19,611 research outputs found

    The Evolution of Web Search User Interfaces -- An Archaeological Analysis of Google Search Engine Result Pages

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    Web search engines have marked everyone's life by transforming how one searches and accesses information. Search engines give special attention to the user interface, especially search engine result pages (SERP). The well-known ''10 blue links'' list has evolved into richer interfaces, often personalized to the search query, the user, and other aspects. More than 20 years later, the literature has not adequately portrayed this development. We present a study on the evolution of SERP interfaces during the last two decades using Google Search as a case study. We used the most searched queries by year to extract a sample of SERP from the Internet Archive. Using this dataset, we analyzed how SERP evolved in content, layout, design (e.g., color scheme, text styling, graphics), navigation, and file size. We have also analyzed the user interface design patterns associated with SERP elements. We found that SERP are becoming more diverse in terms of elements, aggregating content from different verticals and including more features that provide direct answers. This systematic analysis portrays evolution trends in search engine user interfaces and, more generally, web design. We expect this work will trigger other, more specific studies that can take advantage of our dataset.Comment: 10 pages, Full Paper of CHIIR 202

    Produção de mudas de palma-forrageira utilizando fragmentos de cladódios.

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    A palma (Opuntia ficus-indica L.) Ă© uma das principais alternativas para alimentação de caprinos, ovinos e bovinos no SemiĂĄrido brasileiro. Contudo, o ataque da cochonilhado-carmim (Dactylopius opuntiae Cockerel) erradicou grande parte da ĂĄrea plantada, jĂĄ que a maioria das variedades cultivadas sĂŁo suscetĂ­veis Ă  praga. TrĂȘs novas variedades resistentes Ă  praga foram identificadas: Orelha-de-elefante mexicana, MiĂșda ou Doce e a variedade MĂŁo-de-moça (clones IPA-SertĂąnea e PALMEPA-PB1). Contudo, a disponibilidade de material propagativo (cladĂłdios ou raquetes) ainda Ă© baixa, aumentando o preço da palma-semente. Assim, desenvolveu-se uma metodologia utilizando-se fragmentos (pedaços) de raquetes para a obtenção de novas mudas

    How Does a Fundamental String Stretch its Horizon?

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    It has recently been shown that if we take into account a class of higher derivative corrections to the effective action of heterotic string theory, the entropy of the black hole solution representing elementary string states correctly reproduces the statistical entropy computed from the degeneracy of elementary string states. So far the form of the solution has been analyzed at distance scales large and small compared to the string scale. We analyze the solution that interpolates between these two limits and point out a subtlety in constructing such a solution due to the presence of higher derivative terms in the effective action. We also study the T-duality transformation rules to relate the moduli fields of the effective field theory to the physical compactification radius in the presence of higher derivative corrections and use these results to find the physical radius of compactification near the horizon of the black hole. The radius approaches a finite value even though the corresponding modulus field vanishes. Finally we discuss the non-leading contribution to the black hole entropy due to space-time quantum corrections to the effective action and the ambiguity involved in comparing this result to the statistical entropy.Comment: LaTeX file, 38 pages; v2: minor changes and added reference

    Chiral Zeromodes on Vortex-type Intersecting Heterotic Five-branes

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    We solve the gaugino Dirac equation on a smeared intersecting five-brane solution in E_8\times E_8 heterotic string theory to search for localized chiral zeromodes on the intersection. The background is chosen to depend on the full two-dimensional overall transverse coordinates to the branes. Under some appropriate boundary conditions, we compute the complete spectrum of zeromodes to find that, among infinite towers of Fourier modes, there exist only three localized normalizable zeromodes, one of which has opposite chirality to the other two. This agrees with the result previously obtained in the domain-wall type solution, supporting the claim that there exists one net chiral zeromode localized on the heterotic five-brane system.Comment: 10 pages, 2 figure

    Phenomenological study of the electronic transport coefficients of graphene

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    Using a semi-classical approach and input from experiments on the conductivity of graphene, we determine the electronic density dependence of the electronic transport coefficients -- conductivity, thermal conductivity and thermopower -- of doped graphene. Also the electronic density dependence of the optical conductivity is obtained. Finally we show that the classical Hall effect (low field) in graphene has the same form as for the independent electron case, characterized by a parabolic dispersion, as long as the relaxation time is proportional to the momentum.Comment: 4 pages, 1 figur

    Spectrally narrow exciton luminescence from monolayer MoS2 exfoliated onto epitaxially grown hexagonal BN

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    The strong light-matter interaction in transition Metal dichalcogenides (TMDs) monolayers (MLs) is governed by robust excitons. Important progress has been made to control the dielectric environment surrounding the MLs, especially through hexagonal boron nitride (hBN) encapsulation, which drastically reduces the inhomogeneous contribution to the exciton linewidth. Most studies use exfoliated hBN from high quality flakes grown under high pressure. In this work, we show that hBN grown by molecular beam epitaxy (MBE) over a large surface area substrate has a similarly positive impact on the optical emission from TMD MLs. We deposit MoS2_2 and MoSe2_2 MLs on ultrathin hBN films (few MLs thick) grown on Ni/MgO(111) by MBE. Then we cover them with exfoliated hBN to finally obtain an encapsulated sample : exfoliated hBN/TMD ML/MBE hBN. We observe an improved optical quality of our samples compared to TMD MLs exfoliated directly on SiO2_2 substrates. Our results suggest that hBN grown by MBE could be used as a flat and charge free substrate for fabricating TMD-based heterostructures on a larger scale.Comment: 5 pages, 3 figure

    Eigenfunctions of the Laplacian and associated Ruelle operator

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    Let Γ\Gamma be a co-compact Fuchsian group of isometries on the Poincar\'e disk \DD and Δ\Delta the corresponding hyperbolic Laplace operator. Any smooth eigenfunction ff of Δ\Delta, equivariant by Γ\Gamma with real eigenvalue λ=−s(1−s)\lambda=-s(1-s), where s=1/2+its={1/2}+ it, admits an integral representation by a distribution \dd_{f,s} (the Helgason distribution) which is equivariant by Γ\Gamma and supported at infinity \partial\DD=\SS^1. The geodesic flow on the compact surface \DD/\Gamma is conjugate to a suspension over a natural extension of a piecewise analytic map T:\SS^1\to\SS^1, the so-called Bowen-Series transformation. Let â‰Șs\ll_s be the complex Ruelle transfer operator associated to the jacobian −sln⁥∣Tâ€Č∣-s\ln |T'|. M. Pollicott showed that \dd_{f,s} is an eigenfunction of the dual operator â‰Șs∗\ll_s^* for the eigenvalue 1. Here we show the existence of a (nonzero) piecewise real analytic eigenfunction ψf,s\psi_{f,s} of â‰Șs\ll_s for the eigenvalue 1, given by an integral formula \psi_{f,s} (\xi)=\int \frac{J(\xi,\eta)}{|\xi-\eta|^{2s}} \dd_{f,s} (d\eta), \noindent where J(Ο,η)J(\xi,\eta) is a {0,1}\{0,1\}-valued piecewise constant function whose definition depends upon the geometry of the Dirichlet fundamental domain representing the surface \DD/\Gamma
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