18,331 research outputs found
Weighted Configuration Model
The configuration model is one of the most successful models for generating
uncorrelated random networks. We analyze its behavior when the expected degree
sequence follows a power law with exponent smaller than two. In this situation,
the resulting network can be viewed as a weighted network with non trivial
correlations between strength and degree. Our results are tested against large
scale numerical simulations, finding excellent agreement.Comment: Proceedings CNET200
Rich-club vs rich-multipolarization phenomena in weighted networks
Large scale hierarchies characterize complex networks in different domains.
Elements at their top, usually the most central or influential, may show
multipolarization or tend to club forming tightly interconnected communities.
The rich-club phenomenon quantified this tendency based on unweighted network
representations. Here, we define this metric for weighted networks and discuss
the appropriate normalization which preserves nodes' strengths and discounts
structural strength-strength correlations if present. We find that in some real
networks the results given by the weighted rich-club coefficient can be in
sharp contrast to the ones in the unweighted approach. We also discuss that the
scanning of the weighted subgraphs formed by the high-strength hubs is able to
unveil features contrary to the average: the formation of local alliances in
rich-multipolarized environments, or a lack of cohesion even in the presence of
rich-club ordering. Beyond structure, this analysis matters for understanding
correctly functionalities and dynamical processes relying on hub
interconnectedness.Comment: 12 pages, 2 figure
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Modelling the integration of BP and IT using business process simulation
Information Technology (IT) and Business Process (BP) communities argues that the use of IT to support business processes can bring a number of benefits to the organisation. Most of these benefits, however, can only be seen after the implementation of such technology. Moreover, there are many cases where the benefits brought by the implementation of IT do not fulfil the organisation’s expectations. One reason of this may happen is because research in BP and IS domains show little indication of which modelling methods, techniques or tools can help organisations to foresee the benefits of the integration of IT with BP. This paper describes the insights gained during a UK funded research project, namely ASSESS-IT, which used simulation techniques to address this problem. Considering IT as a two layered system, namely Information Systems (IS) and Computer Networks (CN), ASSESS-IT aimed to depict the benefits that new IT may bring to the BP. This paper uses the outcomes derived from ASSESS-IT to suggest that, in some cases; the relationship between BP and IT could be better understood by looking at the relationship between BP and IS alone. It then proposes an alternative simulation framework, namely ISBPS, that provides the means to develop simulation models that portray quantifiable metrics of the integration of BP and IS, offering in this way an alternative mechanism that can help BP and IS analyst to foresee the benefits that the insertion of a given IS design may bring to the organisational processes
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A programme management approach for ensuring coherence in IS (higher) education
This paper examines IS higher education, concentrating on issues of ‘coherence’ in IS curricula. While curriculum coherence can be jeopardized by poor curriculum design, misalignment between module content and/or misalignment between module or course aims can cause serious coherence issues over time. Misalignment of this type is exacerbated by the traditional processes of curriculum (re)design, which rely heavily on the (singular) interpretation of highly abstract documents, such as module syllabi and course specifications – often produced by curriculum designers in isolation. To improve curriculum coherence, this paper examines the use of a programme management framework as a means of (a) ‘humanizing’ the abstract aims and goals of curricula schemes and (b) managing the delivery and evolution of curricula in relation to the stakeholders in the process of delivery. The practical use of the framework is examined in the context of a Masters-level course in ‘Information Systems Management’. An action research approach is used to demonstrate the practical utility of the framework in terms of (a) improving communication of curricula, (b) improving the coherence between modules and between modules and course and (c) removing content redundancy. Guidelines are presented that generalize the findings in order that key practices may be adopted by others
Correlated enhancement of Hc2 and Jc in carbon nanotube-doped MgB2
The use of MgB2 in superconducting applications still awaits for the
development of a MgB2-based material where both current-carrying performance
and critical magnetic field are optimized simultaneously. We achieved this by
doping MgB2 with double-wall carbon nanotubes (DWCNT) as a source of carbon in
polycrystalline samples. The optimum nominal DWCNT content for increasing the
critical current density, Jc is in the range 2.5-10%at depending on field and
temperature. Record values of the upper critical field, Hc2(4K) = 41.9 T (with
extrapolated Hc2(0) ~ 44.4 T) are reached in a bulk sample with 10%at DWCNT
content. The measured Hc2 vs T in all samples are successfully described using
a theoretical model for a two-gap superconductor in the dirty limit first
proposed by Gurevich et al.Comment: 12 pages, 3 figure
Quark-Meson Coupling model based upon the Nambu-Jona Lasinio model
The NJL model for the octet baryons, using proper time regularization to
simulate some of the features of confinement, is solved self-consistently in
nuclear matter. This provides an alternative framework to the MIT bag model
which has been used in the quark-meson coupling model. After fitting the
parameters of the model to the saturation properties of symmetric nuclear
matter the model is used to explore the equation of state of pure neutron
matter as well as nuclear matter at densities relevant to heavy ion collisions.
With a view to future studies of high mass neutron stars, the binding of
hyperons is also explored.Comment: 7 pages and 4 figure
Genetic and Molecular Factors in Drug-Induced Liver Injury: A Review
The diagnosis of drug-induced liver injury (DILI) is challenging and based on complex diagnostic criteria. DILI falls into two main categories i) intrinsic 'dose-dependent' Type A reactions ii) 'idiosyncratic' or Type B reactions (which are usually not predictable). Idiosyncratic reactions can be immunoallergic (hypersensitivity), or metabolic, although overlap between categories can occur. The aim of this review is to summarise the general view of underlying mechanisms in DILI and to highlight individual risk factors for developing hepatotoxicity. Polymorphisms of bioactivation/ toxification pathways through CYP450 enzymes (Phase I), detoxification reactions (Phase II) and excretion/transport (Phase III) are explored together with immunological factors that might determine DILI. The importance of establishing a multidisciplinary and multi-centric network to promote the understanding and research in hepatotoxicity is underlined. Challenges such as genetic analyses for association studies and whole genome studies, pharmacogenetic testing and future approaches to study DILI are considered. Knowledge regarding these operational mechanisms could provide further insight for the prospective identification of susceptible patients at risk of developing drug-induced hepatotoxicity.
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