1,085 research outputs found

    Choreography in IRS-III – coping with heterogeneous interaction patterns in web services

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    In this paper we describe how we handle heterogeneity in web service interaction through a choreography mechanism that we have developed for IRS-III. IRS-III is a framework and platform for developing semantic web services which utilizes the WSMO ontology. The overall design of our choreography framework is based on: the use of ontologies and state, IRS-III playing the role of a broker, differentiating between communication direction and which actor has the initiative, having representations which can be executed, a formal semantics, and the ability to suspend communication. Our framework has a full implementation which we illustrate through an example application

    Problem solving using artificial intelligence techniques

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    Real-world problems often do not lend themselves to an algorithmic solution. Humans, however, cope with these problems despite their fallible problem solving techniques. Instead of trying to construct algorithms to solve problems AI researchers have concentrated on using the more successful methods used by humans. This paper reviews the area of problem solving in the field of Artificial Intelligence. This includes problem representation for computation, "weak" methods of searching for a problems solution, knowledge representations that facilitate more efficient search strategies and planning - an advanced problem solving technique

    Optical properties of planar chiral meta-materials

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    The polarization state of visible light is found to be altered upon reflection from artificial two-dimensional chiral media. Arrays of metallic planar chiral structures were fabricated by electron beam lithography and ion beam milling. The characteristic dimensions on the chiral elements correspond to wavelengths in the near-IR. Our chiral media are found to induce strong polarization effects, with the handedness of individual elements having a direct effect on the sense and magnitude of rotation of the diffracted light

    Effect of Residual Sugar in High Sugar Grass Silages on Aerobic Stability

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    New varieties of Lolium perenne, bred for high sugar content, can contain up to 30% of water soluble carbohydrates (WSC). Only a fraction of such high contents are metabolised during a normal fermentation and the high residual sugar content (RSC) of these silages can improve the efficiency of use of nitrogen by ruminants. However, these RSC at opening for feed-out could be preferentially metabolised relative to fermentation products by all aerobically growing fungi and bacteria present on the forage. A high RSC thus can increase the risk of aerobic deterioration over that of extensively fermented silages, containing predominantly organic acids, which are initially utilised by certain yeasts. The objective of this study was to assess the relationship between RSC and aerobic stability of silages prepared with either optimal ensiling conditions or with a defined air challenge treatment to make them prone to aerobic deterioration. The latter is a useful method to test the efficacy of aerobic stability improving silage additives, requiring unstable controls (Pahlow et al., 1999)

    Kroniek: Bestuurlijke organisatie

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    Differences between <i>Trypanosoma brucei gambiense</i> groups 1 and 2 in their resistance to killing by Trypanolytic factor 1

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    &lt;p&gt;&lt;b&gt;Background:&lt;/b&gt; The three sub-species of &lt;i&gt;Trypanosoma brucei&lt;/i&gt; are important pathogens of sub-Saharan Africa. &lt;i&gt;T. b. brucei&lt;/i&gt; is unable to infect humans due to sensitivity to trypanosome lytic factors (TLF) 1 and 2 found in human serum. &lt;i&gt;T. b. rhodesiense&lt;/i&gt; and &lt;i&gt;T. b. gambiense&lt;/i&gt; are able to resist lysis by TLF. There are two distinct sub-groups of &lt;i&gt;T. b. gambiense&lt;/i&gt; that differ genetically and by human serum resistance phenotypes. Group 1 &lt;i&gt;T. b. gambiense&lt;/i&gt; have an invariant phenotype whereas group 2 show variable resistance. Previous data indicated that group 1 &lt;i&gt;T. b. gambiense&lt;/i&gt; are resistant to TLF-1 due in-part to reduced uptake of TLF-1 mediated by reduced expression of the TLF-1 receptor (the haptoglobin-hemoglobin receptor (&lt;i&gt;HpHbR&lt;/i&gt;)) gene. Here we investigate if this is also true in group 2 parasites.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Methodology:&lt;/b&gt; Isogenic resistant and sensitive group 2 &lt;i&gt;T. b. gambiense&lt;/i&gt; were derived and compared to other T. brucei parasites. Both resistant and sensitive lines express the &lt;i&gt;HpHbR&lt;/i&gt; gene at similar levels and internalized fluorescently labeled TLF-1 similar fashion to &lt;i&gt;T. b. brucei&lt;/i&gt;. Both resistant and sensitive group 2, as well as group 1 &lt;i&gt;T. b. gambiense&lt;/i&gt;, internalize recombinant APOL1, but only sensitive group 2 parasites are lysed.&lt;/p&gt; &lt;p&gt;&lt;b&gt;Conclusions:&lt;/b&gt; Our data indicate that, despite group 1 &lt;i&gt;T. b. gambiense&lt;/i&gt; avoiding TLF-1, it is resistant to the main lytic component, APOL1. Similarly group 2 &lt;i&gt;T. b. gambiense&lt;/i&gt; is innately resistant to APOL1, which could be based on the same mechanism. However, group 2 &lt;i&gt;T. b. gambiense&lt;/i&gt; variably displays this phenotype and expression does not appear to correlate with a change in expression site or expression of &lt;i&gt;HpHbR&lt;/i&gt;. Thus there are differences in the mechanism of human serum resistance between &lt;i&gt;T. b. gambiense&lt;/i&gt; groups 1 and 2.&lt;/p&gt
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