Detecting unknown computer worm activity via support vector machines and active learning

To detect the presence of unknown worms, we propose a technique based on computer measurements extracted from the operating system. We designed a series of experiments to test the new technique by employing several computer configurations and background application activities. In the course of the experiments, 323 computer features were monitored. Four feature-ranking measures were used to reduce the number of features required for classification. We applied support vector machines to the resulting feature subsets. In addition, we used active learning as a selective sampling method to increase the performance of the classifier and improve its robustness in the presence of misleading instances in the data. Our results indicate a mean detection accuracy in excess of 90?%, and an accuracy above 94?% for specific unknown worms using just 20 features, while maintaining a low false-positive rate when the active learning approach is applied.     

The Pareto managerial principle: when does it apply?

The well-known 80/20 Pareto principle and its refinement into “A”, “B”, and “C” categories give rise to a managerial methodology consisting of three steps: classification; differentiation; and resource allocation. This is an easy-to-implement and extremely effective methodology. It starts with the creation of “Pareto diagrams”, i.e. bar charts of attributes and their relative frequency, presented in descending order. Typically, Pareto diagrams are useful in that they provide managers with a summary of practical information, revealing critical attributes. However, sometimes a Pareto diagram is less informative than it might be, because the relative frequency is almost uniform. The objective of this article is to provide an analytical tool (an index) that employs the above-mentioned methodology to measure the closeness of empirical Pareto diagrams to an “ideal” Pareto diagram. The index developed is based upon entropy.     

Charge Transport in Disordered Organic Materials and Its Relevance to Thin‐Film Devices: A Tutorial Review

Semiconducting polymers and small molecules form an extremely flexible class of amorphous materials that can be used in a wide range of applications, some of which are display, radio‐frequency tags, and solar cells. The rapid progress towards functional devices is occurring despite the lack of sufficient understanding of the physical processes and very little experience in device engineering. This tutorial review aims to provide sufficient intuitive background to draw more researchers to look into the fundamental aspects of device physics and engineering.     

Thin‐Film‐Based Integrated High‐Transition‐Temperature Superconductor Devices

Since the discovery of superconductivity at temperatures above the technologically promising liquid nitrogen temperatures, applications based on superconductors have expanded and are being put to commercial use. However, superconductivity at higher temperatures typically occurs in complex materials requiring stringent material and environmental constraints. Such restraints make the realization and integration of these materials with normal materials a nontrivial aspect. In this progress report, unique features of these superconductors in terms of their synthesis, physical properties determining interface electrical transport, and their applications are discussed. A detailed progress report on these applications with remarks on efforts taken to integrate these devices with traditional platforms and semiconducting materials is provided.     

Selenium in Diketopyrrolopyrrole-based Polymers: Influence on Electronic Properties and Charge Carrier Mobilities

Diketopyrrolopyrrole (DPP)-based π-conjugated copolymers with thiophene have exceptionally high electron mobilities. This paper investigates electronic properties and charge carrier mobilities of selenophene containing analogues. Two new copolymers, with alternating thiophene DPP (TDPP) and selenophene DPP (SeDPP) units, were synthesized. Two side-chains, hexyl (Hex) and triethylene glycol (TEG) were employed, yielding polymers designated as PTDPPSeDPP-Hex and PTDPPSeDPP-TEG. Selenophene systems have smaller band gaps, with concomitant enhancement of the stability of the reduced state. For both polymers, ambipolar mobilities were observed in organic field-effect transistors (OFET). Grazing incidence X-ray diffraction (GIXD) data indicates preferential edge-on orientation of PTDPPSeDPP-TEG, which leads to superior charge transport properties of the TEG substituted polymer, as compared to its Hex analogue. Time-dependent-density functional theory (TDDFT) calculations corroborate the decrease in the optical band gap with the inclusion of selenophene. Ambipolar charge transport is rationalized by exceptionally wide conduction bands. ΔSCF calculations confirm the larger electron affinity, and therefore the greater stability, of the reduced form of the selenophene-containing DPP polymer in presence of chloroform.     

Polymer LEDs as a physics tool

We present a systematic experimental and theoretical study of physical mechanisms governing the operation of polymer light-emitting diodes. We show that through self-consistent modeling we can address both charge transport and exciton generation. Electron and hole mobility in several polymers has been characterized experimentally. Characterization of excitons and especially of triplet-excitons is achieved through use of a triplet-emitting molecule.     

Conjugates of Unsaturated Fatty Acids with Propylene Glycol as Potentially Less-Irritant Skin Penetration Enhancers

Fatty acids (FA) are well known as efficient enhancers for transdermal delivery of drugs; however, their frequent dermal toxicity limits their regular use. In order to utilize the fatty acid as a safe enhancer devoid of its irritant effect, we have synthesized and evaluated a series of fatty acids conjugated to propylene glycol (FA-PG). Each one of the conjugates was prepared as a mono- or di- acyl ester derivative. The effects of the synthetic enhancers on the porcine skin permeability were evaluated in a diffusion cell system using lidocaine as the model drug. In addition, in vivo examinations in rabbits were preformed for skin toxicological evaluation. The results indicate that among the FA-PG conjugates, oleic acid (C18:1_n–9)-PG, linoleic acid (C18:2_n–6)-PG and α-linolenic acid (C18:3_n–3)-PG, mono- or di-esters, enhance the penetration of lidocaine relatively to the vehicle (without enhancer). The conjugates of oleic acid (C18:1_n–9) and linoleic acid (C18:2_n–6) with PG have demonstrated a similar enhancing effect as the corresponding free fatty acids. Interestingly, although the mono- or the di- conjugates of α-linolenic acid (C18:3_n–3) with PG enhanced the lidocaine flux as the other two fatty acid conjugates, they resulted in a reduced permeability as compared to the action of their free acid. In addition, the mono-conjugates of α-linolenic acid (C18:3_n–3) with PG exhibited elevated skin irritation in rabbits (relative to the fatty acid alone) compared to the significantly reduced irritation of oleate-PG and linoeate-PG mono-conjugates. In conclusion, except saturated FA-PG and α-linolenic acid (C18:3_n–3)—PG mono-conjugates, unsaturated fatty acids (e.g., oleic and linoleic acids) after conjugation to PG may be safe and effective enhancers for delivering topical drugs.     

Spin-dependent plasmonics based on interfering topological defects

Observation of spin-dependent plasmonics based on the interference of topological defects in the near-field is presented. We utilize the surface plasmons' scattering dynamics from localized vortex sources to create spinoptical devices as an ensemble of isolated nanoantennas to observe a "giant" spin-dependent plasmonic vortex and a spin-dependent plasmonic focusing lens. The spin-orbit point spread function, a spiral wavefront, is introduced, where the optical spin is a degree of freedom.     

Decomposition of adsorbed VX on activated carbons studied by 31P MAS NMR

The fate of the persistent OP nerve agent O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX) on granular activated carbons that are used for gas filtration was studied by means of 31P magic angle spinning (MAS) NMR spectroscopy. VX as vapor or liquid was adsorbed on carbon granules, and MAS NMR spectra were recorded periodically. The results show that at least 90% of the adsorbed VX decomposes within 20 days or less to the nontoxic ethyl methylphosphonic acid (EMPA) and bis(S-2-diisopropylaminoethane) {(DES)2}. Decomposition occurred irrespective of the phase from which VX was loaded, the presence of metal impregnation on the carbon surface, and the water content of the carbon. Theoretical and practical aspects of the degradation are discussed.