Instabilities on graphene's honeycomb lattice with electron-phonon interactions

We study the impact of electron-phonon interactions on the many-body instabilities of electrons on the honeycomb lattice and their interplay with repulsive local and non-local Coulomb interactions at charge neutrality. To that end, we consider in-plane optical phonon modes with wavevectors close to the $\Gamma$ point as well as to the $K, -K$ points and calculate the effective phonon-mediated electron-electron interaction by integrating out the phonon modes. Ordering tendencies are studied by means of a momentum-resolved functional renormalization group approach allowing for an unbiased investigation of the appearing instabilities. In the case of an exclusive and supercritical phonon-mediated interaction, we find a Kekul\'e and a nematic bond ordering tendency being favored over the $s$-wave superconducting state. The competition between the different phonon-induced orderings clearly shows a repulsive interaction between phonons at small and large wavevector transfers. We further discuss the influence of phonon-mediated interactions on electronically-driven instabilities induced by onsite, nearest neighbor and next-to-nearest neighbor density-density interactions. We find an extension of the parameter regime of the spin density wave order going along with an increase of the critical scales where ordering occurs, and a suppression of competing orders.Comment: 9 pages, 5 figure

Response Mapping in Evaluative Priming

Recently, Scherer and Lambert: 2009) proposed a new model of priming, which they called the Response Mapping: RM) Model. That model assumes that under some circumstances, priming effects are the result of an unintentional tendency for participants to impose the target categorization task onto the primes: which they are supposed to ignore). In the present dissertation, the RM model is reviewed, and the implications and boundary conditions of the model are explored. In Experiments 1 and 2, it was predicted and found that response mapping processes can result in evaluative conditioning effects. That is, priming tasks do not always simply measure attitudes, but rather these tasks can additionally create new attitudes towards the prime stimuli. In Experiments 3 and 4, two boundary conditions of the RM model were tested. In those experiments, it was found that evaluative priming effects depend on participants\u27 ability to perceive the primes as belonging to distinct categories: boundary condition 1), and that those distinct categories must have different evaluative connotations: boundary condition 2). Importantly, results showed that priming effects are significantly stronger when primes are easily categorizable, relative to when they are not, even when the evaluative strength of the primes is held constant. Implications for theory and research involving priming measures and implicit attitudes more generally are discussed

Fermion-induced quantum criticality in two-dimensional Dirac semimetals: Non-perturbative flow equations, fixed points and critical exponents

We establish a scenario where fluctuations of new degrees of freedom at a quantum phase transition change the nature of a transition beyond the standard Landau-Ginzburg paradigm. To this end we study the quantum phase transition of gapless Dirac fermions coupled to a $\mathbb{Z}_3$ symmetric order parameter within a Gross-Neveu-Yukawa model in 2+1 dimensions, appropriate for the Kekul\'e transition in honeycomb lattice materials. For this model the standard Landau-Ginzburg approach suggests a first order transition due to the symmetry-allowed cubic terms in the action. At zero temperature, however, quantum fluctuations of the massless Dirac fermions have to be included. We show that they reduce the putative first-order character of the transition and can even render it continuous, depending on the number of Dirac fermions $N_f$. A non-perturbative functional renormalization group approach is employed to investigate the phase transition for a wide range of fermion numbers. For the first time we obtain the critical $N_f$, where the nature of the transition changes. Furthermore, it is shown that for large $N_f$ the change from the first to second order of the transition as a function of dimension occurs exactly in the physical 2+1 dimensions. We compute the critical exponents and predict sizable corrections to scaling for $N_f =2$.Comment: 12+5 pages, 5 figure

Ground state phase diagram of the half-filled bilayer Hubbard model

Employing a combination of functional renormalization group calculations and projective determinantal quantum Monte Carlo simulations, we examine the Hubbard model on the square lattice bilayer at half filling. From this combined analysis, we obtain a comprehensive account on the ground state phase diagram with respect to the extent of the system's metallic and (antiferromagnetically ordered) Mott-insulating as well as band-insulating regions. By means of an unbiased functional renormalization group approach, we exhibit the antiferromagnetic Mott-insulating state as the relevant instability of the free metallic state, induced by any weak finite onsite repulsion. Upon performing a careful analysis of the quantum Monte Carlo data, we resolve the difficulty of identifying this antiferromagnetic ground state for finite interlayer hopping in the weak-coupling regime, where nonmonotonous finite-size corrections are shown to relate to the two-sheeted Fermi surface structure of the metallic phase. On the other hand, quantum Monte Carlo simulations are well suited to identify the transition between the Mott-insulating phase and the band insulator in the intermediate-to-strong coupling regime. Here, we compare our numerical findings to indications for the transition region obtained from the functional renormalization group procedure.Comment: 12 pages, 15 figure

Migração, trabalho imaterial e subjetividade : (re)invenção dos modos de viver de migrantes e refugiados

Tendo em vista o recrudescimento dos novos fluxos migratórios do sul global para o Brasil na última década, a tendência à hegemonia do trabalho imaterial no capitalismo flexível e globalizado e as limitações de estudos da Administração acerca de migrantes e refugiados no entrelaçamento entre mobilidade internacional e trabalho, tem-se como objetivo geral, nesta tese, cartografar os processos de subjetivação que compõem o trabalho imaterial nos percursos de migrantes e refugiados. Para tanto, se alicerça nos pilares Migração, Trabalho e Subjetividade, os quais confluem na abordagem da Autonomia das Migrações (MEZZADRA, 2012; 2015). Pauta-se fundamentalmente nas produções teóricas sobre migração e refúgio (AGIER, 2016; CASTLES, 2010, SAYAD, 1979), seus dispositivos de proteção e regulação (ACNUR; OIM; BRASIL, 1997; 2017), trabalho imaterial (GORZ, 2005; LAZZARATO; NEGRI, 2001), espaços liso e estriado (DELEUZE; GUATTARI, 2012b), modos de individuação e singularização (GUATTARI; ROLNIK, 1996) e modos de viver em deslocamento (BAUMAN, 1999; 2011). A cartografia, enquanto método, permitiu uma experimentação da pesquisadora como flâneur-cartógrafa na cidade de Porto Alegre/RS e possibilitou a participação-intervenção em um território-rizoma formado por 36 eventos-atividades, cinco informantes-chave e 16 migrantes econômicos e refugiados que desenvolvem trabalhos nas áreas de música, dança, alimentação, moda, idioma e representação político-cultural utilizando referências de seus países de origem, que são Venezuela, Haiti, Síria, Senegal, Costa do Marfim e Nigéria. A partir das observações-participantes e das entrevistas, produziram-se quatro dimensões analíticas: Partir, Chegar, Empreender(-se) e (Re)inventar(-se). A tese defendida é a de que, pela via do trabalho imaterial, desponta a (re)invenção de modos de viver de migrantes e refugiados no país de destino. Tal argumento se sustenta nas frequentes investidas em traçar linhas de fuga de um espaço estriado individuante em direção a um espaço liso singularizante que visibiliza o trabalho imaterial dos migrantes e refugiados, evidenciado, sobretudo, pelo uso de referências dos países de origem e pela situação de migração ou refúgio. Os momentos preponderantes da processualidade dessas passagens e sobreposições podem ser percebidos nas restrições de vida devido às situações-limite instaladas nos países de origem; no empenho para migrar ou refugiar-se sobrelevando o paradoxo das migrações empurradas e autônomas; nos dispositivos legais, burocráticos e políticos que gerenciam as vidas (e possibilidades de trabalho) nas travessias e no país de destino; no direcionamento ao ―mercado de trabalho para migrantes e refugiados‖ vinculado à precarização, à desvalorização social e à aporofobia; nos investimentos em form(a)ções; nos modos de criação de atividades artísticas, técnico-manuais e comunicacionais do trabalho imaterial; no que eles trazem na bagagem; na (co)participação de clientes e no uso de redes sociais da internet no ciclo de produção; na formação de um novo ―mercado de trabalho para migrantes e refugiados‖ vinculado ao afeto e à política; na rede de cooperação afetiva, social, rentabilizadora e emancipatória consubstanciada ao trabalho imaterial e agenciada ao longo do percurso; e, enfim, no devir-migrante e no devir-refugiado como leitura dos modos de viver em deslocamento. Sem abandonar o que são, migrantes e refugiados percebem, nas atividades do trabalho imaterial, outras formas de viver, de se envolver na vida já existente e, ao mesmo tempo, de continuar em deslocamento, provocando outros devires.In view of the recrudescence of new migratory flows from the global south to Brazil in the last decade, the tendency to hegemony immaterial labour in flexible and globalized capitalism, and the limitations of Business Studies about migrants and refugees between international mobility and labour, the general objective of this thesis is to map the processes of subjectivation that compose immaterial labour in the paths of migrants and refugees. To do so, it is based on the Migration, Work, and Subjectivity pillars, which converge in the Autonomy of Migration approach (MEZZADRA, 2012; 2015). It is fundamentally based on theoretical productions on migration and refuge (AGIER, 2016; CASTLES, 2010, SAYAD, 1979), its protection and regulation devices (UNHCR; IOM; BRAZIL, 1997; 2017), immaterial labour (GORZ, 2005); LAZZARATO; NEGRI, 2001), concepts of smooth and striated spaces (DELEUZE; GUATTARI, 2012b), modes of individuation and singularization (GUATTARI; ROLNIK, 1996), and modes of living in displacement (BAUMAN, 1999; 2011). Cartography as a method allowed the researcher to experiment as a flâneur-cartographer in Porto Alegre - RS and enabled participation-intervention in a territory formed by 36 events-activities, five key informants and 16 economic migrants and refugees who develop work in the areas of music, dance, food, fashion, language and political-cultural representation with references from their countries of origin: Venezuela, Haiti, Syria, Senegal, Ivory Coast and Nigeria. From the participant observations and interviews, four analytical dimensions were produced: Leaving, Arriving, Endeavoring (oneself) and (Re)Inventing (oneself). The thesis is that through immaterial labour emerges the (re)invention of ways of living for migrants and refugees in the country of destination. This argument is based on the frequent attempts to draw lines of flight from an individuating striated space towards a singularizing smooth space that highlights the immaterial labour of migrants and refugees, evidenced, mainly, by the use of references from the countries of origin and the situation of migration or refuge. The preponderant moments of the procedurality of these passages and overlaps can be seen in the restrictions of life due to the limiting situations installed in their countries of origin; in the effort to migrate or take refuge, raising the paradox of pushed and autonomous migrations; in the legal, bureaucratic and political devices that manage their lives (and work possibilities) in the crossings and in the country of destination; in the direction of the "labour market for migrants and refugees" linked to precariousness, social devaluation and aporophobia; in the investments in education; in the ways of creating artistic, technical-manual and communicational activities of immaterial labour; in what they bring in their luggage; in the (co)participation of clients and in the use of Internet social networks in the production cycle; in the formation of a new "labour market for migrants and refugees" linked to affection and politics; in the affective, social, profitable and emancipatory networks cooperation consubstantiated in the immaterial labour and managed along the paths; and finally, in the becoming-migrant and becoming-refugee as a reading of the ways of living in displacement. Without abandoning who they are, the activities of immaterial labour provide other ways of living, of feeling, of getting involved in the already existing life and, at the same time, ways of continuing in displacement, provoking other becomings

Viabilidade de Mycoplasma hyopneumoniae e Mycoplasma hyorhinis em diferentes condições de cultivo

Micoplasmas estão difundidos pela natureza e são caracterizados por um genoma relativamente pequeno, baixo conteúdo GC e ausência de parede celular e de algumas rotas biossintéticas. Mycoplasma hyopneumoniae é o agente etiológico da pneumonia enzoótica suína, capaz de colonizar o trato respiratório e seu crescimento in vitro, comparado com o de outros micoplasmas, é mais lento. Mycoplasma hyorhinis também é encontrado no trato respiratório de suínos. Devido à falta de algumas vias biossintéticas, micoplasmas são incapazes de sintetizar alguns nutrientes e componentes essenciais, sendo forçados a obtê-los do ambiente. Assim, um dos maiores empecilhos enfrentados na pesquisa e diagnóstico de micoplasma tem sido a dificuldade do cultivo in vitro. Portanto, o desenvolvimento de um meio de composição definida que sustente o crescimento celular serviria como uma ferramenta controladamente manipulável, permitindo a definição de suas vias metabólicas assim como análises genéticas. O objetivo do presente estudo foi analisar a viabilidade, taxa de crescimento e regulação gênica de M. hyopneumoniae e M. hyorhinis em diferentes meios de cultivo, assim como em diferentes condições de cultura. Neste trabalho, foi utilizado o meio Friis (1975) como meio complexo, e quatro meios definidos: (i) meio descrito para Mycoplasma pneumoniae por Yus et al. (2009); (ii) meio Yus sem adição de peptona; (iii) meio comercial CMRL e (iv) meio CMRL+ (complementado com lipídeos, aminoácidos e vitaminas). A viabilidade celular foi avaliada em todos os meios definidos e a taxa de crescimento de ambas as espécies nos cinco meios foi avaliada por citometria de fluxo. Os resultados demonstraram que a composição do meio influencia no crescimento da bactéria, uma vez que há diferença entre a concentração celular em cada meio testado. Entretanto, ambas as espécies apresentaram concentração celular semelhante em cada meio. Os resultados demonstram que, dentre os meios definidos testados, o meio CMRL+, desenvolvido no presente estudo, é o meio mais adequado, podendo ser considerado um meio de manutenção para estes microrganismos. Para a avaliação da regulação gênica através de qPCR, M. hyopneumoniae foi cultivado em meio Friis e CMRL+ sendo posteriormente submetido a condições de estresse (choque térmico e estresse oxidativo). Os resultados obtidos sugerem que M. hyopneumoniae altera seus níveis transcricionais mais rapidamente quando cultivado em meio CMRL+, provavelmente devido ao estresse duplo causado pela privação nutricional e estresse oxidativo ou choque térmico. Na condição de choque térmico, o tipo de regulação predominante diferiu entre os dois meios, enquanto que, quando submetido a estresse oxidativo, os genes apresentaram um padrão de regulação semelhante entre Friis e CMRL+. O meio de cultivo definido CMRL+ forneceu uma taxa de crescimento semelhante à do meio complexo Friis, e demonstrou presença de regulação gênica em M. hyopneumoniae em resposta à sua composição e às condições de estresse testadas. Portanto, este meio pode ser usado como uma ferramenta para o avanço da pesquisa com Mycoplasma.Mycoplasmas are widespread in nature, and are characterized by a relative small genome, low GC content, absence of cell wall and lack of some biosynthetic pathways. Mycoplasma hyopneumoniae is the infective agent of enzootic pneumonia in swine, able to colonize the respiratory tract. Its growth is slower than other porcine mycoplasmas. Mycoplasma hyorhinis f y y . Ty y, ’ f mycoplasma that grows in culture, and its presence can frequently prevent the isolation of other Mycoplasma spp. Due to the lack of some biosynthetic pathways, mycoplasmas are incapable of synthesize some nutrients and essential compounds, being forced to obtain from the environment. Therefore, the major impediment to Mycoplasma research and laboratory diagnosis has been the difficulty of in vitro cultivation. Thus, the development of a defined medium that support mycoplasma growth would provide a tool that can be controllably manipulated to enable the definition of mycoplasmal metabolic pathways as well as genetic analysis. The aim of this work was to analyze viability, growth rate and gene regulation of M. hyopneumoniae and M. hyorhinis in different culture media, and cultivation conditions. In this work, we used Friss broth (1975) as a complex medium, and four different defined media: (i) a medium described for M. pneumoniae by Yus et al. (2009), (ii) defined Yus medium without peptone, (iii) commercial medium CMRL and (iv) CMRL+ medium (supplemented with lipids, amino acids and vitamins). All the defined media were tested towards cell viability and the growth rate of both species in the five media was assessed, through flow cytometry assay comparing between them. The results from flow cytometry assay showed that the composition of the media influences the bacterial growth, once cell concentration in each of the tested media was different. However, both species presented similar cell concentration in each media. The results demonstrate that, amongst the defined media tested, CMRL+ broth, developed in this study, b , g ’ y b . To gene regulation assessment, M. hyopneumoniae was cultivated in Friis and CMRL+ and underwent two stress conditions (heat shock and oxidative stress). Results suggest that M. hyopneumoniae alters the transcriptional levels of some genes more promptly when cultivated in CMRL+ broth, probably due to the dual stress caused by the combination of nutrients deprivation in CMRL+ broth plus heat shock or oxidative stress. In the heat shock condition, the prevailing kind of regulation differed between the two media, while when submitted to oxidative stress, genes presented similar pattern of regulation between Friis and CMRL+. CMRL+ medium provided a growth rate resembling the complex broth and M. hyopneumoniae showed to have gene expression regulation in response to its composition and to the culture conditions tested. Thus, it can be used as a tool that can be controllably manipulated enabling the definition of mycoplasmal nutritional requirements and metabolic pathways as well as genetic analysis, such as gene regulation

Linking country level food supply to global land and water use and biodiversity impacts : The case of Finland

The agricultural products consumed in Finland are increasingly grown on foreign farms. We analyze the Finnish imports of food and feed crops from 1986 to 2011 by products and by their geographic origin drawing a link to environmental impacts. The share of foreign crops consumed in Finland nearly doubled in the study period. The imports increased especially with commodities that could also be produced domestically. While the production of food increasingly shifted abroad, also the exports from Finland increased. >90% of the blue water of the Finnish crop supply came from foreignwater resources. Wemap the results of land and water use together with their impacts on global biodiversity, and show thatmost of the land and water use related biodiversity impacts (>93%) associated with the Finnish food consumption are related to the imports and therefore taken place outside the Finnish borders. The use ofmultiple environmental indicators can help identifying products and spatial hotspots associated with themost severe environmental impacts of the Finnish crop imports contributing to a more holistic decision-making and the promoting of sustainable food consumption both domestically and globally. (C) 2016 Elsevier B. V. All rights reserved.Peer reviewe