The volume fraction of brain ventricles to total brain volume: a computed tomography stereological study

This study has been designed to estimate the volume fraction of the brain ventricles volume to total brain volume and to correlate them with gender and age in normal subjects. Cranial computed tomography (CT) images of 80 normally evaluated subjects (five female and five male for each decade) were selected from 1,073 CT examinations. The volumes of total brain, cerebral aqueduct, fourth, third, and lateral ventricles and their ratios were estimated using the Cavalieri method and volume fraction-stereological methods. The ratio of total brain ventricle volume to total brain volume was comparable between the two genders (p > 0.05, independent t test). Mean volume fraction of total ventricle volume to total brain volume was found to be 1.21% in the first and 3.37% in the last decades. Mean volume fraction was found to increase significantly with age (p < 0.01, r = 0.630, Pearson). In conclusion, the mean percentage of total ventricle volume within the total brain volume was found to be 2%. We demonstrated the volume fraction of total ventricle to total brain in normal subjects. Total ventricle volume to total brain volume fractions can be important tools in determining ventricle volumes, which denote variability in some diseases (Alzheimer, schizophrenia, neurodegenerative disorders, etc.) and can be estimated by stereological methods. (Folia Morphol 2010; 69, 4: 193-200

Distributed Massive MIMO for LEO Satellite Networks

The ultra-dense deployment of interconnected satellites will characterize future low Earth orbit (LEO) mega-constellations. Exploiting this towards a more efficient satellite network (SatNet), this paper proposes a novel LEO SatNet architecture based on distributed massive multiple-input multiple-output (DM-MIMO) technology allowing ground user terminals to be connected to a cluster of satellites. To this end, we investigate various aspects of DM-MIMO-based satellite network design, the benefits of using this architecture, the associated challenges, and the potential solutions. In addition, we propose a distributed joint power allocation and handover management (D-JPAHM) technique that jointly optimizes the power allocation and handover management processes in a cross-layer manner. This framework aims to maximize the network throughput and minimize the handover rate while considering the quality-of-service (QoS) demands of user terminals and the power capabilities of the satellites. Moreover, we devise an artificial intelligence (AI)-based solution to efficiently implement the proposed D-JPAHM framework in a manner suitable for real-time operation and the dynamic SatNet environment. To the best of our knowledge, this is the first work to introduce and study DM-MIMO technology in LEO SatNets. Extensive simulation results reveal the superiority of the proposed architecture and solutions compared to conventional approaches in the literature.Comment: arXiv admin note: text overlap with arXiv:2106.0983

Future Ultra-Dense LEO Satellite Networks: A Cell-Free Massive MIMO Approach

Low Earth orbit (LEO) satellite networks (SatNets) are envisioned to play a crucial role in providing global and ubiquitous connectivity efficiently. Accordingly, in the coming years, thousands of LEO satellites will be launched to create ultradense LEO mega-constellations, and the Third Generation Partnership Project (3GPP) is working on evolving fifth-generation (5G) systems to support such non-terrestrial networks (NTN). However, many challenges are associated with the deployment of LEOs from communications and networking perspectives. In this paper, we propose a novel cell-free massive multiple-input multiple-output (CF-mMIMO) based architecture for future ultra-dense LEO SatNets. We discuss various aspects of network design, such as duplexing mode, pilot assignment, beamforming, and handover management. In addition, we propose a joint optimization framework for the power allocation and handover management processes to maximize the network throughput and minimize the handover rate while ensuring quality-of-service (QoS) satisfaction for users. To the best of our knowledge, this is the first work to introduce and study CF-mMIMO-based LEO SatNets. Extensive simulation results demonstrate the superior performance of the proposed architecture and solutions compared to those of conventional single-satellite connectivity and handover techniques from the literature.Comment: 6 pages, 3 figure

Reconfigurable Intelligent Surfaces for the Connectivity of Autonomous Vehicles

The use of real-time software-controlled reconfigurable intelligent surface (RIS) units is proposed to increase the reliability of vehicle-to-everything (V2X) communications. The optimum placement problem of the RIS units is formulated by considering their sizes and operating modes. The solution of the problem is given, where it is shown that the placement of the RIS depends on the locations of the transmitter and the receiver. The proposed RIS-supported highway deployment can combat the high path loss experienced by the use of higher frequency bands, including the millimeter-wave and the terahertz bands, that are expected to be used in the next-generation wireless networks, enabling the use of the existing base station deployment plans to remain operational, while providing reliable and energy-efficient connectivity for autonomous vehicles.Comment: 5 pages, 4 figures

Mycobacterial infection of intraparenchymal bronchogenic cysts

Bronchogenic cysts (BCs) may rarely cause some interesting and unusual complications. Although infection is a common complication of BCs, there are only two patients with BC infected with mycobacterium in English literature. Two intraparencymal BCs infected with mycobacterium are presented here as unusual complications. Cystectomy was performed for the cysts. They were given antituberculosis treatment. No complication or recurrences were detected in follow up period. © 2006 Elsevier Ltd. All rights reserved

Non-invasive detection of biliary leaks using Gd-EOB-DTPA-enhanced MR cholangiography: Comparison with T2-weighted MR cholangiography

Objective: To evaluate the added role of T1-weighted (T1w) gadolinium ethoxybenzyl diethylenetriamine penta-acetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance cholangiography (MRC) compared with T2-weighted MRC (T2w-MRC) in the detection of biliary leaks. Methods: Ninety-nine patients with suspected biliary complications underwent routine T2w-MRC and T1w contrast-enhanced (CE) MRC using Gd-EOB-DTPA to identify biliary leaks. Two observers reviewed the image sets separately and together. MRC findings were compared with those of surgery and percutaneous transhepatic cholangiopancreatography. The sensitivity, specificity and accuracy of the techniques in identifying biliary leaks were calculated. Results: Accuracy of locating biliary leaks was superior with the combination of Gd-EOB-DTPA-enhanced MRC and T2w-MRC (P < 0.05).The mean sensitivities were 79 % vs 59 %, and the mean accuracy rates were 84 % vs 58 % for combined CE-MRC and T2w-MRC vs sole T2w-MRC. Nineteen out of 21 patients with biliary-cyst communication, 90.4 %, and 12/15 patients with post-traumatic biliary extravasations, 80 %, were detected by the combination of Gd-EOB-DTPA-enhanced MRC and T2w-MRC images, P < 0.05. Conclusions: Gd-EOB-DTPA-enhanced MRC yields information that complements T2w-MRC findings and improves the identification and localisation of the bile extravasations (84 % accuracy, 100 % specificity, P < 0.05). We recommend Gd-EOB-DTPA-enhanced MRC in addition to T2w-MRC to increase the preoperative accuracy of identifying and locating extravasations of bile. Key Points: • Magnetic resonance cholangiography (MRC) does not always detect bile leakage and cysto-biliary communications. • Gd-EOB-DTPA-enhanced MRC helps by demonstrating extravasation of contrast material into fluid collections. • Gd-EOB-DTPA-enhanced MRC also demonstrates the leakage site and bile duct injury type. • Combined Gd-EOB-DTPA-enhanced and T2w-MRC can provide comprehensive information about biliary system. • Gd-EOB-DTPA-enhanced MRC is non-invasive and does not use ionising radiation. © 2013 The Author(s)

The effect of racemic gossypol and AT-101 on angiogenic profile of OVCAR-3 cells: a preliminary molecular framework for gossypol enantiomers

To compare the effect of racemic gossypol with its (–)/(–) enantiomer (AT-101) on expression profiles of angiogenic molecules by mRNA levels in human ovarian cancer cell line OVCAR-3. Methods: Cell viability assay (2,3-bis (2-methoxy-4-nitro-5- sulfophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide) was used to detect cytotoxicity of gossypol enantiomers. DNA fragmentation by an enzyme-linked immunosorbent (ELISA) assay was used to evaluate the rate of apoptosis. The mRNA expression levels of angiogenic molecules were investigated by Human Angiogenesis RT2 ProfilerTM PCR Array (SuperArray, Frederick, MD). Results: Both racemic form and AT-101 resulted in a significant cytotoxicity and induced apoptosis. This effect was observed in a dose- and time dependent manner. However, AT-101 was much more potent. In addition, the treatment of 10 μM of racemic gossypol alone and 3 μM of AT-101 alone resulted in significant down-regulation (≥ 3 fold) in mRNA levels of some pivotal angiogenic molecules in OVCAR-3, but altered gene profiles were different by the treatment of each enantiomer. Conclusion: The efficacy of two gossypol enantiomers in OVCAR-3 cells showed distinction. AT-101 was much more potent than racemic gossypol, not only by means of cell death and apoptosis, but also by modulation of angiogenic molecules released from OVCAR-3 cells. Further studies with endothelial cells should be done to verify the anti-angiogenic effect of gossypol enantiomers in cancer treatment