139 research outputs found

    Design and Discovery of Sensor Web Registry Services for Wireless Sensor Network with x-SOA Approach

    Get PDF
    The application of wireless sensor network is emerging as a new trend in different sphere of modern society. However due to the advancement of SWE, designing & discovering sensor web registry services throughout heterogeneous environments is becoming a challenging task and raises several concerns like performance, reliability, and robustness. Many approaches and frameworks have been proposed to discover the sensor web registry services. Some of the approaches assume that the requests are placed in SOAP compatible formats while others focus on GUI based parametric query processing. We have formulated an approach that uses the Natural Language Query Processing which is a convenient and easy method of data access, especially for casual users who do not understand complicated database query languages such as SQL or XML based Query Language like XQuery and XPath. SOA is the proven technology for designing an efficient Sensor Web Registry by describing various parameters and sensor web services needed. We also propose an architecture based on x-SOA that organizes the method of sensor web registry service discovery in an efficient and structured manner using an intermediary, requester friendly layer called the Request Parser & Query Generator (RPQ) between the service provider and service requester via a service registry. We describe how RPQ facilitates the processing of plain text request query to a most appropriate sensor web service and also an algorithm with implementation for a complete cycle of sensor web registry service discovery

    The nature of sulphation of uronic acid-containing glycosaminoglycans catalysed by brain sulphotransferase

    Get PDF
    A sulphotransferase system of rat brain catalyses the transfer of sulphate from 3'-phosphoadenosine 5'-phosphosulphate to the low-sulphated glycosaminoglycans isolated from normal adult human brain. These were shown to be precursors of higher-sulphated glycosaminoglycans by DEAE-Sephadex column chromatography and paper electrophoresis. Nitrous acid degradation and mild acid hydrolysis of enzymically-sulphated fractions further confirmed the presence of heparan sulphate in human brain. A partially purified sulphotransferase preparation was obtained from neonatal human brain using chondroitin-4-sulphate as sulphate acceptor. This sulphotransferase catalyses the transfer of sulphate to the various uronic acid containing glycosaminoglycans. Heparan sulphate was the best sulphate acceptor followed by dermatan sulphate, N-desulphoheparin, chondroitin-4-sulphate and chondroitin-6-sulphate in decreasing order. Sulphotransferase obtained from 1-day-old rat, rabbit and guinea pig brain also had the same pattern of specificity towards various sulphate acceptors. This sulphotransferase catalyses both N-sulphation and O-sulphation. Studies on the sulphotransferase obtained from both rat and human brain of various age groups indicate that the ratio of N-sulphation: O-sulphation decreases as the brain matures

    Lead-Acid Battery Model Under Discharge with a Fast Splitting Method

    Full text link
    A mathematical model of a valve-regulated lead-acid battery under discharge is presented as simplified from a standard electrodynamics model. This nonlinear reaction–diffusion model of a battery cell is solved using an operator splitting method to quickly and accurately simulate sulfuric acid concentration. This splitting method incorporates one-sided approximation schemes to preserve continuity over material interfaces encompassing discontinuous parameters. Numerical results are compared with measured data by calculating battery voltage from modeled acid concentration as derived from the Nernst equation

    Design of RF Receiver Front end Subsystems with Low Noise Amplifier and Active Mixer for Intelligent Transportation Systems Application

    Get PDF
    This paper presents the design, simulation, and characterization of a novel low-noise amplifier (LNA) and active mixer for intelligent transportation system applications. A low noise amplifier is the key component of RF receiver systems. Design, simulation, and characterization of LNA have been performed to obtain the optimum value of noise figure, gain and reflection coefficient. Proposed LNA achieves measured voltage gains of ~18 dB, reflection coefficients of -20 dB, and noise figures of ~2 dB at 5.9 GHz, respectively. The active mixer is a better choice for a modern receiver system over a passive mixer. Key sight advanced design system in conjunction with the electromagnetic simulation tool, has been to obtain the optimal conversion gain and noise figure of the active mixer. The lower and upper resonant frequencies of mixer have been obtained at 2.45 GHz and 5.25 GHz, respectively. The measured conversion gains at lower and upper frequencies are 12 dB and 10.2 dB, respectively. The measured noise figures at lower and upper frequencies are 5.8 dB and 6.5 dB, respectively. The measured mixer interception point at lower and upper frequencies are 3.9 dBm and 4.2 dBm

    Shape transition in ZnO nanostructures and its effect on blue-green photoluminescence

    Get PDF
    We report that ZnO nanostructures synthesized by chemical route undergo a shape transition at ~ 20 nm from spherical to hexagonal morphology thereby changing the spectral components of the blue-green emission. Spherically shaped nanocrystals (size range 11 -18 nm) show emission in the range of 555-564 nm and the emission shifts to the longer wavelength as the size increases. On the other hand, rods and hexagonal platelets (size range 20-85 nm), which is the equilibrium morphology after the shape transition, show emission near 465-500 nm and it shifts to shorter wavelength as the size increases. The shape transition also leads to relaxation of microstrain in the system. Our analysis shows that the visible emission originates from a defect layer on the nanostructure surface which is affected by the shape transition. The change in the spectral component of the blue green emission on change of shape has been explained as arising from band bending due to depletion layer in smaller spherical particles which is absent in the larger particles with flat faces.Comment: 8 pages, 8 figure

    Electromagnetically induced transparency in cold 85Rb atoms trapped in the ground hyperfine F = 2 state

    Full text link
    We report electromagnetically induced transparency (EIT) in cold 85Rb atoms, trapped in the lower hyperfine level F = 2, of the ground state 52S1/2^{2}S_{1/2} (Tiwari V B \textit{et al} 2008 {\it Phys. Rev.} A {\bf 78} 063421). Two steady state Λ\Lambda-type systems of hyperfine energy levels are investigated using probe transitions into the levels F′^{\prime} = 2 and F′^{\prime} = 3 of the excited state 52P3/2^{2}P_{3/2} in the presence of coupling transitions F = 3 →\to F′^{\prime} = 2 and F = 3 →\to F′^{\prime} = 3, respectively. The effects of uncoupled magnetic sublevel transitions and coupling field's Rabi frequency on the EIT signal from these systems are studied using a simple theoretical model.Comment: 12 pages, 7 figure

    Role of Surface Area, Primary Particle Size, and Crystal Phase on Titanium Dioxide Nanoparticle Dispersion Properties

    Get PDF
    Characterizing nanoparticle dispersions and understanding the effect of parameters that alter dispersion properties are important for both environmental applications and toxicity investigations. The role of particle surface area, primary particle size, and crystal phase on TiO2 nanoparticle dispersion properties is reported. Hydrodynamic size, zeta potential, and isoelectric point (IEP) of ten laboratory synthesized TiO2 samples, and one commercial Degussa TiO2 sample (P25) dispersed in different solutions were characterized. Solution ionic strength and pH affect titania dispersion properties. The effect of monovalent (NaCl) and divalent (MgCl2) inert electrolytes on dispersion properties was quantified through their contribution to ionic strength. Increasing titania particle surface area resulted in a decrease in solution pH. At fixed pH, increasing the particle surface area enhanced the collision frequency between particles and led to a higher degree of agglomeration. In addition to the synthesis method, TiO2 isoelectric point was found to be dependent on particle size. As anatase TiO2 primary particle size increased from 6 nm to 104 nm, its IEP decreased from 6.0 to 3.8 that also results in changes in dispersion zeta potential and hydrodynamic size. In contrast to particle size, TiO2 nanoparticle IEP was found to be insensitive to particle crystal structure

    Erythropoietin Amplifies Stroke-Induced Oligodendrogenesis in the Rat

    Get PDF
    Erythropoietin (EPO), a hematopoietic cytokine, enhances neurogenesis and angiogenesis during stroke recovery. In the present study, we examined the effect of EPO on oligodendrogenesis in a rat model of embolic focal cerebral ischemia.Recombinant human EPO (rhEPO) at a dose of 5,000 U/kg (n = 18) or saline (n = 18) was intraperitoneally administered daily for 7 days starting 24 h after stroke onset. Treatment with rhEPO augmented actively proliferating oligodendrocyte progenitor cells (OPCs) measured by NG2 immunoreactive cells within the peri-infarct white matter and the subventricular zone (SVZ), but did not protect against loss of myelinating oligodendrocytes measured by cyclic nucleotide phosphodiesterase (CNPase) positive cells 7 days after stroke. However, 28 and 42 days after stroke, treatment with rhEPO significantly increased myelinating oligodendrocytes and myelinated axons within the peri-infarct white matter. Using lentivirus to label subventricular zone (SVZ) neural progenitor cells, we found that in addition to the OPCs generated in the peri-infarct white matter, SVZ neural progenitor cells contributed to rhEPO-increased OPCs in the peri-infarct area. Using bromodeoxyuridine (BrdU) for birth-dating cells, we demonstrated that myelinating oligodendrocytes observed 28 days after stroke were derived from OPCs. Furthermore, rhEPO significantly improved neurological outcome 6 weeks after stroke. In vitro, rhEPO increased differentiation of adult SVZ neural progenitor cells into oligodendrocytes and enhanced immature oligodendrocyte cell proliferation.Our in vivo and in vitro data indicate that EPO amplifies stroke-induced oligodendrogenesis that could facilitate axonal re-myelination and lead to functional recovery after stroke

    Inflammasome-dependent Pyroptosis and IL-18 Protect against Burkholderia pseudomallei Lung Infection while IL-1β Is Deleterious

    Get PDF
    Burkholderia pseudomallei is a Gram-negative bacterium that infects macrophages and other cell types and causes melioidosis. The interaction of B. pseudomallei with the inflammasome and the role of pyroptosis, IL-1β, and IL-18 during melioidosis have not been investigated in detail. Here we show that the Nod-like receptors (NLR) NLRP3 and NLRC4 differentially regulate pyroptosis and production of IL-1β and IL-18 and are critical for inflammasome-mediated resistance to melioidosis. In vitro production of IL-1β by macrophages or dendritic cells infected with B. pseudomallei was dependent on NLRC4 and NLRP3 while pyroptosis required only NLRC4. Mice deficient in the inflammasome components ASC, caspase-1, NLRC4, and NLRP3, were dramatically more susceptible to lung infection with B. pseudomallei than WT mice. The heightened susceptibility of Nlrp3-/- mice was due to decreased production of IL-18 and IL-1β. In contrast, Nlrc4-/- mice produced IL-1β and IL-18 in higher amount than WT mice and their high susceptibility was due to decreased pyroptosis and consequently higher bacterial burdens. Analyses of IL-18-deficient mice revealed that IL-18 is essential for survival primarily because of its ability to induce IFNγ production. In contrast, studies using IL-1RI-deficient mice or WT mice treated with either IL-1β or IL-1 receptor agonist revealed that IL-1β has deleterious effects during melioidosis. The detrimental role of IL-1β appeared to be due, in part, to excessive recruitment of neutrophils to the lung. Because neutrophils do not express NLRC4 and therefore fail to undergo pyroptosis, they may be permissive to B. pseudomallei intracellular growth. Administration of neutrophil-recruitment inhibitors IL-1ra or the CXCR2 neutrophil chemokine receptor antagonist antileukinate protected Nlrc4-/- mice from lethal doses of B. pseudomallei and decreased systemic dissemination of bacteria. Thus, the NLRP3 and NLRC4 inflammasomes have non-redundant protective roles in melioidosis: NLRC4 regulates pyroptosis while NLRP3 regulates production of protective IL-18 and deleterious IL-1β
    • …
    corecore