ADAPTIVE CAPACITY ALLOCATION IN MPLS NETWORKS

Traffic Congestion is one of the salient issues that affect overall network performance. Network traffic has become very dynamic due to a variety of factors, such as, the number of users varies with time of the day, multimedia applications, bursts in traffic due to a failure and so on. Recently, Multi-Protocol Label Switching (MPLS) networks have emerged as a technology with many promising features such as traffic engineering, QoS provisioning, and speeding up the traffic transmission. However, MPLS still suffers from the nonstationary/transient conditions that sometimes cause congestion. Actually, congestion does not always occur when the network is short capacity, but rather, when the network resources are not efficiently utilized. Thus, it is very important to develop an algorithm that efficiently and dynamically adjusts the available capacity. In this thesis, we propose an adaptive capacity allocation scheme. We have started our consideration with a single traffic class system that has dynamic traffic where traffic arrival is considered at the level of connection/call arrival. We assume that the virtual network for this traffic class operates as a loss system; i.e. if a connection does not find bandwidth, the connection is blocked and cleared from the system. Then, we extended our work to include the multiple traffic classes. Two cases have been studied and analyzed; when classes have no coupling and when they are coupled. The capacity allocation scheme is derived from a first-order, differential equation-based, fluid-flow model that captures the traffic dynamics. The scheme aims to maintain the connection blocking probability within a specified range by dynamically adjusting the allocated capacity. A fluid flow differential equation model is developed to model the changing traffic environment. Using the fluid flow model, Lyapunov Stability theory is used to derive a novel adaptive capacity adjustment scheme which guarantees overall system stability while maintaining the target QoS parameters. Numerical results are given which show that the Lyapunov control based scheme successfully provides the desired QoS requirements and performs better than existing schemes in the literature

The role of NF-κB and AhR transcription factors in lead-induced lung toxicity in human lung cancer A549 cells.

Lead (Pb) is recognized as the first heavy metal of the top six toxic air pollutants threatening human health and the second hazardous substance. Pb exposure is associated with lung impairment and high incidences of lung cancer. Nuclear factor kappa B (NF-κB) and aryl hydrocarbon receptor (AhR) signaling pathways are known to be expressed and play an important role in the lung. However, the link between Pb lung toxicity and NF-κB and/or AhR pathways remains unclear. This study was established to explore the role of NF-κB and AhR modulation in Pb-induced lung toxicity in human lung cancer A549 cells. In the current study, treatment of A549 cells with Pb significantly induced cell apoptosis as evidenced by increasing a) the percentage of cells underwent apoptosis determined by flow cytometry and b) p53 mRNA level. Pb treatment induced oxidative stress by a) increasing the formation of reactive oxygen species and b) decreasing GSTA1 mRNA levels. The toxic effects of Pb on the lung was associated with significant increases in NF-κB and AhR levels which was accompanied with increases in downstream targets genes, iNOS and CYP1A1, respectively. Inhibition of NF-κB or AhR either chemically using resveratrol or genetically using small interfering RNA (siRNA) significantly rescued A549 cells from Pb-mediated lung toxicity. The results clearly indicate that Pb-mediated lung toxicities are NF-κB and AhR-dependent mechanism.King Abdulaziz City for Science and Technology KACST Qatar National Library QN

Early outcomes of transection of secondary chordae with downsized ring annuloplasty in low recurrence risk severe ischemic mitral regurgitation

Background: Relying solely on restrictive annuloplasty for the repair of ischemic mitral regurgitation is associated with an unacceptable rate of recurrence. Transection of secondary chordae as an adjunctive procedure has been proposed to improve results.Patient and methods: This is a prospective observational study including 20 patients who underwent mitral repair using downsized annuloplasty ring and transection of the secondary chordae, at the time of CABG at the Cardiothoracic Surgery Department of Cairo University Hospitals through the period between March 2016 and October 2018. The primary outcome being examined was the recurrence of significant mitral regurgitation at 6 months postoperatively. Secondary outcomes included coaptation length and ejection fraction.Results: The mean age was 57.5 ± 6.9 years. The mean ejection fraction was 45.1 ± 11%. There was one early mortality (5%). At 6 months postoperatively, there was no incidence of recurrence of significant mitral regurgitation. Coaptation length was quite satisfactory (7.2 ± 0.67 mm).Conclusion: Transection of secondary chordae is a safe and simple option. It may be beneficial when performed in combination with downsized ring annuloplasty in patients with low-risk ischemic mitral regurgitation

Mitral valve annuloplasty with a homemade single-sized polytetrafluoroethylene band in degenerative mitral regurgitation

Background: Although mitral annuloplasty is an essential component of mitral repair, there remains little agreement on the ideal device to be used or the ideal sizing method.Objectives: The purpose of this study was to report the early clinical and echocardiographic outcomes of patients undergoing repair for degenerative mitral regurgitation using a homemade single-sized (65 mm) Polytetrafluoroethylene band, and comparing it to the use of commercially available complete rigid rings.Patients and methods: This is a retrospective study including 106 patients, who underwent mitral repair for degenerative mitral regurgitation at Cairo University Hospitals between February 2013 and July 2019. These patients were divided into 2 groups. Group (A) included 69 patients who underwent repair with a single-sized band, and group (B) included 37 patients whose repair included the use of a commercial rigid ring. The primary endpoint was freedom from significant mitral regurgitation at one-year follow-up. Secondary endpoints included mean mitral valve gradient measured postoperatively, and freedom from reoperation at one year.Results: There was no statistically significant difference between both groups in any of the above-mentioned endpoints being examined.Conclusion: The use of a single-sized Polytetrafluoroethylene band for annuloplasty in degenerative mitral disease showed satisfactory results comparable to the commercial rigid rings. Further studies with longer follow-up are needed to confirm the durability of mitral repair using this technique

Timing of Coronary Artery Bypass Grafting Surgery after Acute Myocardial Infarction

Background: Optimal timing for CABG surgery after myocardial infarction remains a matter of debate. The aim of our study was to analyze the effect of timing of CABG after acute myocardial infarction on operative mortality and morbidity. Methods: This prospective study included 60 patients who underwent isolated CABG within 30 days of acute myocardial infarction over 20 months (from the first of November 2014 till the end of June 2016) in Kasr Al-Ainy University Hospitals. Patients were divided into two groups; the early group (0 – 3 days) included 14 patients (23.3%) and the late group (4 – 30 days) included 46 patients (76.7%). The primary outcome was all-cause hospital mortality. Results: Our study included 43 males (71.7%) and 17 females (28.3%). The mean age was 58.4 ± 7.3 years. The total mortality rate was 8.3%. Patients undergoing early CABG experienced a higher mortality rate than those undergoing late CABG (21.4% vs 4.3%, P = 0.043). Also, early CABG was associated with more postoperative complications. Cardiogenic shock and early CABG were independent risk factors of mortality. Conclusion: CABG in the first 3 days after acute myocardial infarction was associated with high mortality and morbidity in comparison with late CABG. This suggests that CABG may best be deferred for more than 3 days after acute MI in non-urgent cases

Tricuspid valve repair by DeVega technique versus ring annuloplasty in patients with functional severe tricuspid regurge

AbstractBackgroundRepairing the tricuspid valve in patients undergoing left heart valve surgery is still controversial. Severe Tricuspid regurge is repaired by most surgeons, while moderate regurge is frequently unaddressed. Another controversy is the technique of repair. DeVega technique is widely used; still, the longevity of this repair is still questioned. The risk of its early failure and subsequent recurrence of significant regurge requiring redo surgery has led many surgeons to adopt the use of annuloplasty rings. The aim of our study was to assess the short term results (1 year) of tricuspid repair with or without ring annuloplasty.Patients and methods80 patients who had tricuspid repair concomitantly with mitral valve surgery at Cairo University Hospitals over 5 years were studied by echocardiography at discharge and at 1 year after surgery.Results62 patients had repair using the DeVega annuloplasty (group A) while 18 had ring annuloplasty (group B). The mean age was 33 ± 6 years and 37 ± 8 years for group A and B respectively. The cardiopulmonary bypass (CPB) time was relatively longer in group B. There was only one mortality in group A. Echocardiography done for all patients of both groups at discharge and at 1 year postoperatively showed no significant difference between both groups.ConclusionTricuspid repair using ring annuloplasty has good results but with no significant benefits over DeVega annuloplasty at one year

Isolation of Thermoalkalophilic-?-amylase Producing Bacteria and Optimization of Potato Waste Water Medium for Enhancement of ?-amylase Production

Sixty one thermoalkalophilic bacteria were isolated from soil samples in Saudi Arabia’s southern region. Isolate TA-38, obtained from the Tanomah region, showed the best performance for enzyme production and was submitted for further study. It was identified as Bacillus axarquiensis based on 16S rRNA gene sequencing studies. The feasibility of using potato waste water as a simple and cheap medium for the production of ?-amylase was evaluated compared with starch broth medium. The production of ?-amylase in the potato waste water medium was only 13.8% less than that of the starch medium. Maximum enzyme production was achieved after 48 hours of cultivation at the beginning of the stationary phase at pH 10.0 and 50 0C. The appropriate addition of starch; nitrogen; phosphate; and calcium to potato waste water significantly enhanced the production of ?-amylase. The enzyme production reached a maximum of 64.5 Uml-1 with the potato wastewater adding with 0.5 % starch; 0.4 % yeast extract; 0.04% CaCl2-2H2O and 0.05 % KH2PO4.  The optimization of the potato waste water medium led to an approximately 4.02 fold increase in the production of ?-amylase compared to starch broth medium. Data indicated that the potato waste water contained substrates which could be used by bacterial isolate for the production of ?-amylase production and the developed procedure was cost effective since it requires only a slightly addition of nutrients to the medium. Keywords: Isolation; ?-amylase; 16S rRNA; Production; Potato waste water; Thermoalkaliphilic bacteria

Crocin mitigates carbon tetrachloride-induced liver toxicity in rats

AbstractObjectivesCarbon tetrachloride (CCl4) is one of the most dangerous hepatotoxic environmental pollutants thus this study aimed at investigating the potential preventive effect and mechanism of crocin against CCl4-induced hepatotoxicity.MethodsForty Male rats were allocated for two weeks treatment with; corn oil, CCl4 in corn oil, crocin (100mg/kg), or crocin plus CCl4. At time of euthanasia liver was removed, weighted and processed for histopathological evaluation and estimation of liver contents of active caspase3, lipid peroxidation (MDA) and reduced glutathione (GSH). We also evaluated antioxidant enzymes activities [superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT)], phase I metabolizing enzyme [cytochrome P450 sub family 2E1 (CYP2E1)] an Phase II metabolizing enzyme, [glutathione-S-transferase (GST)] in liver tissue. Blood samples were used for evaluation of liver function tests and inflammatory cytokines [interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α)].ResultsCCl4 induced significant (p < 0.001), increase in: relative liver weight to body weight, liver MDA content, liver active caspase-3 and plasma levels of IL-6 and TNF-α. In addition, CCl4 disturbed liver histology, liver metabolizing enzymes (CYP2E1 and GST), and liver function tests (aspartate aminotransferase, alanine aminotransferase, total bilirubin and alkaline phosphatase). CCl4 induced significant decrease in activities of SOD, CAT, GSH-Px and GSH content. Administration of crocin with CCl4 mitigated all CCl4-disturbed parameters and preserved liver histology close to normal.ConclusionCrocin ameliorated CCl4-induced liver injury via inhibition of inflammatory cytokines, caspase3 and oxidative stress along with modulation of liver metabolizing enzymes favoring elimination of CCl4 toxic metabolite

Fabrication and characterization of cellulose acetate-based nanofibers and nanofilms for H2S gas sensing application

Electrospun nanofibers and solution-casting nanofilms were produced from an environmentally friendly cellulose acetate (CA) blended with glycerol (as an ionic liquid (IL)), mixed with polypyrrole (PPy, a conducting polymer) and doped with tungsten oxide (WO3) nanoparticles. The sensing membranes fabricated were used to detect H2S gas at room temperature and shown to exhibit high performance. The results revealed that the lowest operating temperature of both nanofiber and nanofilm sensors was 20oC, with a minimum gas detection limit of 1 ppm. Moreover, the sensor exhibits a reasonably fast response, with a minimum average response time of 22.8 and 31.7 s for the proposed nanofiber and nanofilm based sensors, respectively. Furthermore, the results obtained indicated an excellent reproducibility, long-term stability, and low humidity dependence. Such distinctive properties coupled with an easy fabrication technique provide a promising potential to achieve a precise monitoring of harmful H2S gas in both indoor and outdoor atmospheres