501 research outputs found

    Targeting antigens to dendritic cell receptors for vaccine development

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    Dendritic cells (DCs) are highly specialized antigen presenting cells of the immune system which play a key role in regulating immune responses. Depending on the method of antigen delivery, DCs stimulate immune responses or induce tolerance. As a consequence of the dual function of DCs, DCs are studied in the context of immunotherapy for both cancer and autoimmune diseases. In vaccine development, a major aim is to induce strong, specific T-cell responses. This is achieved by targeting antigen to cell surface molecules on DCs that efficiently channel the antigen into endocytic compartments for loading onto MHC molecules and stimulation of T-cell responses. The most attractive cell surface receptors, expressed on DCs used as targets for antigen delivery for cancer and other diseases, are discussed

    Conformally symmetric vacuum solutions of the gravitational field equations in the brane-world models

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    A class of exact solutions of the gravitational field equations in the vacuum on the brane are obtained by assuming the existence of a conformal Killing vector field, with non-static and non-central symmetry. In this case the general solution of the field equations can be obtained in a parametric form in terms of the Bessel functions. The behavior of the basic physical parameters describing the non-local effects generated by the gravitational field of the bulk (dark radiation and dark pressure) is also considered in detail, and the equation of state satisfied at infinity by these quantities is derived. As a physical application of the obtained solutions we consider the behavior of the angular velocity of a test particle moving in a stable circular orbit. The tangential velocity of the particle is a monotonically increasing function of the radial distance and, in the limit of large values of the radial coordinate, tends to a constant value, which is independent on the parameters describing the model. Therefore a brane geometry admitting a one-parameter group of conformal motions may provide an explanation for the dynamics of the neutral hydrogen clouds at large distances from the galactic center, which is usually explained by postulating the existence of the dark matter.Comment: 15 pages, 5 figures, to appear in Annals of Physic

    Self-similar Bianchi models: I. Class A models

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    We present a study of Bianchi class A tilted cosmological models admitting a proper homothetic vector field together with the restrictions, both at the geometrical and dynamical level, imposed by the existence of the simply transitive similarity group. The general solution of the symmetry equations and the form of the homothetic vector field are given in terms of a set of arbitrary integration constants. We apply the geometrical results for tilted perfect fluids sources and give the general Bianchi II self-similar solution and the form of the similarity vector field. In addition we show that self-similar perfect fluid Bianchi VII0_0 models and irrotational Bianchi VI0_0 models do not exist.Comment: 14 pages, Latex; to appear in Classical and Quantum Gravit

    A Modular Approach for a Family of Ground Mobile Robots

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    This paper deals with Epi.q, a family of mobile robots whose main characteristic is a wheel-legged hybrid locomotion. These multi-purpose robots can be successfully exploited for security and surveillance tasks. The document presents state of the art security robotics, the Epi.q mechanical architecture, the concept behind the robot driving unit, three prototypes and the design of a new on

    Wave-like Solutions for Bianchi type-I cosmologies in 5D

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    We derive exact solutions to the vacuum Einstein field equations in 5D, under the assumption that (i) the line element in 5D possesses self-similar symmetry, in the classical understanding of Sedov, Taub and Zeldovich, and that (ii) the metric tensor is diagonal and independent of the coordinates for ordinary 3D space. These assumptions lead to three different types of self-similarity in 5D: homothetic, conformal and "wave-like". In this work we present the most general wave-like solutions to the 5D field equations. Using the standard technique based on Campbell's theorem, they generate a large number of anisotropic cosmological models of Bianchi type-I, which can be applied to our universe after the big-bang, when anisotropies could have played an important role. We present a complete review of all possible cases of self-similar anisotropic cosmologies in 5D. Our analysis extends a number of previous studies on wave-like solutions in 5D with spatial spherical symmetry

    Restoring Holographic Dark Energy in Brane Cosmology

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    We present a generalized version of holographic dark energy arguing that it must be considered in the maximally subspace of a cosmological model. In the context of brane cosmology it leads to a bulk holographic dark energy which transfers its holographic nature to the effective 4D dark energy. As an application we use a single-brane model and we show that in the low energy limit the behavior of the effective holographic dark energy coincides with that predicted by conventional 4D calculations. However, a finite bulk can lead to radically different results.Comment: 11 pages, version published in Phys. Lett.

    JPSEC for Secure Imaging in JPEG 2000

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    In this paper, we first review the on-going JPSEC standardization activity. Its goal is to extend the baseline JPEG 2000 specification to provide a standardized framework for secure imaging, in order to support tools needed to secure digital images, such as content protection, data integrity check, authentication, and conditional access control. We then present two examples of JPSEC tools. The first one is a technique for secure scalable streaming and secure transcoding. It allows the protected JPSEC codestream to be transcoded while preserving the protection, i.e. without requiring unprotecting (e.g. decrypting) the codestream. The second one is a technique for conditional access control. It can be used for access control by resolution or quality, but also by regions of interest
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