501 research outputs found
Targeting antigens to dendritic cell receptors for vaccine development
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
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
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 VII models and irrotational Bianchi
VI 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
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
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
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
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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