Dynamic organization schemes for cooperative proxy caching

In a generic cooperative caching architecture, web proxies form a mesh network. When a proxy cannot satisfy a request, it forwards the request to the other nodes of the mesh. Since a local cache cannot fulfill the majority of the arriving requests (typical values of the local hit ratio are about 30-50%), the volume of queries diverted to neighboring nodes can substantially grow and may consume considerable amount of system resources. A proxy does not need to cooperate with every node of the mesh due to the following reasons: (i) the traffic characteristics may be highly diverse; (ii) the contents of some nodes may extensively overlap; (iii) the inter-node distance might be too large. Furthermore, organizing N proxies in a mesh topology introduces scalability problems, since the number of queries is of the order of N/sup 2/. Therefore, restricting the number of neighbors for each proxy to k < N - 1 will likely lead to a balanced trade-off between query overhead and hit ratio, provided cooperation is done among useful neighbors. For a number of reasons the selection of useful neighbors is not efficient. An obvious reason is that web access patterns change dynamically. Furthermore, availability of proxies is not always globally known. This paper proposes a set of algorithms that enable proxies to independently explore the network and choose the k most beneficial (according to local criteria) neighbors in a dynamic fashion. The simulation experiments illustrate that the proposed dynamic neighbor reconfiguration schemes significantly reduce the overhead incurred by the mesh topology while yielding higher hit ratios compared to the static approach.published_or_final_versio

A 12-fold ths interpenetrated network utilizing a glycine-based pseudopeptidic ligand

We report the synthesis and characterization of a 3D Cu(II) coordination polymer, [Cu3(L1)2(H2O)8]·8H2O (1), with the use of a glycine-based tripodal pseudopeptidic ligand (H3L1 = N,N’,N’’-tris(carboxymethyl)-1,3,5-benzenetricarboxamide or trimesoyl-tris-glycine). This compound presents the first example of a 12-fold interpenetrated ths net. We attempt to justify the unique topology of 1 through a systematic comparison of the synthetic parameters in all reported structures with H3L1 and similar tripodal pseudopeptidic ligands. We additionally explore the catalytic potential of 1 in the A3 coupling reaction for the synthesis of propargylamines. The compound acts as a very good heterogeneous catalyst with yields up to 99% and loadings as low as 3 mol%

Review: Recent advances of one-dimensional coordination polymers as catalysts

This review aims to provide reports of one dimensional (1-D) coordination polymers that have been used as catalysts in various organic reactions in the last decade, covering the literature from 2007 and onwards. The CPs have been mainly categorized into homometallic and heterometallic compounds; additional parameters such as the metal and ligand selection for the CP are discussed to provide a more detailed look into each system

Dinuclear Lanthanide (III) coordination polymers in a domino reaction

A systematic study was performed to further optimise the catalytic room-temperature synthesis of trans-4,5- diaminocyclopent-2-enones from 2-furaldehyde and primary or secondary amines under a non-inert atmosphere. For this purpose, a series of dinuclear lanthanide (III) coordination polymers were synthesised using a dianionic Schiff base and their catalytic activities were investigated

A general framework for searching in distributed data repositories

This paper proposes a general framework for searching large distributed repositories. Examples of such repositories include sites with music/video content, distributed digital libraries, distributed caching systems, etc. The framework is based on the concept of neighborhood; each client keeps a list of the most beneficial sites according to past experience, which are visited first when the client searches for some particular content. Exploration methods continuously update the neighborhoods in order to follow changes in access patterns. Depending on the application, several variations of search and exploration processes are proposed. Experimental evaluation demonstrates the benefits of the framework in different scenarios.published_or_final_versio

Non-adaptive Measurement-based Quantum Computation and Multi-party Bell Inequalities

Quantum correlations exhibit behaviour that cannot be resolved with a local hidden variable picture of the world. In quantum information, they are also used as resources for information processing tasks, such as Measurement-based Quantum Computation (MQC). In MQC, universal quantum computation can be achieved via adaptive measurements on a suitable entangled resource state. In this paper, we look at a version of MQC in which we remove the adaptivity of measurements and aim to understand what computational abilities still remain in the resource. We show that there are explicit connections between this model of computation and the question of non-classicality in quantum correlations. We demonstrate this by focussing on deterministic computation of Boolean functions, in which natural generalisations of the Greenberger-Horne-Zeilinger (GHZ) paradox emerge; we then explore probabilistic computation, via which multipartite Bell Inequalities can be defined. We use this correspondence to define families of multi-party Bell inequalities, which we show to have a number of interesting contrasting properties.Comment: 13 pages, 4 figures, final version accepted for publicatio

CEO Education and the Ability to Raise Capital

We examine whether heterogeneity of CEO academic qualifications matters in explaining the performance of Initial Public Offerings (IPOs). We find that CEO education attainments perform a signaling role which depends not only on the level but also on the major of education. Specifically, we show that, irrespective of the level of academic achievements, IPO investors have a preference for top managers with practice or business oriented degrees as opposed to liberal arts degrees. Importantly, our findings suggest that both the level and quality of education training tend to reduce IPO underpricing, and this effect is less pronounced for less specialized degrees

Corporate Political Activism, Information Transparency, and IPO Compliance Costs

Due to their covert and often dubious nature, corporate political activities may encourage or facilitate opportunistic behaviors. Yet, they also subject firms to heightened visibility, which brings greater public and regulatory scrutiny. Using a hand-collected data set of politically connected US initial public offerings (IPOs), we investigate how this tension shapes the financial reporting incentives of firms going public and the accompanying direct compliance costs. Consistent with the agency view of corporate political activism (CPA), politically active IPO issuers have worse financial reporting quality, more litigation risk and eventually pay 28% more accounting fees than their peers. Additional analysis exploiting the US Supreme Court's landmark ruling on Citizens United versus Federal Election Commission suggests that the link between CPA and IPO accounting fees is likely to be causal. Finally, our evidence indicates that the involvement of specialized financial intermediaries in the political process has implications for the IPO financial reporting quality.</p