Self-stabilizing algorithms for Connected Vertex Cover and Clique decomposition problems

In many wireless networks, there is no fixed physical backbone nor centralized network management. The nodes of such a network have to self-organize in order to maintain a virtual backbone used to route messages. Moreover, any node of the network can be a priori at the origin of a malicious attack. Thus, in one hand the backbone must be fault-tolerant and in other hand it can be useful to monitor all network communications to identify an attack as soon as possible. We are interested in the minimum \emph{Connected Vertex Cover} problem, a generalization of the classical minimum Vertex Cover problem, which allows to obtain a connected backbone. Recently, Delbot et al.~\cite{DelbotLP13} proposed a new centralized algorithm with a constant approximation ratio of $2$ for this problem. In this paper, we propose a distributed and self-stabilizing version of their algorithm with the same approximation guarantee. To the best knowledge of the authors, it is the first distributed and fault-tolerant algorithm for this problem. The approach followed to solve the considered problem is based on the construction of a connected minimal clique partition. Therefore, we also design the first distributed self-stabilizing algorithm for this problem, which is of independent interest

Highly sensitive frequency selective surface for structural health monitoring system

This paper is introduced a passive sensor to detect the performance of the structure using three-dimensional (3D) Frequency Selective Surfaces (FSS). The proposed 3D Circular FSS results are proved behave as passive sensor with changing of sensitivity incident angles to be apply in Structural Health Monitoring (SHM) system. Moreover, this 3D Circular FSS capable to operate without stand to any (DC/AC) power and very low cost in term of installation and maintenance

FSS on energy saving glass for rf communication enhancement in modern building

The use of energy saving glass has become very popular in the modern day building design. This energy saving property is achieved by applying a very thin tin oxide (SnO2) coating on one side of the glass. This coating can provide good thermal insulation to the buildings by blocking infrared rays while being transparent to visible part of the spectrum. Drawbacks of these energy saving windows is that it also attenuates the transmission of useful microwave signals through them. These signals fall within the frequency band of 0.8GHz to 2.2GHz. In order to pass these signals through the coated glass, the use of aperture type frequency selective surface (FSS) has being proposed. In the present work, SnO2 thin film with FSS structure was fabricated. Microwave transmission through SnO2 coated glass with FSS structure was also analyzed using network analyzer. The result of computer simulation was confirmed and consistent with the network analyzer results that showed the improvement of SnO2 coated glass with the FSS structure

Frequency selective surfaces on flexible thin plastic substrates

The capability of the flexible substrate of the frequency selective surface (FSS) to filter out particular frequency is discussed in this paper. A new type of FSS are applied using flexible thin plastic substrate to enhance the performance of the conventional FSS that lacks of flexibility and cannot be used in bending surface. A simulation based investigation shows that the diameter or length of the square has a significant effect on the band-stop selective characteristic of the FSS. The frequency response of the band-stop are at 2.45GHz that drop at -10dB

Analysis and design of directive antenna using frequency selective surface superstrate

The design of directive antenna using Frequency Selective Surface (FSS) superstrate is proposed in this project. The suitable design FSS as superstrate layer is very important to enhance the high directivity and narrow bandwidth on the antenna. By using the FSS layer to design the superstrate layer, there are able to determine the reflection coefficient accordingly to the desired frequency

On Thin Flexible Wideband Printed Antenna for Sub-6 GHz Wearable Applications

Abstract Body Area Networks (BANs) have gained significant popularity in recent years, leading to a substantial rise in the demand for wearable antennas. Printed antenna on the flexible substrate can be an excellent choice for wearable since it can be used as a smart garment (i.e. shirt, T-shirt, or jacket). Unlike rigid antennas, the fabrication and measurement procedures for wearable antennas are particularly critical and sensitive. In BANs, the presence of the human body presents another significant challenge such as structural deformation (like bending). This paper has provided an overview of the fabrication process and measurement considerations for printed flexible wearable antenna. It also compared these antennas with conventional copper tape antenna across all aspects. Bending deformation of the printed antenna is performed as well to ensure the antenna's functionality under such circumstances.Abstract Body Area Networks (BANs) have gained significant popularity in recent years, leading to a substantial rise in the demand for wearable antennas. Printed antenna on the flexible substrate can be an excellent choice for wearable since it can be used as a smart garment (i.e. shirt, T-shirt, or jacket). Unlike rigid antennas, the fabrication and measurement procedures for wearable antennas are particularly critical and sensitive. In BANs, the presence of the human body presents another significant challenge such as structural deformation (like bending). This paper has provided an overview of the fabrication process and measurement considerations for printed flexible wearable antenna. It also compared these antennas with conventional copper tape antenna across all aspects. Bending deformation of the printed antenna is performed as well to ensure the antenna's functionality under such circumstances

Host-specific genetic variation of highly pathogenic avian influenza viruses (H5N1)

The complete genome sequences of two isolates A/chicken/Egypt/CL6/07 (CL6/07) and A/duck/Egypt/D2br10/07 (D2br10/07) of highly pathogenic avian influenza virus (HPAI) H5N1 isolated at the beginning of 2007 outbreak in Egypt were determined and compared with all Egyptian HPAI H5N1 sequences available in the GenBank. Sequence analysis utilizing the RNA from the original tissue homogenate showed amino acid substitutions in seven of the viral segments in both samples. Interestingly, these changes were different between the CL6/07 and D2br10/07 when compared to other Egyptian isolates. Moreover, phylogenetic analysis showed independent sub-clustering of the two viruses within the Egyptian sequences signifying a possible differential adaptation in the two hosts. Further, pre-amplification analysis of H5N1 might be necessary for accurate data interpretation and identification of distinct factor(s) influencing the evolution of the virus in different poultry species

Nitric oxide synthases and tubal ectopic pregnancies induced by Chlamydia infection: basic and clinical insights

Human ectopic pregnancy (EP) remains a common cause of pregnancy-related first trimester death. Nitric oxide (NO) is synthesized from L-arginine by three NO synthases (NOS) in different tissues, including the Fallopian tube. Studies of knockout mouse models have improved our understanding of the function of NOS isoforms in reproduction, but their roles and specific mechanisms in infection-induced tubal dysfunction have not been fully elucidated. Here, we provide an overview of the expression, regulation and possible function of NOS isoforms in the Fallopian tube, highlighting the effects of infection-induced changes in the tubal cellular microenvironment (imbalance of NO production) on tubal dysfunction and the potential involvement of NOS isoforms in tubal EP after Chlamydia trachomatis genital infection. The non-equivalent regulation of tubal NOS isoforms during the menstrual cycle suggests that endogenous ovarian steroid hormones regulate NOS in an isoform-specific manner. The current literature suggests that infection with C. trachomatis induces an inflammatory response that eventually leads to tubal epithelial destruction and functional impairment, caused by a high NO output mediated by inducible NOS (iNOS). Therefore, tissue-specific therapeutic approaches to suppress iNOS expression may help to prevent ectopic implantation in patients with prior C. trachomatis infection of the Fallopian tube

Role of Position 627 of PB2 and the Multibasic Cleavage Site of the Hemagglutinin in the Virulence of H5N1 Avian Influenza Virus in Chickens and Ducks

Highly pathogenic H5N1 avian influenza viruses have caused major disease outbreaks in domestic and free-living birds with transmission to humans resulting in 59% mortality amongst 564 cases. The mutation of the amino acid at position 627 of the viral polymerase basic-2 protein (PB2) from glutamic acid (E) in avian isolates to lysine (K) in human isolates is frequently found, but it is not known if this change affects the fitness and pathogenicity of the virus in birds. We show here that horizontal transmission of A/Vietnam/1203/2004 H5N1 (VN/1203) virus in chickens and ducks was not affected by the change of K to E at PB2-627. All chickens died between 21 to 48 hours post infection (pi), while 70% of the ducks survived infection. Virus replication was detected in chickens within 12 hours pi and reached peak titers in spleen, lung and brain between 18 to 24 hours for both viruses. Viral antigen in chickens was predominantly in the endothelium, while in ducks it was present in multiple cell types, including neurons, myocardium, skeletal muscle and connective tissues. Virus replicated to a high titer in chicken thrombocytes and caused upregulation of TLR3 and several cell adhesion molecules, which may explain the rapid virus dissemination and location of viral antigen in endothelium. Virus replication in ducks reached peak values between 2 and 4 days pi in spleen, lung and brain tissues and in contrast to infection in chickens, thrombocytes were not involved. In addition, infection of chickens with low pathogenic VN/1203 caused neuropathology, with E at position PB2-627 causing significantly higher infection rates than K, indicating that it enhances virulence in chickens