16,437 research outputs found
Grayscale-image encryption using Random Hill Cipher over SLn(F) associated with Discrete Wavelet Transformation
Image data are highly sensitive and prone to incidental decoding by intruders. The security of image data in an insecure network is therefore a major issue. In this paper, we have presented a novel approach for grayscale-image encryption and decryption using Random Hill cipher over SLn(F) associated with discrete wavelet transformation. Earlier techniques for encryption and decryption of image data discussed missing the keys, but in this approach, both the keys and the arrangement of RHC are emphasized. Additionally, keys multiplication side (pre or post) over a grayscale-image data matrix also inevitable to know, to correctly decrypt the encrypted image data. In proposed approach, consider keys from special linear group over field F. The key space of the whole cryptosystem is exorbitant. We have presented a computer simulation with a standard examples and the results is given to analyze the robustness of the proposed technique. Security analysis and detailed comparison among earlier developed techniques with proposed approach are also discussed for the robustness of the technique
Current-Induced Spin Polarization in Gallium Nitride
Electrically generated spin polarization is probed directly in bulk GaN using
Kerr rotation spectroscopy. A series of n-type GaN epilayers are grown in the
wurtzite phase both by molecular beam epitaxy (MBE) and metalorganic chemical
vapor deposition (MOCVD) with a variety of doping densities chosen to broadly
modulate the transverse spin lifetime, T2*. The spin polarization is
characterized as a function of electrical excitation energy over a range of
temperatures. Despite weak spin-orbit interactions in GaN, a current-induced
spin polarization (CISP) is observed in the material at temperatures of up to
200 K.Comment: 16 pages, 3 figure
Effects of Dirac sea polarization on hadronic properties - A chiral SU(3) approach
The effect of vacuum fluctuations on the in-medium hadronic properties is
investigated using a chiral SU(3) model in the nonlinear realization. The
effect of the baryon Dirac sea is seen to modify hadronic properties and in
contrast to a calculation in mean field approximation it is seen to give rise
to a significant drop of the vector meson masses in hot and dense matter. This
effect is taken into account through the summation of baryonic tadpole diagrams
in the relativistic Hartree approximation (RHA), where the baryon self energy
is modified due to interactions with both the non-strange and the
strange scalar fields.Comment: 25 pages including 13 figures,figure styles modified,few clarifying
sentences added in text, to appear in Phys. Rev.
Some New Graceful Generalized Classes of Diameter Six Trees
Here we denote a {\it diameter six tree} by , where is the center of the tree; , , and are the vertices of the tree adjacent to ; each is the center of a diameter four tree, each is the center of a star, and each is a pendant vertex. Here we give graceful labelings to some new classes of diameter six trees in which a diameter four tree may contain any combination of branches with the total number of branches odd though with some conditions on the number of odd, even, and pendant branches. Here by a branch we mean a star, i.e. we call a star an odd branch if its center has an odd degree, an even branch if its center has an even degree, and a pendant branch if it is a pendant vertex
Force-induced desorption of a linear polymer chain adsorbed on an attractive surface
We consider a model of self-avoiding walk on a lattice with on-site repulsion
and an attraction for every vertex of the walk visited on the surface to study
force-induced desorption of a linear polymer chain adsorbed on an attractive
surface and use the exact enumeration technique for analyzing how the critical
force for desorption depends on the temperature. The curve
gives the boundary separating the adsorbed phase from the desorbed phase. Our
results show that in two dimensions where surface is a line the force
increases monotonically as temperature is lowered and becomes almost constant
at very low temperatures. In case of three-dimensions we, however, find
re-entrance, i. e. goes through a maximum as temperature is lowered.
The behaviour of the polymer chain at different values of temperature and force
is examined by calculating the probability distribution of the height from the
surface of the vertex at which external force is applied.Comment: Preprint 15 pages with 8figures and two tables. The file table-2d.ps
and table-3d.ps lists C_N(Ns,h) for given N with all possible Ns and h in two
and three dimension
Dissolution Behaviour of Fe-Co Alloy in Leaching of Sea-Nodule
Recovery of cobalt from the ammoniacal leaching of polymetallic sea-nodules was often found around 50%, whereas copper and nickel recovered in the range of 90-95%. It is believed that Fe-Co alloy system form during reduction roasting is very stable to ammonia solution. To enhance the cobalt recovery some additives were selected and it was observed that by the use of these additives electrochemical dissolution rate increases in comparison to the system without any additive. Also, the presence of additive lowers the dissolution potential to –454 mV which is a requirement for better recovery of cobalt. Work was further extended with the use of metals powder in pure as well as mixed condition in presence these additives and it was found that cobalt recovery increased above 80%
Long-term occupational exposure to DDT
Blood serum of twenty workers occupationally exposed to DDT for an average duration of 14 years was analysed for organochlorine pesticides by gas-liquid chromatography with an electron capture detector. Significant levels of BHC, p,p'-DDT, p,p'-DDD and p,p-DDE were detected. A higher incidence of total DDT equivalent, about 10 times, was observed in DDT exposed workers when compared with a comparable sample of unexposed persons from the general population. Levels of DDT in serum of occupationally exposed workers were more than the permitted level of 200 ppb. The daily intake was computed to be about 10 mg/man/day as against 0.25 mg-the acceptable daily intale. Abnormal nerve conduction was encountered in a few cases of DDT sprayers. No significant correlation was observed between the total DDT equivalent in serum and duration of occupational exposure in workers. Levels of BHC in controls was 2.3 times the level in exposed workers, possibly due to induction of hepatic drug metabolising enzymes by high levels of DDT in the latter group. Findings are discussed in the light of existing knowledge of the bio-chemical effects evoked due to residual intoxication of DDT during occupational exposure
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