Purine and pyrimidine bases as growth substances for lactic acid bacteria

In 1936 Richardson (1) showed that uracil was essential for the anaerobic growth of Staphylococcus aureus, but not for aerobic growth of the same organism. Of five strains tested three required uracil, while one required both guanine and uracil for growth. Thymine or cytosine did not replace uracil for this organism. These experiments suggested that hydrolytic products of nucleic acids might become factors limiting growth of various organisms under certain conditions. Bonner and Haagen-Smit (2) in 1939 showed that adenine greatly stimulated growth of leaves under defined conditions, while Möller (3) showed that adenine was required for growth of Streptobacterium plantarum. Pappenheimer and Hottle (4) recently showed that adenine was necessary for the growth of a strain of Group A hemolytic streptococci; it could be replaced by hypoxanthine, guanine, anthine, guanylic acid or adenylic acid. They made the very interesting observation that adenine was unnecessary for growth of this organism if the carbon dioxide tension was maintained at a sufficiently high level

On the minimum FLOPs problem in the sparse Cholesky factorization

Prior to computing the Cholesky factorization of a sparse, symmetric positive definite matrix, a reordering of the rows and columns is computed so as to reduce both the number of fill elements in Cholesky factor and the number of arithmetic operations (FLOPs) in the numerical factorization. These two metrics are clearly somehow related and yet it is suspected that these two problems are different. However, no rigorous theoretical treatment of the relation of these two problems seems to have been given yet. In this paper we show by means of an explicit, scalable construction that the two problems are different in a very strict sense. In our construction no ordering, that is optimal for the fill, is optimal with respect to the number of FLOPs, and vice versa. Further, it is commonly believed that minimizing the number of FLOPs is no easier than minimizing the fill (in the complexity sense), but so far no proof appears to be known. We give a reduction chain that shows the NP hardness of minimizing the number of arithmetic operations in the Cholesky factorization.Comment: Fix various spelling errors, move auxiliary proof to appendix, add two figure

‘I don’t make out how important it is or anything’: identity and identity formation by part-time higher education students in an English further education college.

Policymakers in England have recently, in common with other Anglophone countries, encouraged the provision of higher education within vocational Further Education Colleges. Policy documents have emphasised the potential contribution of college-based students to widening participation: yet the same students contribute in turn to the difficulties of this provision. This article draws on a study of part-time higher education students in a college, a group whose perspectives, identities and voices have been particularly neglected by educational research. Respondents’ narratives of non-participation at 18 indicated the range of social and geographical constraints shaping their decisions and their aspirations beyond higher education; whilst they drew on vocational and adult traditions to legitimate college participation, their construction of identity was also shaped by the boundaries between further education and the university. These distinctive processes illustrate both possibilities and constraints for future higher education provision within collegesN/

'Bridging' the gap between VET and higher education: permeability or perpetuation?

Demands for admission to higher education from vocational routes are widespread across Eu-rope but take different forms, depending on the recognition of tertiary VET or whether sharp-er distinctions between VET and higher education exist. In England, alongside policies pro-moting more employer-responsive tertiary provision, opportunities for ‘bridging’ from voca-tional routes to general university education, and vice versa, have been discussed. The study reported here examined four cases of existing provision supporting transitions into higher edu-cation, potential sites of practices supporting bridging across pathways. Each case provided valued support for progression to higher levels of study; yet these practices focused on exist-ing routes rather than transitions between more academic or vocationally-oriented sites. It is suggested, therefore, that the explicit denotation of separate tertiary provision may be more likely to constrain ‘bridging’ provision than for the latter to help students move beyond their existing route into substantially different forms of higher education.The paper draws on a study funded by the Gatsby Charitable Foundation GAT3398/J

Beyond comparative institutional analysis: a workplace turn in English TVET

Vocational education analyses often compare national patterns seen to favour industry-based training, state schooling or personal investment in skills acquisition: these are increasingly offered as ‘templates’ to new and established industrial economies. Institutionalist scholarship has correspondingly foregrounded skill formation as key to national policy differences; in particular historical institutionalism has focused on the role of labour market and state actors in negotiating and contesting arrangements for skill formation. Whilst paying relatively little direct attention to educational practice, these approaches provide theoretical tools to understand policy differences and to identify possibilities, limitations and strategies for change. This paper draws on their application in England, where apprenticeship and technical education reforms are periodically represented as relocating skills formation to the point of production on the model of collectivist systems: case study data is examined for evidence of institutional change strategies within emerging educational practices. Whilst the absence of engaged labour market actors renders the adoption of a substantially different model improbable, contestation over knowledge, control and educational roles is nevertheless evident, indicating the deployment of strategies for significant change. Their outcomes will determine the availability of transitions, with a layering of selective opportunities threatening to diminish the opportunities available to others.N/

The Reverse Cuthill-McKee Algorithm in Distributed-Memory

Ordering vertices of a graph is key to minimize fill-in and data structure size in sparse direct solvers, maximize locality in iterative solvers, and improve performance in graph algorithms. Except for naturally parallelizable ordering methods such as nested dissection, many important ordering methods have not been efficiently mapped to distributed-memory architectures. In this paper, we present the first-ever distributed-memory implementation of the reverse Cuthill-McKee (RCM) algorithm for reducing the profile of a sparse matrix. Our parallelization uses a two-dimensional sparse matrix decomposition. We achieve high performance by decomposing the problem into a small number of primitives and utilizing optimized implementations of these primitives. Our implementation shows strong scaling up to 1024 cores for smaller matrices and up to 4096 cores for larger matrices

More morphostasis than morphogenesis? The ‘dual professionalism’ of English Further Education workshop tutors

An international repositioning of vocational teachers in relation to knowledge and the workplace is reflected in English Further Education through the terminology of ‘dual professionalism’. Particularly in settings most closely linked to specific occupations, this discourse privileges occupational expertise that vocational educators bring from their former employment alongside pedagogic expectations of the teaching role. In a qualitative study of recently qualified teachers employed substantially in workshop settings, using the analytical framework of Margaret Archer, workplace skills and generic attributes provided a basis for claims to expertise, extending to a custodianship of former occupations. Further augmentation of educator roles, however, appeared constrained by market approaches to development and employment insecurity in the sector and beyond. In Archer’s terms, the current environment appears to cast ‘dual professionalism’ as morphostasis, drawing on former practice at the expense of teacher identity in the face of insecurity. Morphogenesis into enhanced professional teacher identities, for example, developing coherent vocational pedagogies informed by research into advances in knowledge, appears the less likely outcome in the current and emerging sector.N/

Ab Initio No Core Shell Model with Leadership-Class Supercomputers

Nuclear structure and reaction theory is undergoing a major renaissance with advances in many-body methods, strong interactions with greatly improved links to Quantum Chromodynamics (QCD), the advent of high performance computing, and improved computational algorithms. Predictive power, with well-quantified uncertainty, is emerging from non-perturbative approaches along with the potential for guiding experiments to new discoveries. We present an overview of some of our recent developments and discuss challenges that lie ahead. Our foci include: (1) strong interactions derived from chiral effective field theory; (2) advances in solving the large sparse matrix eigenvalue problem on leadership-class supercomputers; (3) selected observables in light nuclei with the JISP16 interaction; (4) effective electroweak operators consistent with the Hamiltonian; and, (5) discussion of A=48 system as an opportunity for the no-core approach with the reintroduction of the core.Comment: 23 pages, 7 figures, Conference Proceedings online at http://ntse.khb.ru/files/uploads/2016/proceedings/Vary.pd