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

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

Measuring arbitrary-order coherences: Tomography of single-mode multiphoton polarization-entangled states

A scheme is discussed for measuring Nth-order coherences of two orthogonally polarized light fields in a single spatial mode at very limited experimental cost. To implement the scheme, the only measurements needed are the Nth-order intensity moments after the light beam has passed through two quarter-wave plates, one half-wave plate, and a polarizing beam splitter for specific settings of the wave plates. It is shown that this method can be applied for arbitrarily large N. A set of explicit values is given for the settings of the wave plates, constituting an optimal measurement of the Nth-order coherences for any N. For Fock states the method introduced here corresponds to a full state tomography. Applications of the scheme to systems other than polarization optics are discussed.Comment: 6 pages, 1 figure, 1 table, published versio

Mesophase behaviour of polyhedral particles

Translational and orientational excluded-volume fields encoded in particles with anisotropic shapes can lead to purely entropy-driven assembly of morphologies with specific order and symmetry. To elucidate this complex correlation, we carried out detailed Monte Carlo simulations of six convex space-filling polyhedrons, namely, truncated octahedrons, rhombic dodecahedrons, hexagonal prisms, cubes, gyrobifastigiums and triangular prisms. Simulations predict the formation of various new liquid-crystalline and plastic-crystalline phases at intermediate volume fractions. By correlating these findings with particle anisotropy and rotational symmetry, simple guidelines for predicting phase behaviour of polyhedral particles are proposed: high rotational symmetry is in general conducive to mesophase formation, with low anisotropy favouring plastic-solid behaviour and intermediate anisotropy (or high uniaxial anisotropy) favouring liquid-crystalline behaviour. It is also found that dynamical disorder is crucial in defining mesophase behaviour, and that the apparent kinetic barrier for the liquid-mesophase transition is much lower for liquid crystals (orientational order) than for plastic solids (translational order).This work was supported by a Department of Energy Basic Energy Science Grant ER46517. This publication is based on work supported in part by award no. KUS-C1-018-02, made by King Abdullah University of Science and Technology (KAUST)

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

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.

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

It is shown that the the quantum phase space distributions corresponding to a density operator $\rho$ can be expressed, in thermofield dynamics, as overlaps between the state $\mid \rho >$ 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

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

Ultrafast electron dynamics at water covered alkali adatoms adsorbed on Cu(111)

Here we report on the ultrafast electron dynamics of the alkalis Na, K, and Cs coadsorbed with D2O on Cu(111) surfaces, which we investigated with femtosecond time-resolved two-photon photoemission. The well known transient electronic binding energy stabilization in bare adsorbed alkalis is enhanced by the presence of water which acts as a solvent and increases the transient energy gain. We observe for all adsorbed alkalis a transient binding energy stabilization of 100–300 meV. The stabilization rates range from 1 to 2 eV ps-1. Here the heavier alkali exhibits a slower stabilization which we explain by their weaker static alkali–water interaction observed in thermal desorption spectroscopy. The population dynamics at low water coverage is described by a single exponential. With increasing water coverage the behavior becomes non-exponential suggesting an additional excited state due to electron solvatio

Suppression of auxin stimulated growth of barley coleoptile sections by endosulfan

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

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