4,620 research outputs found

    The Mass Function of Dark Halos in Superclusters and Voids

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    A modification of the Press-Schechter theory allowing for presence of a background large-scale structure (LSS) - a supercluster or a void, is proposed. The LSS is accounted as the statistical constraints in form of linear functionals of the random overdensity field. The deviation of the background density within the LSS is interpreted in a pseudo-cosmological sense. Using the constraints formalism may help us to probe non-trivial spatial statistics of haloes, e.g. edge and shape effects on boundaries of the superclusters and voids. Parameters of the constraints are connected to features of the LSS: its mean overdensity, a spatial scale and a shape, and spatial momenta of higher orders. It is shown that presence of a non-virialized LSS can lead to an observable deviation of the mass function. This effect is exploited to build a procedure to recover parameters of the background perturbation from the observationally estimated mass function.Comment: 23 pages, 6 figures; to be appeared in Astronomy Reports, 2014, Vol. 58, No. 6, pp. 386-39

    Authorization and access control of application data in Workflow systems

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    Workflow Management Systems (WfMSs) are used to support the modeling and coordinated execution of business processes within an organization or across organizational boundaries. Although some research efforts have addressed requirements for authorization and access control for workflow systems, little attention has been paid to the requirements as they apply to application data accessed or managed by WfMSs. In this paper, we discuss key access control requirements for application data in workflow applications using examples from the healthcare domain, introduce a classification of application data used in workflow systems by analyzing their sources, and then propose a comprehensive data authorization and access control mechanism for WfMSs. This involves four aspects: role, task, process instance-based user group, and data content. For implementation, a predicate-based access control method is used. We believe that the proposed model is applicable to workflow applications and WfMSs with diverse access control requirements

    Reconstructing the Stellar Mass Distributions of Galaxies Using S4G IRAC 3.6 and 4.5 Îźm Images. I. Correcting for Contamination by Polycyclic Aromatic Hydrocarbons, Hot Dust, and Intermediate-age Stars

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    With the aim of constructing accurate two-dimensional maps of the stellar mass distribution in nearby galaxies from Spitzer Survey of Stellar Structure in Galaxies 3.6 and 4.5 Îźm images, we report on the separation of the light from old stars from the emission contributed by contaminants. Results for a small sample of six disk galaxies (NGC 1566, NGC 2976, NGC 3031, NGC 3184, NGC 4321, and NGC 5194) with a range of morphological properties, dust content, and star formation histories are presented to demonstrate our approach. To isolate the old stellar light from contaminant emission (e.g., hot dust and the 3.3 Îźm polycyclic aromatic hydrocarbon (PAH) feature) in the IRAC 3.6 and 4.5 Îźm bands we use an independent component analysis (ICA) technique designed to separate statistically independent source distributions, maximizing the distinction in the [3.6]-[4.5] colors of the sources. The technique also removes emission from evolved red objects with a low mass-to-light ratio, such as asymptotic giant branch (AGB) and red supergiant (RSG) stars, revealing maps of the underlying old distribution of light with [3.6]-[4.5] colors consistent with the colors of K and M giants. The contaminants are studied by comparison with the non-stellar emission imaged at 8 Îźm, which is dominated by the broad PAH feature. Using the measured 3.6 Îźm/8 Îźm ratio to select individual contaminants, we find that hot dust and PAHs together contribute between ~5% and 15% to the integrated light at 3.6 Îźm, while light from regions dominated by intermediate-age (AGB and RSG) stars accounts for only 1%-5%. Locally, however, the contribution from either contaminant can reach much higher levels; dust contributes on average 22% to the emission in star-forming regions throughout the sample, while intermediate-age stars contribute upward of 50% in localized knots. The removal of these contaminants with ICA leaves maps of the old stellar disk that retain a high degree of structural information and are ideally suited for tracing stellar mass, as will be the focus in a companion paper

    Flame retardant spandex type polyurethanes

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    Flame retardant elastomeric compositions were developed, comprised of: (1) spandex type polyurethane having incorporated into the polymer chain, halogen containing polyols; (2) conventional spandex type polyurethanes in physical admixture flame retardant additives; and (3) fluoroelastomeric resins in physical admixture with flame retardant additives. Methods of preparing fibers of the flame retardant elastomeric materials are presented and articles of manufacture comprised of the elastomeric materials are mentioned

    Dynamic Perceptual Changes in Audiovisual Simultaneity

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    Background: The timing at which sensory input reaches the level of conscious perception is an intriguing question still awaiting an answer. It is often assumed that both visual and auditory percepts have a modality specific processing delay and their difference determines perceptual temporal offset. Methodology/Principal Findings: Here, we show that the perception of audiovisual simultaneity can change flexibly and fluctuates over a short period of time while subjects observe a constant stimulus. We investigated the mechanisms underlying the spontaneous alternations in this audiovisual illusion and found that attention plays a crucial role. When attention was distracted from the stimulus, the perceptual transitions disappeared. When attention was directed to a visual event, the perceived timing of an auditory event was attracted towards that event. Conclusions/Significance: This multistable display illustrates how flexible perceived timing can be, and at the same time offers a paradigm to dissociate perceptual from stimulus-driven factors in crossmodal feature binding. Our findings suggest that the perception of crossmodal synchrony depends on perceptual binding of audiovisual stimuli as a common event

    Flame resistant elastic elastomeric fiber

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    Compositions exhibit elastomeric properties and possess various degrees of flame resistance. First material polyurethane, incorporates halogen containing polyol and is flame resistant in air; second contains spandex elastomer with flame retardant additives; and third material is prepared from fluorelastomer composition of copolymer of vinylidene fluoride and hexafluoropropylene

    Flame resistant elastomeric polymer development

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    Elastomeric products were developed for use in the space shuttle program, and investigations were conducted to improve the properties of elastomers developed in previous programs, and to evaluate the possibility of using lower-cost general purpose polymers. Products were fabricated and processed on conventional processing equipment; these products include: foams based on fluorinated rubber flame-retarded compounds with a density of 20-30 pounds/cubic foot for use as padding and in helmets; foams based on urethane for use in instrument packaging in the space shuttle; flexible and semi-rigid films of fluorinated rubber and neoprene compounds that would not burn in a 70% nitrogen, 30% oxygen atmosphere, and in a 30% nitrogen, 70% oxygen atmosphere, respectively for use in packaging or in laminates; coated fabrics which used both nylon and Kelvar fabric substrates, coated with either fluorinated or neoprene polymer compositions to meet specific levels of flame retardancy; and other flame-resistant materials

    Brickbats and bouquets for marketing

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    Purpose The purpose of this paper is to consider the development and application of marketing theory and practice over time and its current status. The terms “brickbats” and “bouquets” are used as metaphors to extend praise or criticism for marketing. In doing so, the authors draw upon the views of leading theorists over time and apply these in the current environmental context. Design/methodology/approach The approach adopted is discursive, critical and conceptual. Findings Following literature review, and drawing upon current examples, marketing as a discipline is subject to both kudos and criticisms. Nonetheless, it is concluded optimistically in that marketing can be an even greater source for societal good. That “goodness” is partly based upon the added impetus of social media adoption and use by consumers, the need for growth and accelerative innovation in the digital age coupled with the democratisation of consumption. Nonetheless, the authors offer the caveat that free competitive markets lead to market failures, and the need for market regulation by governments is becoming more evident. Research limitations/implications The implications of the paper are profound. Academics should be concerned in and involved with marketing theory. Questions need to be raised concerning non-robust definitions of marketing and its application. The authors wait for a consumer-led approach to marketing to add depth to the marketing theory. Practical implications Marketers need to be made more accountable for their actions. Consumers need to become part of the marketing process. Marketing claims need to be verified by delivered benefits. Companies need to take steps to ensure that the marketing process does not end at purchase. Satisfaction needs to be made manifest. Likewise, dissatisfactions need to be managed well as part of the marketing process. Social implications Too much marketing currently is relatively unregulated in the sense that there are so few opportunities to evade its myriad reach and – despite social media – little chance of changing marketing practice for the good of societies. Many criticisms of marketing practice are not being addressed in the literature. Originality/value Marketing is a vibrant force in all nations and markets. It is deeply rooted in business practice. It is contemporaneous and relevant. It is global and national. But, it is not entirely all good news. There are caveats and criticisms as well as kudos and praise. While both are addressed here, the topic needs to be considered for marketing and its accompanying theory and practice to change
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