2,798 research outputs found

    The Credit Union Difference

    Get PDF
    The credit union difference is in part reflected in its social impact. This report enables credit unions to identify, measure and report on their social impact with members and in society at large

    Traffic Modelling and Simulation Techniques for Evaluating ACL Implementation

    Get PDF
    This paper presents a modelling and simulation framework for analysing Access Control List (ACL) implementation on Internet devices. It uses the established modelling/simulation techniques of abstraction and simplification to isolate the essential components of the system from peripheral issues. As a case study, the viability of a simple real-time optimisation technique is demonstrated

    An argument for simple embedded ACL optimisation

    Get PDF
    The difficulty of efficiently reordering the rules in an Access Control List is considered and the essential optimisation problem formulated. The complexity of exact and sophisticated heuristics is noted along with their unsuitability for real time implementation embedded in the hardware of the network device. A simple alternative is proposed, in which a very limited rule reordering is considered following the processing of each packet. Simulation results are given from a range of traffic types. The method is shown to achieve savings that make its use worthwhile for lists longer than a given number of rules. This number is dependent on traffic characteristics but generally around 25 for typical network conditions

    Extended end-to-end cost metrics for improved dynamic route calculation

    Get PDF
    This paper considers the use of compound cost functions in routing calculations. Using an abstracted version of Cisco’s EIGRP as its basic model, it develops the theoretical principals of optimal end-to-end interior routing then details the limitations of conventional and current implementation. The requirements of an improved system are discussed and proposals for an enhanced Ant Colony Optimisation - DUAL protocol given. A comparative example is used to illustrate the points made and further work needed and other open questions are considered in conclusion. The paper has two purposes. In the main, it provides an analysis of current routing protocols and a model for future ones. In part, however, it is also intended to promote debate into many aspects of Internet routing and its ‘optimality’ in advance of long-term development of the new protocol

    Variable Dielectrics in the Calcium Magnesium Titanate System Characterized with Scanning Microwave Microscopy

    Full text link
    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65839/1/j.1551-2916.2006.00962.x.pd

    Rule Dependencies in Access Control Lists

    Get PDF
    This paper considers the effects of dependencies between rules in Access Control Lists (ACLs). Dependent rules may not be reordered in an ACL if the policies of the list are to be preserved. This is an obstacle to the optimisation of rule order intended to reduce the time taken matching packets against rules. In this paper, the concept of rule dependency is defined in relation to the problem of minimising processing latency. The concepts of dependence and possible dependence are introduced and the relationship between them considered. Two measures of dependency, the dependency index and the fragmented dependency index are defined and formulated and an upper bound for each is derived. Examples of real-world ACLs are studied and the implications for practical optimisation discussed

    Planar Anchoring Strength And Pitch Measurements In Achiral And Chiral Chromonic Liquid Crystals Using 90-Degree Twist Cells

    Get PDF
    Chromonic liquid crystals are formed by molecules that spontaneously assemble into anisotropic structures in water. The ordering unit is therefore a molecular assembly instead of a molecule as in thermotropic liquid crystals. Although it has been known for a long time that certain dyes, drugs, and nucleic acids form chromonic liquid crystals, only recently has enough knowledge been gained on how to control their alignment so that studies of their fundamental liquid crystal properties can be performed. In this article, a simple method for producing planar alignment of the nematic phase in chromonic liquid crystals is described, and this in turn is used to create twisted nematic structures of both achiral and chiral chromonic liquid crystals. The optics of 90-degree twist cells allows the anchoring strength to be measured in achiral systems, which for this alignment technique is quite weak, about 3 x 10(-7) J/m2 for both disodium cromoglycate and Sunset Yellow FCF. The addition of a chiral amino acid to the system causes the chiral nematic phase to form, and similar optical measurements in 90-degree twist cells produce a measurement of the intrinsic pitch of the chiral nematic phase. From these measurements, the helical twisting power for L-alanine is found to be (1.1 +/- 0.4) x 10(-2) mu m(-1) wt%(-1) for 15 wt% disodium cromoglycate

    Why the idea of framework propositions cannot contribute to an understanding of delusions

    Get PDF
    One of the tasks that recent philosophy of psychiatry has taken upon itself is to extend the range of understanding to some of those aspects of psychopathology that Jaspers deemed beyond its limits. Given the fundamental difficulties of offering a literal interpretation of the contents of primary delusions, a number of alternative strategies have been put forward including regarding them as abnormal versions of framework propositions described by Wittgenstein in On Certainty. But although framework propositions share some of the apparent epistemic features of primary delusions, their role in partially constituting the sense of inquiry rules out their role in helping to understand delusions

    Detection of H3N8 influenza A virus with multiple mammalian-adaptive mutations in a rescued Grey seal (Halichoerus grypus) pup

    Get PDF
    Avian influenza A viruses (IAVs) in different species of seals display a spectrum of pathogenicity, from sub-clinical infection to mass mortality events. Here we present an investigation of avian IAV infection in a 3- to 4-month-old Grey seal (Halichoerus grypus) pup, rescued from St Michael’s Mount, Cornwall in 2017. The pup underwent medical treatment but died after two weeks; post-mortem examination and histology indicated sepsis as the cause of death. IAV NP antigen was detected by immunohistochemistry in the nasal mucosa, and sensitive real-time reverse transcription polymerase chain reaction assays detected trace amounts of viral RNA within the lower respiratory tract, suggesting that the infection may have been cleared naturally. IAV prevalence among Grey seals may therefore be underestimated. Moreover, contact with humans during the rescue raised concerns about potential zoonotic risk. Nucleotide sequencing revealed the virus to be of subtype H3N8. Combining a GISAID database BLAST search and time-scaled phylogenetic analyses, we inferred that the seal virus originated from an unsampled, locally circulating (in Northern Europe) viruses, likely from wild Anseriformes. From examining the protein alignments, we found several residue changes in the seal virus that did not occur in the bird viruses, including D701N in the PB2 segment, a rare mutation, and a hallmark of mammalian adaptation of bird viruses. IAVs of H3N8 subtype have been noted for their particular ability to cross the species barrier and cause productive infections, including historical records suggesting that they may have caused the 1889 pandemic. Therefore, infections such as the one we report here may be of interest to pandemic surveillance and risk and help us better understand the determinants and drivers of mammalian adaptation in influenza

    Astrometric Microlensing with the GAIA satellite

    Get PDF
    GAIA is the ``super-Hipparcos'' survey satellite selected as a Cornerstone 6 mission by the European Space Agency. GAIA can measure microlensing by the small excursions of the light centroid that occur during events. The all-sky source-averaged astrometric microlensing optical depth is about 10^{-5}. Some 25000 sources will have a significant variation of the centroid shift, together with a closest approach, during the lifetime of the mission. A covariance analysis is used to study the propagation of errors and the estimation of parameters from realistic sampling of the GAIA datastream of transits in the along-scan direction during microlensing events. Monte Carlo simulations are used to study the 2500 events for which the mass can be recovered with an error of less than 50 per cent. These high quality events are dominated by disk lenses within a few tens of parsecs and source stars within a few hundred parsecs. We show that the local mass function can be recovered from the high quality sample to good accuracy. GAIA is the first instrument with the capabilities of measuring the mass locally in very faint objects like black holes and very cool white and brown dwarfs. For only 5 per cent of all astrometric events will GAIA record even one photometric datapoint. There is a need for a dedicated telescope that densely samples the Galactic Centre and spiral arms, as this can improve the accuracy of parameter estimation by a factor of about 10.Comment: 18 pages, 18 figures, MNRAS, in pres
    corecore