On Robustness of Massive MIMO Systems Against Passive Eavesdropping under Antenna Selection

In massive MIMO wiretap settings, the base station can significantly suppress eavesdroppers by narrow beamforming toward legitimate terminals. Numerical investigations show that by this approach, secrecy is obtained at no significant cost. We call this property of massive MIMO systems `secrecy for free' and show that it not only holds when all the transmit antennas at the base station are employed, but also when only a single antenna is set active. Using linear precoding, the information leakage to the eavesdroppers can be sufficiently diminished, when the total number of available transmit antennas at the base station grows large, even when only a fixed number of them are selected. This result indicates that passive eavesdropping has no significant impact on massive MIMO systems, regardless of the number of active transmit antennas.Comment: 7 pages, 2 figures; To be presented in IEEE Global Communications Conference (Globecom) 2018 in Abu Dhabi, UA

Effect of dietary virgin olive oil on infarct volume and brain ceramide, cerebroside and phosphatidylcholine levels in rat stroke model

زمینه و هدف: سکته مغزی سومین عامل مرگ و میر در کشورهای صنعتی بعد از بیماری های قلبی- عروقی و سرطان است. این مطالعه با هدف بررسی ارتباط بین اثر روغن زیتون بکر بر سطح لیپیدهای مغزی و کاهش حجم سکته مغزی در مدل سکته مغزی موش صحرایی انجام گرفت. روش بررسی: در این مطالعه تجربی از 5 گروه 12 تایی موش صحرایی نر استفاده شد. این گروه ها شامل کنترل، شم و سه گروه آزمایشی بودند که دوزهای 25/0، 5/0 و 75/0 میلی لیتر بر کیلوگرم وزن بدن روغن زیتون بکر را به صورت خوراکی از طریق گاواژ به مدت 30 روز دریافت نمودند. دو گروه کنترل و شم آب مقطر دریافت کردند. دو ساعت بعد از آخرین دوز گاواژ شده هر گروه 12 تایی به دو زیر گروه تقسیم شدند. زیر گروه (middle cerebral artery occlusion)MCAO، به منظور اندازه گیری حجم سکته مغزی و زیر گروه دیگر برای آنالیز لیپیدهای مغزی استفاده شد. داده ها با استفاده از آزمون های ANOVA و تست تعقیبی LSDو آزمون ضریب همبستگی پیرسون تجزیه و تحلیل شدند. یافته ها: پیش تیمار با روغن زیتون بکر خوراکی با دوز 5/0 و 75/0 میلی لیتر بر کیلوگرم در روز باعث افزایش سطح فسفاتیدیل کولین بافت مغز گردید (05/0

Optimal Number of Transmit Antennas for Secrecy Enhancement in Massive MIMOME Channels

This paper studies the impact of transmit antenna selection on the secrecy performance of massive MIMO wiretap channels. We consider a scenario in which a multi-antenna transmitter selects a subset of transmit antennas with the strongest channel gains. Confidential messages are then transmitted to a multi-antenna legitimate receiver while the channel is being overheard by a multi-antenna eavesdropper. For this setup, we approximate the distribution of the instantaneous secrecy rate in the large-system limit. The approximation enables us to investigate the optimal number of selected antennas which maximizes the asymptotic secrecy throughput of the system. We show that increasing the number of selected antennas enhances the secrecy performance of the system up to some optimal value, and that further growth in the number of selected antennas has a destructive effect. Using the large-system approximation, we obtain the optimal number of selected antennas analytically for various scenarios. Our numerical investigations show an accurate match between simulations and the analytic results even for not so large dimensions.Comment: 6 pages, 4 figures, IEEE GLOBECOM 201

Genetic characterization of Lactococcus garvieae isolated from farmed rainbow trout by random amplified polymorphic DNA-PCR in Iran

ΔΕΝ ΔΙΑΤΙΘΕΤΑΙ ΠΕΡΙΛΗΨΗLactococcosis is one of the main bacterial infections of fish around the world. Lactococcus garvieae has been a major cause of rainbow trout losses in freshwater farming. This study aimed to genotype and determine the variability of L. garvieae isolated from infected farmed rainbow trout in Iran by the RAPD-PCR method. Bacterial samples were collected from 12 farms located in the western part of Iran and suspect ted to carry Lactococcus infection. Two hundred bacterial cultures containing cocci shaped bacteria were cultured in Trypticase soy agar (TSA) and blood agar mediums. All bacterial cultures were tested by conventional microbiological and biochemical tests, and PCR assay to identify L. garvieae by 16S rDNA genes. The RAPD-PCR method was used to determine the genetic patternof all isolates. The sample strain pattern of the isolates was analyzed in the NTSYS program. According to a similarity coefficient index of 70%, all L. garvieae isolates were separated into two groups with four RAPD profile types. The highest and the lowest genetic pairwise similarity among the isolates were 98% and 54%, respectively. The results of the present study revealed that RAPD-PCR is an applicable method to describe the genetic diversity of different strains of L .garvieae among farmed fish

Genetic characterization of Lactococcus garvieae isolated from farmed rainbow trout by random amplified polymorphic DNA-PCR in Iran

Lactococcosis is one of the main bacterial infections of fish around the world. Lactococcus garvieae has been a major cause of rainbow trout losses in freshwater farming. This study aimed to genotype and determine the variability of L. garvieae isolated from infected farmed rainbow trout in Iran by the RAPD-PCR method. Bacterial samples were collected from 12 farms located in the western part of Iran and suspected to carry Lactococcus infection. Two hundred bacterial cultures containing cocci shaped bacteria were cultured in Trypticase soy agar (TSA) and blood agar mediums. All bacterial cultures were tested by conventional microbiological and biochemical tests, and PCR assay to identify L. garvieae by 16S rDNA genes. The RAPD-PCR method was used to determine the genetic pattern of all isolates. The sample strain pattern of the isolates was analyzed in the NTSYS program. According to a similarity coefficient index of 70%, all L. garvieae isolates were separated into two groups with four RAPD profile types. The highest and the lowest genetic pairwise similarity among the isolates were 98% and 54%, respectively. The results of the present study revealed that RAPD-PCR is an applicable method to describe the genetic diversity of different strains of L. garvieae among farmed fish

Relationship between dietary virgin olive oil on brain cholesterol, cholesteryl ester and triglyceride levels and blood brain barrier (BBB) permeability in a rat stroke model

Introduction: Recent studies suggest that dietary virgin olive oil (VOO) reduces hypoxia-re oxygenation injury in rat brain. We have attempted to determine the effect of dietary virgin olive oil on brain lipidomics and its relationship with brain edema in a rat stroke model. Methods: Five groups, each consisting of 6 male Wistar rats, were studied. The first and second groups (control and sham) received distilled water, while three treatment groups received oral VOO for 30 days (0.25, 0.5 and 0.75 ml/kg/day, respectively). Two hours after the last dose, each main group was subdivided into middle cerebral artery occlusion (MCAO)-operated and intact subgroups for assessment of neuropathology (blood brain barrier permeability) and brain lipid analysis. Results: VOO increased the brain cholesteryl ester and cholesterol levels in doses of 0.5 and 0.75 ml/kg/day. VOO in all three doses increased the brain triglyceride levels (p<0.05). Oral administration of VOO reduces infarct volume, brain edema, blood brain barrier permeability, after transient MCAO in rats. Conclusion: Although further studies are needed to clarify the mechanisms of ischemic tolerance, VOO is partly associated with increased levels of brain cholesteryl ester, cholesterol and triglyceride in rats

Antioxidative effects of tempol on mitochondrial dysfunction in diabetic nephropathy

Introduction. Oxidative stress has a well-known role in diabetic nephropathy, and mitochondria are the major source of reactive oxygen species production. This study aimed to assess the effect of tempol, a superoxide dismutase mimetic agent, on mitochondrial antioxidant enzymes and cell viability in diabetic nephropathy. Materials and Methods. Adult male Wistar rats were divided into 4 groups of 7 animals. Diabetes mellitus was induced by injection of streptozotocin in 2 groups, the rat in one of which were also treated with tempol for 4 weeks. Another group without diabetes mellitus received tempol, and the last group was the control. At the end of the treatment period, the kidney mitochondria were isolated and their antioxidant enzymes, including superoxide dismutase, glutathione peroxidase, and catalase were assessed. Malondialdehyde, total antioxidant capacity, and kidney cells viability were studied, as well. Results. The diabetic group was significantly different compared with the control group in malondialdehyde, catalase, and glutathione peroxidase activities. Superoxide dismutase and total antioxidative capacity did not show any significant differences among the four groups. Moreover, the diabetic group treated with tempol had significantly different glutathione peroxidase level and kidney cells viability, compared to the other diabetic group (P <.05) Conclusions. Diabetic nephropathy induces changes in mitochondrial antioxidative biomarkers and cells viability, some of which can be modified by tempol administration in rats. © 2018, Iranian Society of Nephrology. All rights reserved

Anti-amnesic activity of Citrus aurantium flowers extract against scopolamine-induced memory impairments in rats

Alzheimer's disease (AD) is a progressive neurological disorder that mostly affects the elderly population. Learning and memory impairment as the most characteristic manifestation of dementia could be induced chemically by scopolamine, a cholinergic antagonist. Cholinergic neurotransmission mediated brain oxidative stress. Citrus aurantium (CA) has traditionally been used for the treatment of insomnia, anxiety and epilepsy. The present study was designed to investigate the effect of Citrus aurantium on scopolamine-induced learning and memory deficit in rats. Forty-two Wistar rats were divided into six equal groups. (1) Control (received saline), (2) SCOP (scopolamine at a dose of 1 mg/kg for 15 days), (3) and (4) SCOP + CA (scopolamine and CA extract at doses of 300 and 600 mg/kg per day for 15 days), (5) and (6) intact groups (CA extract at 300 and 600 mg/kg per day for 15 days, respectively). Administration of CA flower extract significantly restored memory and learning impairments induced by scopolamine in the passive avoidance test and also reduced escape latency during trial sessions in the Morris water maze test. Citrus aurantium flower extract significantly decreased the serum malondialdehyde (MDA) levels. Citrus aurantium flower extract has repairing effects on memory and behavioral disorders produced by scopolamine and may have beneficial effects in the treatment of AD