175,667 research outputs found

    How many networks are we to manage?

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    The continuous transformation of the industrial society into a service and knowledge society is accompanied by profound change of demand: Customer requests will increasingly focus on individual products, shorter delivery times and appropriate prices. To encounter these challenges under the conditions of dynamic global markets and inter-regional competition, the CRC 457 Non-Hierarchical Regional Production-Networks at the Chemnitz University of Technology focuses on SME and investigates ways to implement customer-oriented, temporary networking of smallest, autonomous units (competence cells) in the region of South-West-Saxony. As a partial result of this research we are able to present a model of competence cell based networking distinguishing between three levels of networking, each with its own logic of reproduction (cp. Figure 1): 1) According to a most general concept, networks can be seen as given in any social context. Regarding a specific region, one has to assume that there is a broad array of infra-structural, mental and communicative relations; that as a whole we call the Regional Network. This level can be seen as basic level of competence cell based networking, specific elements (competence cells) of this network can be seen as necessary resources of the following level. 2) The second level of networking we call Competence Network. The first continuous problem of this network is to select competence cells according to relevant parameters that may be defined by customer orders or, in view of new market entry, be generated by the Competence Network itself. The second problem is to arrange these cells along a product specific value chain and, by this means, to create temporary production networks. Concerning both of the problems, the third is to find a non-hierarchical mode of negotiation. 3) On the third level temporary alliances of basically autonomous competence cells can be observed. After executing their order, these Production Networks dissolve and the constituent cells reenter the second or even the first level of networking. Generalising our observation we now assume that every phenomena labelled as regional or industrial network or district should be investigated in view of (these) different levels of networking, especially if we are interested in dealing more efficiently with the problems of network management. Hence, we suggest to first answer the question Which (of these) networks are we to manage? before asking how. Concerning the latter, a synopsis on the discourse on managing networks shows three major approaches: 1) Networks are assumed to be uncontrollable (cp. e.g. Castells 2001), as they are self-organised systems selecting external control impulses only by their own criterias of relevance, so we have either to adapt the logic of the target system (which implies self-adaption) or to take the risk of being totally ignored. With this in mind we can't speak of control in terms of causal logic. 2) Networks are assumed to be cultivable: According to Wenger and Snyder (2000) for example networks are uncontrollable, but - like a gardener - we are able to set adequate general conditions for their growth and continuity. 3) Networks are assumed to be controllable: For authors like Sydow (2000) networks are to be seen as hybrid forms of coordination recombining aspects of market and hierarchy. Thus, recombining the classical means of control will finally lead to the ability to manage networks. It will be to show that each of these approaches focuses on specific aspects of networking, thus, each of them is creating a self-contained concept of networks: Castells refers to networks as a basal nexus of (global) interconnectedness that, like the Regional Network in our case, obviously can't be managed. Wenger and Snyder are interested in network-organisations that (like Competence Networks) also can't be controlled but can be implemented by and embedded in other social systems (cp. Grabher 1993). Sydow finally observes networks of more or less autonomous organisations corresponding to our Production Networks, which are in deed more or less controllable. Not least because of their different theoretical assumptions, all these concepts seemed to be not only incommensurable but incompatible so far. Nonetheless, during our work in CRC 457 we were to manage all these concepts while approaching to one single objective of research. Therefore, we had to ask, how many perspectives on network are we to manage? The answer is: at least three. Integrating these, we generated a holistic life-cycle model of network, which we like to present as starting point for further research in the field network management. --

    Differences in chronic pain prevalence between men and women at mid-life: a systematic review protocol

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    Introduction Epidemiological literature shows differences in chronic pain (CP) prevalence in men and women. Women are more likely to develop CP at different points of the life course, such as adolescence and old age. Less is known about the prevalence of CP by sex and the difference in prevalence during mid-life, when changes may predispose to an earlier differentiation in CP distribution. The aim of this study is to describe the difference in prevalence of CP at mid-life (ages 40-60) in men and women in the general population. Methods and analysis This systematic review follows Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Appropriate studies will be identified in the following databases: MEDLINE, EMBASE, AMED and PsycINFO. Two reviewers will independently screen each title and abstract. Studies eligible for data extraction will report estimates of CP prevalence for each sex, and/or a measure of the difference in prevalence between sexes. The findings will be reported in a narrative synthesis following the Social Research Council Methods Programme guidelines. A random effects meta-analysis will be conducted where the reviewers can justify combining results. Ethics and dissemination This review will summarise the prevalence of CP in men and women at mid-life, based on existing evidence. It is expected that the results will identify gaps in knowledge and areas for further research. The review will be submitted for publication in topic specific journals and disseminated to professional networks. Individual patient data are not included, so ethical approval is not required. PROSPERO registration number CRD42021295895

    Photodegradation of cytostatic drugs by g-C3N4: Synthesis, properties and performance fitted by selecting the appropriate precursor

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    Graphitic carbon nitride (g-C3N4) was synthetized by a one-step thermal method from different N-rich precursors, namely melamine, dicyandiamide, urea, thiourea and cyanamide. The structure, optical and physicochemical properties of g-C3N4 materials were studied by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy, among others. Both melamine and dicyandiamide provided a less porous structure composed by large flake sheets, whereas urea and thiourea favoured g-C3N4 composed by small flat sheets and wrinkles with a larger porosity. The establishment of more condensed g-C3N4 networks with a reduced band gap was also evidenced for melamine and dicyandiamide precursors, while urea favoured less condensed melem or melon structures. The photoactivity of the different g-C3N4 was assessed for the removal of an aqueous solution containing 5-fluorouracil (5-FU), cyclophosphamide (CP) or a mixture of both cytostatic drugs, under near UV-Vis and solar-LED irradiations. The best performing photocatalysts under near UV-Vis irradiation, were those prepared from melamine (kapp = 14.6 × 10–2 min–1 for 5-FU) and thiourea (kapp = 2.5 × 10–2 min–1 for CP), while urea was the most active under solar-LED irradiation (kapp = 0.183 × 10–2 min–1 for 5-FU). In addition, CP was more resistant to be degraded than 5-FU, and a competitive effect for the generated hydroxyl radicals was evidenced when both pollutant molecules were in the same solution. The photoactivity of g-C3N4 materials was justified by the combination of various effects: (i) surface area, (ii) well-connected and condensed g-C3N4 structures and (iii) high surface C/N ratios with nitrogen vacanciesSpanish Projects from MCIN/AEI/FEDER "Una manera de hacer Europa" RTI2018-099224-B-I00FEDER/Junta de Andalucia-Consejeria de Transformacion Economica, Industria, Conocimiento y Universidades B-RNM-486-UGR20Junta de Andalucia-Consejeria de Universidad, Investigacion e Innovacion -Proyecto P21_00208MICIN/AEIEuropean Social Found (FSE) PRE2019-087946MICIN/AEI RYC-2019-026634-IFSE "El FSE invierte en tu futuro"Universidad de Granada/CBU

    Detecting Core-Periphery Structures by Surprise

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    Detecting the presence of mesoscale structures in complex networks is of primary importance. This is especially true for financial networks, whose structural organization deeply affects their resilience to events like default cascades, shocks propagation, etc. Several methods have been proposed, so far, to detect communities, i.e. groups of nodes whose connectivity is significantly large. Communities, however do not represent the only kind of mesoscale structures characterizing real-world networks: other examples are provided by bow-tie structures, core-periphery structures and bipartite structures. Here we propose a novel method to detect statistically-signifcant bimodular structures, i.e. either bipartite or core-periphery ones. It is based on a modification of the surprise, recently proposed for detecting communities. Our variant allows for bimodular nodes partitions to be revealed, by letting links to be placed either 1) within the core part and between the core and the periphery parts or 2) just between the (empty) layers of a bipartite network. From a technical point of view, this is achieved by employing a multinomial hypergeometric distribution instead of the traditional (binomial) hypergeometric one; as in the latter case, this allows a p-value to be assigned to any given (bi)partition of the nodes. To illustrate the performance of our method, we report the results of its application to several real-world networks, including social, economic and financial ones.Comment: 11 pages, 10 figures. Python code freely available at https://github.com/jeroenvldj/bimodular_surpris
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