36,777 research outputs found

    Finite-size effects in roughness distribution scaling

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    We study numerically finite-size corrections in scaling relations for roughness distributions of various interface growth models. The most common relation, which considers the average roughness asscalingfactor,isnotobeyedinthesteadystatesofagroupofballisticlikemodelsin2+1dimensions,evenwhenverylargesystemsizesareconsidered.Ontheotherhand,goodcollapseofthesamedataisobtainedwithascalingrelationthatinvolvestherootmeansquarefluctuationoftheroughness,whichcanbeexplainedbyfinitesizeeffectsonsecondmomentsofthescalingfunctions.Wealsoobtaindatacollapsewithanalternativescalingrelationthataccountsfortheeffectoftheintrinsicwidth,whichisaconstantcorrectiontermpreviouslyproposedforthescalingof as scaling factor, is not obeyed in the steady states of a group of ballistic-like models in 2+1 dimensions, even when very large system sizes are considered. On the other hand, good collapse of the same data is obtained with a scaling relation that involves the root mean square fluctuation of the roughness, which can be explained by finite-size effects on second moments of the scaling functions. We also obtain data collapse with an alternative scaling relation that accounts for the effect of the intrinsic width, which is a constant correction term previously proposed for the scaling of . This illustrates how finite-size corrections can be obtained from roughness distributions scaling. However, we discard the usual interpretation that the intrinsic width is a consequence of high surface steps by analyzing data of restricted solid-on-solid models with various maximal height differences between neighboring columns. We also observe that large finite-size corrections in the roughness distributions are usually accompanied by huge corrections in height distributions and average local slopes, as well as in estimates of scaling exponents. The molecular-beam epitaxy model of Das Sarma and Tamborenea in 1+1 dimensions is a case example in which none of the proposed scaling relations works properly, while the other measured quantities do not converge to the expected asymptotic values. Thus, although roughness distributions are clearly better than other quantities to determine the universality class of a growing system, it is not the final solution for this task.Comment: 25 pages, including 9 figures and 1 tabl

    Off-axis retrieval of orbital angular momentum of light stored in cold atoms

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    We report on the storage of orbital angu- lar momentum (OAM) of light of a Laguerre-Gaussian mode in an ensemble of cold cesium atoms and its re- trieval along an axis different from the incident light beam. We employed a time-delayed four-wave mixing configuration to demonstrate that at small angle (2o), after storage, the retrieved beam carries the same OAM as the one encoded in the input beam. A calculation based on mode decomposition of the retrieved beam over the Laguerre-Gaussian basis is in agreement with the experimental observations done at small angle values. However, the calculation shows that the OAM retrieving would get lost at larger angles, reducing the fidelity of such storing-retrieving process. In addition, we have also observed that by applying an external magnetic field to the atomic ensemble the retrieved OAM presents Larmor oscillations, demonstrating the possibility of its manipulation and off-axis retrieval.Comment: 9 pages, 4 figure

    On Universality in Human Correspondence Activity

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    Identifying and modeling patterns of human activity has important ramifications in applications ranging from predicting disease spread to optimizing resource allocation. Because of its relevance and availability, written correspondence provides a powerful proxy for studying human activity. One school of thought is that human correspondence is driven by responses to received correspondence, a view that requires distinct response mechanism to explain e-mail and letter correspondence observations. Here, we demonstrate that, like e-mail correspondence, the letter correspondence patterns of 16 writers, performers, politicians, and scientists are well-described by the circadian cycle, task repetition and changing communication needs. We confirm the universality of these mechanisms by properly rescaling letter and e-mail correspondence statistics to reveal their underlying similarity.Comment: 17 pages, 3 figures, 1 tabl

    Índices de emissão de ramos em pereiras.

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    A elaboração de escalas de emissão de ramos em pereiras objetiva classificar os genótipos quanto a seu hábito de crescimento, as quis serão úteis para compor o índice de vigor de plantas e para a seleção de genitores em programas de melhoramento genético. Para isso, foram desenvolvidas duas escalas: a primeira, para avaliar a quantidade de emissão de ramos secundários, ou seja, os ramos originados do tronco principal da planta, composta por três classes e com notas variando entre 1 e 5, contendo desenhos e exemplos de genótipos; a segunda, para avaliar o tipo e a quantidade de ramos terciários e quaternários emitidos a partir dos ramos secundários, sendo ela composta também por três classes e notas variando de 1 a 5. Utilizando as duas tabelas, foram avaliadas duas (em alguns casos somente uma) plantas/genótipo do Banco de Germoplasma de Pereira existente na Estação Experimental de Caçador, em Caçador, SC, no ano agrícola 2012/13. As plantas ficaram sem poda e condução durante 2 anos. Exemplos de genótipos com menor emissão de ramos secundários foram os cvs. Kousui, Kikusui, Nijisseiki, Beurre d?Anjou e Doyenne du Comice; e com maior emissão os cvs. Le Conte e Md. Siebold. Quanto à menor emissão de ramos terciários e quaternários, destacaram-se os cvs. Rugosa e Md. Siebold; e com maior emissão os cvs. Feliz e Choujuurou. As escalas foram eficientes na separação dos genótipos

    Classes de vigor de plantas de genótipos de pereira.

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    O índice de vigor de pereiras pode ser utilizado como referência em trabalhos de melhoramento genético para a seleção de genitores e também como indicativo de manejo de plantas em pomares comerciais. Para isso, foi gerado um índice de vigor utilizando informações de emissão de ramos secundários (originados do tronco principal da planta), de ramos terciários e quaternários (gerados respectivamente dos ramos secundários e terciários), além da medida da altura da planta

    The halloween effect in european equity mutual funds

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    Bouman and Jacobsen (2002) documented the existence of a calendar anomaly in stock market returns, which they call the Halloween effect, based on the fact that the returns during the months of May to October tend to be lower than returns during the months of November to April. Following closely the methodology used by Bouman and Jacobsen (2002), we investigate the presence of the Halloween effect in the European Equity Mutual Funds from 1997 to 2013. We conclude that: i) the Halloween Effect is statistically and economically significant; ii) this effect has disappeared after the Bouman and Jacobsen publication; iii) this anomaly might be due to the negative average returns during the months of May to October, rather than a higher performance during the period from November to April; and iv) an investment strategy based on this anomaly clearly beats the classical buy and hold strategy

    Universal 2-local Hamiltonian Quantum Computing

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    We present a Hamiltonian quantum computation scheme universal for quantum computation (BQP). Our Hamiltonian is a sum of a polynomial number (in the number of gates L in the quantum circuit) of time-independent, constant-norm, 2-local qubit-qubit interaction terms. Furthermore, each qubit in the system interacts only with a constant number of other qubits. The computer runs in three steps - starts in a simple initial product-state, evolves it for time of order L^2 (up to logarithmic factors) and wraps up with a two-qubit measurement. Our model differs from the previous universal 2-local Hamiltonian constructions in that it does not use perturbation gadgets, does not need large energy penalties in the Hamiltonian and does not need to run slowly to ensure adiabatic evolution.Comment: recomputed the necessary number of interactions, new geometric layout, added reference
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