Efficient channel estimation for reconfigurable MIMO antennas: Training techniques and performance analysis

Multifunctional and reconfigurable multiple-input multiple-output (MR-MIMO) antennas are capable of dynamically changing the operation frequencies, polarizations, and radiation patterns, and can remarkably enhance system capabilities. However, in coherent communication systems, using MR-MIMO antennas with a large number of operational modes may incur prohibitive complexity due to the need for channel state estimation for each mode. To address this issue, we derive an explicit relation among the radiation patterns for the antenna modes and the resulting channel gains. We propose a joint channel estimation/prediction scheme where only a subset of all the antenna modes is trained for estimation, and then, the channels associated with the modes that are not trained are predicted using the correlations among the different antenna modes. We propose various training mechanisms with reduced overhead and improved estimation performance, and study the impact of channel estimation error and training overhead on the MR-MIMO system performance. We demonstrate that one can achieve significantly improved data rates and lower error probabilities utilizing the proposed approaches. For instance, under practical settings, we observe about 25% throughput increase or about 3-dB signal-to-noise ratio improvement under the same training overhead with respect to non-reconfigurable antenna systems. © 2002-2012 IEEE

Refining Kidney Survival in 383 Genetically Characterized Patients With Nephronophthisis

Introduction: Nephronophthisis (NPH) comprises a group of rare disorders accounting for up to 10% of end-stage kidney disease (ESKD) in children. Prediction of kidney prognosis poses a major challenge. We assessed differences in kidney survival, impact of variant type, and the association of clinical characteristics with declining kidney function. Methods: Data was obtained from 3 independent sources, namely the network for early onset cystic kidney diseases clinical registry (n = 105), an online survey sent out to the European Reference Network for Rare Kidney Diseases (n = 60), and a literature search (n = 218). Results: A total of 383 individuals were available for analysis: 116 NPHP1, 101 NPHP3, 81 NPHP4 and 85 NPHP11/TMEM67 patients. Kidney survival differed between the 4 cohorts with a highly variable median age at onset of ESKD as follows: NPHP3, 4.0 years (interquartile range 0.3–12.0); NPHP1, 13.5 years (interquartile range 10.5–16.5); NPHP4, 16.0 years (interquartile range 11.0–25.0); and NPHP11/TMEM67, 19.0 years (interquartile range 8.7–28.0). Kidney survival was significantly associated with the underlying variant type for NPHP1, NPHP3, and NPHP4. Multivariate analysis for the NPHP1 cohort revealed growth retardation (hazard ratio 3.5) and angiotensin-converting enzyme inhibitor (ACEI) treatment (hazard ratio 2.8) as 2 independent factors associated with an earlier onset of ESKD, whereas arterial hypertension was linked to an accelerated glomerular filtration rate (GFR) decline. Conclusion: The presented data will enable clinicians to better estimate kidney prognosis of distinct patients with NPH and thereby allow personalized counseling

A study on forces acting on a flapping wing

In order to study the forces acting on a flapping wing, an experimental investigation is performed in steady water flow. In this study, a SD7003 airfoil undergoes combined pitching and plunging motion which simulates the forward flight of small birds. The frequency of pitching motion is equal to the frequency of plunging motion and pitch leads the plunge by a phase angle of 90 degrees. The experiments are conducted at Reynolds numbers of 2500 ≤ Re ≤ 13700 and the vortex formation is recorded using the digital particle image velocimetry (DPIV) technique. A prediction of thrust force and efficiency is calculated from the average wake deficit of DPIV data, the near-wake vorticity patterns and time dependent velocity vectors are determined to comment on the thrust and drag indication. Direct force measurements are attempted using a Force/Torque sensor which is capable of measuring forces and moments in three axial directions

Oxidative Stress and Apoptosis in Relation to Exposure to Magnetic Field

PubMedID: 20824388We investigated the effect of extremely low-frequency electromagnetic field (ELF-EMF) with pulse trains exposure on lipid peroxidation, and, hence, oxidative stress in the rat liver tissue. The parameters that we measured were the levels of plasma alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase as well as plasma albumin, bilirubin, and total protein levels in 30 adult male Wistar rats exposed to ELF. We also determined the percentage of apoptotic and necrotic cells of the kidney extracts from the animals by flow cytometry method. Apoptotic cell death was further characterized by monitoring DNA degradation using gel electrophoresis. The results showed an increase in the levels of oxidative stress indicators, and the flow cytometric data suggested a possible relationship between the exposure to magnetic field and the cell death. We showed significantly lower necrotic cell percentages in experimental animals compared to either unexposed or sham control groups. However, DNA ladder analyses did not differentiate between the groups. Our results were discussed in relation to the response of biological systems to EMF. © 2010 Springer Science+Business Media, LLC.Acknowledgment The authors acknowledge with thanks the support provided by the Biochemistry department of Cukurova Medical School by way of valuable contributions in the determination of oxidative stress parameters

A novel pathway for rapid shoot regeneration from the proximal zone of the hypocotyl of melon (Cucumis melo L.)

Hypocotyl explants of melon (Cucumis melo L.) are capable of regenerating multiple shoots on Murashige and Skoog (1962) medium, augmented with 4.4 µM benzyladenine. Regeneration from the hypocotyl is much more rapid than the more commonly reported regeneration from cotyledonary explants, producing shoots within 2 wk compared to more than a month required for cotyledon explants. The rapid regeneration response depends on the presence of a fragment of the cotyledon remaining attached to the hypocotyl. Controls were performed to ensure that the regeneration was not due to the presence of the shoot apical bud of the melon seedling after explant production. Scanning electron microscopy revealed that microsurgery to remove the apical bud left no excess bud material. Regeneration from the proximal part of the hypocotyl was due to production of a new shoot apical meristem, observed by histology. The apical meristem can be produced before leaf primordia in regeneration from the hypocotyl, in contrast to the regeneration process from the melon cotyledon

Is there any relationship between serum levels of interleukin-10 and atherosclerosis in hemodialysis patients

PubMedID: 16257843Objective. Cardiovascular complications due to atherosclerosis (AS) are the major cause of mortality in hemodialysis (HD) patients. Inflammation may play an important role in the development of AS. Several studies have demonstrated an association between AS and acute-phase proteins and cytokines in the general population and in HD patients. Interleukin-10 (IL-10) is an anti-inflammatory cytokine. The aim of this study was to compare serum levels of inflammatory and anti-inflammatory indicators in HD patients according to the presence or absence of AS. Material and methods. A total of 33 HD patients were studied. AS was defined as the presence of plaques as detected by Doppler ultrasonography. The patients were subgrouped according to the presence or absence of plaques. Serum levels of IL-1, -2, -6 and -10, C-reactive protein (CRP) and tumor necrosis factor-? (TNF-?) were measured. Risk factors for AS, such as age, gender, hypertension, hyperlipidemia and duration of HD, were also evaluated. Results. Patients with AS had significantly higher high sensitivity (hs)-CRP and lower IL-10 levels. Blood pressure was also elevated in patients with AS. There was an inverse correlation between CRP and IL-10 levels in patients with AS. Conclusion. Patients with AS undergoing HD had low serum levels of the anti-inflammatory cytokine IL-10 and high serum levels of hs-CRP. These results may suggest that limitation of the anti-inflammatory response in atherosclerotic uremic patients is a triggering or contributory factor for AS. © 2005 Taylor & Francis