Orbital-selective Mott transitions: Heavy fermions and beyond

Quantum phase transitions in metals are often accompanied by violations of Fermi liquid behavior in the quantum critical regime. Particularly fascinating are transitions beyond the Landau-Ginzburg-Wilson concept of a local order parameter. The breakdown of the Kondo effect in heavy-fermion metals constitutes a prime example of such a transition. Here, the strongly correlated f electrons become localized and disappear from the Fermi surface, implying that the transition is equivalent to an orbital-selective Mott transition, as has been discussed for multi-band transition-metal oxides. In this article, available theoretical descriptions for orbital-selective Mott transitions will be reviewed, with an emphasis on conceptual aspects like the distinction between different low-temperature phases and the structure of the global phase diagram. Selected results for quantum critical properties will be listed as well. Finally, a brief overview is given on experiments which have been interpreted in terms of orbital-selective Mott physics.Comment: 29 pages, 4 figs, mini-review prepared for a special issue of JLT

O Largo da Banana e a presença negra em São Paulo

The Largo da Banana relates to the history of the black population in São Paulo. Acknowledged as one of São Paulo’s “cradle” of samba, samba musicians are its main spokespersons. Largo da Banana used to be located near the former Barra Funda Railway Station. From the first decades to around half the Twentieth century, informal laborers in the railway logistics used to gather together in that space. Within a precarious and unsteady daily life, they used to play samba and tiririca. In the fifties, the municipality built the Pacaembu Viaduct in that area, aiming to extend the homonym avenue beyond the railway road. In the sixties, samba musician Geraldo Filme wrote two songs in which he paid homage to Largo da Banana and regrettedits disappearance after the viaduct’s inauguration. In these and other of his songs, the artist recorded his perceptions on the life conditions of São Paulo’s blacks and samba musicians, their sociabilities, and also the urban changes he witnessed. Considering that his artistic work contributes to enlighten aspects of social reality, I analyze some of his songs to interpret the sociabilities at Largo da Banana, as well as the urban intervention in that location.O Largo da Banana está associado à história da população negra em São Paulo. Reconhecido como um dos “berços” do samba paulista, é sobretudo através dos próprios sambistas que essa história pode hoje ser conhecida. Localizado junto à antiga estação da Barra Funda, desde as primeiras décadas até meados do século passado, aquele espaço concentrou trabalhadores informais vinculados às atividades da ferrovia. Em meio a um cotidiano precário e instável, essa população realizava rodas de samba e de tiririca. Nos anos 1950, foi construído naquele local o Viaduto Pacaembu, que prolongava a avenida homônima para além davia férrea. A partir da década de 1960, o sambista negro Geraldo Filme compôs duas canções em que homenageava o Largo da Banana e lamentava seu desaparecimento após a inauguração do viaduto. Nessas e em outras composições, o artista registrou suas percepções sobre as condições de vida da população negra e sambista na cidade, suas sociabilidades, bem como sobre as transformações urbanas que testemunhou. Considerando que sua obra artística contribui para iluminar aspectos da realidade social, ela é adotada como fonte para analisar as formas de sociabilidade no Largo da Banana e a intervenção urbanística naquele local

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

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