1,749 research outputs found

    Applying system dynamics to model advanced persistent threats

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    © 2019 Association for Computing Machinery. System dynamics (SD) concept has been successfully applied to analyze issues that are non-linear, complex, and dynamic in disciplines namely social sciences and technology. However, its application to cyber security issues especially threats that involves multiple variables interacting with the technical as well as the organizational domain is lacking. In this respect, Advanced Persistent Threat (APT) is regarded as a highly targeted and sophisticated attack using zero-day malware, stealth, and multiple advanced techniques to gain entry and maintain its presence inside organizational network unnoticed. Being a threat that exploits technical as well as organizational vulnerabilities, preventing it at the security perimeter and, detecting it once it enters the system is a challenge till date. To demonstrate the application of SD in identifying and analyzing the effect of each of the variables, we took the Equinox data breach as a case study. The variables leading to the breach were identified, entered into Vensim software and simulated to get the results. Through this exercise, we could identify seven key independent management variables for the technical security and three key independent variables for records breach. This research being the foremost study to apply SD to APT, we presume that by modelling APT attacks using SD through a case study this paper, thus provides insights into the dynamics of the threat. Furthermore, it suggests \u27what if\u27 strategies to minimize APT risks thereby reduce the extent of damages should an APT attack occur

    Comparisons of commercial frozen yogurt with ksu formulation

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    Ten samples of vanilla frozen yogurt were purchased in Kansas and compared to a highprotein, KSU formulation. The KSU formulation had similar solids, fat, and sugar contents as the commercial samples. All commercial samples had lower protein (almost less than half) content and more lactose, and almost all samples had fewer lactic acid bacteria than the KSU formulation. All but one commercial sample had lower b-galactosidase activity than the KSU formulation. This may reflect the differing lactic acid bacterial populations in the frozen yogurts

    Boundary Effects on Dynamic Behavior of Josephson-Junction Arrays

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    The boundary effects on the current-voltage characteristics in two-dimensional arrays of resistively shunted Josephson junctions are examined. In particular, we consider both the conventional boundary conditions (CBC) and the fluctuating twist boundary conditions (FTBC), and make comparison of the obtained results. It is observed that the CBC, which have been widely adopted in existing simulations, may give a problem in scaling, arising from rather large boundary effects; the FTBC in general turn out to be effective in reducing the finite-size effects, yielding results with good scaling behavior. To resolve the discrepancy between the two boundary conditions, we propose that the proper scaling in the CBC should be performed with the boundary data discarded: This is shown to give results which indeed scale well and are the same as those from the FTBC.Comment: RevTex, Final version to appear in Phys. Rev.

    Sliderule-like property of Wigner's little groups and cyclic S-matrices for multilayer optics

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    It is noted that two-by-two S-matrices in multilayer optics can be represented by the Sp(2) group whose algebraic property is the same as the group of Lorentz transformations applicable to two space-like and one time-like dimensions. It is noted also that Wigner's little groups have a sliderule-like property which allows us to perform multiplications by additions. It is shown that these two mathematical properties lead to a cyclic representation of the S-matrix for multilayer optics, as in the case of ABCD matrices for laser cavities. It is therefore possible to write the N-layer S-matrix as a multiplication of the N single-layer S-matrices resulting in the same mathematical expression with one of the parameters multiplied by N. In addition, it is noted, as in the case of lens optics, multilayer optics can serve as an analogue computer for the contraction of Wigner's little groups for internal space-time symmetries of relativistic particles.Comment: RevTex 13 pages, Secs. IV and V revised and expande

    Astrophysical S-factor of the 7^7Be(p,γ)8p,\gamma)^8B reaction from Coulomb dissociation of 8^8B

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    The Coulomb dissociation method to obtain the astrophysical S-factor, S17(0)S_{17}(0), for the 7^7Be(p,γ)8p,\gamma)^8B reaction at solar energies is investigated by analysing the recently measured data on the breakup reaction 208^{208}Pb(8(^8B,7^7Be p)208~p)^{208}Pb at 46.5 MeV/A beam energy. Breakup cross sections corresponding to E1, E2E2 and M1M1 transitions are calculated with a theory of Coulomb excitation that includes the effects of the Coulomb recoil as well as relativistic retardation. The interplay of nuclear and Coulomb contributions to the breakup process is studied by performing a full quantum mechanical calculation within the framework of the distorted-wave Born Approximation. In the kinematical regime of the present experiment, both nuclear as well as Coulomb-nuclear interference processes affect the pure Coulomb breakup cross sections very marginally. The E2E2 cross sections are strongly dependent on the model used to describe the structure of 8^8B. The value of S17(0)S_{17}(0) is deduced with and without E2E2 and M1M1 contributions added to the E1E1 cross sections and the results are discussed.Comment: 10 pages, with 4 figures included with psfig; Physics Letters B, in pres

    Golgi Outpost Synthesis Impaired by Toxic Polyglutamine Proteins Contributes to Dendritic Pathology in Neurons

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    Dendrite aberration is a common feature of neurodegenerative diseases caused by protein toxicity, but the underlying mechanisms remain largely elusive. Here, we show that nuclear polyglutamine (polyQ) toxicity resulted in defective terminal dendrite elongation accompanied by a loss of Golgi outposts (GOPs) and a decreased supply of plasma membrane (PM) in Drosophila class IV dendritic arborization (da) (C4 da) neurons. mRNA sequencing revealed that genes downregulated by polyQ proteins included many secretory pathway-related genes, including COPII genes regulating GOP synthesis. Transcription factor enrichment analysis identified CREB3L1/CrebA, which regulates COPII gene expression. CrebA overexpression in C4 da neurons restores the dysregulation of COPII genes, GOP synthesis, and PM supply. Chromatin immunoprecipitation (ChIP)-PCR revealed that CrebA expression is regulated by CREB-binding protein (CBP), which is sequestered by polyQ proteins. Furthermore, co-overexpression of CrebA and Rac1 synergistically restores the polyQ-induced dendrite pathology. Collectively, our results suggest that GOPs impaired by polyQ proteins contribute to dendrite pathology through the CBP-CrebA-COPII pathway. ? 2017 The Author(s)113Ysciescopu

    Polaron features of the one-dimensional Holstein Molecular Crystal Model

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    The polaron features of the one-dimensional Holstein Molecular Crystal Model are investigated by improving a variational method introduced recently and based on a linear superposition of Bloch states that describe large and small polaron wave functions. The mean number of phonons, the polaron kinetic energy, the electron-phonon local correlation function, and the ground state spectral weight are calculated and discussed. A crossover regime between large and small polaron for any value of the adiabatic parameter ω0/t\omega_0/t is found and a polaron phase diagram is proposed.Comment: 12 pages, 2 figure

    XUV digital in-line holography using high-order harmonics

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    A step towards a successful implementation of timeresolved digital in-line holography with extreme ultraviolet radiation is presented. Ultrashort XUV pulses are produced as high-order harmonics of a femtosecond laser and a Schwarzschild objective is used to focus harmonic radiation at 38 nm and to produce a strongly divergent reference beam for holographic recording. Experimental holograms of thin wires are recorded and the objects reconstructed. Descriptions of the simulation and reconstruction theory and algorithms are also given. Spatial resolution of few hundreds of nm is potentially achievable, and micrometer resolution range is demonstrated.Comment: 8 pages, 8 figure

    HARES: an efficient method for first-principles electronic structure calculations of complex systems

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    We discuss our new implementation of the Real-space Electronic Structure method for studying the atomic and electronic structure of infinite periodic as well as finite systems, based on density functional theory. This improved version which we call HARES (for High-performance-fortran Adaptive grid Real-space Electronic Structure) aims at making the method widely applicable and efficient, using high performance Fortran on parallel architectures. The scaling of various parts of a HARES calculation is analyzed and compared to that of plane-wave based methods. The new developments that lead to enhanced performance, and their parallel implementation, are presented in detail. We illustrate the application of HARES to the study of elemental crystalline solids, molecules and complex crystalline materials, such as blue bronze and zeolites.Comment: 17 two-column pages, including 9 figures, 5 tables. To appear in Computer Physics Communications. Several minor revisions based on feedbac

    Elastic scattering and breakup of 17^F at 10 MeV/nucleon

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    Angular distributions of fluorine and oxygen produced from 170 MeV 17^F incident on 208^Pb were measured. The elastic scattering data are in good agreement with optical model calculations using a double-folding potential and parameters similar to those obtained from 16^O+208^Pb. A large yield of oxygen was observed near \theta_lab=36 deg. It is reproduced fairly well by a calculation of the (17^F,16^O) breakup, which is dominated by one-proton stripping reactions. The discrepancy between our previous coincidence measurement and theoretical predictions was resolved by including core absorption in the present calculation.Comment: 9 pages, 5 figure
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