180,803 research outputs found
Random Isotropic Structures and Possible Glass Transitions in Diblock Copolymer Melts
We study the microstructural glass transitions in diblock-copolymer melts
using a thermodynamic replica approach. Our approach performs an expansion in
terms of the natural smallness parameter -- the inverse of the scaled degree of
polymerization, which allows us to systematically study the approach to
mean-field behavior as the degree of polymerization increases. We find that in
the limit of infinite long polymer chains, both the onset of glassiness and the
vitrification transition (Kauzmann temperature) collapse to the mean-field
spinodal, suggesting that the spinodal can be regarded as the mean-field
signature for glass transitions in this class of systems. We also study the
order-disorder transitions (ODT) within the same theoretical framework; in
particular, we include the leading-order fluctuation corrections due to the
cubic interaction in the coarse-grained Hamiltonian, which has been ignored in
previous works on the ODT in block copolymers. We find that the cubic term
stabilizes both the ordered (body-centered-cubic) phase and the glassy state
relative to the disordered phase. While in melts of symmetric copolymers the
glass transition always occurs after the order-disorder transition (below the
ODT temperature), for asymmetric copolymers, it is possible that the glass
transition precedes the ordering transition.Comment: An error corrected in the referenc
Further results on independent Metropolis-Hastings-Klein sampling
Sampling from a lattice Gaussian distribution is emerging as an important problem in coding and cryptography. This paper gives a further analysis of the independent Metropolis-Hastings-Klein (MHK) algorithm we presented at ISIT 2015. We derive the exact spectral gap of the induced Markov chain, which dictates the convergence rate of the independent MHK algorithm. Then, we apply the independent MHK algorithm to lattice decoding and obtained the decoding complexity for solving the CVP as Õ(e∥Bx-c∥2 / mini ∥b̂i∥2). Finally, the tradeoff between decoding radius and complexity is also established
Electron-hydrogen scattering in Faddeev-Merkuriev integral equation approach
Electron-hydrogen scattering is studied in the Faddeev-Merkuriev integral
equation approach. The equations are solved by using the Coulomb-Sturmian
separable expansion technique. We present - and -wave scattering and
reactions cross sections up to the threshold.Comment: 2 eps figure
Dynamic Provable Data Possession Protocols with Public Verifiability and Data Privacy
Cloud storage services have become accessible and used by everyone.
Nevertheless, stored data are dependable on the behavior of the cloud servers,
and losses and damages often occur. One solution is to regularly audit the
cloud servers in order to check the integrity of the stored data. The Dynamic
Provable Data Possession scheme with Public Verifiability and Data Privacy
presented in ACISP'15 is a straightforward design of such solution. However,
this scheme is threatened by several attacks. In this paper, we carefully
recall the definition of this scheme as well as explain how its security is
dramatically menaced. Moreover, we proposed two new constructions for Dynamic
Provable Data Possession scheme with Public Verifiability and Data Privacy
based on the scheme presented in ACISP'15, one using Index Hash Tables and one
based on Merkle Hash Trees. We show that the two schemes are secure and
privacy-preserving in the random oracle model.Comment: ISPEC 201
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