56,651 research outputs found

    A parallel algorithm for the enumeration of benzenoid hydrocarbons

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    We present an improved parallel algorithm for the enumeration of fixed benzenoids B_h containing h hexagonal cells. We can thus extend the enumeration of B_h from the previous best h=35 up to h=50. Analysis of the associated generating function confirms to a very high degree of certainty that BhAκh/hB_h \sim A \kappa^h /h and we estimate that the growth constant κ=5.161930154(8)\kappa = 5.161930154(8) and the amplitude A=0.2808499(1)A=0.2808499(1).Comment: 14 pages, 6 figure

    More Holographic Berezinskii-Kosterlitz-Thouless Transitions

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    We find two systems via holography that exhibit quantum Berezinskii-Kosterlitz-Thouless (BKT) phase transitions. The first is the ABJM theory with flavor and the second is a flavored (1,1) little string theory. In each case the transition occurs at nonzero density and magnetic field. The BKT transition in the little string theory is the first example of a quantum BKT transition in (3+1) dimensions. As in the "original" holographic BKT transition in the D3/D5 system, the exponential scaling is destroyed at any nonzero temperature and the transition becomes second order. Along the way we construct holographic renormalization for probe branes in the ABJM theory and propose a scheme for the little string theory. Finally, we obtain the embeddings and (half of) the meson spectrum in the ABJM theory with massive flavor.Comment: 24 pages, 5 figure

    Reconsidering "the love of art" : evaluating the potential of art museum outreach

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    Art museums have long been identified as bastions of social and cultural exclusion. This conclusion was best evidenced by the large-scale 1967 French study by Bourdieu and Darbel demonstrating the exclusionary nature of “The Love of Art.” However, in recent years there have been increasing efforts to reach out to a broader range of visitors beyond conventional audiences. The present study investigates the impacts of an outreach program at a UK art museum, which sought to engage socially excluded young mothers. This study employs ethnographic research methods on a longitudinal basis to develop qualitative insights about the program seeking to mitigate cultural exclusion. While the study’s findings uphold many longstanding critiques of art museums’ conventional approaches, the study also indicates that carefully designed outreach activities can overcome such limitations and enhance cultural engagement. Thus, art museums’ limited appeal is tied to problematic public engagement practices that can be changed

    Effective interactions and the nuclear shell-model

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    This review aims at a critical discussion of the interplay between effective interactions derived from various many-body approaches and spectroscopic data extracted from large scale shell-model studies. To achieve this, our many-body scheme starts with the free nucleon-nucleon (NN) interaction, typically modelled on various meson exchanges. The NN interaction is in turn renormalized in order to derive an effective medium dependent interaction. The latter is in turn used in shell-model calculations of selected nuclei. We also describe how to sum up the parquet class of diagrams and present initial uses of the effective interactions in coupled cluster many-body theory.Comment: 61 pages, submitted to Prog. Part. Nucl. Phy

    Jets in strongly-coupled N = 4 super Yang-Mills theory

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    We study jets of massless particles in N=4 super Yang-Mills using the AdS/CFT correspondence both at zero and finite temperature. We set up an initial state corresponding to a highly energetic quark/anti-quark pair and follow its time evolution into two jets. At finite temperature the jets stop after traveling a finite distance, whereas at zero temperature they travel and spread forever. We map out the corresponding baryon number charge density and identify the generic late time behavior of the jets as well as features that depend crucially on the initial conditions.Comment: 21 pages, 12 figures. Added discussion regarding string profiles in more than one spatial dimension. Refs adde

    Tunable effective g-factor in InAs nanowire quantum dots

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    We report tunneling spectroscopy measurements of the Zeeman spin splitting in InAs few-electron quantum dots. The dots are formed between two InP barriers in InAs nanowires with a wurtzite crystal structure grown by chemical beam epitaxy. The values of the electron g-factors of the first few electrons entering the dot are found to strongly depend on dot size and range from close to the InAs bulk value in large dots |g^*|=13 down to |g^*|=2.3 for the smallest dots. These findings are discussed in view of a simple model.Comment: 4 pages, 3 figure
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