarkonium symmetric with respect to the rotation axis, the depth of the potential is reduced by the rotation. For the quarkonium oriented in parallel to the rotation axis, the bind force is weakened and the force range becomes longer. We also compared our holographic formulation with others in the literature.Comment: 28 pages, 3 figure

Morphological Variation in Pachytriton labiatus and a Re-Assessment of the Taxonomic Status of P. granulosus (Amphibia: Urodela: Salamandridae)

Variation in relation to age and sex in a population of Pachytriton labiatus from Mt. Huangshan, Anhui Province, China was examined. There appeared to be distinct morphological variation among age/sex groups. We suggest that some of this variation is associated with ecology and behavior. Examination of the newt species from the type locality and nearby localities of Pachytriton granulosus (=Pingia granulosa), a taxonomically problematic species, revealed that this taxon was almost indistinguishable from juvenile P. labiatus. We therefore conclude that P. granulosus is a junior synonym of P. labiatus