9,889 research outputs found

    Macro and Micro Dynamics of City Size Distributions: The Case of Israel

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    We study the distribution of sizes in the Israeli system of cities, using a rank-size representation of population distributions from 1950 to 2005. Based on a multiplicative model of proportionate growth, we develop a quantitative comparison relating the change in the rank-size curves to the change in the real data of Israeli cities during this period. At the level of macro dynamics, there is good agreement between the model and the real data. At the micro level, however, the model is less successful as the mean variation of the cities’ rank during the period studied is much larger in the model than in the real data. To illustrate this difference, we use the rankclock representation

    Non-linear conformally invariant generalization of the Poisson equation to D>2 dimensions

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    I propound a non-linear generalization of the Poisson equation describing a "medium" in D dimensions with a "dielectric constant" proportional to the field strength to the power D-2. It is the only conformally invariant scalar theory that is second order, and in which the scalar phiphi couples to the sources ρ\rho via a ϕρ\phi\rho contact term. The symmetry is used to generate solutions for the field for some non-trivial configurations (e.g. for two oppositely charged points). Systems comprising N point charges afford further application of the symmetry. For these I derive e.g. exact expressions for the following quantities: the general two-point-charge force; the energy function and the forces in any three-body configuration with zero total charge; the few-body force for some special configurations; the virial theorem for an arbitrary, bound, many-particle system relating the time-average kinetic energy to the particle charges. Possible connections with an underlying conformal quantum field theory are mentioned.Comment: Revtex, 16 pages. To be published in Phys. Rev.

    Mixed-Metal Tungsten Oxide Photoanode Materials Made by Pulsed-Laser in Liquids Synthesis

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    Globally scalable sunlight-driven devices that convert solar energy into storable fuels will require efficient light absorbers that are made of non-precious elements. Suitable photoanode materials are yet to be discovered. Here we utilised the timesaving nature of pulsed-laser in liquids synthesis and prepared a series of neat and mixed-metal tungsten oxide photoanode materials to investigate the effect of ad-metals on optical and photocurrent generation properties. We obtained sub-ÎŒm-sized materials with different colours from W, Al, Ta, or first-row transition metal targets in water or aqueous ammonium metatungstate solutions. We observed metastable polymorphs of WO3 and tungsten oxides with varying degrees of oxygen deficiency. Pulsed-laser in liquids synthesis of Ni in ammonium metatungstate solutions produced hollow spheres (with ≀ 6% Ni with respect to W). Photocurrent generation in strong aqueous acid was highest in mixed-metal tungsten oxide photoanode materials with around 5% of iron or nickel

    Pacta Sunt Servanda State Legalization of Marijuana and Subnational Violations of International Treaties: A Historical Perspective

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    In November 2012, voters in the states of Colorado and Washington passed ballot initiatives to legalize recreational marijuana industries. Since then, eight additional states and the District of Columbia have followed suit, and many more have seen legalization debates in their legislative halls and among their electorates. Over twenty bills recently introduced in Congress have sought to break federal marijuana laws away from prohibition. Although the national debate is indeed a vibrant one, it has neglected to address how legalization may be jeopardizing the compliance status of the United States under international drug treaties, and what the consequences may be if legalization means breach. For decision-making over marijuana policy to produce creditable outcomes, it must take into consideration the factor of international relations. Subnational conduct implicating treaty commitments is in fact not without precedent in America, and one episode in particular—notable for its contributions to the nation’s constitutional origins—reveals how treaty noncompliance can degrade a nation’s diplomatic standing. This article examines both past and present controversies and uses the advantages of historical perspective to draw international drug law issues into the legalization debate

    The lesbian, gay, bisexual and transgender community online: discussions of bullying and self-disclosure in YouTube videos

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    Computer-mediated communication has become a popular platform for identity construction and experimentation as well as social interaction for those who identify as lesbian, gay, bisexual or transgender (LGBT). The creation of user-generated videos has allowed content creators to share experiences on LGBT topics. With bullying becoming more common amongst LGBT youth, it is important to obtain a greater understanding of this phenomenon. In our study, we report on the analysis of 151 YouTube videos which were identified as having LGBT- and bullying-related content. The analysis reveals how content creators openly disclose personal information about themselves and their experiences in a non-anonymous rhetoric with an unknown public. These disclosures could indicate a desire to seek friendship, support and provide empathy

    Nuclear break-up of 11Be

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    The break-up of 11Be was studied at 41AMeV using a secondary beam of 11Be from the GANIL facility on a 48Ti target by measuring correlations between the 10Be core, the emitted neutrons and gamma rays. The nuclear break-up leading to the emission of a neutron at large angle in the laboratory frame is identified with the towing mode through its characteristic n-fragment correlation. The experimental spectra are compared with a model where the time dependent Schrodinger equation (TDSE) is solved for the neutron initially in the 11 Be. A good agreement is found between experiment and theory for the shapes of neutron experimental energies and angular distributions. The spectroscopic factor of the 2s orbital is tentatively extracted to be 0.46+-0.15. The neutron emission from the 1p and 1d orbitals is also studied

    Status of the HIE-ISOLDE project at CERN

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    The HIE-ISOLDE project represents a major upgrade of the ISOLDE nuclear facility with a mandate to significantly improve the quality and increase the intensity and energy of radioactive nuclear beams produced at CERN. The project will expand the experimental nuclear physics programme at ISOLDE by focusing on an upgrade of the existing Radioactive ion beam EXperiment (REX) linac with a 40 MV superconducting linac comprising thirty-two niobium-on-copper sputter-coated quarter-wave resonators housed in six cryomodules. The new linac will raise the energy of post-accelerated beams from 3 MeV/u to over 10 MeV/u. The upgrade will be staged to first deliver beam energies of 5.5 MeV/u using two high-ÎČ\beta cryomodules placed downstream of REX, before the energy variable section of the existing linac is replaced with two low-ÎČ\beta cryomodules and two additional high-ÎČ\beta cryomodules are installed to attain over 10 MeV/u with full energy variability above 0.45 MeV/u. An overview of the project including a status summary of the different R&D activities and the schedule will outlined.Comment: 7 pages, 12 figures, submitted to the Heavy Ion Accelerator Technology conference (HIAT) 2012, in Chicag
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