153 research outputs found
Malicious vehicle detection based on beta reputation and trust management for secure communication in smart automotive cars network
High reliance on wireless network connectivity makes the vehicular ad hoc network (VANET) vulnerable to several kinds of cyber security threats. Malicious vehicles accessing the network can lead to hazardous situation by disseminating misleading information or data in the network or by performing cyber-attacks. It is a requirement that the information must be originated from the authentic and authorized vehicle and confidentiality must be maintained. In these circumstances, to protect the network from malicious vehicles, reputation system based on beta probability distribution with trust management model has been proposed to differentiate trustworthy vehicles from malicious vehicles. The trust model is based on adaptive neuro fuzzy inference system (ANFIS) which takes trust metrics as input to evaluate the trustworthiness of the vehicles. The simulation platform for the model is in MATLAB. Simulation results show that the vehicles need at least 80% trustworthiness to be considered as a trusted vehicle in the network
Spatial distribution and functional significance of activated vinculin in living cells
Conformational change is believed to be important to vinculin's function at sites of cell adhesion. However, nothing is known about vinculin's conformation in living cells. Using a Forster resonance energy transfer probe that reports on changes in vinculin's conformation, we find that vinculin is in the actin-binding conformation in a peripheral band of adhesive puncta in spreading cells. However, in fully spread cells with established polarity, vinculin's conformation is variable at focal adhesions. Time-lapse imaging reveals a gradient of conformational change that precedes loss of vinculin from focal adhesions in retracting regions. At stable or protruding regions, recruitment of vinculin is not necessarily coupled to the actin-binding conformation. However, a different measure of vinculin conformation, the recruitment of vinexin β by activated vinculin, shows that autoinhibition of endogenous vinculin is relaxed at focal adhesions. Beyond providing direct evidence that vinculin is activated at focal adhesions, this study shows that the specific functional conformation correlates with regional cellular dynamics
Genetic transformation of Artemisia carvifolia Buch with rol genes enhances artemisinin accumulation
The potent antimalarial drug artemisinin has a high cost, since its only viable source to date is Artemisia annua (0.010.8% DW). There is therefore an urgent need to design new strate- gies to increase its production or to find alternative sources. In the current study, Artemisia carvifolia Buch was selected with the aim of detecting artemisinin and then enhancing the production of the target compound and its derivatives. These metabolites were determined by LC-MS in the shoots of A. carvifolia wild type plants at the following concentrations: arte- misinin (8ÎĽg/g), artesunate (2.24ÎĽg/g), dihydroartemisinin (13.6ÎĽg/g) and artemether (12.8ÎĽg/g). Genetic transformation of A. carvifolia was carried out with Agrobacterium tumefaciens GV3101 harboring the rol B and rol C genes. Artemisinin content increased 3-7-fold in transgenics bearing the rol B gene, and 2.3-6-fold in those with the rol C gene. A similar pattern was observed for artemisinin analogues. The dynamics of artemisinin con- tent in transgenics and wild type A.carvifolia was also correlated with the expression of genes involved in its biosynthesis. Real time qPCR analysis revealed the differential expression of genes involved in artemisinin biosynthesis, i.e. those encoding amorpha-4, 11 diene synthase (ADS), cytochrome P450 (CYP71AV1), and aldehyde dehydrogenase 1 (ALDH1), with a relatively higher transcript level found in transgenics than in the wild type plant. Also, the gene related to trichome development and sesquiterpenoid biosynthesis (TFAR1) showed an altered expression in the transgenics compared to wild type A.carvifolia, which was in accordance with the trichome density of the respective plants. The trichome index was significantly higher in the rol B and rol C gene-expressing transgenics with an increased production of artemisinin, thereby demonstrating that the rol genes are effective inducers of plant secondary metabolism
Elastomer-based skins for morphing aircraft applications: Effect of biaxial strain rates and prestretch
There is an emerging trend in the morphing aircraft research where two or more morphing degrees of freedom are used on a wing which leads to the concept of polymorphing. The skin of the morphing wing must be flexible in the morphing direction but stiff in other directions to withstand the aerodynamic loads and maintain the airfoil shape. Polymorphing changes the loadings profile (from uniaxial to biaxial) and increases the complexity of designing suitable morphing skins. Furthermore, elastomeric materials used on morphing wings are usually prestretched to prevent wrinkling and to increase their out-of-plane stiffness. This paper focuses on elastomeric morphing skins and it studies the effect of biaxial strain rates and prestretch ratios on important mechanical properties such as stiffness, hysteresis losses (%), and stress relaxations (%) from an experimental perspective. Three polymeric materials are considered: Latex, Oppo, and Ecoflex. This study provides a mechanical comparative understanding of the three polymers used in the morphing wing under biaxial loading (two morphing degrees of freedom)
Biochemical characterization of thermostable cellulase enzyme from mesophilic strains of actinomycete
A few mesophilic strains of actinomycete were used for detection, extraction and characterization of cellulase enzymes. These strains responded to produce all the three components of cellulase complex (endoglucanase, exoglucanase and â-glucosidase) in balanced quantities. Cellulase activity was determined on solid medium supplemented with 1% carboxy methyl cellulose (CMC). Production of cellulase was detected by the formation of clear or transparent zone around colonies. The greater size of transparent zone has been found proportional to the higher capabilities of the strains for enzymes. The extraction of cellulase enzyme was done in liquid basal medium. The assay of cellulase was observed by measuring the release of reducing sugar (RS) by DNS method. All the three components of cellulase viz. endoglucanase, exoglucanase and â -glucosidase were assayed in terms of CMCase, FPase and cellobiase, respectively and expressed in International units (IU). These strains were further tested for their ability to produce cellulase complex enzyme by growing on a defined substrates as well as on delignified cellulosics. The optimization for â-glucosidase enzyme was carried out by studying the various parameters viz. effect of pH, incubation period and nitrogen sources.Key words: Cellulase, actinomycete, optimization, reducing sugar, carboxy methyl cellulose
Enhanced artemisinin yield by expression of rol genes in artemisia annua
Background: Despite of many advances in the treatment of malaria, it is still the fifth most prevalent disease worldwide and is one of the major causes of death in the developing countries which accounted for 584,000 deaths in 2013, as estimated by World Health Organization. Artemisinin from Artemisia annua is still one of the most effective treatments for malaria. Increasing the artemisinin content of A. annua plants by genetic engineering would improve the availability of this much-needed drug. Methods: In this regard, a high artemisinin-yielding hybrid of A. annua produced by the centre for novel agricultural products of the University of York, UK, was selected (artemisinin maximally 1.4 %). As rol genes are potential candidates of biochemical engineering, genetic transformation of A. annua with Agrobacterium tumefaciens GV3101 harbouring vectors with rol B and rol C genes was carried out with the objective of enhancement of artemisinin content. Transgenic lines produced were analysed by the LC-MS for quantitative analysis of artemisinin and analogues. These high artemisinin yielding transgenics were also analysed by real time quantitative PCR to find the molecular dynamics of artemisinin enhancement. Genes of artemisinin biosynthetic pathway were studied including amorphadiene synthase (ADS), cytochrome P450, (CYP71AV1) and aldehyde dehydrogenase 1 (ALDH1). Trichome-specific fatty acyl-CoA reductase 1(TAFR1) is an enzyme involved in both trichome development and sesquiterpenoid biosynthesis and both processes are important for artemisinin biosynthesis. Thus, real time qPCR analysis of the TAFR1 gene was carried out, and trichome density was determined. Results: Transgenics of rol B gene showed two- to ninefold (the decimal adds nothing in the abstract, please simplify to two- to ninefold) increase in artemisinin, 4-12-fold increase in artesunate and 1.2-3-fold increase in dihydroartemisinin. Whereas in the case of rol C gene transformants, a fourfold increase in artemisinin, four to ninefold increase in artesunate and one- to twofold increase in dihydroartemisinin concentration was observed. Transformants with the rol B gene had higher expression of these genes than rol C transformants. TAFR1 was also found to be more expressed in rol gene transgenics than wild type A. annua, which was also in accordance with the trichome density of the respective plant. Conclusion: Thus it was proved that rol B and rol C genes are effective in the enhancement of artemisinin content of A. annua, rol B gene being more active to play part in this enhancement than rol C gene
FastSurfer-HypVINN: Automated sub-segmentation of the hypothalamus and adjacent structures on high-resolutional brain MRI
The hypothalamus plays a crucial role in the regulation of a broad range of
physiological, behavioural, and cognitive functions. However, despite its
importance, only a few small-scale neuroimaging studies have investigated its
substructures, likely due to the lack of fully automated segmentation tools to
address scalability and reproducibility issues of manual segmentation. While
the only previous attempt to automatically sub-segment the hypothalamus with a
neural network showed promise for 1.0 mm isotropic T1-weighted (T1w) MRI, there
is a need for an automated tool to sub-segment also high-resolutional (HiRes)
MR scans, as they are becoming widely available, and include structural detail
also from multi-modal MRI. We, therefore, introduce a novel, fast, and fully
automated deep learning method named HypVINN for sub-segmentation of the
hypothalamus and adjacent structures on 0.8 mm isotropic T1w and T2w brain MR
images that is robust to missing modalities. We extensively validate our model
with respect to segmentation accuracy, generalizability, in-session test-retest
reliability, and sensitivity to replicate hypothalamic volume effects (e.g.
sex-differences). The proposed method exhibits high segmentation performance
both for standalone T1w images as well as for T1w/T2w image pairs. Even with
the additional capability to accept flexible inputs, our model matches or
exceeds the performance of state-of-the-art methods with fixed inputs. We,
further, demonstrate the generalizability of our method in experiments with 1.0
mm MR scans from both the Rhineland Study and the UK Biobank. Finally, HypVINN
can perform the segmentation in less than a minute (GPU) and will be available
in the open source FastSurfer neuroimaging software suite, offering a
validated, efficient, and scalable solution for evaluating imaging-derived
phenotypes of the hypothalamus.Comment: Submitted to Imaging Neuroscienc
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