Opportunistic Secrecy with a Strict Delay Constraint

We investigate the delay limited secrecy capacity of the flat fading channel under two different assumptions on the available transmitter channel state information (CSI). The first scenario assumes perfect prior knowledge of both the main and eavesdropper channel gains. Here, upper and lower bounds on the delay limited secrecy capacity are derived, and shown to be tight in the high signal-to-noise ratio (SNR) regime. In the second scenario, only the main channel CSI is assumed to be available at the transmitter where, remarkably, we establish the achievability of a non-zero delay-limited secure rate, for a wide class of channel distributions, with a high probability. In the two cases, our achievability arguments are based on a novel two-stage key-sharing approach that overcomes the secrecy outage phenomenon observed in earlier works.Comment: Submitted to IEEE Transactions on Information Theor

Pattern of systemic lupus erythematosus in Egyptian patients: the impact of disease activity on the quality of life

INTRODUCTION: Systemic lupus erythematosus (SLE) afflicts young people disproportionately, often at a crucial time in their lives when they are trying to establish relationships, start families and launch careers. As a result, persons with SLE may experience a wide range of physical and psychosocial problems that are not always fully captured by descriptions of the disease’s physiological consequences alone. METHODS: In order to characterize the spectrum of the effects of SLE with regards to disease activity and its impact on the quality of life (QoL), a case control study involving 59 SLE Egyptian patients (mean age 28.6 years , 94.9% females) and 20 healthy controls was undertaken. Disease activity was measured by SLE Disease Activity Index (SLEDAI), and quality of life was measured by Short Form 36 health questionnaire (SF-36). RESULTS: Mucocutaneous and hematological manifestations were present in most of the patients and arthralgia in half of them. All domains of SF-36 including general health, physical functions, physical limitations, energy/fatigue, emotional well-being, pain, social functions, and health changes were significantly lower in SLE patients compared to controls. Except for emotional limitations, all domains were correlated with disease activity and low in class IV-V lupus nephritis. CONCLUSION: Physicians should focus on QoL and how to improve it; health education regarding the negative impact of disease activity on the patients should be given attention. The results of QoL studies help physicians to understand and provide better support to SLE patients beside rapid meticulous control of disease activit

Polymer/Noble Metal Nanocomposites

Recently, the polymeric materials have extensive uses because of their amazing combination of properties, durability, light weight and simplicity of processing. However, these materials face some problems like their weak thermal stability and also poor mechanical stability. Therefore, a large number of additives especially metal nanoparticles were added to polymeric matrix to overcome these problems and designed polymer matrix nanocomposite. A composite is defined as the combination between two individuals or more than one material by physical or mechanical method to get a new material with unique and elegant structure and properties and carrying the feature of the two separated materials and distinguishable interface. Many approaches are used to prepare the polymer nanocomposites such as ex situ, in situ and radiolytic methods. The nanocomposites have important features such as excellent mechanical properties like high stiffness, strength, toughness; good chemical properties like corrosion resistance; and high physical properties like high optical, mechanical, thermal, low density and specific antibacterial properties. The nanocomposite materials with these higher properties have a wonderful and different range of functional applications. The deep view on the synthesis strategies and physical properties of the polymer/noble metal nanocomposites is offered in this book and also their applications in many fields

Epidemiological study of risk factors in pediatric asthma

Background: Childhood asthma is a major public health problem in Egypt and worldwide. Epidemiologic, physiologic, and social factors appear to be associated with an increased risk of asthma. Objective: The aim of the study was to determine the most frequent risk factors of childhood asthma exacerbation and severity in our community. Methods: This cross sectional study involved 206 asthmatic children, 5 to 15 years old. They were enrolled from the School Students Health Insurance facility of El-Matareya Teaching Hospital and from the Pediatric Outpatient Clinic of Saint Mark Charity Hospital representing several social and residential classes. They were assessed clinically and by peak expiratory flow rate (PEFR). Parents of children were interviewed for symptoms and some demographic, social, environmental, housing and familial data as well as asthma triggers through a comprehensive detailed questionnaire. Results: Residential distribution and social status were significantly associated with asthma severity as most moderate persistent asthmatics lived in semi-urban areas (70.8%) and belonged to the low-level segment of social classification (47.9%). In the majority of the study population (69.9%), a family member or more had a positive history of bronchial asthma, and this was especially evident in moderate persistent cases (70.8%). Passive smoking and dust triggered exacerbations in 48.6% and 65% of the studied sample respectively and in most moderate persistent asthmatics (83.4% and 93.7%). Most houses of moderate asthmatics were infested with cockroaches (91.7%) and domestic animals were present in 56.2%. Recurrent chest infections and cold/flu attacks were strongly associated with asthma exacerbation and severity (93.8% and 93.7% of moderate persistent cases respectively). Most moderate persistent asthmatics (91.7%) reported exercise-induced asthma while 64.6% stated that emotional stress triggered their symptoms. Indoor pollutants such as insecticides, household chemicals and odors were strongly associated with asthma severity and exacerbation especially in moderate persistent cases (triggered symptoms in 66.7%, 52.1% and 58.3% of cases respectively). Conclusion: Smoking, emotional stress and dust were the most significant triggers of asthma exacerbation and severity in our series. Identification and avoidance of risk factors for persistent asthma, combined with early institution of pharmacologic and other intervention strategies, may lead to a better outcome.Keywords: asthma severity; asthma triggers; children; residence; risk factors; smoking; social statusEgypt J Pediatr Allergy Immunol 2007; 5(1): 11-1

On the Delay Limited Secrecy Capacity of Fading Channels

In this paper, the delay limited secrecy capacity of the flat fading channel is investigated under two different assumptions on the available transmitter channel state information (CSI). The first scenario assumes perfect prior knowledge of both the main and eavesdropper channel gains. Here, upper and lower bounds on the secure delay limited capacity are derived and shown to be tight in the high signal-to-noise ratio (SNR) regime (for a wide class of channel distributions). In the second scenario, only the main channel CSI is assumed to be available at the transmitter. Remarkably, under this assumption, we establish the achievability of non-zero secure rate (for a wide class of channel distributions) under a strict delay constraint. In the two cases, our achievability arguments are based on a novel two-stage approach that overcomes the secrecy outage phenomenon observed in earlier works.Comment: Proceedings of the 2009 IEEE International Symposium on Information Theory (ISIT 2009), Seoul, Korea, June 28-July 3, 200

Epidemiological study of school performance and asthma medications among asthmatic Egyptian school children

Background: Childhood asthma is a major health problem in Egypt and worldwide. Barriers to reducing the burden of asthma include symptom-based rather than disease-based approaches, tendency of care to be ‘‘acute’’ rather than “regular” and cultural attitudes towards drugs and drug delivery systems. Objective: To measure the disease effect on school performance and to map asthma medications with respect to types, routes and course of use. Methods: This cross sectional study involved 206 Cairene asthmatic school children, enrolled from the school students’ health insurance facility of El-Matareya Teaching Hospital and the pediatric outpatient clinic of Saint Mark Charity Hospital representing different social classes and residential locations. Their ages ranged between 5 and 15 years and they comprised 100 males and 106 females. They were assessed clinically and by peak expiratory flowmetry. Parents or caregivers were interviewed about disease symptoms, school achievement and attendance and medications used including relievers and controllers, route and course of use, whether continuously, intermittently and/or during attacks. Results: Asthma had a strong impact on school achievement and school absence; 77.3% of study population reported school absence due to asthma and 41.3% reported weak to average school achievement. School performance was associated with asthma severity; the majority of moderate asthmatics (64.6%) had average and weak school performance. Number of days of school absence demonstrated highly significant relation with asthma severity; 43.6% of moderate asthmatics had 5-6 absent days/month and 33.4% had 3-4 absent days/month. Combined β2-agonists and xanthines was the most commonly used (54.8%) reliever therapy followed by β2-agonists alone (44.2%) while corticosteroids were the most common controllers used (97.6%). Therapy was taken mainly by oral than inhalation route. Other medications like cromolyns, anti-histamines, anti-leukotrienes and anti-cholinergics were rarely used. Both rectal and injection routes were rarely used also. Conclusion: Asthma has a social burden on asthmatic children as it affects both school achievement and school attendance. Medical management of asthma in Egyptian children still lags behind available medical knowledge. Patients’ and health care givers’ education is a cornerstone in improving the current status of asthma management in Egypt.Keywords: asthma medications; asthma severity; children; school performanceEgypt J Pediatr Allergy Immunol 2009;7(1):23-3

Microencapsulated 3-Dimensional Sensor for the Measurement of Oxygen in Single Isolated Pancreatic Islets

Background: Oxygen consumption reflects multiple processes in pancreatic islets including mechanisms contributing to insulin secretion, oxidative stress and viability, providing an important readout in studies of islet function, islet viability and drug testing. Due to the scarcity, heterogeneity, and intrinsic kinetic properties of individual islets, it would be of great benefit to detect oxygen consumption by single islets. We present a novel method we have developed to image oxygen in single islets. Methodology/Principal Findings: Using a microfluidics system, individual islets and a fluorescent oxygen-sensitive dye were encased within a thin alginate polymer layer. Insulin secretion by the encapsulated islets was normal. Fluorescent signal from the encased dye, detected using a standard inverted fluorescence microscope and digital camera, was stable and proportional to the amount of oxygen in the media. When integrated into a perifusion system, the sensing system detected changes in response to metabolic substrates, mitochondrial poisons, and induced-oscillations. Glucose responses averaged 30.167.1 % of the response to a metabolic inhibitor (cyanide), increases were observed in all cases (n = 6), and the system was able to resolve changes in oxygen consumption that had a period greater than 0.5 minutes. The sensing system operated similarly from 2–48 hours following encapsulation, and viability and function of the islets were not significantly affected by the encapsulation process

Oxygen pressure measurement using singlet oxygen emission

Pressure sensitive paint (PSP) provides a visualization of two-dimensional pressure distributions on airfoil and model automobile surfaces. One type of PSP utilizes platinum tetra(pentafluorophenyl)porphine (PtTFPP) dissolved in a fluoro-polymer film. Since the intense 650 nm triplet emission of PtTFPP is quenched by ground state oxygen, it is possible to measure two-dimensional oxygen concentration from the 650 nm emission intensity using a Stern-Volmer-type relationship. This article reports an alternative luminescence method to measure oxygen concentration based on the porphyrin-sensitized 1270 nm singlet oxygen emission, which can be imaged with an InGaAs near infrared camera. This direct measurement of oxygen emission complements and further validates the oxygen measurement based on PtTFPP phosphorescence quenching. Initial success at obtaining a negative correlation between the 650nm PtTFPP emission and the 1270 nm O_2 emission in solution led us to additional two-dimensional film studies using surfaces coated with PtTFPP, MgTFPP, and H_2TFPP in polymers in a pressure and temperature controlled chamber