111 research outputs found
Quasirandom permutations are characterized by 4-point densities
For permutations π and τ of lengths |π|≤|τ| , let t(π,τ) be the probability that the restriction of τ to a random |π| -point set is (order) isomorphic to π . We show that every sequence {τj} of permutations such that |τj|→∞ and t(π,τj)→1/4! for every 4-point permutation π is quasirandom (that is, t(π,τj)→1/|π|! for every π ). This answers a question posed by Graham
The quest for companions to post-common envelope binaries: I. Searching a sample of stars from the CSS and SDSS
As part of an ongoing collaboration between student groups at high schools
and professional astronomers, we have searched for the presence of
circum-binary planets in a bona-fide unbiased sample of twelve post-common
envelope binaries (PCEBs) from the Catalina Sky Survey (CSS) and the Sloan
Digital Sky Survey (SDSS). Although the present ephemerides are significantly
more accurate than previous ones, we find no clear evidence for orbital period
variations between 2005 and 2011 or during the 2011 observing season. The
sparse long-term coverage still permits O-C variations with a period of years
and an amplitude of tens of seconds, as found in other systems. Our
observations provide the basis for future inferences about the frequency with
which planet-sized or brown-dwarf companions have either formed in these
evolved systems or survived the common envelope (CE) phase.Comment: accepted by A&
Land Law, Property Ideologies and the British-Irish relationship
English and Irish land law are deeply influenced by the historical context of the British-Irish relationship, yet property scholarship comparing the two jurisdictions is surprisingly rare. The current Brexit negotiations provide a timely reminder of the strategic importance of property and trade relations between the two countries; and of their related-but-different legal cultures. In this article we examine how the property cultures of England and Ireland were shaped by the politics and practices of land tenure, by competing economic and property ideologies, and by the influence of both on national identity and statehood in both jurisdictions. The article reveals the role of local contexts and events in shaping land reform, and demonstrates the fertile potential of the comparative frame to contextualise each jurisdiction’s doctrines and practices. As domestic land law systems are drawn together in the context of emerging EU jurisdiction over areas like mortgage credit, each jurisdiction’s underpinning ideological commitments have important implications for the ease – or not – of attempts to harmonize member state practices. We explain the alignments and divergences between domestic underpinnings of Irish and English law, and reflect on the implications of our findings for contemporary property problems in the context of evolving economic and political relationships between the UK and Ireland
Compósito para a construção civil a partir de resÃduos industriais
RESUMO Os estudos que visam à utilização dos resÃduos industriais vêm se intensificando diante da pressão das organizações ambientais, escassez de recursos naturais, busca de certificações para ganho de mercado e minimização de impacto ambiental. O presente trabalho desenvolveu um novo compósito a base de resÃduos industriais como cinzas de madeira, lodo de estação de tratamento de água (ETA) e resÃduos de produção de cal com propriedades mecânicas que atendem à s exigências da ASSOCIAÇÃO BRASILEIRA DE NORMAS TÉCNICAS - NBR 15270-1/2005, NBR 15270-2/2005 e NBR 5739/2007, objetivando a sua utilização na construção civil sem o acréscimo de cimento Portland. As resistências à compressão variaram de 2,35 a 16,48 MPa. O Ãndice de absorção de água das amostras testadas também atendeu à s normas aplicadas, demonstrando que ao longo do tempo de cura houve diminuição da porosidade com possÃvel hidratação da cal. Os resultados do ensaio de resistência à compressão apresentaram variações durante o tempo de cura que podem ser justificadas pela presença de material orgânico no lodo de ETA e pelo tamanho das partÃculas de cinza de madeira que durante a homogeneização não foram destruÃdas completamente. Apesar das variações observadas nos resultados, as resistências dos compósitos se enquadram na classificação para blocos cilÃndricos de concreto e blocos cerâmicos para alvenaria
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