287,065 research outputs found
Link stability estimation based on link connectivity changes in mobile ad-hoc networks
No full textDear Wang,
Re: Link Stability Estimation Based on Link Connectivity Changes in Mobile Ad-hoc Networks
I have not been able to assess if this is an author version peer-reviewed or is it an author version non peer reviewed. Could you please clarify this so I can proceed to add your paper to Spiral. Spiral digital repository only accept peer-reviewed papers.
30/11/12 author has confirmed peer reviewe
An initial exploration of the link relationship between UK university Web sites.
No full textAggregates of links are of interest to information scientists in the same way as citation counts are: as potential sources of data from which new knowledge can be mined. Builds on the recent discovery of a correlation between a Web link count measure and the research quality of British universities by applying a range of multivariate statistical techniques to counts of links between pairs of universities. This represents an initial attempt at developing an understanding of this phenomenon. Extracts plausible results. Also identifies outliers in the data by the techniques, some of which were verified by being tracked down to identifiable Web phenomena. This is an important outcome because successful anomaly identification is a precondition to more effective analysis of this kind of data. The identification of groupings is encouraging evidence that Web links between universities can be mined for significant results, although it is clear that more methodological development is needed, if any but the simplest patterns are to be extracted. Finally, based upon the types of patterns extracted, argues that none of the methods used are capable of fully analysing link structures on their own
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Towards a localization of the “vc-“gene responsible for low vicine and convicine content in seeds of faba bean (Vicia faba L.) and towards a low vicine and convicine winter faba bean cultivar
No full textSynthesis and photochemistry of 8-substituted 5-deazaflavins
No full text5-Deazaflavin has been applied as a photocatalyst in the reduction of a wide variety of biological redox systems. The use of 5-deazaflavin as a photocatalyst has serious drawbacks in that continuous UV irradiation is required to drive the process and that the needed wavelength (300-400 nm) corresponds to an energy level high enough to destroy the protein enzyme in time.To avoid photodestruction of the protein a number of 5-deazaflavins, which have a chromophoric group at position 8 of the 5-deazaisoalloxazine skeleton, causing the absorption maximum to undergo a red shift, were synthesized (chapter 2). This was accomplished i) by the oxidative cyclization of 5,5'-arylmethylenebis(6-methylaminouracil) derivatives and ii) by the cyclization of N -methylanilinouracil derivatives with a one-carbon reagent. The latter method led to the formation of impure products. Condensation and oxidation reactions with the π-electron deficient C(8) methyl group in 5-deazalumiflavin did not occur. By the former method a number of 8-substituted 5-deazaflavins with a carboxymethyl group at the N(3) position were synthesized (chapter 3). This polar group was introduced prior to the oxidative cyclization and increased the solubility of 5-deazaflavins in aqueous media, in which photoreduction of redox enzymes are to be carried out. Introduction of substituents at position 8 caused a bathochromic shift that varied between 1 and 147 nm (chapter 6).Since the 5-deazaflavin radical is the actual reducing species within the photosystem, the effect of the substituents, introduced at position 8, on the reducing power of the radical was determined by measuring the half-wave potentials of the 5-deazaflavins (chapter 4). The dissociation constants of 5-deazaflavosemiquinones were successfully determined on the basis of the polarographic properties of 5-deazaflavins. Both half- wave potentials and dissociation constants appeared to be very sensitive to the substituent at position 8 and to meet the Hammett relation.The effect of the substituent on the spectroscopic (chapter 6) and photochemical (chapters 5, 6 and 7) properties was investigated. In contrast with the findings of others that irradiation of 5-deazaflavins in the presence of oxalate or ethylenediaminetetraacetate (EDTA) as electron donor exclusively leads to the formation of dimeric compounds as end-products of the photoreduction, illumination of 8-R-5-deazaflavins (R=Cl, N(CH 3 ) 2 , NH 2 , p -NH 2 -C 6 H 4 ) in the presence of various electron donors (EDTA, oxalate and triethanolamine) yielded the dimeric species 5,5'-bis(1,5-dihydro-8-R-5-deazaflavin) and/or 6,7-dihydro-8-R-5-deazaflavin. It was found that reduction of the C(6)-C(7) bond is highly promoted by strong electron donating substituents at position 8 and bulky electron donors. 5-Deazaflavins with a reducible substituent at position 8 (R=NO 2 , p -NO 2 -C 6 H 4 , p -N(CH 3 ) 2 -C 6 H 4 -N=N) exhibited the reduction of the substituent prior to the reduction of the 5-deazaisoalloxazine skeleton.The course (chapter 6) and rate (chapter 7) of the photoreduction of 8-R-5-deazaflavins were established and explained in terms of electronic and steric effects, exerted by the substituent at position 8 and the electron donor. In some cases the rate of photoreduction appeared to contain an autocatalytic element.The catalytic effect of 8-R-5-deazaflavins in the photoreduction of methyl viologen by EDTA was investigated (chapter 7). The substituent effect on the rate of the 8-R-5-deazaflavin mediated photoreduction of methyl viologen by EDTA was found to be comparable with that on the photoreduction rate of 8-R-5-deazaflavin in the presence of EDTA with the exception of 8-R-5-deazaflavin (R=N(CH 3 ) 2 ), which showed a remarkable relative enhancement of the reactivity towards methyl viologen photoreduction
Assessing collaborative, pre-competitive R & D projects: The case of the UK LINK scheme
No full textThe paper addresses the evaluation of outcomes of collaborative, pre-competitive R & D projects. It draws on some empirical analysis carried out on data and information gathered under the UK 'LINK' scheme, a programme supporting R & D collaborative projects and assessing collaboration outcomes. A new indicator of performance, based on the outputs of LINK projects, has been constructed. It provides a relative and quite consistent measure of performance for making comparisons among different LINK projects. However it does not correlate with the more subjective grade applied by LINK's own management. For further improving evaluating mechanisms, more attention should be paid to the benefits that universities and companies as well as governments are drawing from R & D collaborations
Link Augmentation: A Context-Based Approach to Support Adaptive Hypermedia
No full textIn today’s adaptive hypermedia systems, adaptivity is provided based on accumulative data gained from observing the user. User modelling, the capturing of information about the user such as their knowledge, tasks, attitudes, interests etc., is only a small part of the global context in which the user is working. At Southampton University we have formed a model of one particular aspect of context that can be applied in different ways to the problem of linking in context. This paper describes how that context model has been used to provide link augmentation. Link augmentation is an existing open hypermedia technique, which has a direct application in adaptive hypermedia systems. This paper presents a technique for cross-domain adaptive navigational support by combining link augmentation with a model of the user’s spatial context
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Existence Criteria of Two-Loop Six-Link R-R-C-C-R-C-C Spatial Mechanism
No full textThe necessary conditions for the existence of two-loop six-link R-R-C-C-R-C-C overconstrained mechanism are developed by extending Dimentberg’s approach of passive coupling. The developed conditions are examined to describe the geometry of the R-R-C-C-R-C-C mechanism for the existence of one general constraint.</jats:p
Modeling link adaptation algorithm for IEEE 802.11 wireless LAN networks
No full textLink adaptation is a critical component of IEEE 802.11 systems. In this paper, we analytically model a retransmission based Auto Rate Fallback (ARF) link adaptation algorithm. Both packet collisions and packet corruptions are modeled with the algorithm. The models can provide insights into the dynamics of the link adaptation algorithms and configuration of algorithms parameters. It is also observed that when the competing number of stations is high, packet collisions can largely affected the performance of ARF and make ARF operate with the lowest date rate, even when no packet corruption occur. This is in contrast to the existing assumption that packet collision will not affect the correct operation of ARF and can be ignored in the evaluation of ARF. The work presented in this paper can provide guidelines on configuring the link adaptation algorithms and designing new link adaptation algorithms for future high speed 802.11 systems
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