2,875 research outputs found

    Generic Black-Box End-to-End Attack Against State of the Art API Call Based Malware Classifiers

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    In this paper, we present a black-box attack against API call based machine learning malware classifiers, focusing on generating adversarial sequences combining API calls and static features (e.g., printable strings) that will be misclassified by the classifier without affecting the malware functionality. We show that this attack is effective against many classifiers due to the transferability principle between RNN variants, feed forward DNNs, and traditional machine learning classifiers such as SVM. We also implement GADGET, a software framework to convert any malware binary to a binary undetected by malware classifiers, using the proposed attack, without access to the malware source code.Comment: Accepted as a conference paper at RAID 201

    CAFOs, NPDES Permits and the 590 Standard: What does it mean for manure management?

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    Increased regulatory pressure, policy-driven programs designed to protect water quality, and a concern to make the most profitable use of manure resources are driving manure management issues. This session will look at some of the current events and practices, changes to the 590 Nutrient Management Standard, and some crystal-ball gazing related to manure nutrient management in Iowa

    The crystal structure of potassium tungstate, K 2

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    Density-functional studies of tungsten trioxide, tungsten bronzes, and related systems

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    Tungsten trioxide adopts a variety of structures which can be intercalated with charged species to alter the electronic properties, thus forming `tungsten bronzes'. Similar optical effects are observed upon removing oxygen from WO_3, although the electronic properties are slightly different. Here we present a computational study of cubic and hexagonal alkali bronzes and examine the effects on cell size and band structure as the size of the intercalated ion is increased. With the exception of hydrogen (which is predicted to be unstable as an intercalate), the behaviour of the bronzes are relatively consistent. NaWO_3 is the most stable of the cubic systems, although in the hexagonal system the larger ions are more stable. The band structures are identical, with the intercalated atom donating its single electron to the tungsten 5d valence band. Next, this was extended to a study of fractional doping in the Na_xWO_3 system (0 < x < 1). A linear variation in cell parameter, and a systematic change in the position of the Fermi level up into the valence band was observed with increasing x. In the underdoped WO_3-x system however, the Fermi level undergoes a sudden jump into the conduction band at around x = 0.2. Lastly, three compounds of a layered WO_4&#215;a,wdiaminoalkane hybrid series were studied and found to be insulating, with features in the band structure similar to those of the parent WO_3 compound which relate well to experimental UV-visible spectroscopy results.Comment: 12 pages, 16 figure

    Fractionation of MG Isotopes between the Sun’s Photosphere and the Solar Wind

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    The Genesis mission goal is to precisely determine the elemental and isotopic composition of the solar photosphere through measurements of solar wind; the photospheric composition being a proxy for the early solar nebula. So, how elements and isotopes are fractionated (or not) when accelerated out of the photosphere is fundamental to interpreting Genesis data

    A Two-dimensional Superconductor in a Tilted Magnetic Field - new states with finite Cooper-pair momentum

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    Varying the angle Theta between applied field and the conducting planes of a layered superconductor in a small interval close to the plane-parallel field direction, a large number of superconducting states with unusual properties may be produced. For these states, the pair breaking effect of the magnetic field affects both the orbital and the spin degree of freedom. This leads to pair wave functions with finite momentum, which are labeled by Landau quantum numbers 0<n<\infty. The stable order parameter structure and magnetic field distribution for these states is found by minimizing the quasiclassical free energy near H_{c2} including nonlinear terms. One finds states with coexisting line-like and point-like order parameter zeros and states with coexisting vortices and antivortices. The magnetic response may be diamagnetic or paramagnetic depending on the position within the unit cell. The structure of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) states at Theta=0 is reconsidered. The transition n->\infty of the paramagnetic vortex states to the FFLO-limit is analyzed and the physical reason for the occupation of higher Landau levels is pointed out.Comment: 24 pages, 11 figure

    Coupled modelling of ZrO 2 / α-Zr(O) layers growth under thermal and mechanical gradients

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    ABSTRACT The oxidation process of a nuclear reactor fuel rod clad made of zirconium is simulated. It is assumed that oxygen is transported by anionic diffusion in the zirconia layer (ZrO 2 ), reacts at the interface between the zirconia layer and the metal and diffuses in the oxygen-enriched metal volume (α-Zr(O)) by an interstitial mechanism. The model is based on the thermodynamics of irreversible processes and takes into account the influence of driving forces on the oxygen migration in the metal such as the oxygen concentration gradient, the temperature gradient [1] and the mechanical stress gradient This model has been applied on an axisymmetric geometry by imposing a heat flow on the fuel side and a constant temperature on the waterside of the clad. Depending on the value of some coupling parameters, part of them remaining still unevaluated for oxygen in zirconium, results are related to differences in oxidation kinetics and oxygen distributions observed on the inner and outer side of nuclear clads. Thus, we show that negative values for the heat of transport, which relies the gradient of concentration and the gradient of temperature, give coherent results with experimental observations on oxidation kinetics for both sides of the clad

    Anisotropy of the upper critical field in superconductors with anisotropic gaps. Anisotropy parameters of MgB2

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    The upper critical field Hc2 is evaluated for weakly-coupled two-band superconductors. By modeling the actual bands and the gap distribution of MgB2 by two Fermi surface spheroids with average parameters of the real material, we show that H_{c2,ab}/H_{c2,c} increases with decreasing temperature in agreement with available data.Comment: 4 pages, 2 figure

    Determining the Elemental and Isotopic Composition of the preSolar Nebula from Genesis Data Analysis: The Case of Oxygen

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    We compare element and isotopic fractionations measured in solar wind samples collected by NASA's Genesis mission with those predicted from models incorporating both the ponderomotive force in the chromosphere and conservation of the first adiabatic invariant in the low corona. Generally good agreement is found, suggesting that these factors are consistent with the process of solar wind fractionation. Based on bulk wind measurements, we also consider in more detail the isotopic and elemental abundances of O. We find mild support for an O abundance in the range 8.75 - 8.83, with a value as low as 8.69 disfavored. A stronger conclusion must await solar wind regime specific measurements from the Genesis samples.Comment: 6 pages, accepted by Astrophysical Journal Letter
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