3,807 research outputs found

    Introducing IPv6 Tokenised Interface Identifiers into the Linux Kernel

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    IPv6 Stateless Address Autoconfiguration (SLAAC) enables network administrators to deploy devices in a network and have those devices automatically generate global addresses without any administrative intervention, and without the need for any stateful configuration service such as DHCPv6. However, certain services --- such as HTTP, SMTP and IMAP --- may better benefit from having "well known" identifiers that do not depend on the physical hardware address of the server's network interface card. Tokenised addresses offer facility for administrators to specify the bottom 64 bits of an IPv6 address for a node whilst allowing the top 64 bits (the network prefix) to be automatically configured from router advertisements. This report documents the approach taken and experience gained from introducing tokenised interface identifiers into the Linux 2.6.11 kernel, as shipped with Redhat Fedora Core 4. This proof of concept work demonstrates the relative ease of introducing this useful utility for network node deployment, and further motivates wider deployment of the semi-automatic configuration approach

    To germinate or not to germinate: more than just a question of dormancy

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    Consider the following four quotations concerning the distinction between breaking dormancy and stimulating germination

    Hypermedia by coincidence

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    We introduce an approach to linking hypermedia documents dynamically in a decentralised, peer-to-peer manner using resources that are available by coincidence, without explicit configuration. The particular approach presented utilises an open platform in combination with Distributed Link Service technology enabling dynamic hypertext generation

    Personality disorder and intellectual disability: the impacts of horticultural therapy within a medium-secure unit

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    This study was designed to explore the efficacy of a horticultural therapy intervention for the enhancement of subjective health and wellbeing in male service users with a dual diagnosis of personality disorder and intellectual disability in a medium secure unit in the north of England, UK. Service users (n=7) were involved in three focus groups; one just prior to a new garden facility opening, and then again at the six and twelve month points, which explored the personal impacts upon service users’ health and wellbeing. The garden was itself an upshot of participant involvement; service users were involved in all aspects of the garden design and maintenance, and also assisted with dissemination of the research goals and findings. Service users reported numerous personal health benefits as a result of their engagement with horticultural activities, allied to personal development enhancements in respect of gardening knowledge, employability skills, personal achievements and positive changes in behaviour towards self and others. Particularly, underlying these outputs, participants identified reduced stress, and a general “feel good” factor as key to their improved life-satisfaction. The mechanisms providing for these impacts included: interaction with a natural environment; enhanced intrinsic motivation derived from participation in a variety of tasks; and opportunities to develop specific horticultural skills. Immersion in horticultural activity may thus be an effective treatment modality in promoting positive health benefits to service users

    Resolving singular forces in cavity flow: Multiscale modeling from atoms to millimeters

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    A multiscale approach for fluid flow is developed that retains an atomistic description in key regions. The method is applied to a classic problem where all scales contribute: The force on a moving wall bounding a fluid-filled cavity. Continuum equations predict an infinite force due to stress singularities. Following the stress over more than six decades in length in systems with characteristic scales of millimeters and milliseconds allows us to resolve the singularities and determine the force for the first time. The speedup over pure atomistic calculations is more than fourteen orders of magnitude. We find a universal dependence on the macroscopic Reynolds number, and large atomistic effects that depend on wall velocity and interactions.Comment: 4 pages,3 figure

    Generation and sampling of quantum states of light in a silicon chip

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    Implementing large instances of quantum algorithms requires the processing of many quantum information carriers in a hardware platform that supports the integration of different components. While established semiconductor fabrication processes can integrate many photonic components, the generation and algorithmic processing of many photons has been a bottleneck in integrated photonics. Here we report the on-chip generation and processing of quantum states of light with up to eight photons in quantum sampling algorithms. Switching between different optical pumping regimes, we implement the Scattershot, Gaussian and standard boson sampling protocols in the same silicon chip, which integrates linear and nonlinear photonic circuitry. We use these results to benchmark a quantum algorithm for calculating molecular vibronic spectra. Our techniques can be readily scaled for the on-chip implementation of specialised quantum algorithms with tens of photons, pointing the way to efficiency advantages over conventional computers

    Object recognition in clutter: cortical responses depend on the type of learning

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    Theoretical studies suggest that the visual system uses prior knowledge of visual objects to recognize them in visual clutter, and posit that the strategies for recognizing objects in clutter may differ depending on whether or not the object was learned in clutter to begin with. We tested this hypothesis using functional magnetic resonance imaging (fMRI) of human subjects. We trained subjects to recognize naturalistic, yet novel objects in strong or weak clutter. We then tested subjects' recognition performance for both sets of objects in strong clutter. We found many brain regions that were differentially responsive to objects during object recognition depending on whether they were learned in strong or weak clutter. In particular, the responses of the left fusiform gyrus (FG) reliably reflected, on a trial-to-trial basis, subjects' object recognition performance for objects learned in the presence of strong clutter. These results indicate that the visual system does not use a single, general-purpose mechanism to cope with clutter. Instead, there are two distinct spatial patterns of activation whose responses are attributable not to the visual context in which the objects were seen, but to the context in which the objects were learned

    Navigational Hypertext Models For Physical Hypermedia Environments

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    In this paper we identify a common aim between ubiquitous computing and hypertext systems: the desire to present navigable, located and structured information. We propose that existing navigational hypertext models might be valuable as a formalisation of ubiquitous information and explore the challenges of applying standard hypertext operations, such as anchor resolution, display and link traversal, to links that have physical anchors

    U.S. Fresh Fruit and Vegetable Marketing: Emerging Trade Practices, Trends, and Issues

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    In the past year, trade practices between fresh produce shippers and food retailers gained national attention. Shippers are concerned that recent retail consolidation has led to market power and the growing incidence of fees and services. Retailers argue that these new trade practices reflect their costs of doing business and the demands of consumers. Trade practices include fees such as volume discounts and slotting fees, as well as services like automatic inventory replenishment, special packaging, and requirements for third-party food safety certification. Trade practices also refer to the overall structure of a transaction-for example, long-term relationships or contracts versus daily sales with no continuing commitment. This study compares trade practices in 1999 with those prevalent in 1994, placing them in the broader context of the evolving shipper/retailer relationship. Most shippers and retailers reported that the incidence and magnitude of fees and services associated with transactions has increased over the last 5 years. Fees paid to retailers are usually around 1-2 percent of sales for most of the commodities we examined, but 1-8 percent for bagged salads. Information on the incidence and magnitude of these new practices is scarce. To augment information that is publicly available, we interviewed a limited number of shippers, retailers, and wholesalers about their firms and trade practices. We received a high level of voluntary cooperation from the interviewed firms.produce, fresh fruit and vegetables, fresh-cut produce, trade practices, fees and services, slotting fees, retail consolidation, produce shipper consolidation, Crop Production/Industries, Marketing,
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