3,449 research outputs found
Negative differential resistance in nanoscale transport in the Coulomb blockade
Motivated by recent experiments, we have studied transport behavior of
coupled quantum dot systems in the Coulomb blockade regime using the master
(rate) equation approach. We explore how electron-electron interactions in a
donor-acceptor system, resembling weakly coupled quantum dots with varying
charging energy, can modify the systems response to an external bias, taking it
from normal Coulomb blockade behavior to negative differential resistance (NDR)
in the curent-voltage characteristics
Neutron matter - Quark matter phase transition and Quark star
We consider the neutron matter quark matter phase transition along with
possible existence of hybrid quark stars. The equation of state for neutron
matter is obtained using a nonperturbative method with pion dressing of the
neutron matter and an analysis similar to that of symmetric nuclear matter. The
quark matter sector is treated perturbatively in the small distance domain. For
bag constant =148 MeV, a first order phase transition is seen. In the
context of neutron quark hybrid stars, Tolman-Oppenheimer-Volkoff equations are
solved using the equations of state for quark matter and for neutron matter
with a phase transition as noted earlier. Stable solutions for such stars are
obtained with the Chandrasekhar limit as 1.58 and radius around 10
km. The bulk of the star is quark matter with a thin crust of neutron matter of
less than a kilometer.Comment: 28 pages including 9 figures, Revtex, IP/BBSR/92-8
Radiative stability of neutrino-mass textures
Neutrino-mass textures proposed at high-scales are known to be unstable
against radiative corrections especially for nearly degenerate eigen values.
Within the renormalization group constraints we find a mechanism in a class of
gauge theories which guarantees reproduction of any high-scale texture at low
energies with radiative stability. We also show how the mechanism explains
solar and atmospheric neutrino anomalies through the bimaximal texture at high
scale.Comment: 4 pages REVTEX, 1 Postscript fi
A Blind Signature Scheme using Biometric Feature Value
Blind signature has been one of the most charming research fields of public key cryptography through which authenticity, data integrity and non-repudiation can be verified. Our research is based on the blind signature schemes which are based on two hard problems – Integer factorization and discrete logarithm problems. Here biological information like finger prints, iris, retina DNA, tissue and other features whatever its kind which are unique to an individual are embedded into private key and generate cryptographic key which consists of private and public key in the public key cryptosystem. Since biological information is personal identification data, it should be positioned as a personal secret key for a system. In this schemes an attacker intends to reveal the private key knowing the public key, has to solve both the hard problems i.e. for the private key which is a part of the cryptographic key and the biological information incorporated in it. We have to generate a cryptographic key using biometric data which is called biometric cryptographic key and also using that key to put signature on a document. Then using the signature we have to verify the authenticity and integrity of the original message. The verification of the message ensures the security involved in the scheme due to use of complex mathematical equations like modular arithmetic and quadratic residue as well
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