507 research outputs found

    Risk and Business Goal Based Security Requirement and Countermeasure Prioritization

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    Companies are under pressure to be in control of their assets but at the same time they must operate as efficiently as possible. This means that they aim to implement “good-enough security” but need to be able to justify their security investment plans. Currently companies achieve this by means of checklist-based security assessments, but these methods are a way to achieve consensus without being able to provide justifications of countermeasures in terms of business goals. But such justifications are needed to operate securely and effectively in networked businesses. In this paper, we first compare a Risk-Based Requirements Prioritization method (RiskREP) with some requirements engineering and risk assessment methods based on their requirements elicitation and prioritization properties. RiskREP extends misuse case-based requirements engineering methods with IT architecture-based risk assessment and countermeasure definition and prioritization. Then, we present how RiskREP prioritizes countermeasures by linking business goals to countermeasure specification. Prioritizing countermeasures based on business goals is especially important to provide the stakeholders with structured arguments for choosing a set of countermeasures to implement. We illustrate RiskREP and how it prioritizes the countermeasures it elicits by an application to an action case

    Adiabatic creation of coherent superposition states via multiple intermediate states

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    We consider an adiabatic population transfer process that resembles the well established stimulated Raman adiabatic passage (STIRAP). In our system, the states have nonzero angular momentums JJ, therefore, the coupling laser fields induce transitions among the magnetic sublevels of the states. In particular, we discuss the possibility of creating coherent superposition states in a system with coupling pattern J=0J=1J=0\Leftrightarrow J=1 and J=1J=2J=1\Leftrightarrow J=2. Initially, the system is in the J=0 state. We show that by two delayed, overlapping laser pulses it is possible to create any final superposition state of the magnetic sublevels 2,2>|2,-2>, 2,0>|2,0>, 2,+2>|2,+2>. Moreover, we find that the relative phases of the applied pulses influence not only the phases of the final superposition state but the probability amplitudes as well. We show that if we fix the shape and the time-delay between the pulses, the final state space can be entirely covered by varying the polarizations and relative phases of the two pulses. Performing numerical simulations we find that our transfer process is nearly adiabatic for the whole parameter set.Comment: 7 pages, 10 figure

    Quantum trajectory approach to stochastically-induced quantum interference effects in coherently-driven two-level atoms

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    Stochastic perturbation of two-level atoms strongly driven by a coherent light field is analyzed by the quantum trajectory method. A new method is developed for calculating the resonance fluorescence spectra from numerical simulations. It is shown that in the case of dominant incoherent perturbation, the stochastic noise can unexpectedly create phase correlation between the neighboring atomic dressed states. This phase correlation is responsible for quantum interference between the related transitions resulting in anomalous modifications of the resonance fluorescence spectra.Comment: paper accepted for publicatio

    Competitive stochastic noises in coherently driven two-level atoms and quantum interference

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    A system of coherently-driven two-level atoms is analyzed in presence of two independent stochastic perturbations: one due to collisions and a second one due to phase fluctuations of the driving field. The behaviour of the quantum interference induced by the collisional noise is considered in detail. The quantum-trajectory method is utilized to reveal the phase correlations between the dressed states involved in the interfering transition channels. It is shown that the quantum interference induced by the collisional noise is remarkably robust against phase noise. This effect is due to the fact that the phase noise, similarly to collisions, stabilizes the phase-difference between the dressed states.Comment: accepted for publication in J. Opt.

    The NASA X-Ray Mission Concepts Study

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    The 2010 Astrophysics Decadal Survey recommended a significant technology development program towards realizing the scientific goals of the International X-ray Observatory (IXO). NASA has undertaken an X-ray mission concepts study to determine alternative approaches to accomplishing IXO's high ranking scientific objectives over the next decade given the budget realities, which make a flagship mission challenging to implement. The goal of the study is to determine the degree to which missions in various cost ranges from 300Mto300M to 2B could fulfill these objectives. The study process involved several steps. NASA released a Request for Information in October 2011, seeking mission concepts and enabling technology ideas from the community. The responses included a total of 14 mission concepts and 13 enabling technologies. NASA also solicited membership for and selected a Community Science Team (CST) to guide the process. A workshop was held in December 2011 in which the mission concepts and technology were presented and discussed. Based on the RFI responses and the workshop, the CST then chose a small group of notional mission concepts, representing a range of cost points, for further study. These notional missions concepts were developed through mission design laboratory activities in early 2012. The results of all these activities were captured in the final X-ray mission concepts study report, submitted to NASA in July 2012. In this presentation, we summarize the outcome of the study. We discuss background, methodology, the notional missions, and the conclusions of the study report

    The Infrared Array Camera (IRAC) for the Spitzer Space Telescope

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    The Infrared Array Camera (IRAC) is one of three focal plane instruments in the Spitzer Space Telescope. IRAC is a four-channel camera that obtains simultaneous broad-band images at 3.6, 4.5, 5.8, and 8.0 microns. Two nearly adjacent 5.2x5.2 arcmin fields of view in the focal plane are viewed by the four channels in pairs (3.6 and 5.8 microns; 4.5 and 8 microns). All four detector arrays in the camera are 256x256 pixels in size, with the two shorter wavelength channels using InSb and the two longer wavelength channels using Si:As IBC detectors. IRAC is a powerful survey instrument because of its high sensitivity, large field of view, and four-color imaging. This paper summarizes the in-flight scientific, technical, and operational performance of IRAC.Comment: 7 pages, 3 figures. Accepted for publication in the ApJS. A higher resolution version is at http://cfa-www.harvard.edu/irac/publication

    Characterization of the gene encoding human sarcolipin (SLN), a proteolipid associated with SERCA1: Absence of structural mutations in five patients with brody disease

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    Sarcolipin (SLN) is a low-molecular-weight protein that copurifies with the fast-twitch skeletal muscle sarcoplasmic reticulum Ca2+ ATPase (SERCA1). Genomic DNA and cDNA encoding human sarcolipin (SLN) were isolated and characterized and the SLN gene was mapped to chromosome 11q22-q23. Human, rabbit, and mouse cDNAs encode a protein of 31 amino acids. Homology of SLN with phospholamban (PLN) suggests that the first 7 hydrophilic amino acids are cytoplasmic, the next 19 hydrophobic amino acids form a single transmembrane helix, and the last 5 hydrophilic amino acids are lumenal. The cytoplasmic and transmembrane sequences are not well conserved among the three species, but the lumenal sequence is highly conserved. Like SERCA1, SLN is highly expressed in rabbit fast-twitch skeletal muscle, but it is expressed to a lower extent in slow-twitch muscle and to an even lower extent in cardiac muscle, where SERCA2a and PLN are highly expressed. It is expressed in only trace amounts in pancreas and prostate. SLN and PLN genes resemble each other in having two small exons, with their entire coding sequences lying in exon 2 and a large intron separating the two segments. Brody disease is an inherited disorder of skeletal muscle function, characterized by exercise-induced impairment of muscle relaxation. Mutations in the ATP2A1 gene encoding SERCA1 have been associated with the autosomal recessive inheritance of Brody disease in three families, but not with autosomal dominant inheritance of the disease. A search for mutations in the SLN gene in five Brody families, four of which were not linked to ATP2A1, did not reveal any alterations in coding, splice junction or promoter sequences. The homozygous deletion of C438 in the coding sequence of ATP2A1 in Brody disease family 3, leading to a frameshift and truncation following Pro147 in SERCA1, is the fourth ATP2A1 mutation to be associated with autosomal recessive Brody disease

    Dystrophin expression in muscle following gene transfer with a fully deleted ("Gutted") adenovirus is markedly improved by Trans-acting adenoviral gene products

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    Helper-dependent adenoviruses (HDAd) are Ad vectors lacking all or most viral genes. They hold great promise for gene therapy of diseases such as Duchenne muscular dystrophy (DMD), because they are less immunogenic than E1/E3-deleted Ad (first-generation Ad or FGAd) and can carry the full-length (Fl) dystrophin (dys) cDNA (12 kb). We have compared the transgene expression of a HDAd (HDAdCMVDysFl) and a FGAd (FGAdCMV-dys) in cell culture (HeLa, C2C12 myotubes) and in the muscle of mdx mice (the mouse model for DMD). Both vectors encoded dystrophin regulated by the same cytomegalovirus (CMV) promoter. We demonstrate that the amount of dystrophin expressed was significantly higher after gene transfer with FGAdCMV-dys compared to HDAdCMVDysFl both in vitro and in vivo. However, gene transfer with HDAdCMVDysFl in the presence of a FGAd resulted in a significant increase of dystrophin expression indicating that gene products synthesized by the FGAd increase, in trans, the amount of dystrophin produced. This enhancement occurred in cell culture and after gene transfer in the muscle of mdx mice and dystrophic golden retriever (GRMD) dogs, another animal model for DMD. The E4 region of Ad is required for the enhancement, because no increase of dystrophin expression from HDAdCMVDysFl was observed in the presence of an E1/E4-deleted Ad in vitro and in vivo. The characterization of these enhancing gene products followed by their inclusion into an HDAd may be required to produce sufficient dystrophin to mitigate the pathology of DMD by HDAd-mediated gene transfer

    Inclusion Body Myositis: Laser Microdissection Reveals Differential Up-Regulation of IFN-γ Signaling Cascade in Attacked versus Nonattacked Myofibers

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    Sporadic inclusion body myositis (IBM) is a muscle disease with two separate pathogenic components, degeneration and inflammation. Typically, nonnecrotic myofibers are focally surrounded and invaded by CD8+ T cells and macrophages. Both attacked and nonattacked myofibers express high levels of human leukocyte antigen class I (HLA-I) molecules, a prerequisite for antigen presentation to CD8+ T cells. However, only a subgroup of HLA-I+ myofibers is attacked by immune cells. By using IHC, we classified myofibers from five patients with sporadic IBM as attacked (AIBM) or nonattacked (NIBM) and isolated the intracellular contents of myofibers separately by laser microdissection. For comparison, we isolated myofibers from control persons (HCTRL). The samples were analyzed by microarray hybridization and quantitative PCR. HLA-I up-regulation was observed in AIBM and NIBM, whereas HCTRL were negative for HLA-I. In contrast, the inducible chain of the interferon (IFN) γ receptor (IFNGR2) and several IFN-γ–induced genes were up-regulated in AIBM compared with NIBM and HCTRL fibers. Confocal microscopy confirmed segmental IFNGR2 up-regulation on the membranes of AIBM, which positively correlated with the number of adjacent CD8+ T cells. Thus, the differential up-regulation of the IFN-γ signaling cascade observed in the attacked fibers is related to local inflammation, whereas the ubiquitous HLA-I expression on IBM muscle fibers does not require IFNGR expression
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