OPERATED VERSUS NON-OPERATED PATIENTS WITH ACQUIRED VALVULAR HEART DISEASE: A FOLLOW-UP STUDY IN THREE YEAR PERIOD

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Threshold Implementations of all 3x3 and 4x4 S-boxes

Side-channel attacks have proven many hardware implementations of cryptographic algorithms to be vulnerable. A recently proposed masking method, based on secret sharing and multi-party computation methods, introduces a set of sufficient requirements for implementations to be provably resistant against first-order DPA with minimal assumptions on the hardware. The original paper doesn\u27t describe how to construct the Boolean functions that are to be used in the implementation. In this paper, we derive the functions for all invertible $3 \times 3$, $4 \times 4$ S-boxes and the $6 \times 4$ DES S-boxes. Our methods and observations can also be used to accelerate the search for sharings of larger (e.g. $8 \times 8$) S-boxes. Finally, we investigate the cost of such protection

Weighted complex projective 2-designs from bases: optimal state determination by orthogonal measurements

We introduce the problem of constructing weighted complex projective 2-designs from the union of a family of orthonormal bases. If the weight remains constant across elements of the same basis, then such designs can be interpreted as generalizations of complete sets of mutually unbiased bases, being equivalent whenever the design is composed of d+1 bases in dimension d. We show that, for the purpose of quantum state determination, these designs specify an optimal collection of orthogonal measurements. Using highly nonlinear functions on abelian groups, we construct explicit examples from d+2 orthonormal bases whenever d+1 is a prime power, covering dimensions d=6, 10, and 12, for example, where no complete sets of mutually unbiased bases have thus far been found.Comment: 28 pages, to appear in J. Math. Phy

Novel method of phase determination in neutron reflectometry using reference layer

We describe a novel method for phase recovery in neutron reflectometry which is based on using Gd reference layer of known thickness. Deposition of Gd reference layer at the top of unknown nanostructure allows us to reconstruct the complex reflection coefficient from the structure and to solve phase problem for magnetic nanostructures under investigation. This method makes it possible to use direct model-independent approaches (for example, Gelfand-Levitan-Marchenko approach) to obtain the scattering potential. © Published under licence by IOP Publishing Ltd.Russian Foundation for Basic Research, RFBR: 19-02-00674The research was carried out within the state assignment «Spin» АААА-А18-118020290104-2 and was supported in part by RFBR (project 19-02-00674)

Applying General Access Structure to Proactive Secret Sharing Schemes

Verifiable secret sharing schemes (VSS) are secret sharing schemes (SSS) dealing with possible cheating by participants. In this paper we use the VSS proposed by Cramer, Damgard and Maurer \cite{CDM99,CDM00,Cra00}. They introduced a purely linear algebraic method to transform monotone span program (MSP) based secret sharing schemes into VSS. In fact, the monotone span program model of Karchmer and Wigderson \cite{KW93} deals with arbitrary monotone access structures and not just threshold ones. Stinson and Wei \cite{SW99} proposed a proactive SSS based on threshold (polynomial) VSS. The purpose of this paper is to build unconditionally secure proactive SSS over any access structure, as long as it admits a linear secret sharing scheme (LSSS)

Features of electronic transport in relaxed Si/Si1-X GeX heterostructures with high doping level

The low-temperature electrical and magnetotransport characteristics of partially relaxed Si/Si1-x Gex heterostructures with two-dimensional electron channel (ne≥1012 cm-2) in an elastically strained silicon layer of nanometer thickness have been studied. The detailed calculation of the potential and of the electrons distribution in layers of the structure was carried out to understand the observed phenomena. The dependence of the tunneling transparency of the barrier separating the 2D and 3D transport channels in the structure, was studied as a function of the doping level, the degree of blurring boundaries, layer thickness, degree of relaxation of elastic stresses in the layers of the structure. Tunnel characteristics of the barrier between the layers were manifested by the appearance of a tunneling component in the current-voltage characteristics of real structures. Instabilities, manifested during the magnetotransport measurements using both weak and strong magnetic fields are explained by the transitions of charge carriers from the two-dimensional into three-dimensional state, due to interlayer tunneling transitions of electrons. © 2013 Elsevier B.V. All rights reserved

Tight informationally complete quantum measurements

We introduce a class of informationally complete positive-operator-valued measures which are, in analogy with a tight frame, "as close as possible" to orthonormal bases for the space of quantum states. These measures are distinguished by an exceptionally simple state-reconstruction formula which allows "painless" quantum state tomography. Complete sets of mutually unbiased bases and symmetric informationally complete positive-operator-valued measures are both members of this class, the latter being the unique minimal rank-one members. Recast as ensembles of pure quantum states, the rank-one members are in fact equivalent to weighted 2-designs in complex projective space. These measures are shown to be optimal for quantum cloning and linear quantum state tomography.Comment: 20 pages. Final versio

Masking Proofs are Tight (and How to Exploit it in Security Evaluations)

Evaluating the security level of a leaking implementation against side-channel attacks is a challenging task. This is especially true when countermeasures such as masking are implemented since in this case: (i) the amount of measurements to perform a key recovery may become prohibitive for certification laboratories, and (ii) applying optimal (multivariate) attacks may be computationally intensive and technically challenging. In this paper, we show that by taking advantage of the tightness of masking security proofs, we can significantly simplify this evaluation task in a very general manner. More precisely, we show that the evaluation of a masked implementation can essentially be reduced to the one of an unprotected implementation. In addition, we show that despite optimal attacks against masking schemes are computationally intensive for large number of shares, heuristic (soft analytical side-channel) attacks can approach optimality very efficiently. As part of this second contribution, we also improve over the recent multivariate (aka horizontal) side-channel attacks proposed at CHES 2016 by Battistello et al