3,687 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

    Nonleptonic two-body charmless B decays involving a tensor meson in ISGW2 model

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    Nonleptonic charmless B decays into a pseudoscalar (P) or a vector (V) meson accompanying a tensor (T) meson are re-analyzed. We scrutinize the hadronic uncertainties and ambiguities of the form factors which appear in the literature. The Isgur-Scora-Grinstein-Wise updated model (ISGW2) is adopted to evaluate the relevant hadronic matrix elements. We calculate the branching ratios and CP asymmetries for various B→P(V)TB\to P(V)T decay processes. With the ISGW2 model, the branching ratios are enhanced by about an order of magnitude compared to the previous estimates. We show that the ratios \calB(B\to VT)/\calB(B\to PT) for some strangeness-changing processes are very sensitive to the CKM angle γ\gamma (ϕ3\phi_3).Comment: 23 pages, REVTEX; minor clarifications included; to appear in Phys. Rev.

    Hospital productivity and the Norwegian ownership reform – A Nordic comparative study

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    In a period where decentralisation seemed to be the prominent trend, Norway in 2002 chose to re-centralise the hospital sector. The reform had three main aims; cost control, efficiency and reduced waiting times. This study investigates whether the hospital reform has improved hospital productivity using the other four major Nordic countries as controls. Hospital productivity measures are obtained using data envelopment analysis (DEA) on a comparable dataset of 728 Nordic hospitals in the period 1999 to 2004. First a common reference frontier is established for the four countries, enveloping the technologies of each of the countries and years. Bootstrapping techniques are applied to the obtained productivity estimates to assess uncertainty and correct for bias. Second, these are regressed on a set of explanatory variables in order to separate the effect of the hospital reform from the effects of other structural, financial and organizational variables. A fixed hospital effect model is used, as random effects and OLS specifications are rejected. Robustness is examined through alternate model specifications, including stochastic frontier analysis (SFA). The SFA approach in performed using the Battese & Coelli (1995) one stage procedure where the inefficiency term is estimated as a function of the set of explanatory variables used in the second stage in the DEA approach. Results indicate that the hospital reform in Norway seems to have improved the level of productivity in the magnitude of approximately 4 % or more. While there are small or contradictory estimates of the effects of case mix and activity based financing, the length of stay is clearly negatively associated with estimated productivity. Results are robust to choice of efficiency estimation technique and various definition of when the reform effect takes place.Efficiency; productivity; DEA; SFA; hospitals

    Quantum Electrodynamics in the Light-Front Weyl Gauge

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    We examine QED(3+1) quantised in the `front form' with finite `volume' regularisation, namely in Discretised Light-Cone Quantisation. Instead of the light-cone or Coulomb gauges, we impose the light-front Weyl gauge A−=0A^-=0. The Dirac method is used to arrive at the quantum commutation relations for the independent variables. We apply `quantum mechanical gauge fixing' to implement Gau{\ss}' law, and derive the physical Hamiltonian in terms of unconstrained variables. As in the instant form, this Hamiltonian is invariant under global residual gauge transformations, namely displacements. On the light-cone the symmetry manifests itself quite differently.Comment: LaTeX file, 30 pages (A4 size), no figures. Submitted to Physical review D. January 18, 1996. Originally posted, erroneously, with missing `Weyl' in title. Otherwise, paper is identica

    Hadronic Charmed Meson Decays Involving Tensor Mesons

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    Charmed meson decays into a pseudoscalar meson P and a tensor meson T are studied. The charm to tensor meson transition form factors are evaluated in the Isgur-Scora-Grinstein-Wise (ISGW) quark model. It is shown that the Cabibbo-allowed decay Ds+→f2(1270)π+D_s^+\to f_2(1270)\pi^+ is dominated by the W-annihilation contribution and has the largest branching ratio in D→TPD\to TP decays. We argue that the Cabibbo-suppressed mode D+→f2(1270)π+D^+\to f_2(1270)\pi^+ should be suppressed by one order of magnitude relative to Ds+→f2(1270)π+D_s^+\to f_2(1270)\pi^+. When the finite width effect of the tensor resonances is taken into account, the decay rate of D→TPD\to TP is generally enhanced by a factor of 2∼32\sim 3. Except for Ds+→f2(1270)π+D_s^+\to f_2(1270)\pi^+, the predicted branching ratios of D→TPD\to TP decays are in general too small by one to two orders of magnitude compared to experiment. However, it is very unlikely that the D→TD\to T transition form factors can be enhanced by a factor of 3∼53\sim 5 within the ISGW quark model to account for the discrepancy between theory and experiment. As many of the current data are still preliminary and lack sufficient statistic significance, more accurate measurements are needed to pin down the issue.Comment: 11 page

    Statistics and Characteristics of Spatio-Temporally Rare Intense Events in Complex Ginzburg-Landau Models

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    We study the statistics and characteristics of rare intense events in two types of two dimensional Complex Ginzburg-Landau (CGL) equation based models. Our numerical simulations show finite amplitude collapse-like solutions which approach the infinite amplitude solutions of the nonlinear Schr\"{o}dinger (NLS) equation in an appropriate parameter regime. We also determine the probability distribution function (PDF) of the amplitude of the CGL solutions, which is found to be approximately described by a stretched exponential distribution, P(∣A∣)≈e−∣A∣ηP(|A|) \approx e^{-|A|^\eta}, where η<1\eta < 1. This non-Gaussian PDF is explained by the nonlinear characteristics of individual bursts combined with the statistics of bursts. Our results suggest a general picture in which an incoherent background of weakly interacting waves, occasionally, `by chance', initiates intense, coherent, self-reinforcing, highly nonlinear events.Comment: 7 pages, 9 figure

    Cavity QED and quantum information processing with "hot" trapped atoms

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    We propose a method to implement cavity QED and quantum information processing in high-Q cavities with a single trapped but non-localized atom. The system is beyond the Lamb-Dick limit due to the atomic thermal motion. Our method is based on adiabatic passages, which make the relevant dynamics insensitive to the randomness of the atom position with an appropriate interaction configuration. The validity of this method is demonstrated from both approximate analytical calculations and exact numerical simulations. We also discuss various applications of this method based on the current experimental technology.Comment: 14 pages, 8 figures, Revte

    Computational identification of anthocyanin-specific transcription factors using a rice microarray and maximum boundary range algorithm

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    This study identifies 2,617 candidate genes related to anthocyanin biosynthesis in rice using microarray analysis and a newly developed maximum boundary range algorithm. Three seed developmental stages were examined in white cultivar and two black Dissociation insertion mutants. The resultant 235 transcription factor genes found to be associated with anthocyanin were classified into nine groups. It is compared the 235 genes by transcription factor analysis and 593 genes from among clusters of COGs related to anthocyanin functions. Total 32 genes were found to be expressed commonly. Among these, 9 unknown and hypothetical genes were revealed to be expressed at each developmental stage and were verified by RT-PCR. These genes most likely play regulatory roles in either anthocyanin production or metabolism during flavonoid biosynthesis. While these genes require further validation, our results underline the potential usefulness of the newly developed algorithm

    BCC vs. HCP - The Effect of Crystal Symmetry on the High Temperature Mobility of Solid 4^4He

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    We report results of torsional oscillator (TO) experiments on solid 4^4He at temperatures above 1K. We have previously found that single crystals, once disordered, show some mobility (decoupled mass) even at these rather high temperatures. The decoupled mass fraction with single crystals is typically 20- 30%. In the present work we performed similar measurements on polycrystalline solid samples. The decoupled mass with polycrystals is much smaller, ∼\sim 1%, similar to what is observed by other groups. In particular, we compared the properties of samples grown with the TO's rotation axis at different orientations with respect to gravity. We found that the decoupled mass fraction of bcc samples is independent of the angle between the rotation axis and gravity. In contrast, hcp samples showed a significant difference in the fraction of decoupled mass as the angle between the rotation axis and gravity was varied between zero and 85 degrees. Dislocation dynamics in the solid offers one possible explanation of this anisotropy.Comment: 10 pages, 5 figures, to appear in Journal of Low Temperature Physics - special issue on Supersolidit
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