4,699 research outputs found

    Numerical investigation of unsteady laminar incompressible co-axial boundary layer flows

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    Finite difference method for analysis of laminar incompressible boundary layer flows at jet exi

    Off Resonant Pumping for Transition from Continuous to Discrete Spectrum and Quantum Revivals in Systems in Coherent States

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    We show that in parametrically driven systems and, more generally, in systems in coherent states, off-resonant pumping can cause a transition from a continuum energy spectrum of the system to a discrete one, and result in quantum revivals of the initial state. The mechanism responsible for quantum revivals in the present case is different from that in the non-linear wavepacket dynamics of systems such as Rydberg atoms. We interpret the reported phenomena as an optical analog of Bloch oscillations realized in Fock space and propose a feasible scheme for inducing Bloch oscillations in trapped ions.Comment: 5 pages, 4 figures, submitted to Jnl. of Optics

    Phosphorylation of the activation loop tyrosine 823 in c-Kit is crucial for cell survival and proliferation.

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    The receptor tyrosine kinase c-Kit, also known as the stem cell factor receptor, plays a key role in several developmental processes. Activating mutations in c-Kit lead to alteration of these cellular processes and have been implicated in many human cancers such as gastrointestinal stromal tumors (GISTs), acute myeloid leukemia (AML), testicular seminomas and mastocytosis. Regulation of the catalytic activity of several kinases is known to be governed by phosphorylation of tyrosine residues in the activation loop of the kinase domain. However, in the case of c-Kit phosphorylation of Y823 has been demonstrated to be a late event that is not required for kinase activation. However, since phosphorylation of Y823 is a ligand-activated event, we sought to investigate the functional consequences of Y823 phosphorylation. By using a tyrosine to phenylalanine mutant of tyrosine 823 we investigated the impact of Y823 on c-Kit signaling. We here demonstrate that Y823 is crucial for cell survival and proliferation and mutation of Y823 to phenylalanine leads to decreased sustained phosphorylation and ubiquitination of c-Kit as compared to the wild-type receptor. Furthermore, the mutated receptor was upon ligand-stimulation quickly internalized and degraded. Phosphorylation of the E3 ubiquitin ligase, Cbl was transient followed by a substantial reduction in phosphorylation of downstream signaling molecules such as Akt, Erk, Shc and Gab2. Thus, we propose that activation loop tyrosine 823 is crucial for activation of both the MAPK and PI3K pathways and that its disruption leads to a destabilization of the c-Kit receptor and decreased survival of cells

    Quantum phase space distributions in thermofield dynamics

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    It is shown that the the quantum phase space distributions corresponding to a density operator ρ\rho can be expressed, in thermofield dynamics, as overlaps between the state ρ>\mid \rho > and "thermal" coherent states. The usefulness of this approach is brought out in the context of a master equation describing a nonlinear oscillator for which exact expressions for the quantum phase distributions for an arbitrary initial condition are derived.Comment: 17 pages, revtex, no figures. number of pages were incorrectly stated as 3 instead of 17. No other correction

    Securing IoT with Trusted Authority Validation in Homomorphic Encryption Technique with ABE

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    Existing security system includes levels of encryption. IoT access is very important aspect. Failure of IoT security can cause more risks of physical and logical damage. IoT contain both functionalities including physical or computational process. In proposed approach, levels of encryption are enhanced by increasing levels of security. User can access IoT through central trusted authority only. Instead of actual data like user credentials or I/O functionality of Internet of things, encrypted data is delivered. Trusted authorities are been involved in secured IoT access structure by considering their credentials. Trusted authority is selected randomly, based on randomized selection algorithm. Based on secured logic, decryption key will be delivered to the IoT through separate channel by trusted authority. Session management has been added by considering initial and waiting time after which all encryption or decryption data will be expired. Homomorphism is applied in encryption process where proposed logic is applied on considered data after which again RSA algorithm is applied. Overall, proposed logical approach, homomorphism, session management, secured access structure and trusted authority involvement improves the security level in IoT access process

    Suppression of auxin stimulated growth of barley coleoptile sections by endosulfan

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    Endosulfan, a cyclic sulphurous acid ester commonly used as a broad spectrum insecticide, suppressed the elongation of barley coleoptiles. Indoleacetic acid at optimum concentration overcame the inhibition of growth of coleoptiles treated with 10 ppm endosulfan. However, perfusion of the coleoptile sections with endosulfan and subsequent treatment with indoleacetic acid could not stimulate cell elongation to the extent observed in the control

    Oxygen Activity Dependence Of The Electrical Conductivity Of Li‐Doped Cr2O3

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    The electrical conductivity of Li‐doped Cr2O3 was investigated as a function of PO2, temperature, and dopant content. Results show that the electrical conductivity remains almost unchanged with decreasing P O2 in the high‐P O2 region but decreases rapidly at low P O2. A second phase was found in samples which contained more than 0.85 mol% Li. The results are explained by a model in which the concentration of charge carriers is dependent on the acceptor dopant and oxygen vacancy concentration. Copyright © 1984, Wiley Blackwell. All rights reserve

    Entanglement by linear SU(2) transformations: generation and evolution of quantum vortex states

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    We consider the evolution of a two-mode system of bosons under the action of a Hamiltonian that generates linear SU(2) transformations. The Hamiltonian is generic in that it represents a host of entanglement mechanisms, which can thus be treated in a unified way. We start by solving the quantum dynamics analytically when the system is initially in a Fock state. We show how the two modes get entangled by evolution to produce a coherent superposition of vortex states in general, and a single vortex state under certain conditions. The degree of entanglement between the modes is measured by finding the explicit analytical dependence of the Von Neumann entropy on the system parameters. The reduced state of each mode is analyzed by means of its correlation function and spatial coherence function. Remarkably, our analysis is shown to be equally as valid for a variety of initial states that can be prepared from a two-mode Fock state via a unitary transformation and for which the results can be obtained by mere inspection of the corresponding results for an initial Fock state. As an example, we consider a quantum vortex as the initial state and also find conditions for its revival and charge conjugation. While studying the evolution of the initial vortex state, we have encountered and explained an interesting situation in which the entropy of the system does not evolve whereas its wave function does. Although the modal concept has been used throughout the paper, it is important to note that the theory is equally applicable for a two-particle system in which each particle is represented by its bosonic creation and annihilation operators.Comment: 6 figure

    Effect of triple drug antiretroviral therapy on CD4+ count in pregnant women with HIV and prevention of parent to child transmission

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    Background: India has moved from single drug Antiretroviral Therapy (ART) in 2002 to triple drug ART in 2013 to prevent parent to child transmission of HIV. The aim of the study was to know the effects of triple drug ART on maternal CD4+ count and prevention of HIV transmission to baby along with its adherence, side effects and pregnancy outcome.Methods: A prospective study wsas done in Safdarjung Hospital, New Delhi on 40 HIV positive pregnant women who received single dose combination of triple drug ART. CD4+ count, LFT and KFT were done before beginning of ART and repeated after 6 months of ART. The infants received nevirapine prophylaxis and HIV status was determined by DBS PCR at 6 weeks.Results: The median CD4+ count was 317 and 397 pre and post ART for 6 months respectively (p value<0.001. Low birth weight (LBW) was seen in 43.59% which was statistically significant but confounded as 76.4% of these babies were preterm. 23.08% of babies had an APGAR of < 7 at 1 minute, out of which 77.7% were preterm. Nine out of 39 infants (one had abortion) needed NICU admission. Only one baby (2.56%) was HIV positive who died at 4 months of age due to pneumonia. There was no defaulter and no statistically significant changes in LFT and KFT after 6 months of ART.Conclusions: Triple drug ART offers greater convenience improves fetomaternal outcome and minimize the risk of HIV transmission from mother to child

    Quantum State Tomography of Complex Multimode Fields using Array Detectors

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    We demonstrate that it is possible to use the balanced homodyning with array detectors to measure the quantum state of correlated two-mode signal field. We show the applicability of the method to fields with complex mode functions, thus generalizing the work of Beck (Phys. Rev. Letts. 84, 5748 (2000)) in several important ways. We further establish that, under suitable conditions, array detector measurements from one of the two outputs is sufficient to determine the quantum state of signals. We show the power of the method by reconstructing a truncated Perelomov state which exhibits complicated structure in the joint probability density for the quadratures.Comment: 14 pages text and 3 figures. To be submitted to PR
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