Packet Relaying Control in Sensing-based Spectrum Sharing Systems

Cognitive relaying has been introduced for opportunistic spectrum access systems by which a secondary node forwards primary packets whenever the primary link faces an outage condition. For spectrum sharing systems, cognitive relaying is parametrized by an interference power constraint level imposed on the transmit power of the secondary user. For sensing-based spectrum sharing, the probability of detection is also involved in packet relaying control. This paper considers the choice of these two parameters so as to maximize the secondary nodes' throughput under certain constraints. The analysis leads to a Markov decision process using dynamic programming approach. The problem is solved using value iteration. Finally, the structural properties of the resulting optimal control are highlighted

Adaptive Modulation in Multi-user Cognitive Radio Networks over Fading Channels

In this paper, the performance of adaptive modulation in multi-user cognitive radio networks over fading channels is analyzed. Multi-user diversity is considered for opportunistic user selection among multiple secondary users. The analysis is obtained for Nakagami-$m$ fading channels. Both adaptive continuous rate and adaptive discrete rate schemes are analysed in opportunistic spectrum access and spectrum sharing. Numerical results are obtained and depicted to quantify the effects of multi-user fading environments on adaptive modulation operating in cognitive radio networks

The protective role of melatonin on L-arginine-induced acute pancreatitis in adult male albino rats

Background: Acute pancreatitis (AP) is an inflammatory disease that has an increasing incidence worldwide. AP is associated with high morbidity and mortality rates ranging 15–40% in its severe form. Oxidative stress plays an important role in pancreatic acinar cell injury in case of AP. Melatonin (Mel) is proven to have both antioxidant and anti-inflammatory effects. The aim of the work was to investigate the protective role of Mel against L-arginine (L-arg)-induced AP in adult male albino rats. Materials and methods: Thirty-six adult male albino rats were used in this study. Animals were divided into four groups; Control group (Group A; n = 6), Mel group (Group B; n = 6), L-arg group (Group C; n = 12) receiving two doses of L-arg injection with 1 h interval in-between, and L-arg+Mel group (Group D; n = 12) receiving Mel 1 h after each L-arg injection. 24 h after the second L-arg injection, the serum levels of amylase (AM), lipase (LP), interleukin-6 (IL-6) and tumour necrotic factor-alpha (TNF-α) were determined. Then, pancreatic specimens were processed for histological and immunohistochemical staining with vascular endothelial growth factor (VEGF) and the area percentage of VEGF and collagen content were measured by digital image analysis. Results: Microscopic examination revealed that animals received L-arg only (Group C) showed loss of the pancreatic lobular architecture with marked fibrosis, acinar degeneration, inflammatory reaction and marked oedema with vascular congestion. Also, L-arg-induced AP caused a significant elevation of the serum levels of AM, LP, IL-6. All these histo-pathological and serological parameters were markedly improved by Mel administration. Conclusions: Melatonin exhibits strong therapeutic effects in the course of AP. Hence, the use of Mel as adjuvant treatment in AP is recommended.

Channel Secondary Random Process for Robust Secret Key Generation

The broadcast nature of wireless communications imposes the risk of information leakage to adversarial users or unauthorized receivers. Therefore, information security between intended users remains a challenging issue. Most of the current physical layer security techniques exploit channel randomness as a common source between two legitimate nodes to extract a secret key. In this paper, we propose a new simple technique to generate the secret key. Specifically, we exploit the estimated channel to generate a secondary random process (SRP) that is common between the two legitimate nodes. We compare the estimated channel gain and phase to a preset threshold. The moving differences between the locations at which the estimated channel gain and phase exceed the threshold are the realization of our SRP. We simulate an orthogonal frequency division multiplexing (OFDM) system and show that our proposed technique provides a drastic improvement in the key bit mismatch rate (BMR) between the legitimate nodes when compared to the techniques that exploit the estimated channel gain or phase directly. In addition to that, the secret key generated through our technique is longer than that generated by conventional techniques

Communicationless overcurrent relays coordination for active distribution network considering fault repairing periods

This paper presents an integrated overcurrent relays coordination approach for an Egyptian electric power distribution system. The protection scheme suits all network topologies, including adding distribution generation units (DGs) and creating new paths during fault repair periods. The optimal types, sizes, and locations of DGs are obtained using HOMER software and genetic algorithm (GA). The obtained values align with minimizing energy costs and environmental pollution. The proposed approach maintains dependability and security under all configurations using a single optimum setting for each relay. The calculations consider probable operating conditions, including DGs and fault repair periods. The enhanced coordination procedure partitions the ring into four parts and divides the process into four paths. The worst condition of two cascaded over current relays from the DGs' presence viewpoint is generalized for future work. Moreover, a novel concept addresses the issue of insensitivity during fault repair periods. The performance is validated through simulating an Egyptian primary distribution network

Obstructive jaundice secondary to pancreatic head adenocarcinoma in a young teenage boy: a case report

<p>Abstract</p> <p>Introduction</p> <p>Pancreatic adenocarcinoma is extremely rare in childhood. We report a case of metastatic pancreatic adenocarcinoma in a 13-year-old boy, revealed by jaundice.</p> <p>Case presentation</p> <p>A 13-year-old Moroccan boy was admitted with obstructive jaundice to the children's Hospital of Rabat, Department of Pediatric Oncology. Laboratory study results showed a high level of total and conjugated bilirubin. Computerized tomography of the abdomen showed a dilatation of the intra-hepatic and extra-hepatic bile ducts with a tissular heterogeneous tumor of the head of the pancreas and five hepatic lesions. Biopsy of a liver lesion was performed, and a histopathological examination of the sample confirmed the diagnosis of metastatic ductal adenocarcinoma of the pancreas. Our patient underwent a palliative biliary derivation. After that, chemotherapy was administered (5-fluorouracil and epirubicin), however no significant response to treatment was noted and our patient died six months after diagnosis.</p> <p>Conclusion</p> <p>Malignant pancreatic tumors, especially ductal carcinomas, are exceedingly rare in the pediatric age group and their clinical features and treatment usually go unappreciated by most pediatric oncologists and surgeons.</p

A novel mutation in HSD11B2 causes apparent mineralocorticoid excess in an Omani kindred

Apparent mineralocorticoid excess (AME) is a rare autosomal recessive genetic disorder causing severe hypertension in childhood due to a deficiency of 11β-hydroxysteroid dehydrogenase type 2 (11βHSD2), which is encoded by HSD11B2. Without treatment, chronic hypertension leads to early development of end-organ damage. Approximately 40 causative mutations in HSD11B2 have been identified in ∼100 AME patients worldwide. We have studied the clinical presentation, biochemical parameters, and molecular genetics in six patients from a consanguineous Omani family with AME. DNA sequence analysis of affected members of this family revealed homozygous c.799A>G mutations within exon 4 of HSD11B2, corresponding to a p.T267A mutation of 11βHSD2. The structural change and predicted consequences owing to the p.T267A mutation have been modeled in silico. We conclude that this novel mutation is responsible for AME in this family

A Critical Examination of the Potential Benefits of Theophylline on Extended Acute Inflammation in Old Age.

This chapter presents a critical review of the potential benefits of theophylline as a means to reduce the burden of post-acute inflammation in older age groups. A pro-inflammatory state often persists, or is extended, after sepsis, trauma and other acute illnesses in old age, particularly above the age of 80 years. The presence of inflammation at above-baseline amplitudes or excessive duration is associated with a higher likelihood of delirium, anorexia, unplanned weight loss, lethargy, depression, weakness and other markers of frailty. There is also an association with less favourable clinical outcomes and a higher risk of losing personal independence. Theophylline has been shown to have an anti-inflammatory effect, probably mediated through the induction of histone deacetylase-dependent gene switching in immune competent cells, that has been observed at cellular and whole organism levels. The main effects are a reduction in the production and release of TNF, IL-1 and IL-6, with a sequential fall in CRP and increase in IL-10, and a change of immune cells to their anti-inflammatory phenotypes. This happens when theophylline levels are between 5 and 10 mg/L, which is lower than the range for bronchodilators (10 to 15 mg/L) and presents a relatively low risk of toxicity. We hypothesize that low-dose theophylline treatment given to elderly subjects with acute inflammation, for example due to respiratory infection, septicaemia or trauma, will change the setting of their biochemical status from an inappropriately extended pro-inflammatory pattern toward a more normalized baseline pattern and consequently reduce the risk of adverse clinical outcomes

Detection of splenic microabscesses with ultrasound as a marker for extrapulmonary tuberculosis in patients with HIV: A systematic review

Background. In 2015, 1.2 million new cases of tuberculosis (TB) were diagnosed in patients with HIV. Diagnostic limitations and resource shortages in endemic areas can delay diagnosis and treatment, particularly with extrapulmonary TB (EPTB). Research suggests that ultrasound can identify splenic microabscesses caused by EPTB, but data are limited on the frequency of this finding in patients with culture-proven EPTB.Objectives. To estimate the frequency of splenic EPTB microabscesses detected with ultrasound in patients with HIV and TB co-infection.Methods. Studies published in six major databases as of November 2017 were systematically reviewed based on the PRISMA guidelines. Cohen’s kappa test was used to determine inter-rater agreement. Articles included for data abstraction passed the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) evaluation. Freeman-Tukey transformation was used to calculate weighted proportions. Heterogeneity was evaluated by Forest plot and I2 calculation.Results. After abstract screening, article review and QUADAS-2 evaluation, five studies were selected for data extraction. A total of 774 patients in these studies were infected with HIV. Splenic lesions were seen with ultrasound in 21.0% of patients with HIV (95% confidence interval (CI) 10.6 - 33.8). TB diagnosed by culture, biopsy, smear, or molecular methods was found to be the cause of 88.3% (95% CI 72.3 - 97.9) of splenic microabscesses seen on ultrasound in patients with HIV.Conclusions. Ultrasound evaluation of the spleen in patients with HIV and symptoms suggestive of TB in endemic regions is a viable diagnostic adjunct. Ultrasound detection of splenic microabscesses in HIV patients is probably sufficient indication to initiate TB treatment prior to obtaining culture data. Strong conclusions cannot be drawn owing to the high heterogeneity of this small number of studies.