1,052 research outputs found
Symmetric encryption relying on chaotic henon system for secure hardware-friendly wireless communication of implantable medical systems
Healthcare remote devices are recognized as a promising technology for treating health related issues. Among them are the wireless Implantable Medical Devices (IMDs): These electronic devices are manufactured to treat, monitor, support or replace defected vital organs while being implanted in the human body. Thus, they play a critical role in healing and even saving lives. Current IMDs research trends concentrate on their medical reliability. However, deploying wireless technology in such applications without considering security measures may offer adversaries an easy way to compromise them. With the aim to secure these devices, we explore a new scheme that creates symmetric encryption keys to encrypt the wireless communication portion. We will rely on chaotic systems to obtain a synchronized Pseudo-Random key. The latter will be generated separately in the system in such a way that avoids a wireless key exchange, thus protecting patients from the key theft. Once the key is defined, a simple encryption system that we propose in this paper will be used. We analyze the performance of this system from a cryptographic point of view to ensure that it offers a better safety and protection for patients. 2018 by the authors.Acknowledgments: This publication was made possible by NPRP grant #8-408-2-172 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors.Scopu
Relativistic graphene ratchet on semidisk Galton board
Using extensive Monte Carlo simulations we study numerically and analytically
a photogalvanic effect, or ratchet, of directed electron transport induced by a
microwave radiation on a semidisk Galton board of antidots in graphene. A
comparison between usual two-dimensional electron gas (2DEG) and electrons in
graphene shows that ratchet currents are comparable at very low temperatures.
However, a large mean free path in graphene should allow to have a strong
ratchet transport at room temperatures. Also in graphene the ratchet transport
emerges even for unpolarized radiation. These properties open promising
possibilities for room temperature graphene based sensitive photogalvanic
detectors of microwave and terahertz radiation.Comment: 4 pages, 4 figures. Research done at Quantware
http://www.quantware.ups-tlse.fr/. More detailed analysis is give
Collaborative custodianship through collaborative cloud mapping : challenges and opportunities
Collaborative custodianship refers to an arrangement where a number of custodians work together to produce integrated datasets for a spatial data infrastructure (SDI), e.g. local authorities contributing address or street data to a national SDI dataset. Collaborative cloud mapping allows for ubiquitous, convenient, on-demand, configured and tailor-made mapping with resources shared between various entities collaborating on a specific initiative, such as an SDI or for disaster management. This paper presents the results of a workshop in South Africa during which case studies from the Netherlands, Belgium and Austria of collaborative custodianship of address data were presented, and OpenStreetMap as a case study of collaborative cloud mapping. Subsequently, challenges and opportunities for implementing similar initiatives in the context of the South African SDI were debated in break-away sessions. The results from these sessions were analysed using the PESTEL framework
Reduction in risk-taking behaviors among MSM in Senegal between 2004 and 2007 and prevalence of HIV and others STIs
Approximation Algorithms for Scheduling Parallel Jobs: Breaking the Approximation Ratio of 2
In this paper we study variants of the non-preemptive parallel job scheduling problem in which the number of machines is polynomially bounded in the number of jobs. For this problem we show that a schedule with length at most (1 + ε)OPT can be calculated in polynomial time. Unless P = NP, this is the best possible result (in the sense of approximation ratio), since the problem is strongly NP-hard. For the case, where all jobs must be allotted to a subset of consecutive machines, a schedule with length at most (1.5 + ε)OPT can be calculated in polynomial time. The previously best known results are algorithms with absolute approximation ratio 2. Furthermore, we extend both algorithms to the case of malleable jobs with the same approximation ratios
Phase diagram of the ferroelectric-relaxor (1-x)PbMg(1/3)Nb(2/3)O3-xPbTiO3
Synchrotron x-ray powder diffraction measurements have been performed on
unpoled ceramic samples of (1-x)PbMg(1/3)Nb(2/3)O3-xPbTiO3 (PMN-xPT) with 30%<=
x<= 39% as a function of temperature around the morphotropic phase boundary
(MPB), which is the line separating the rhombohedral and tetragonal phases in
the phase diagram. The experiments have revealed very interesting features
previously unknown in this or related systems. The sharp and well-defined
diffraction profiles observed at high and intermediate temperatures in the
cubic and tetragonal phases, respectively, are in contrast to the broad
features encountered at low temperatures. These peculiar characteristics, which
are associated with the monoclinic phase of MC-type previously reported by Kiat
et al and Singh et al., can only be interpreted as multiple coexisting
structures with MC as the major component. An analysis of the diffraction
profiles has allowed us to properly characterize the PMN-xPT phase diagram and
to determine the stability region of the monoclinic phase, which extends from
x= 31% to x= 37% at 20 K. The complex lansdcape of observed phases points to an
energy balance between the different PMN-xPT phases which is intrinsically much
more delicate than that of related systems such as PbZr(1-x)TixO3 or
(1-x)PbZn(1/3)Nb(1/3)O3-xPbTiO3. These observations are in good accord with an
optical study of x= 33% by Xu et al., who observed monoclinic domains with
several different polar directions coexisting with rhombohedral domains, in the
same single crystal.Comment: REVTeX4, 11 pages, 10 figures embedde
Signature of new physics in B -> phi pi decay
We investigate the effect of an extra fourth quark generation and FCNC
mediated and bosons on the rare decay mode . In
the standard model, this mode receives only penguin contributions and
therefore, highly suppressed with branching ratio . This
in turn makes this mode a very sensitive probe for new physics. We find that
due to the above mentioned new physics contributions there is a significant
enhancement in its branching ratio. Furthermore, the direct CP violation
parameter which is identically zero in the SM is found to be quite significant.
If this mode will be observed in the upcoming LHCb experiment, it will not only
provide a clear signal of new physics but also can be used to constrain the new
physics parameter space.Comment: 13 pages, 3 figures, version to appear in Phys. Lett.
Distributed phase-covariant cloning with atomic ensembles via quantum Zeno dynamics
We propose an interesting scheme for distributed orbital state quantum
cloning with atomic ensembles based on the quantum Zeno dynamics. These atomic
ensembles which consist of identical three-level atoms are trapped in distant
cavities connected by a single-mode integrated optical star coupler. These
qubits can be manipulated through appropriate modulation of the coupling
constants between atomic ensemble and classical field, and the cavity decay can
be largely suppressed as the number of atoms in the ensemble qubits increases.
The fidelity of each cloned qubit can be obtained with analytic result. The
present scheme provides a new way to construct the quantum communication
network.Comment: 5 pages, 4 figure
Experimental Tests of Factorization in Charmless Non-Leptonic Two-Body B Decays
Using a theoretical framework based on the next-to-leading order QCD-improved
effective Hamiltonian and a factorization Ansatz for the hadronic matrix
elements of the four-quark operators, we reassess branching fractions in
two-body non-leptonic decays , involving the lowest lying
light pseudoscalar and vector mesons in the standard model. Using
the sensitivity of the decay rates on the effective number of colors, , as
a criterion of theoretical predictivity, we classify all the current-current
(tree) and penguin transitions in five different classes. The recently measured
charmless two-body decays and charge conjugates) are
dominated by the -stable QCD penguins (class-IV transitions) and their
estimates are consistent with data. The measured charmless and transition ,
on the other hand, belong to the penguin (class-V) and tree (class-III)
transitions. The class-V penguin transitions are in general more difficult to
predict. We propose a number of tests of the factorization framework in terms
of the ratios of branching ratios for some selected decays
involving light hadrons and , which depend only moderately on the
form factors. We also propose a set of measurements to determine the effective
coefficients of the current-current and QCD penguin operators. The potential
impact of decays on the CKM phenomenology is emphasized by
analyzing a number of decay rates in the factorization framework.Comment: 64 pages (LaTex) including 13 figures, requires epsfig.sty; submitted
to Phys. Rev.
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