A Signal-Space Aligned Network Coding Approach to Distributed MIMO

© 2016 IEEE. This paper studies an uplink distributed MIMO (DMIMO) system that consists of $K$ users and K distributed base stations (BSs), where the BSs are connected to a central unit (CU) via independent rate-constrained backhaul (BH) links. We propose a new signal-space aligned network coding scheme. First, a network coding generator matrix is selected subject to certain structural properties. Next, distributed linear precoding is employed by the users to create aligned signal-spaces at the BSs, according to the pattern determined by the network coding generator matrix. For each aligned signal-space at a BS, physical-layer network coding is utilized to compute the corresponding network-coded (NC) messages, where the actual number of NC messages forwarded to the CU is determined by the BH rate-constraint. We derive an achievable rate of the proposed scheme based on the existence of the NC generator matrix and signal-space alignment precoding matrices. For DMIMO with two and three BSs, the achievable rates and degrees of freedom (DoF) are evaluated and shown to outperform existing schemes. For example, for DMIMO with two BSs where each user and BS have N and N antennas, respectively, the proposed scheme achieves a DoF of 2 min N,N-1, if the BH capacity scales like 2 min (N,N-1) log SNR. This leads to greater DoF compared to that utilizes the strategy for interference channel, whose DoF is min (N,N right). Numerical results demonstrate the performance advantage of the proposed scheme

Mapping QTLs for mineral accumulation and shoot dry biomass under different Zn nutritional conditions in Chinese cabbage ( Brassica rapa L. ssp. pekinensis )

Abstract Chinese cabbage (Brassica rapa L. ssp. pekinensis) is one of the most important vegetables in China. Genetic dissection of leaf mineral accumulation and tolerance to Zn stress is important for the improvement of the nutritional quality of Chinese cabbage by breeding. A mapping population with 183 doubled haploid (DH) lines was used to study the genetics of mineral accumulation and the growth response to Zn. The genetic map was constructed based on 203 AFLPs, 58 SSRs, 22 SRAPs and four ESTPs. The concentration of 11 minerals was determined in leaves for 142 DH lines grown in an open field. In addition shoot dry biomass (SDB) under normal, deficient and excessive Zn nutritional conditions were investigated in hydroponics experiments. Ten QTLs, each explaining 11.1¿17.1% of the Na, Mg, P, Al, Fe, Mn, Zn and Sr concentration variance, were identified by multiple-QTL model (MQM) mapping. One common QTL was found affecting SDB under normal, deficient and excessive Zn nutritional conditions. An additional QTL was detected for SDB under Zn excess stress only. These results offer insights into the genetic basis of leaf mineral accumulation and plant growth under Zn stress conditions in Chinese cabbag

Delay-dependent robust stability of stochastic delay systems with Markovian switching

In recent years, stability of hybrid stochastic delay systems, one of the important issues in the study of stochastic systems, has received considerable attention. However, the existing results do not deal with the structure of the diffusion but estimate its upper bound, which induces conservatism. This paper studies delay-dependent robust stability of hybrid stochastic delay systems. A delay-dependent criterion for robust exponential stability of hybrid stochastic delay systems is presented in terms of linear matrix inequalities (LMIs), which exploits the structure of the diffusion. Numerical examples are given to verify the effectiveness and less conservativeness of the proposed method

MicroRNA expression profiling during upland cotton gland forming age by microarray and quantitative reverse-transcription polymerase chain reaction (qRTPCR)

Plant microRNAs (miRNAs) have important impacts on growth, development, flowering, metabolism and response to stress. Studies indicate that post-transcriptional processes are important for regulating gene expression during development. However, we still have very limited knowledge on the regulatory mechanisms associated with this process. In particular, the function of miRNAs during gland morphogenesis in cotton remains unknown. In this study, we used the Affymetrix GeneChip miRNA Array (v11.0-ther Species) and quantitative reverse transcriptase-PCR (qRT-PCR) to identify additional microRNAs during gland morphogenesis of near-isogenic lines in upland cotton. The results showed that 30 miRNAs were differentially expressed: 24 up-regulated (miR156, miR157, miR166 and miR390 families) and six down-regulated (miR149, miR169, miR289, miR705, miR1224 and miR1227 families). Some microRNAs, such as ghb-miR169a_st and ghr-miR166b_st, were confirmed by qRT-PCR assays. There was no significant difference in miRNA levels between the microarray and qRT-PCR. Analysis of the transcript data for some miRNA target genes indicated that they play an important role in the pathogenesis and development of gland morphogenesis. In summary, our results showed that some known miRNAs were expressed in the gland of upland cotton, and most of them were of low abundance. This data may be useful in future studies associated with gland control involved in the terpenoid aldehyde biosynthesis pathway, genetic engineering and molecular breeding of cotton.Key words: MicroRNA, cotton, gland morphogenesis, microRNA microarray, quantitative real-time reversetranscription polymerase chain reaction (qRT-PCR)

Effect of process parameters on the force parameters in warm skew rolling of copper ball

In order to better control the forming quality of copper ball by warm skew rolling process, a Finite Element Model (FEM) of copper ball warm skew rolling for the coupling of thermal and mechanical was established. The influence of process parameters on force and rolling torque was analyzed by using single factor research method. The results show that the smaller the cross angle, the lower the rolling temperature, the slower the rolling rotation speed, the greater the forming force and rolling torque, the more difficult for forming. The optimum rolling temperature is 600 °C; the optimum cross angle is 2,5°; the optimum rolling rotation speed is 60 rpm

Megalin: a Novel Determinant of Renin-Angiotensin System Activity in the Kidney?

Purpose of Review: Megalin is well known for its role in the reabsorption of proteins from the ultrafiltrate. Recent studies suggest that megalin also reabsorbs renin and angiotensinogen. Indeed, without megalin urinary renin and angiotensinogen levels massively increase, and even prorenin becomes detectable in urine. Recent Findings: Intriguingly, megalin might also contribute to renal angiotensin production, as evidenced from studies in megalin knockout mice. This review discusses these topics critically, concluding that urinary renin-angiotensin system components reflect diminished reabsorption rather than release from renal tissue sites and that alterations in renal renin levels or megalin-dependent signaling need to be ruled out before concluding that angiotensin production at renal tissue sites is truly megalin dependent. Summary: Future studies should evaluate megalin-mediated renin/angiotensinogen transcytosis (allowing interstitial angiotensin generation), and determine whether megalin prefers prorenin over renin, thus explaining why urine normally contains no prorenin