A novel real-time MAC layer protocol for wireless sensor network applications

This paper presents a comparative study of existing real-time MAC layer protocols for wireless sensor networks. Then, a new real-Time MAC protocol is presented that is based on a general purpose MAC protocol, called S-MAC. While medium access strategy in S-MAC is based on contention and back-off schemes, protocol proposed in this paper uses feedback approach as a medium access strategy. As a result of this, it increases consistency in data transmission pattern, which enables it to guarantee end-to-end delay deadlines for soft realtime applications. Proposed protocol works in continuous ON mode of operation at MAC layer and is intended to be used for randomly deployed single stream wireless sensor applications. Finally, a comparative performance analysis of proposed realtime protocol is done with other real-time and general purpose MAC protocols for wireless sensor networks

Numerical Simulation of Plane Crack Problems Using Extended Isogeometric Analysis

AbstractThis paper presents the simulation of plane crack problems using extended isogeometric analysis (XIGA). In XIGA, both geometry and solution are approximated using NURBS basis functions. Discontinuous Heaviside function is used to model the crack face, while crack tip singularity is modeled using asymptotic crack tip enrichment functions. Few plane crack problems are solved in the presence of multiple holes and inclusions using XIGA. These simulations show that the SIFs obtained using XIGA gives more accurate results as compared to those obtained by XFEM

Hepatitis E virus: the current scenario

SummaryHepatitis E infection, caused by the hepatitis E virus (HEV), is a common cause of acute hepatitis in developing countries with poor sanitation and hygiene. The virus is classified into four genotypes (1–4) with one serotype. Genotypes 1 and 2 exclusively infect humans, whereas genotypes 3 and 4 also infect other animals, particularly pigs. In endemic areas, large outbreaks of acute hepatitis caused by viruses of genotype 1 or 2 frequently occur due to fecal–oral transmission, usually through contamination of drinking water. With a high attack rate in young adults (aged 15–45 years), the disease is particularly severe among pregnant women (20–30% mortality). HEV appears to be a zoonotic disease, with transmission from pigs, wild boars, and deer, or foodborne. Chronic infections are rare, except in immunosuppressed persons, such as organ transplant recipients. A subunit vaccine has been shown to be effective in preventing the clinical disease, but is not yet commercially available. Our understanding of HEV has undergone major changes in recent years and in this article we review the currently available information with regard to the molecular biology, pathobiology, and epidemiology of HEV infection. We also review the current therapeutic interventions and strategies being used to control HEV infection, with emphasis on possible approaches that could be used to develop an effective vaccine against HEV

Modelling , of Polyurethanes Based on Hydroxyl- Terminated Polybutadiene

Forty formulations based on four different grades ofhydroxyl-terminated polybutadiene, HTPB(hydroxyl value 20- 40 mg KOHlg) at r = [NCO] / [OH] values in the range 0.7 -1.0 with varyingamounts of trimethylol propane and butane diol and containing 86 per cent solid loading wereconsidered to test the applicability of a.-model of Marsh, et al. for prediction of the mechanicalproperties of composite solid propellants. Two network parameters, crosslink density (Ve) andeffective chain length (LX), were calculated from the model. Tensile strength and modulus werecorrelated to Ve and elongation at break to LX. Using the correlations obtained from experimental dataat r< 0.8, mechanical properties of the various fonnulations were predicted. Good agreement betweenexperimental and predicted properties was obtained for fonnulations with modulus 10 KSC. Probablereasons for deviation observed at stoichiometric ratio r < 0.8 and low modulus values are discussed.Improved correlations between mechanical properties and network parameters, applicable over a widerange of fonnulations, were arrived at. The standard errors of prediction were found to be close to :+- 1 0-value of the measurement

Scoping biological indicators of soil quality Phase II. Defra Final Contract Report SP0534

This report presents results from a field assessment of a limited suite of potential biological indicators of soil quality to investigate their suitability for national-scale soil monitoring

Security Issues and Challenges (SIC) of Ad-hoc Networking.

As the approach of ad hoc networking varies from traditional networking approaches, the security aspects that are valid in the conventional wired networks are not fully applicable in the context of ad hoc networks. While the basic security requirements such as confidentiality and authenticity remain, the ad hoc networking approach restricts the set of applicable security mechanisms to be used since the level of security and the performance are related to each other and must be carefully balanced. The security goals and challenges that the field of ad hoc networking faces are explored in more detail. An overview of the most important active attacks is included. Some of the most important security schemes are presented in order to illustrate common approaches that are currently followed to ensure network security in infrastructure less networks. The protected resourceful Ad hoc Distance vector routing protocol (SEAD)[2] employ the use of hash chains to substantiate hop counts and sequence numbers. SEAD[2] is based on the design of the proactive ad hoc routing protocol DSDV[9]. The final secure routing protocol to be presented is the Secure Routing Protocol (SRP)

Carotid Atherosclerosis and Relation to Growth of Infrarenal Aortic Diameter and Follow-up Diameter: The Tromsø Study

AbstractObjectivesThis research aims to study how carotid atherosclerosis is related to growth of infrarenal aortic diameter and aneurysmal formation.DesignPopulation-based follow-up study.Materials and methodsAt baseline, ultrasound examination of the carotid artery and the abdominal aorta was performed in 4241 persons from a general population with no evidence of abdominal aortic aneurysm (AAA). The burden of atherosclerosis was assessed as carotid total plaque area (TPA). After a mean follow-up of 6.3 years, a new ultrasound examination was performed and measurements of the aortic diameter and carotid TPA were repeated. The effects on aortic diameter progression, follow-up diameter and risk for AAA were assessed in multiple linear and logistic regression models according to carotid TPA, adjusted for known risk factors.ResultsWhen analysing AAA as a dichotomous variable, a borderline association between atherosclerosis and AAA could be demonstrated. When modelling aortic diameter as a continuous variable, a 1-SD increase in 5 years' carotid plaque area (ΔTPA) was associated with a 0.12-mm growth in infrarenal aortic diameter (standard error (SE) 0.04) and a 0.20-mm wider aorta at follow-up (SE 0.06). No independent relation was seen for baseline atherosclerosis.ConclusionsCarotid plaque progression was positively related to growth in infrarenal aortic diameter and aortic diameter at follow-up. Whether this co-variation between plaque growth and aortic diameter growth is causally related or independent events is still an open question

Sequential extraction of proanthocyanidin fractions from Ficus species and their effects on rumen enzyme activities in vitro

Three proanthocyanidin fractions per species were sequentially extracted by 50% (v/v) methanol–water, 70% (v/v) acetone–water, and distilled water from leaves of Ficus racemosa (fractions FR) and F. religiosa (fractions FRL) to yield fractions FR-50, FR-70, FR-DW, FRL-50, FRL-70, and FRL-DW. Fractions were examined for their molecular structure, effect on ruminal enzyme activities, and principal leaf protein (Rubisco) solubilization in vitro. All fractions except FRL-70 contained flavonoids including (+) catechin, (−) epicatechin, (+) gallocatechin, (−) epigallocatechin, and their -4-phloroglucinol adducts. The fractions FRL-50 and FRL-DW significantly (p < 0.05) inhibited the activity of ruminal glutamic oxaloacetic transaminase and glutamic pyruvic transaminase. All fractions inhibited glutamate dehydrogenase activity (p < 0.05) with increasing concentration, while protease activity decreased 15–18% with increasing concentrations. Fractions FRL-50 and FRL-DW completely inhibited the activity of cellulase enzymes. Solubilization of Rubisco was higher in F. religiosa (22.36 ± 1.24%) and F. racemosa (17.26 ± 0.61%) than that of wheat straw (WS) (8.95 ± 0.95%) and berseem hay (BH) (3.04 ± 0.08%). A significant (p < 0.05) increase in protein solubilization was observed when WS and BH were supplemented with FR and FRL leaves at different proportions. The efficiency of microbial protein was significantly (p < 0.05) greater in diets consisting of WS and BH with supplementation of F. racemosa leaves in comparison to those supplemented with F. religiosa leaves. The overall conclusion is that the fractions extracted from F. religiosa showed greater inhibitory effects on rumen enzymes and recorded higher protein solubilization in comparison to the F. racemosa. Thus, PAs from F. religiosa are potential candidates to manipulate rumen enzymes activities for efficient utilization of protein and fiber in ruminants

Nonlinear Free Vibration Analysis of Laminated Carbon/Epoxy Curved Panels

Nonlinear frequency responses of the laminated carbon/epoxy composite curved shell panels have been investigated numerically and validated with in-house experimentation. The nonlinear responses have been computed numerically via customised computer code developed in MATLAB environment with the help of current mathematical model in conjunction with the direct iterative method. The mathematical model of the layered composite structure derived using various shear deformable kinematic models (two higher-order theories) in association with Green-Lagrange nonlinear strains. The current model includes all the nonlinear higher-order strain terms in the formulation to achieve generality. Further, the modal test has been conducted experimentally to evaluate the desired frequency values and are extracted via the transformed signals using fast Fourier transform technique. In addition, the results are computed using the simulation model developed in commercial finite element package (ANSYS) via batch input technique. Finally, numerical examples are solved for different geometrical configurations and discussed the effects of other design parameters (thickness ratio, curvature ratio and constraint condition) on the fundamental linear and nonlinear frequency responses in details