Impact of Transceiver Impairments on the Capacity of Dual-Hop Relay Massive MIMO Systems

Despite the deleterious effect of hardware impairments on communication systems, most prior works have not investigated their impact on widely used relay systems. Most importantly, the application of inexpensive transceivers, being prone to hardware impairments, is the most cost-efficient way for the implementation of massive multiple-input multiple-output (MIMO) systems. Consequently, the direction of this paper is towards the investigation of the impact of hardware impairments on MIMO relay networks with large number of antennas. Specifically, we obtain the general expression for the ergodic capacity of dual-hop (DH) amplify-and-forward (AF) relay systems. Next, given the advantages of the free probability (FP) theory with comparison to other known techniques in the area of large random matrix theory, we pursue a large limit analysis in terms of number of antennas and users by shedding light to the behavior of relay systems inflicted by hardware impairments.Comment: 6 pages, 4 figures, accepted in IEEE Global Communications Conference (GLOBECOM 2015) - Workshop on Massive MIMO: From theory to practice, 201

To study the oxidative stress induced by lindane in epileptic rats brains and their modulation by neurosteroids

Background: Lindane is pesticide has been shown to affect the nervous system adversely. Previous work has shown that lindane is proconvulsant and neurosteroids (NS) has been shown to be neuroprotective against lindane-induced convulsions. As the mechanisms of lindane in epileptogenesis is not completely understood. The present study was designed to investigate the oxidative stress parameters of lindane toxicity in epileptogenesis and their modulation by NS like allopregnanolone (AP), and 4ʹ-chlorodiazepam (4ʹ-CD) in pentylenetetrazole (PTZ) kindling methods.Methods: Kindling was induced by injecting PTZ (30 mg/kg; s.c.) on alternate days i.e., 3 times in a week. Lindane was also administered (15 mg/kg p.o) on alternate days for 6 weeks. AP (2.5 mg/kg, intaperitoneal [i.p.]) and 4ʹ-CD (0.5 mg/kg, i.p.) single dose was given in kindled rats before lindane.Results: Following per oral administration of lindane for 6 weeks produced significant oxidative stress in epileptic brain. There was an increase in brain malondialdehyde (MDA) level and decrease in reduced glutathione (GSH) levels. AP (2.5 mg/kg, i.p.) and 4ʹ-CD (0.5 mg/kg, i.p.) single dose administration were not able to reverse the effect of chronic exposure of lindane.Conclusion: The result of the present study provides evidence that oxidative stress produced in the brain after chronic exposure of lindane may be the mechanism of epileptogenesis. Though NS have been shown to be neuroprotective, but they failed to reverse chronic oxidative stress produced by lindane. Further studies are required to demonstrate interaction of NS with lindane in oxidative stress

Sensing-Throughput Tradeoff for Interweave Cognitive Radio System: A Deployment-Centric Viewpoint

Secondary access to the licensed spectrum is viable only if interference is avoided at the primary system. In this regard, different paradigms have been conceptualized in the existing literature. Of these, Interweave Systems (ISs) that employ spectrum sensing have been widely investigated. Baseline models investigated in the literature characterize the performance of IS in terms of a sensing-throughput tradeoff, however, this characterization assumes the knowledge of the involved channels at the secondary transmitter, which is unavailable in practice. Motivated by this fact, we establish a novel approach that incorporates channel estimation in the system model, and consequently investigate the impact of imperfect channel estimation on the performance of the IS. More particularly, the variation induced in the detection probability affects the detector's performance at the secondary transmitter, which may result in severe interference at the primary users. In this view, we propose to employ average and outage constraints on the detection probability, in order to capture the performance of the IS. Our analysis reveals that with an appropriate choice of the estimation time determined by the proposed model, the degradation in performance of the IS can be effectively controlled, and subsequently the achievable secondary throughput can be significantly enhanced.Comment: 13 pages, 10 figures, Accepted to be published in IEEE Transactions on Wireless Communication

PNA C-C<SUP>+</SUP> i-motif: superior stability of PNA TC<SUB>8</SUB> tetraplexes compared to DNA TC<SUB>8</SUB> tetraplexes at low pH

Study of self-assembly of PNA TC8 monitored by UV thermal transition at 295 nm indicates formation of a C-C+ tetraplex (i-motif) in acidic pH, with higher stability than the analogous dTC8

Expanding the repertoire of pyrrolidyl PNA analogues for DNA/RNA hybridization selectivity: aminoethylpyrrolidinone PNA (aepone-PNA)

New PNA analogues derived from aminoethylpyrrolidin- 5-one backbone show stabilization of aepone-PNA:DNA hybrids and destabilization of the corresponding RNA hybrids compared to unmodified PNA

Anti-chaperone [eszett]A3/A1102-117 peptide interacting sites in human aB-crystallin

Purpose: Our previous work identified 23 low molecular weight (<3.5 kDa) crystallin peptides in the urea-soluble fractions of normal young, normal aged, and aged cataract human lenses. We found that one of these crystallin fragments, [beta]A3/ A1102-117 peptide (SDAYHIERLMSFRPIC), that are present in aged and cataract lens, increased the scattering of light by [beta]- and [gamma]-crystallins and alcohol dehydrogenase (ADH) and also reduced the chaperone-like activity of [alpha][beta]-crystallin. The present study was performed to identify the interacting sites of the [beta]A3/A1102-117 peptide in [alpha]B-crystallin. Methods: [beta]A3/A1102-117 peptide was first derivatized with sulfo-succinimidyl-2-[6-(biotinamido)-2-{pazidobenzamido}- hexanoamido] ethyl-1-3 dithio propionate (sulfo-SBED), a photoactivable, heterotrifunctional biotincontaining cross-linker. The biotin-derivatized peptide was then incubated with [alpha]B-crystallin at 37 [degrees]C for 2 h to allow complex formation followed by photolysis to facilitate the transfer of the biotin label from the peptide to [alpha]B-crystallin. Label transfer was confirmed by western blot, and the labeled [alpha]B-crystallin was digested with trypsin. Tryptic peptides from [alpha]B-crystallin carrying the biotin label were purified by avidin affinity chromatography, and [beta]A3/A1102-117 peptide interacting sites in [alpha]B-crystallin were identified by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) and nanospray quadrupole time-of-flight mass spectrometry (QqTOF MS/MS). Results: We found that the [beta]A3/A1102-117 peptide interacted with [alpha]B-crystallin regions 70LEKDR74, 83HFSPEELKVK92, 91VKVLGDVIEVHGK103, 93VLGDVIEVHGKHEER107, and 121KYR123, which are part of the [alpha]-crystallin domain, and were previously shown to be part of the functional chaperone site in [alpha]B-crystallin. The [beta]A3/A1102-117 peptide also interacted with regions at the COOH-terminal extension of [alpha]B-crystallin, 150KQVSGPER157, 164EEKPAVTAAPK174, and 164EEKPAVTAAPKK175. When two of the hydrophobic residues of [beta]A3/A1102-117 peptide were replaced with hydrophilic residues, the resulting substituted peptide, SDADHGERLMSFRPIC, did not show the anti-chaperone property. Conclusions: This study confirmed the interactions between a low molecular weight peptide derived from [beta]A3/A1- crystallin found in aged and cataract lenses and [alpha]B-crystallin. The binding of [beta]A3/A1102-117 peptide to the chaperone site and the COOH-terminal extension of [alpha]B-crystallin may explain its anti-chaperone property

A complete description of the magnetic ground state in spinel vanadates

Capturing the non-collinear magnetic ground state of the spinel vanadates AV$_2$O$_4$ (A= Mn, Fe and Co) remains an outstanding challenge for state-of-the-art ab-initio methods. We demonstrate that both the non-collinear spin texture, as well as the magnitude of local moments, are captured by a single value of the on-site Hubbard $U$ of 2.7~eV in conjunction with the local spin density approximation (LSDA+$U$), provided the source term (i.e., magnetic monopole term) is removed from the exchange-correlation magnetic field ${\bf B}_{XC}$. We further demonstrate that the magnetic monopole structure in ${\bf B}_{XC}$ is highly sensitive to the value of $U$, to the extent that the interplay between on-site localization and local moment magnitude is qualitatively different depending on whether the source term is removed or not. This suggests that in treating strongly correlated magnetic materials within the LSDA+$U$ formalism, subtraction of the unphysical magnetic monopole term from the exchange-correlation magnetic field is essential to correctly treat the magnetic ground state.Comment: 4 pages, 3 figure