24,900 research outputs found

    A Two Term Truncation of the Multiple Ising Model Coupled to 2d Gravity

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    We consider a model of p independent Ising spins on a dynamical planar phi-cubed graph. Truncating the free energy to two terms yields an exactly solvable model that has a third order phase transition from a pure gravity region (gamma=-1/2) to a tree-like region (gamma=1/2), with gamma=1/3 on the critical line. We are able to make an order of magnitude estimate of the value of p above which there exists a branched polymer (ie tree-like) phase in the full model, that is, p is approximately 13-23, which corresponds to a central charge c of about 6-12.Comment: 18 pages, LaTeX, 12 figure

    Segre Class Computation and Practical Applications

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    Let XYX \subset Y be closed (possibly singular) subschemes of a smooth projective toric variety TT. We show how to compute the Segre class s(X,Y)s(X,Y) as a class in the Chow group of TT. Building on this, we give effective methods to compute intersection products in projective varieties, to determine algebraic multiplicity without working in local rings, and to test pairwise containment of subvarieties of TT. Our methods may be implemented without using Groebner bases; in particular any algorithm to compute the number of solutions of a zero-dimensional polynomial system may be used

    Taming systems to create enabling environments for HCV treatment: negotiating trust in the drug and alcohol setting.

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    HCV (hepatitis C) treatment uptake among the population most affected - people who inject drugs - is suboptimal. Hospital based treatment provision is one evidenced barrier to HCV treatment uptake. In response, HCV treatment is increasingly located in treatment settings seen as more amenable to people who inject drugs, such as drug and alcohol services. We explored the accessibility of HCV treatment provision at two such partnerships. Data collection comprised qualitative interviews collected in 2011 and 2012 with 35 service users and 14 service providers of HCV treatment in London, United Kingdom. We draw here primarily on thematic analyses of service provider accounts, yet narratives relating to trust and environment emerged unsolicited in both user and provider accounts of negotiated HCV treatment access. A key theme in service provider accounts were strategies they deployed to 'tame' the treatment system so as to create an 'enabling environment' of care, in which trust was a critical feature. This 'taming' of the system was enacted through practices of 'negotiated flexibility', including in relation to appointments, eligibility, and phlebotomy. Service user accounts accentuated familiar environments and known health providers as those most trusted, and the potentially stigmatising effects of negotiating treatment in unfamiliar territory, especially hospital settings. Whilst noting the effects of provider strategies to negotiate flexibility on behalf of would-be patients seeking treatment, we conclude by noting the limits of trust relations in settings of constrained choice

    Financial development and stock returns: A cross country analysis

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    We examine stock returns in a cross section of emerging and mature markets (49 countries) over 1980-99. Stock returns are found to be significantly related to the degree of financial development. In general, a deeper and higher quality banking system is associated with lower volatility of stock returns and a greater synchronization in the movements of domestic and world returns. International synchronization is also greater the more liquid the stock market.financial development; stock returns

    Financial Development and the Sensitivity of Stock Markets to External Influences

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    We investigate how the relative contribution of external factors to stock price movements varies with the degree of financial development. We find that financial development makes stock markets more susceptible to external influences (both financial and macroeconomic). Interestingly, this effect is present even after having accounted for capital controls and international trade effects.Financial Development, Stock Markets, External Influences

    Explaining Small-Business Development: A Small-Business Development Model Combining the Maslow and the Hayes and Wheelwright Models

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    This paper looks at small-business management from the standpoint of Maslow’s hierarchy of needs and Hayes and Wheelwright’s four-stage model. The paper adapts Maslow’s hierarchy of needs model to small- business development and evolution. Additionally, Hayes and Wheelwright’s four-stage model is combined with the adapted Maslow small-business development model. The implications of the new model on the development of small businesses and future research are discussed

    Insights into the Fallback Path of Best-Effort Hardware Transactional Memory Systems

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    DOI 10.1007/978-3-319-43659-3Current industry proposals for Hardware Transactional Memory (HTM) focus on best-effort solutions (BE-HTM) where hardware limits are imposed on transactions. These designs may show a significant performance degradation due to high contention scenarios and different hardware and operating system limitations that abort transactions, e.g. cache overflows, hardware and software exceptions, etc. To deal with these events and to ensure forward progress, BE-HTM systems usually provide a software fallback path to execute a lock-based version of the code. In this paper, we propose a hardware implementation of an irrevocability mechanism as an alternative to the software fallback path to gain insight into the hardware improvements that could enhance the execution of such a fallback. Our mechanism anticipates the abort that causes the transaction serialization, and stalls other transactions in the system so that transactional work loss is mini- mized. In addition, we evaluate the main software fallback path approaches and propose the use of ticket locks that hold precise information of the number of transactions waiting to enter the fallback. Thus, the separation of transactional and fallback execution can be achieved in a precise manner. The evaluation is carried out using the Simics/GEMS simulator and the complete range of STAMP transactional suite benchmarks. We obtain significant performance benefits of around twice the speedup and an abort reduction of 50% over the software fallback path for a number of benchmarks.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Stellar Clusters in NGC 1313: Evidence for Infant Mortality

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    We present evidence that infant mortality of stellar clusters is likely to be a major and very efficient process for the dissolution of young clusters in the spiral galaxy NGC 1313. Performing stellar PSF photometry on archival HST/ACS images of the galaxy, we find that a large fraction of early B-type stars are seen outside of star clusters and well spread within the galactic disk, consistent with the scenario of infant mortality. We also calculate the UV flux produced by the stars in and out the clusters and find that 75 to 90% of the UV flux in NGC 1313 is produced by stars outside the clusters. These results suggest that the infant mortality of star clusters is probably the underlying cause of the diffuse UV emission in starburst galaxies. Infant mortality would also explain the numerous B-type stars observed in the background field of our Galaxy as well. We exclude the possibility that unresolved low-mass star clusters and scaled OB associations might be the main source for the diffuse UV emission.Comment: 5 pages, 3 figures, accepted for publication in the Astrophysical Journal Letter
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