970 research outputs found

    A distinctive energy policy for Scotland?

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    This paper explores the emergence of a distinctive energy policy for Scotland and raises the issue of the desirability of any differentiation from UK energy policy. This requires an examination of both UK and Scottish energy policies, although we adopt a rather broad-brush overview rather than a very detailed analysis

    Peer-to-Peer vs. the Internet: A Discussion on the Proper and Practical Location of Functionality

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    Peer-to-peer information sharing has become one of the dominant Internet applications, measured not only in the number of users, but also in the network bandwidth consumed. Thus, it is reasonable to examine the location of support functionality such as self-organisation, resource discovery, multipoint-to-multipoint group communication, forwarding, and routing, to provide the needed service to applications while optimising resource usage in the network. This position paper is intended to stimulate discussion in two related areas: First, where {em should} functionality to support peer-to-peer applications be located: in the network, or as an application overlay among end systems. Second, where {em can} functionality be located, given the practical constraints of the modern Internet including closed systems and middleboxes, as well as administrative, legal, and social issues. We will discuss the performance implications of these decisions, including whether low latency bounds for delay sensitive peer-to-peer applications (such as distributed network computing) can ever be achieved in this environment

    Axon: Host-Network Interface Design

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    This paper describes the Axon host-network interface architecture. The Axon project is investigating an integrated design of host architecture, operating systems, and communications protocols to allow applications to utilize the high bandwidth provided by the next generation of communications networks. The Axon host architecture and network interface is designed to provide a high bandwidth low latency path directly between the network and host memory. A pipelined communications processor (CMP) serves as a network interface with direct access to host memory, capable of delivering bandwidth in excess of 1 Gbps to applications. This provides the ability to support demanding applications such as scientific visualizations and imaging, requiring high bandwidth and low latency

    Effect of calf-starter protein solubility on calf performance

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    Three starters containing differently processed protein supplements were fed to Holstein heifer calves, using an early weaning program. One starter contained soybean meal. The other starters contained soybean grits processed through an extrusion cooker to reduce the protein solubility to an intermediate (PDI> 50%) or low (PDI < 15 %) level. Calf performance was similar on all three starters

    Axon: Application-Oriented Lightweight Transport Protocol Design

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    This paper describes the application-oriented lightweight transport protocol for object transfer (ALTP-OT) in the Axon host communication architecture for distributed applications. The Axon Project is investigating an integrated design of host architecture, operating systems, and communication protocols to allow the utilization of the high band-width provided by the next generation of communication networks. ALTP-OT provides the end-to-end transport of segment and message objects for interprocess communication across a very high speed internetwork, supporting demanding applications such as scientific visualization and imaging. ALTP-OT uses rate-based flow control specifically oriented to the transfer of objects directly between application memory spaces. This document is intended to present the design of ALTP-OT, rather than serve as a complete specification and implementation report. It should be treated as a request for comments, and will be periodically updated to reflect comments form the research community and progress on Axon design and prototype implementation. Last revision April 5, 1990

    Axon: Network Virtual Storage Design

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    This paper describes the design of network virtual storage (NVS) in the Axon host communications architecture for distributed applications. The Axon project is investigating an integrated design of host architecture, operating systems, and communications protocols to allow applications to utilize the high bandwidth provided by the next generation of communications networks. NVS extends segmented paged virtual storage management and address translation mechanisms to include segments located across an internetwork. This provides the ability to efficiently use the shared memory paradigm in non-local environments, as well as the support for a very high speed end-to-end data path between demanding applications such as scientific visualization and imaging

    Axon: A High Speed Communication Architecture for Distributed Applications

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    There are two complementary trends in the computer and communication fields. Increasing processor power and memory availability allow more demanding applications, such as scientific visualization and imaging. Advances in network performance and functionality have the potential for supporting programs requiring high bandwidth and predictable performance. However, the bottleneck in increasingly in the host-network interface, and thus the ability to deliver high performance communication capability to applications has not kept up with the advances in computer and network speed. We have proposed a new architecture that meets these challenges called Axon, whose novel aspects include: an integrated design of hardware, operating systems, and communications protocols, stressing both performance and the required functionality for demanding applications; the proper division of hardware and software function; and reorganization of end-to-end protocols to take advantage of the increased functionality of the emerging high speed internetworks

    Axon Host-Network Interface Architecture for Gigabit Communication

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    This paper describes the design of the Axon host-network interface architecture, and performance factors determining its design. The Axon project is investigating an integrated design of the host architecture, operating systems, and communications protocols to allow applications to utilise the high bandwidth provided by the next generation of communications networks. The Axon host architecture and network interface is designed to provide a path directly between the network interface with direct access to host memory, capable of delivering bandwidth in excess of 1 Gbps to applications. This provide the ability to support demanding applications such as scientific visualisation and imaging

    Ultramafic xenoliths from the Bearpaw Mountains, Montana, USA: evidence for multiple metasomatic events in the lithospheric mantle beneath the Wyoming craton

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    Ultramafic xenoliths in Eocene minettes of the Bearpaw Mountains volcanic field (Montana, USA), derived from the lower lithosphere of the Wyoming craton, can be divided based on textural criteria into tectonite and cumulate groups. The tectonites consist of strongly depleted spinel lherzolites, harzburgites and dunites. Although their mineralogical compositions are generally similar to those of spinel peridotites in off-craton settings, some contain pyroxenes and spinels that have unusually low Al2O3 contents more akin to those found in cratonic spinel peridotites. Furthermore, the tectonite peridotites have whole-rock major element compositions that tend to be significantly more depleted than non-cratonic mantle spinel peridotites (high MgO, low CaO, Al2O3 and TiO2) and resemble those of cratonic mantle. These compositions could have been generated by up to 30% partial melting of an undepleted mantle source. Petrographic evidence suggests that the mantle beneath the Wyoming craton was re-enriched in three ways: (1) by silicate melts that formed mica websterite and clinopyroxenite veins; (2) by growth of phlogopite from K-rich hydrous fluids; (3) by interaction with aqueous fluids to form orthopyroxene porphyroblasts and orthopyroxenite veins. In contrast to their depleted major element compositions, the tectonite peridotites are mostly light rare earth element (LREE)-enriched and show enrichment in fluid-mobile elements such as Cs, Rb, U and Pb on mantle-normalized diagrams. Lack of enrichment in high field strength elements (HFSE; e.g. Nb, Ta, Zr and Hf) suggests that the tectonite peridotites have been metasomatized by a subduction-related fluid. Clinopyroxenes from the tectonite peridotites have distinct U-shaped REE patterns with strong LREE enrichment. They have 143Nd/144Nd values that range from 0·5121 (close to the host minette values) to 0·5107, similar to those of xenoliths from the nearby Highwood Mountains. Foliated mica websterites also have low 143Nd/144Nd values (0·5113) and extremely high 87Sr/86Sr ratios in their constituent phlogopite, indicating an ancient (probably mid-Proterozoic) enrichment. This enriched mantle lithosphere later contributed to the formation of the high-K Eocene host magmas. The cumulate group ranges from clinopyroxene-rich mica peridotites (including abundant mica wehrlites) to mica clinopyroxenites. Most contain >30% phlogopite. Their mineral compositions are similar to those of phenocrysts in the host minettes. Their whole-rock compositions are generally poorer in MgO but richer in incompatible trace elements than those of the tectonite peridotites. Whole-rock trace element patterns are enriched in large ion lithophile elements (LILE; Rb, Cs, U and Pb) and depleted in HFSE (Nb, Ta Zr and Hf) as in the host minettes, and their Sr–Nd isotopic compositions are also identical to those of the minettes. Their clinopyroxenes are LREE-enriched and formed in equilibrium with a LREE-enriched melt closely resembling the minettes. The cumulates therefore represent a much younger magmatic event, related to crystallization at mantle depths of minette magmas in Eocene times, that caused further metasomatic enrichment of the lithosphere

    Light and Life: Exotic Photosynthesis in Binary Star Systems

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    The potential for hosting photosynthetic life on Earth-like planets within binary/multiple stellar systems was evaluated by modelling the levels of photosynthetically active radiation (PAR) such planets receive. Combinations of M and G stars in: (i) close-binary systems; (ii) wide-binary systems and (iii) three-star systems were investigated and a range of stable radiation environments found to be possible. These environmental conditions allow for the possibility of familiar, but also more exotic forms of photosynthetic life, such as infrared photosynthesisers and organisms specialised for specific spectral niches.Comment: Accepted for publication in: Astrobiolog
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