6,005 research outputs found

    X-ray Insights Into Interpreting CIV Blueshifts and Optical/UV Continua

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    We present 0.5-8.0 keV Chandra observations of six bright quasars that represent extrema in quasar emission-line properties -- three quasars each with small and large blueshifts of the CIV emission line with respect to the systemic redshift of the quasars. Supplemented with seven archival Chandra observations of quasars that met our selection criteria, we investigate the origin of this emission-line phenomenon in the general context of the structure of quasars. We find that the quasars with the largest CIV blueshifts show evidence, from joint-spectral fitting, for intrinsic X-ray absorption (N_H ~ 10^22 cm^-2). Given the lack of accompanying CIV absorption, this gas is likely to be highly ionized, and may be identified with the shielding gas in the disk-wind paradigm. Furthermore, we find evidence for a correlation of alpha_uv, the ultraviolet spectral index, with the hardness of the X-ray continuum; an analysis of independent Bright Quasar Survey data from the literature supports this conclusion. This result points to intrinsically red quasars having systematically flatter hard X-ray continua without evidence for X-ray absorption. We speculate on the origins of these correlations of X-ray properties with both CIV blueshift and alpha_uv and discuss the implications for models of quasar structure.Comment: 9 figs, 25 pages, AASTeX; accepted for publication in A

    A Novel Data Generation Approach for Digital Forensic Application in Data Mining

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    With the rapid advancements in information and communication technology in the world, crimes committed are also becoming technically intensive. When crimes committed use digital devices, forensic examiners have to adopt practical frameworks and methods for recovering data for analysis as evidence. Data Generation, Data Warehousing and Data Mining, are the three essential features involved in this process. This paper proposes a unique way of generating, storing and analyzing data, retrieved from digital devices which pose as evidence in forensic analysis. A statistical approach is used in validating the reliability of the pre-processed data. This work proposes a practical framework for digital forensics on flash drives

    The international organizational network as core capability : global product development in Fujitsu Limited

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    Includes bibliographical references (p. 51-52).Supported by the Japan-United States Friendship Commission and by the MIT Japan Program Corporate Consortium.Christopher J. Voisey

    Bits, Bytes, and Constitutional Rights: Navigating Digital Data and the Fourth Amendment

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    When Not All Papers are Paper: A Case Study in Digital Archivy

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    Hypertext poet Deena Larsen is worried about the potential loss of her digital poetry, but she has a plan to save it. In a 2004 article, “The Uncertain Fate of Scholarly Artifacts in a Digital Age,” Larsen revealed her plans for preserving her hypertext work Marble Springs. “Ms. Larsen started collecting old Macintosh computers so people will always be able to read Marble Springsin its original format. She has 100 computers in her two-bedroom apartment.” Although Larsen’s two-bedroom mausoleum of circa 1990s technology is one strategy for saving born-digital hypertext works, it is probably not the best. An armada of aging hardware will not protect digital objects from hard drive crashes, hardware failure, inoperable software, operating system malfunctions, unreadability, or natural disasters. Preservation of electronic records requires a commitment to active preservation practices including migration, refreshing, and integrity and authenticity checks of stored digital records. Maintaining the status quo, regardless of the magnitude of hardware and software stockpiles, is not a viable preservation strategy. The Electronic Literature Organization (ELO) notes the inadequacy of just holding onto digital materials and advocates more active digital preservation strategies in their latest publication, Born- Again Bits: “The stakes are even higher when we consider that keeping works of electronic literature alive in their original form does not serve all present needs, let alone those of the future.

    Using Fuzzy Cognitive Maps (FCMs) to Evaluate the Vulnerabilities with ICT Assets Disposal Policies

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    Abstract-- This paper evaluates the possible vulnerabilities of ICT assets disposal policies and the associated impact that can affect the SMEs. A poorly implemented policy or unenforced policy is “potentially the weakest link ” in the cyber-security chain. Do SMEs have an idea of vulnerabilities or threats due to assets disposal? In the event of breaches, the SMEs pay for the cost of notifying the concerned stakeholders, compensate affected parties, invest in improved mitigation technologies and also may be subjected to unwarranted public scrutiny. ICT assets at the end-of-useful life span usually have data left on the hard disk drives or storage media, which is a source of data confidentiality vulnerability. SMEs were surveyed in developing economies on their assets disposal policies. The perceived correlations were analyzed using fuzzy cognitive maps (FCMs) to ascertain if any cyber-security vulnerabilities inherent in a particular policy have implications on others. The study endeavored to show that, SMEs ought to have appropriate assets disposal policies in place. Then, these policies ought to be signed off by all stakeholders as a matter of responsibility. By employing the FCM approach with fuzzy matrix operations, the results indicate positive correlations exist amongst the policy constructs. Thus, vulnerabilities with one policy have implications on others

    NSSDC Conference on Mass Storage Systems and Technologies for Space and Earth Science Applications, volume 2

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    This report contains copies of nearly all of the technical papers and viewgraphs presented at the NSSDC Conference on Mass Storage Systems and Technologies for Space and Earth Science Application. This conference served as a broad forum for the discussion of a number of important issues in the field of mass storage systems. Topics include the following: magnetic disk and tape technologies; optical disk and tape; software storage and file management systems; and experiences with the use of a large, distributed storage system. The technical presentations describe, among other things, integrated mass storage systems that are expected to be available commercially. Also included is a series of presentations from Federal Government organizations and research institutions covering their mass storage requirements for the 1990's

    A Comparison of the Rule and Case-based Reasoning Approaches for the Automation of Help-desk Operations at the Tier-two Level

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    This exploratory study investigates the hypothesis that case-based reasoning (CBR) systems have advantages over rule-based reasoning (RBR) systems in providing automated support for Tier-2 help desk operations. The literature suggests that rule-based systems are best suited for problem solving when the system being analyzed is a single-purpose, specialized system and the rules for solving the problems are clear and do not change with high frequency. Case-based systems, because of their ability to offer alternative solutions for a given problem, give help-desk technicians more flexibility. Specifically, this dissertation aims to answer the following questions: 1. Which paradigm, rule-based or case-based reasoning, results in more precise solutions to problems when compared to the solutions derived from system manuals? 2. Which paradigm, rule-based or case-based reasoning, is more convenient to maintain in terms of knowledge modification (i.e. addition, deletion, or modification of rules/cases)? 3. Which paradigm, rule-based or case-based reasoning, enables help-desk technicians to solve problems in shorter time, and therefore at lower cost? This is an exploratory study based on data collected from field experiments. RBR and CBR based prototypes were set up to support Tier-2 help desk operations. Trained help desk operators used the system to solve a set of benchmark problems. Data collected from this exercise was analyzed to answer the three research questions. This exploratory study supported the hypothesis that the case-based paradigm is better suited for use in help desk environments at the Tier-2 level than is the rule-based paradigm. The case-based paradigm, because of its ability to offer alternative solutions for a given problem, gave the help-desk technician flexibility in applying a solution. Alternatively, the rule-based paradigm provided a solution if, and only if, a rule existed for a solution meeting the exact problem specifications. Further, in the absence of a rule, problem research time, using the rule-based paradigm, extended the time required to formulate a solution thereby increasing the cost. This research provided sufficient information to show that the help-desk knowledge based system utilizing the case-based shell provided better overall solutions to problems than did the rule-based shell

    Identification of Clear Text Data Obfuscated Within Active File Slack

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    Obfuscating text on a hard drive can be done by utilizing the slack space of files. Text can be inserted into the area between the end of the file data and the New Technology File System (NTFS) cluster (the smallest drive space allocated to a file) that in which the file is stored, the data is hidden from traditional methods of viewing. If the hard drive is large, how does a digital forensics expert know where to look to find text that has been obfuscated? Searching through a large hard drive could take up a substantial amount of time that the expert possibly could not justify. If the digital forensics expert lacks the knowledge on how to properly search a hard drive for obfuscated clear text using data carving concepts, how will the obfuscated clear text be located on the drive and identified? To address this, an algorithm was proposed and tested, which resulted in the successful identification of clear text data in slack space with a percentage average of 99.31% identified. This algorithm is a reliable form of slack space analysis which can be used in conjunction with other data extraction methods to see the full scope of evidence on a drive
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