98 research outputs found

    Higher-order phase transitions with line-tension effect

    Get PDF
    The behavior of energy minimizers at the boundary of the domain is of great importance in the Van de Waals-Cahn-Hilliard theory for fluid-fluid phase transitions, since it describes the effect of the container walls on the configuration of the liquid. This problem, also known as the liquid-drop problem, was studied by Modica in [Ann. Inst. Henri PoincarĂ©, Anal. non linĂ©aire 4 (1987) 487–512], and in a different form by Alberti et al. in [Arch. Rational Mech. Anal. 144 (1998) 1–46] for a first-order perturbation model. This work shows that using a second-order perturbation Cahn-Hilliard-type model, the boundary layer is intrinsically connected with the transition layer in the interior of the domain. Precisely, considering the energies \[ {\cal F}_{\varepsilon}(u) := \varepsilon^{3} \int_{\Omega} |D^{2}u|^{2} + \frac{1}{\varepsilon} \int_{\Omega} W (u) + \lambda_{\varepsilon} \int_{\partial \Omega} V(Tu), \] where u is a scalar density function and W and V are double-well potentials, the exact scaling law is identified in the critical regime, when ΔλΔ23∌1\varepsilon\lambda_{\varepsilon}^{\frac{2}{3}} \sim 1

    Thin film limits for Ginzburg--Landau with strong applied magnetic fields

    Full text link
    In this work, we study thin-film limits of the full three-dimensional Ginzburg-Landau model for a superconductor in an applied magnetic field oriented obliquely to the film surface. We obtain Gamma-convergence results in several regimes, determined by the asymptotic ratio between the magnitude of the parallel applied magnetic field and the thickness of the film. Depending on the regime, we show that there may be a decrease in the density of Cooper pairs. We also show that in the case of variable thickness of the film, its geometry will affect the effective applied magnetic field, thus influencing the position of vortices

    PrĂĄticas artĂ­sticas no ensino bĂĄsico e secundĂĄrio

    Get PDF
    A matĂ©ria-prima de que trata esta revista Ă© base de trabalho para um ensino artĂ­stico alargado, estendendo-se fora dos limites da aula, transgredindo os limites formais dos curricula, implicando patrimĂłnio e riqueza cultural, sensibilizando para o imaterial, criando pĂșblicos apreciadores e tambĂ©m agentes criadores. É toda uma comunidade que se interliga atravĂ©s dos valores imateriais que sempre foram os da arte. A tarefa do educador Ă© muito alargada: exige-se que esteja Ă  altura deste desĂ­gnio humanista, que Ă© tambĂ©m um desafio ao destino da humanidade: pela educação artĂ­stica constroem-se futuros, e sem arte hĂĄ intolerĂąncia, materialismo, indiferença, alienação, morte. Os tempos que se vivem sĂŁo exigentes. As questĂ”es da pĂłs modernidade estĂŁo muito acesas, desde as que nos obrigam ao desassossego, como a sustentabilidade e a poluição, como as que nos implicam politicamente, como a justiça, os direitos civis, a desigualdade. Tudo isto Ă© matĂ©ria com a qual se amassa um barro que pode ser mais ou menos criativo: trata-se de extrair a matĂ©ria-prima com que se pode fazer os blocos que constroem o futuro. Aos profissionais da educação e do ensino, esta consciĂȘncia, ao mesmo tempo desamparada – os cortes da economia neoliberal transformaram a arte em indĂșstria, e a sua educação em criação de consumidores – e ao mesmo tempo vigilante e interventiva. Os artigos que responderam a esta chamada, respondem, cada um a seu modo, a este desassossego, a este desconforto, a este mal-estar contemporĂąneo. Dispuseram-se segundo uma sequĂȘncia que se articula com base em temas afins que se podem descrever sucintamente: Todos os que participaram neste nĂșmero mostraram a sua matĂ©ria-prima, a sua reação Ă  falta que a arte nos faz. A chamada soa, e ressoa, e Ă© necessĂĄrio que seja por todos ouvida, em todos os paĂ­ses. É simples: as artes estĂŁo em perigo. Perigo porque hĂĄ menos horas, menos professores, menos opçÔes, menos conhecimento. As reduçÔes no horĂĄrio, a eliminação de disciplinas tĂŁo importantes como a histĂłria da arte, fazem de cada professor um agente da resistĂȘncia, um ser mais implicado na sobrevivĂȘncia da chama da criação. MatĂ©ria-prima: matĂ©ria para resgatar a verdade humana, a arte, a expressĂŁo mais valiosa da sua vaidade. Resgatar o homem que Michel Foucault (1988: 412) vĂȘ ameaçado, como um rosto na areia, desenhado Ă  beira-mar.info:eu-repo/semantics/publishedVersio

    NEOTROPICAL XENARTHRANS: a data set of occurrence of xenarthran species in the Neotropics

    Get PDF
    Xenarthrans – anteaters, sloths, and armadillos – have essential functions for ecosystem maintenance, such as insect control and nutrient cycling, playing key roles as ecosystem engineers. Because of habitat loss and fragmentation, hunting pressure, and conflicts with 24 domestic dogs, these species have been threatened locally, regionally, or even across their full distribution ranges. The Neotropics harbor 21 species of armadillos, ten anteaters, and six sloths. Our dataset includes the families Chlamyphoridae (13), Dasypodidae (7), Myrmecophagidae (3), Bradypodidae (4), and Megalonychidae (2). We have no occurrence data on Dasypus pilosus (Dasypodidae). Regarding Cyclopedidae, until recently, only one species was recognized, but new genetic studies have revealed that the group is represented by seven species. In this data-paper, we compiled a total of 42,528 records of 31 species, represented by occurrence and quantitative data, totaling 24,847 unique georeferenced records. The geographic range is from the south of the USA, Mexico, and Caribbean countries at the northern portion of the Neotropics, to its austral distribution in Argentina, Paraguay, Chile, and Uruguay. Regarding anteaters, Myrmecophaga tridactyla has the most records (n=5,941), and Cyclopes sp. has the fewest (n=240). The armadillo species with the most data is Dasypus novemcinctus (n=11,588), and the least recorded for Calyptophractus retusus (n=33). With regards to sloth species, Bradypus variegatus has the most records (n=962), and Bradypus pygmaeus has the fewest (n=12). Our main objective with Neotropical Xenarthrans is to make occurrence and quantitative data available to facilitate more ecological research, particularly if we integrate the xenarthran data with other datasets of Neotropical Series which will become available very soon (i.e. Neotropical Carnivores, Neotropical Invasive Mammals, and Neotropical Hunters and Dogs). Therefore, studies on trophic cascades, hunting pressure, habitat loss, fragmentation effects, species invasion, and climate change effects will be possible with the Neotropical Xenarthrans dataset

    Overview of JET results for optimising ITER operation

    Get PDF
    The JET 2019–2020 scientific and technological programme exploited the results of years of concerted scientific and engineering work, including the ITER-like wall (ILW: Be wall and W divertor) installed in 2010, improved diagnostic capabilities now fully available, a major neutral beam injection upgrade providing record power in 2019–2020, and tested the technical and procedural preparation for safe operation with tritium. Research along three complementary axes yielded a wealth of new results. Firstly, the JET plasma programme delivered scenarios suitable for high fusion power and alpha particle (α) physics in the coming D–T campaign (DTE2), with record sustained neutron rates, as well as plasmas for clarifying the impact of isotope mass on plasma core, edge and plasma-wall interactions, and for ITER pre-fusion power operation. The efficacy of the newly installed shattered pellet injector for mitigating disruption forces and runaway electrons was demonstrated. Secondly, research on the consequences of long-term exposure to JET-ILW plasma was completed, with emphasis on wall damage and fuel retention, and with analyses of wall materials and dust particles that will help validate assumptions and codes for design and operation of ITER and DEMO. Thirdly, the nuclear technology programme aiming to deliver maximum technological return from operations in D, T and D–T benefited from the highest D–D neutron yield in years, securing results for validating radiation transport and activation codes, and nuclear data for ITER

    Global scaling of the heat transport in fusion plasmas

    Get PDF

    CatĂĄlogo TaxonĂŽmico da Fauna do Brasil: setting the baseline knowledge on the animal diversity in Brazil

    Get PDF
    The limited temporal completeness and taxonomic accuracy of species lists, made available in a traditional manner in scientific publications, has always represented a problem. These lists are invariably limited to a few taxonomic groups and do not represent up-to-date knowledge of all species and classifications. In this context, the Brazilian megadiverse fauna is no exception, and the CatĂĄlogo TaxonĂŽmico da Fauna do Brasil (CTFB) (http://fauna.jbrj.gov.br/), made public in 2015, represents a database on biodiversity anchored on a list of valid and expertly recognized scientific names of animals in Brazil. The CTFB is updated in near real time by a team of more than 800 specialists. By January 1, 2024, the CTFB compiled 133,691 nominal species, with 125,138 that were considered valid. Most of the valid species were arthropods (82.3%, with more than 102,000 species) and chordates (7.69%, with over 11,000 species). These taxa were followed by a cluster composed of Mollusca (3,567 species), Platyhelminthes (2,292 species), Annelida (1,833 species), and Nematoda (1,447 species). All remaining groups had less than 1,000 species reported in Brazil, with Cnidaria (831 species), Porifera (628 species), Rotifera (606 species), and Bryozoa (520 species) representing those with more than 500 species. Analysis of the CTFB database can facilitate and direct efforts towards the discovery of new species in Brazil, but it is also fundamental in providing the best available list of valid nominal species to users, including those in science, health, conservation efforts, and any initiative involving animals. The importance of the CTFB is evidenced by the elevated number of citations in the scientific literature in diverse areas of biology, law, anthropology, education, forensic science, and veterinary science, among others
    • 

    corecore