The Structure of 4-Clusters in Fullerenes

Fullerenes can be considered to be either molecules of pure carbon or the trivalent plane graphs with all hexagonal and (exactly 12) pentagonal faces that models these molecules. Since carbon atoms have valence 4 and our models have valence 3, the edges of a perfect matching are doubled to bring the valence up to 4 at each vertex. The edges in this perfect matching are called a Kekule structure and the hexagonal faces bounded by three Kekule edges are called benzene rings. A maximal independent (disjoint) set of benzene rings for a given Kekule structure is called a Clar set, and the maximum possible size of a Clar set over all Kekule structures is the Clar number of the fullerene. For any patch of hexagonal faces in the fullerene away from all pentagonal faces, there is a perfect Kekule structure: a Kekule structure for which the faces of an independent set of benzene rings are packed together as tightly as possible. Starting with such a patch and extending it as far as possible results in a perfect Kekule structure except for isolated regions, called clusters, containing the pentagonal faces. It has been shown that clusters must contain even numbers of pentagonal faces. It has also been shown that the Kekule structure of the patch can be extended into each of these clusters to give a full Kekule structure. However, these Kekule extensions will not admit as tightly packed benzene rings as in the patch external to the clusters. A basic problem in computing the Clar number of a fullerene is to make these extensions in a way that maximizes the number of benzene rings in each cluster. The simplest case, that of 2-clusters, has been completely solved. This thesis is devoted to developing a complete understanding of the Clar structures of 4-clusters

Menti Aperte e Apprendimento Aperto nella Rete Cosmopolita

The promise of technology, in particular of the internet, was that access to information would become demography blind. But for all of the successes the global web of information has demonstrated to us, has it really achieved its potential as a vehicle for overcoming the divide between the ‘undereducated’ and the ‘overqualified,’ that is between the generations, or indeed between any of the socially divisions so visible in the analogue world? If we are to ask the straightforward question “Is the internet a cosmopolitan space,” that is one promoting tolerance and engagement across boundaries, the answer we are likely to come to is ambiguous, at best. This paper presents both a longitudinal perspective on the internet’s potential as a space for intergenerational learning to occur, and some wider potential barriers to this development.La tecnologia – internet in particolare – prometteva di azzerare lo scarto generazionale nell’accesso alle informazioni. Tuttavia, nonostante il successo globale dimostratoci dalla rete d’informazioni, è possibile sostenere che esso abbia raggiunto il su opotenziale di veicolo per il superamento del divario tra gli individui “sub-formati” e quelli “sovraqualificati” – cioè quello tra generazioni o tra ogni qualsivoglia divisione sociale lampante nel mondoanalogico? Dovendo porci la domanda schietta se Internet sia o meno uno spazio cosmopolita, la risposta che forniremmo sarebbe probabilmente (e nel migliore dei casi) ambigua. Questo articolo presenta sia una prospettiva longitudinale sul potenziale della Rete come spazio ove avviene l’apprendimento intergenerazionale, sia alcuni potenziali barriere estensive al suo sviluppo in tal senso

Building an API is not enough! Investigating Reuse of Cultural Heritage Data

The Europeana cultural heritage archive has a wealth of digital content that can be used for a variety of purposes, both by researchers and practitioners in the community. Vicky Garnett and Jennifer Edmond chart the progression of research into how this content is being used and accessed and what technical requirements would improve the digital archive’s development. For example, is an API the answer? How big a part do web-services actually play in their overall research? One of the most common problems participants have reported encountering is the quality of the metadata in the content they are accessing. If the metadata can’t be relied on, neither can the results

Erin Gruwell: Catalyst For Change

On the evening of February 19th, 2008, we had the distinct honor and pleasure of meeting Ms. Erin Gruwell, teacher, motivational speaker and author of The Freedom Writers’ Diary and Teach With Your Heart. Upon being introduced, Ms. Gruwell focused the attention of the audience on her greatest passion, the students. After asking the teenagers to stand and be recognized, she ardently requested that the adults in the room purchase a copy of her book The Freedom Writers’ Diary, for every student present so that they might be inspired by students like themselves

Open Data for Humanists, A Pragmatic Guide

Most humanists would agree that sharing knowledge with other researchers is a cornerstone of academic life. Many will also fear that sharing too much, too early can be professionally damaging, however. And many also would not find much resonance between how they see their work and the discourses of Open Data, with its emphasis on particular approaches to Data Management Planning that have been adapted from other, more data intensive, disciplines. What we recommend here proposes a different approach to data management, viewing it as a reflective process that exposes and tweaks existing behaviours, rather than one that introduces specific tools. It is intended to encourage awareness of one’s own processes and mindfulness about how they could be more open.Most humanists would agree that sharing knowledge with other researchers is a cornerstone of academic life. Many will also fear that sharing too much, too early can be professionally damaging, however. And many also would not find much resonance between how they see their work and the discourses of Open Data, with its emphasis on particular approaches to Data Management Planning that have been adapted from other, more data intensive, disciplines. What we recommend here proposes a different approach to data management, viewing it as a reflective process that exposes and tweaks existing behaviours, rather than one that introduces specific tools. It is intended to encourage awareness of one’s own processes and mindfulness about how they could be more open

Identification of sleep apnea events using discrete wavelet transform of respiration, ECG and accelerometer signals

Sleep apnea is a common sleep disorder in which patient sleep patterns are disrupted due to recurrent pauses in breathing or by instances of abnormally low breathing. Current gold standard tests for the detection of apnea events are costly and have the addition of long waiting times. This paper investigates the use of cheap and easy to use sensors for the identification of sleep apnea events. Combinations of respiration, electrocardiography (ECG) and acceleration signals were analysed. Results show that using features, formed using the discrete wavelet transform (DWT), from the ECG and acceleration signals provided the highest classification accuracy, with an F1 score of 0.914. However, the novel employment of just the accelerometer signal during classification provided a comparable F1 score of 0.879. By employing one or a combination of the analysed sensors a preliminary test for sleep apnea, prior to the requirement for gold standard testing, can be performed

Using Jacobi iterations and blocking for solving sparse triangular systems in incomplete factorization preconditioning

When using incomplete factorization preconditioners with an iterative method to solve large sparse linear systems, each application of the preconditioner involves solving two sparse triangular systems. These triangular systems are challenging to solve efficiently on computers with high levels of concurrency. On such computers, it has recently been proposed to use Jacobi iterations, which are highly parallel, to approximately solve the triangular systems from incomplete factorizations. The effectiveness of this approach, however, is problem-dependent: the Jacobi iterations may not always converge quickly enough for all problems. Thus, as a necessary and important step to evaluate this approach, we experimentally test the approach on a large number of realistic symmetric positive definite problems. We also show that by using block Jacobi iterations, we can extend the range of problems for which such an approach can be effective. For block Jacobi iterations, it is essential for the blocking to be cognizant of the matrix structure

APIs and Researchers: The Emperor's New Clothes?

As part of the Europeana Cloud (eCloud) project, Trinity College Dublin investigated best practice in the use of web services, such as APIs, for accessing large data sets from cultural heritage collections. This research looked into the provision and use of APIs, and moreover, whether or not more customised programmatic access to datasets is what researchers want or need. In order to understand whether current patterns of API usage reflect a skills gap on the part of researchers or a mismatch of tool to purpose, we looked not only at the creators and developer/users of APIs, but also at humanists already re-using big data; approaches in cultural heritage institutions and other research infrastructures to bring API use to non-technical audiences; and the kinds of training and other support services available or emerging within the data-intensive humanities research lifecycle. We conducted both desk research and a series of 11 interviews with figures working as researchers, developers or data providers, including figures from both the API development and the data usage communities. This research, conducted under the eCloud project and supported by the European Commission’s ICT Policy and Support Programme (Grant number 325091), was begun in March 2014 and is now in its concluding validation stage. The results of the research are not yet finalised, but the contribution is already emerging of this work to the debate about APIs being either the way forward for digital cultural heritage collections, or the Emperor’s New Clothes (or maybe a bit of both)

Sustainability in DARIAH

International audienceNotes jotted in the context of the DARIAH-DE discussion on sustainability