178 research outputs found

    Modeling the Dynamics of Compromised Networks

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    Accurate predictive models of compromised networks would contribute greatly to improving the effectiveness and efficiency of the detection and control of network attacks. Compartmental epidemiological models have been applied to modeling attack vectors such as viruses and worms. We extend the application of these models to capture a wider class of dynamics applicable to cyber security. By making basic assumptions regarding network topology we use multi-group epidemiological models and reaction rate kinetics to model the stochastic evolution of a compromised network. The Gillespie Algorithm is used to run simulations under a worst case scenario in which the intruder follows the basic connection rates of network traffic as a method of obfuscation

    Network Traffic Monitoring Using Poisson Dynamic Linear Models

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    The response of Monoterpenes to Different Enzyme Preparations in Gewürztraminer (Vitis vinifera L.) Wines

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    The α-terpineol, linalool, nerol and geraniol, which are the main aromatic monoterpenes in the grapevine varietyGewürztraminer, were determined in the grapes, must and wine after treatment with six different pectolytic enzymes[Lallzyme-β (‘Lall’); Rohavin VR-C (‘VRX’), Rohapect D5L (‘D5L’), Rohavin MX (‘MX’), Rohapect VRC (‘VRC’),Endozym cultivar A (‘Cult. A’)], and after treatment with β-glucosidase (βG, EC 3.2.1.21). The concentrations ofmonoterpenic compounds were determined by solid-phase microextraction (SPME) and GC-MS. The most abundantmonoterpene in the grapes of Gewürztraminer was geraniol (66.7 μg/L), followed by nerol (13.3 μg/L), α-terpineol(7.8 μg/L) and finally linalool (3.3 μg/L). Gewürztraminer wine from must treated with the Lall enzyme preparationwas the most aromatic, which was also confirmed by chemical and sensory analysis in which the concentrations ofnerol (45.9 μg/L), geraniol (31.8 μg/L), α-terpineol (10.5 μg/L) and linalool (6.1 μg/L) were determined. The winesproduced from must treated chemically with enzymes showed higher concentrations of many of the monoterpenecompounds compared to the control, although the sensorial analysis did not affirm this convincingly

    Fast MAP Search for Compact Additive Tree Ensembles (CATE)

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    Impact of Alternative Skin Contact Procedures on the Aroma Composition of White Wine

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    Zelen, Ribolla Gialla and Malvasia Istriana, grapes from the Vitis vinifera (L.) varieties, were subjectedto four processes involving grape skin contact. Fresh and fruity young wines were produced by adding6% or 12% grape berries, respectively, during alcoholic fermentation, freezing the pomace (Fp) and thefreezing whole grapes (Fg). Wine-free volatile aromatic compounds were determined using two extractiontechniques coupled to gas chromatography (GC). These aromatic compounds and wine standard chemicalparameters were compared to control wines produced without skin contact. Esters, higher alcohols,terpenes, volatile phenols and C6 alcohols proved to be the most important sensorial odorants in wines.Both the content of aromatic compounds and the odour activity values showed some positive effects fromskin contact. The freezing of the grapes and addition of 12% grape berries proved most effective forZelen and Malvasia Istriana, producing a more intensive fruity and floral odour, a less intensive solventodour and additional freshness. The same processes resulted only in additional fruitiness or a less intensivesolvent odour in Ribolla Gialla while the lowest concentrations of grape derived terpenes were achieved forthis variety. The three varieties were most affected by freezing processes. During the sensorial evaluation,the wines that had been subjected to skin contact were generally preferred to the control wines

    Comparative studies on the structure of an upland African stream ecosystem

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    Upland stream systems have been extensively investigated in Europe, North America and Australasia and many of the central ideas concerning their function are based on these systems. One central paradigm, the river continuum concept is ultimately derived from those North American streams whose catchments remain forested with native vegetation. Streams of the tropics may or may not fit the model. They have been little studied. The Amani Nature Reserve in the East Usambara Mountains of north-eastern Tanzania offers an opportunity to bring these naturally forested systems to the attention of the ecological community. This article describes a comparison made between two lengths of the River Dodwe in this area. The work was carried out by a group of postgraduate students from eighteen European and African countries with advice from five staff members, as part of a course organised by the Tropical Biology Association. Rigorous efforts were made to standardise techniques, in a situation where equipment and laboratory facilities were very basic, through a management structure and deliberate allocation of work to specialists in each area.The article offers a summary of invertebrate communities found in the stream and its biomass. Crabs seem to be the key organism in both sections of the streams

    Gigahertz (GHz) hard x-ray imaging using fast scintillators

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    Gigahertz (GHz) imaging technology will be needed at high-luminosity X-ray and charged particle sources. It is plausible to combine fast scintillators with the latest picosecond detectors and GHz electronics for multi-frame hard Xray imaging and achieve an inter-frame time of less than 10 ns. The time responses and light yield of LYSO, LaBr_3, BaF_2 and ZnO are measured using an MCP-PMT detector. Zinc Oxide (ZnO) is an attractive material for fast hard X-ray imaging based on GEANT4 simulations and previous studies, but the measured light yield from the samples is much lower than expected
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