613 research outputs found

    Cyber security research frameworks for coevolutionary network defense

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    Cyber security is increasingly a challenge for organizations everywhere. Defense systems that require less expert knowledge and can adapt quickly to threats are strongly needed to combat the rise of cyber attacks. Computational intelligence techniques can be used to rapidly explore potential solutions while searching in a way that is unaffected by human bias. Several architectures have been created for developing and testing systems used in network security, but most are meant to provide a platform for running cyber security experiments as opposed to automating experiment processes. In the first paper, we propose a framework termed Distributed Cyber Security Automation Framework for Experiments (DCAFE) that enables experiment automation and control in a distributed environment. Predictive analysis of adversaries is another thorny issue in cyber security. Game theory can be used to mathematically analyze adversary models, but its scalability limitations restrict its use. Computational game theory allows us to scale classical game theory to larger, more complex systems. In the second paper, we propose a framework termed Coevolutionary Agent-based Network Defense Lightweight Event System (CANDLES) that can coevolve attacker and defender agent strategies and capabilities and evaluate potential solutions with a custom network defense simulation. The third paper is a continuation of the CANDLES project in which we rewrote key parts of the framework. Attackers and defenders have been redesigned to evolve pure strategy, and a new network security simulation is devised which specifies network architecture and adds a temporal aspect. We also add a hill climber algorithm to evaluate the search space and justify the use of a coevolutionary algorithm --Abstract, page iv

    A Dynamic Programming Approach to De Novo Peptide Sequencing via Tandem Mass Spectrometry

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    The tandem mass spectrometry fragments a large number of molecules of the same peptide sequence into charged prefix and suffix subsequences, and then measures mass/charge ratios of these ions. The de novo peptide sequencing problem is to reconstruct the peptide sequence from a given tandem mass spectral data of k ions. By implicitly transforming the spectral data into an NC-spectrum graph G=(V,E) where |V|=2k+2, we can solve this problem in O(|V|+|E|) time and O(|V|) space using dynamic programming. Our approach can be further used to discover a modified amino acid in O(|V||E|) time and to analyze data with other types of noise in O(|V||E|) time. Our algorithms have been implemented and tested on actual experimental data.Comment: A preliminary version appeared in Proceedings of the 11th Annual ACM-SIAM Symposium on Discrete Algorithms, pages 389--398, 200

    Day-Care Complex for 1000 Children

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    Architectur

    On the relation between the coronal line emission and the IR/X-ray emission in Seyfert galaxies

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    The relation between the X-ray, the coronal line and the infrared (IR) emissions in a sample of the brightest known Seyfert galaxies is analysed. A close relationship between the absorption-corrected soft X-ray emission and both the mid-IR and the coronal line emission is found for the Seyfert type 2 objects in the sample. The coronal line and the X-ray emissions are both main tracers of the central activity, hence their relationship with the mid-IR emission points to nuclear energetic process as the main responsibles of the heating of the circumnuclear dust. On the other hand, the above relations do not seem to hold for the Seyfert type 1 discussed in the sample, at least when the comparisons are done in a flux diagram. This is partially because of the reduced number of objects of this type analysed in this work and the fact that the measured soft X-ray emission in Seyfert 1s is systematically larger, by at least an order of magnitude, than that in the Seyfert 2 counterparts. Finally, the hard X-ray emission in the studied sample appears unrelated to either the mid-IR or the coronal line emission.Comment: 14 pages, 3 figures To be published in MNRAS (accepted

    BeppoSAX view of NGC 526A: a Seyfert 1.9 galaxy with a flat spectrum

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    In the present work we report the BeppoSAX observation of the Seyfert 1.9 galaxy NGC 526A in the band 0.1-150 keV. The high energy instrument onboard, PDS, has succeeded in measuring for the first time the spectrum of this source in the 13-150 keV range. The combined analysis of all Narrow Field Instruments provides a power law spectral index of ~ 1.6 and confirms the flat spectral nature of this source. Although NGC 526A varies strongly in the 2-10 keV over period of months/years, its spectral shape remains constant over these timescales. An Fe K-alpha line, characterized by a complex structure, has been detected in the 6-7 keV range. The line, which has an equivalent width of 120 eV, is not compatible with being produced in an absorbing torus with N_H ~ 10^22 cm^-2, but most likely originates by reflection in an accretion disk viewed at an intermediate inclination angle of ~ 42 deg. The reflection component is however small (R < 0.7) and so it is not sufficient to steepen the spectrum to photon index values more typical of AGNs. Instead, we find that the data are more consistent with a flat power law spectrum cut-off at around 100 keV plus a small reflection component which could explain the observed iron line. Thus NGC 526A is the only bona-fide Seyfert 2 galaxy which maintains a "flat spectrum" even when broad band data are considered: in this sense its properties, with respect to the general class of Seyfert 2's, are analogous to those of NGC 4151 with respect to the vast majority of Seyfert 1's.Comment: 8 pages, 6 PostScript figures, Latex manuscript, new A&A file style included, accepted for publication on Astronomy and Astrophysic

    The Chlamydomonas reinhardtii BBSome is an IFT cargo required for export of specific signaling proteins from flagella

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    In humans, seven evolutionarily conserved genes that cause the cilia-related disorder Bardet-Biedl syndrome (BBS) encode proteins that form a complex termed the BBSome. The function of the BBSome in the cilium is not well understood. We purified a BBSome-like complex from Chlamydomonas reinhardtii flagella and found that it contains at least BBS1, -4, -5, -7, and -8 and undergoes intraflagellar transport (IFT) in association with a subset of IFT particles. C. reinhardtii insertional mutants defective in BBS1, -4, and -7 assemble motile, full-length flagella but lack the ability to phototax. In the bbs4 mutant, the assembly and transport of IFT particles are unaffected, but the flagella abnormally accumulate several signaling proteins that may disrupt phototaxis. We conclude that the BBSome is carried by IFT but is an adapter rather than an integral component of the IFT machinery. C. reinhardtii BBS4 may be required for the export of signaling proteins from the flagellum via IFT

    An XMM-Newton spectral survey of 12 micron selected galaxies. I. X-ray data

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    We present an X-ray spectral analysis of 126 galaxies of the 12 micron galaxy sample. We pay particular attention to Compton thick AGN with the help of new spectral fitting models that we have produced, which are based on Monte-Carlo simulations of X-ray radiative transfer, using both a spherical and torus geometry, and taking into account Compton scattering and Fe fluorescence. We use this data to show that with a torus geometry, unobscured sight lines can achieve a maximum EW of the Fe K\alpha line of ~150 eV, originally shown by Ghisellini, Haardt & Matt (1994). In order for this to be exceeded, the line of sight must be obscured with N_H>10^23 cm^-2, as we show for one case, NGC 3690. We also calculate flux suppression factors from the simulated data, the main conclusion from which is that for N_H>10^25 cm^-2, the X-ray flux is suppressed by a factor of >10 in all X-ray bands and at all redshifts, revealing the biases present against these extremely heavily obscured systems inherent in all X-ray surveys. Furthermore, we confirm previous results from Murphy & Yaqoob (2009) that show that the reflection fraction determined from slab geometries is underestimated with respect to toroidal geometries. For the 12 micron selected galaxies, we investigate the distribution of X-ray power-law indices, finding that the mean =1.900.07+0.05=1.90_{-0.07}^{+0.05} and σΓ=0.310.05+0.05\sigma_\Gamma = 0.31_{-0.05}^{+0.05}) is consistent with previous works, and that the distribution of \Gamma for obscured and unobscured sources is consistent with the source populations being the same, in general support of unification schemes. We determine a Compton thick fraction for the X-ray AGN in our sample to be 18+/-5% which is higher than the hard X-ray (>10 keV) selected samples. Finally we find that the obscured fraction for our sample is a strong function of X-ray luminosity, peaking at L_X~10^42-43 ergs s^-1.Comment: Accepted for publication in MNRAS, 33 pages, 16 figures and 9 tables. XSPEC table models can be found at http://astro.ic.ac.uk/mbrightman/hom

    Adult Height, Nutrition and Population Health:A Review

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    In this review, the potential causes and consequences of adult height, a measure of cumulative net nutrition, in modern populations are summarized. The mechanisms linking adult height and health are examined, with a focus on the role of potential confounders. Evidence across studies indicates that short adult height (reflecting growth retardation) in low- and middle-income countries is driven by environmental conditions, especially net nutrition during early years. Some of the associations of height with health and social outcomes potentially reflect the association between these environmental factors and such outcomes. These conditions are manifested in the substantial differences in adult height that exist between and within countries and over time. This review suggests that adult height is a useful marker of variation in cumulative net nutrition, biological deprivation, and standard of living between and within populations and should be routinely measured. Linkages between adult height and health, within and across generations, suggest that adult height may be a potential tool for monitoring health conditions and that programs focused on offspring outcomes may consider maternal height as a potentially important influence
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