Performance of beamforming and mimo technique in an indoor ricean clustering channel

In this paper, we present a hybrid indoor MIMO channel model for predicting the performance of multiple-element antenna system. The model incorporates the wave clustering phenomena and combines the statistical characteristics of clusters with deterministic ray tracing method. The capacity of the MIMO channel is expressed as a function of spatial correlation at both the transmitter and the receiver. The results obtained by using the channel model are compared with measurement results available in the literature. Simulation results verify that the MIMO technique effectively exploits multipath fading. The paper also presents a comparison between MIMO and beamforming techniques in indoor environments

Experimental investigation of indoor MIMO Ricean channel capacity

We investigate the variation of measured multiple-input multiple-output (MIMO) channel capacity for line-of-sight (LOS) Ricean scenarios inside a typical indoor environment for various transmitter-receiver positions at a center frequency of 2.45 GHz. In order to quantify the effect of LOS component on indoor MIMO performance, an absorber-loaded metal panel was utilized to artificially obstruct the LOS path between the transmit and receive antennas. Our results confirm that MIMO capacity decreases with the increase in the values of Ricean K factor. We have also observed that the variation in channel capacity closely follows the corresponding deviations in root mean square (rms) delay spread of the channel. © 2005 IEEE

Continuous variable entanglement measurement without phase locking

A new simple entanglement measurement method is proposed for the bright EPR beams generated from a non-degenerate optical parametric amplifier operating at deamplification. Due to the output signal and idler modes are frequency degenerate and in phase, the needed phase shift of interference for the measurement of the correlated phase quadratures and anti-correlated amplitude quadratures can be accomplished by a quarter-wave plate and a half wave plate without separating the signal and idler beam. Therefore, phase locking and local oscillators are avoided.Comment: 8 pages,3 figure

A particle swarm optimization based memetic algorithm for dynamic optimization problems

Copyright @ Springer Science + Business Media B.V. 2010.Recently, there has been an increasing concern from the evolutionary computation community on dynamic optimization problems since many real-world optimization problems are dynamic. This paper investigates a particle swarm optimization (PSO) based memetic algorithm that hybridizes PSO with a local search technique for dynamic optimization problems. Within the framework of the proposed algorithm, a local version of PSO with a ring-shape topology structure is used as the global search operator and a fuzzy cognition local search method is proposed as the local search technique. In addition, a self-organized random immigrants scheme is extended into our proposed algorithm in order to further enhance its exploration capacity for new peaks in the search space. Experimental study over the moving peaks benchmark problem shows that the proposed PSO-based memetic algorithm is robust and adaptable in dynamic environments.This work was supported by the National Nature Science Foundation of China (NSFC) under Grant No. 70431003 and Grant No. 70671020, the National Innovation Research Community Science Foundation of China under Grant No. 60521003, the National Support Plan of China under Grant No. 2006BAH02A09 and the Ministry of Education, science, and Technology in Korea through the Second-Phase of Brain Korea 21 Project in 2009, the Engineering and Physical Sciences Research Council (EPSRC) of UK under Grant EP/E060722/01 and the Hong Kong Polytechnic University Research Grants under Grant G-YH60

Gut microbiota-derived propionate reduces cancer cell proliferation in the liver

Peer reviewedPublisher PD

Modeling recursive RNA interference.

An important application of the RNA interference (RNAi) pathway is its use as a small RNA-based regulatory system commonly exploited to suppress expression of target genes to test their function in vivo. In several published experiments, RNAi has been used to inactivate components of the RNAi pathway itself, a procedure termed recursive RNAi in this report. The theoretical basis of recursive RNAi is unclear since the procedure could potentially be self-defeating, and in practice the effectiveness of recursive RNAi in published experiments is highly variable. A mathematical model for recursive RNAi was developed and used to investigate the range of conditions under which the procedure should be effective. The model predicts that the effectiveness of recursive RNAi is strongly dependent on the efficacy of RNAi at knocking down target gene expression. This efficacy is known to vary highly between different cell types, and comparison of the model predictions to published experimental data suggests that variation in RNAi efficacy may be the main cause of discrepancies between published recursive RNAi experiments in different organisms. The model suggests potential ways to optimize the effectiveness of recursive RNAi both for screening of RNAi components as well as for improved temporal control of gene expression in switch off-switch on experiments

Indoor Multipath Characterization for MIMO Wireless Communications

The achievable linear increase in multiple-input multipleoutput (MIMO) capacity is conditioned on sufficiently rich multipath" presenting in a wireless channel. Thus, the characterization of the resolvable multipaths in an indoor environment dictates the obtainable MIMO capacity at a certain SNR level. In this paper, the statistic relationship between the characteristics of multipaths and the performance of MIMO systems in indoor environments is explored using channel measurements. Our investigations demonstrate the terminology of richness, which is generally used to characterize the multipath propagation, highly relates to the number of effective multipaths, their carried power and their angular features. A novel dimensionless parameter, angular spread factor, is proposed in this work.

Novel role for the innate immune receptor toll-like receptor 4 (TLR4) in the regulation of the wnt signaling pathway and photoreceptor apoptosis

Recent evidence has implicated innate immunity in regulating neuronal survival in the brain during stroke and other neurodegenerations. Photoreceptors are specialized light-detecting neurons in the retina that are essential for vision. In this study, we investigated the role of the innate immunity receptor TLR4 in photoreceptors. TLR4 activation by lipopolysaccharide (LPS) significantly reduced the survival of cultured mouse photoreceptors exposed to oxidative stress. With respect to mechanism, TLR4 suppressed Wnt signaling, decreased phosphorylation and activation of the Wnt receptor LRP6, and blocked the protective effect of the Wnt3a ligand. Paradoxically, TLR4 activation prior to oxidative injury protected photoreceptors, in a phenomenon known as preconditioning. Expression of TNFα and its receptors TNFR1 and TNFR2 decreased during preconditioning, and preconditioning was mimicked by TNFα antagonists, but was independent of Wnt signaling. Therefore, TLR4 is a novel regulator of photoreceptor survival that acts through the Wnt and TNFα pathways. © 2012 Yi et al