Design and analysis of grid stiffened concepts for aircraft composite primary structural applications

An approach to buckling resistant design of general grid stiffened flat plates based on smeared stiffener theory for combined inplane loading is discussed. Some results from parametric studies performed to assess the validity of smeared stiffener for practical stiffener configurations and to illustrate the benefits of different stiffening concepts are given. Details of a design study are discussed where the present analysis method is used to design a grid stiffened panel for a fuselage application and verified using a finite element analysis results

Investigating Potential Therapies to Decrease the Rate of Cystine Stone Growth in Slc3a1-/- Mice

Cystinuria is an autosomal recessive disorder characterized by a defective renal transporter involved in the reabsorption of cystine and other dibasic amino acids. This leads to an accumulation of cystine in the urine, resulting in cystine stones. The SLC3A1/SLC7A9 cystine transporter accounts for 90% of cystine reabsorption and mutations in this transporter result in the formation of cystine stones. For this study, micro-computed tomography (µCT) scanning was evaluated for its feasibility to track accurate volumetric measurements of in vivo cystine stone growth in the Slc3a1-/- cystinuric mouse model. Six pharmacological interventions – sulforaphane, methyl selenocysteine, homocysteine, tiopronin, TPEN and a zinc-supplemented diet– were also examined for their efficacy in reducing the rate of cystine stone growth. µCT analysis revealed stone growth proceeds linearly. Sulforaphane and TPEN supplementation resulted in a reduced rate of stone growth when compared to the respective vehicle controls; however, methyl selenocysteine and the zinc-supplemented diet displayed no effect on the rate or nature of stone formation. Homocysteine and tiopronin were shown to worsen stone growth rate. Sulforaphane and TPEN were effective interventions and our findings support both as a potential therapy for a cystinuric mouse model. A combination of treatments targeting the rate of cystine stone formation through similar agents appears to be a novel approach in further understanding cystine stone growth. Therapies that can manage the balance between these agents and adverse side effects provide an avenue to effectively treating cystinuria

Energy and Load Based Routing Protocol for Mobile Ad-Hoc Networks

A Mobile Ad-hoc Network (MANET) is a network with no infrastructure, operating on wireless mobile nodes. MANET consist of quickly deployable, independent as well as self-configuring nodes with no centralized administration. There is no precise topology and have limited energy and computing resources. Jitter, a random, small variation in timing is widely used in between periodic transmission of the control message in wireless communication protocols. It is an especially important technique during route discovery process when a process may cause a situation where adjacent nodes have to broadcast concurrently, then the use of jitter makes a protocol able to avoid concurrent packet transmissions over the same channel by neighbouring nodes in the network. In AODV jitter, i.e., a small delay during the flooding of a control message is used during route discovery process to avoid simultaneous packet transmission by neighbouring nodes, which might result in the collision between these packets. The proposed energy and load based protocol (ENL-AODV) introduces energy and load factor in the calculation of jitter while forwarding of route requests(RREQ), making it select the path with enough energy to transfer the data packet. As simulation results describe, ENL-AODV improves the efficiency of ad-hoc networks, increases packet delivery ratio, throughput and network lifetime, also decreases average end-to-end delay

Identification and characterization of a toxin-antitoxin system in the pVir plasmid of Campylobacter jejuni

Toxin-antitoxin systems are prevalent in different bacterial organisms and are encoded in the chromosomal or plasmid DNA. The primary function of a plasmid toxin-antitoxin module is to stabilize the plasmid by eliminating plasmid-free daughter cells through a post segregation killing mechanism. In Campylobacter jejuni, a pathogen that causes human gastroenteritis, multiple plasmids have been identified, but there have not been any reports on toxin-antitoxin systems. In this study, a toxin-antitoxin system is identified and characterized in the pVir plasmid of C. jejuni IA 3902. pVir encodes a type IV secretion system and is found to be involved in natural transformation and virulence in Campylobacter. Comparative genomic analysis of the pVir45 and pVir46 genes in C. jejuni indicates that they encode a putative toxin-antitoxin system that belongs to the RelE/StbE family. Cloning and expression of the pVir46 gene alone in Escherichia coli inhibited bacterial growth, but co-expression of pVir45-46 led to the restoration of growth, confirming the functions deduced from comparative genomic analysis. The plasmid stability assay in C. jejuni showed that the toxin-antitoxin system is necessary for maintaining the stability of pVir because deletion of the pVir46 gene resulted in loss of the plasmid during passage in conventional media. qRT-PCR data demonstrated that expression of the pVir45-46 genes varied with growth phase, as early logarithmic phase had the highest level of gene expression. Together these results establish that pVir45-46 encode a functional toxin-antitoxin system in C. jejuni, which is required for ensuring the stability of the pVir plasmid. The stable maintenance of pVir may be necessary for optimal virulence of C. jejuni IA 3902

An evaluation of planarity of the spatial QRS loop by three dimensional vectorcardiography: its emergence and loss

Aims: To objectively characterize and mathematically justify the observation that vectorcardiographic QRS loops in normal individuals are more planar than those from patients with ST elevation myocardial infarction (STEMI). Methods: Vectorcardiograms (VCGs) were constructed from three simultaneously recorded quasi-orthogonal leads, I, aVF and V2 (sampled at 1000 samples/s). The planarity of these QRS loops was determined by fitting a surface to each loop. Goodness of fit was expressed in numerical terms. Results: 15 healthy individuals aged 35–65 years (73% male) and 15 patients aged 45–70 years (80% male) with diagnosed acute STEMI were recruited. The spatial-QRS loop was found to lie in a plane in normal controls. In STEMI patients, this planarity was lost. Calculation of goodness of fit supported these visual observations. Conclusions: The degree of planarity of the VCG loop can differentiate healthy individuals from patients with STEMI. This observation is compatible with our basic understanding of the electrophysiology of the human heart