Magnetism And Phase Separation In Polymeric Hubbard Chains

We study a class of one-dimensional chains whose topology leads to flatbands in the electronic spectrum. Using the Hubbard model, we find that these materials should exhibit ferrimagnetic ordering for a half-filled band, in agreement with a theorem by Lieb. Away from half filling the system displays a very rich magnetic phase diagram. Possible experimental realizations are suggested.74101851185

Disordered quantum wires: microscopic origins of the DMPK theory and Ohm's law

We study the electronic transport properties of the Anderson model on a strip, modeling a quasi one-dimensional disordered quantum wire. In the literature, the standard description of such wires is via random matrix theory (RMT). Our objective is to firmly relate this theory to a microscopic model. We correct and extend previous work (arXiv:0912.1574) on the same topic. In particular, we obtain through a physically motivated scaling limit an ensemble of random matrices that is close to, but not identical to the standard transfer matrix ensembles (sometimes called TOE, TUE), corresponding to the Dyson symmetry classes \beta=1,2. In the \beta=2 class, the resulting conductance is the same as the one from the ideal ensemble, i.e.\ from TUE. In the \beta=1 class, we find a deviation from TOE. It remains to be seen whether or not this deviation vanishes in a thick-wire limit, which is the experimentally relevant regime. For the ideal ensembles, we also prove Ohm's law for all symmetry classes, making mathematically precise a moment expansion by Mello and Stone. This proof bypasses the explicit but intricate solution methods that underlie most previous results.Comment: Corrects and extends arXiv:0912.157

Measurement of Entrepreneurial Dynamism Capabilities and Performance in Collaborative Networks

Part 16: Performance Measurement SystemsInternational audienceIn turbulent markets and scenarios that require extremely competitive and innovative organizations, the need to transform the resource base in accordance with the changing markets and technology is apparent. In order to do this, it is necessary to quickly identify and incorporate market opportunities, provide high capacity for learning, innovation and work collaboratively with other organizations in a network – in a collaborative way - to coordinate and transform their resource base. It is based on this information that this work aims to discuss the association between the role of an organization in a collaborative network and the development of dynamic capabilities, in response to environmental pressures and turbulence. Similarly, we seek to identify the impact (the improvement, or not) that generates the dynamics of organizations in a collaborative network. This paper brings two main contributions: the first lists a theoretical framework associating three main constructs: Dynamic Capabilities, Collaborative Networks and Turbulent Environments. The second proposes a conceptual model involving these three main constructs, facing adaptation, resilience and competitiveness of organizations

Salacia campestris root bark extract: peroxidase inhibition, antioxidant and antiradical profile

Reactive oxygen species (ROS) and free radical species have been implicated in initiating or accompanying many diseases in living organisms; there is thus, a continual need for antioxidants molecules to inactivate ROS/free radicals. Many studies of plants crude extracts have demonstrated free-radical scavenging and antioxidant action. Salacia species have long been used, in several countries, as traditional medicines against certain diseases and for their anti-inflammatory properties. In this study, Salacia campestris Walp (Hippocrateaceae) root bark ethanol extract (ScEtOH) was assessed for its ability to scavenge free radicals and reactive oxygen species; the results were expressed as percentage inhibition of the active species. ScEtOH was efficient against studied species: DPPH radical (obtained inhibition = 30%), ABTS•+ (IC50 = 1.8±0.8 &#956;g/mL), HOCl (IC50 = 1.7 ± 0.1 &#956;g/mL), O2•- (obtained inhibition = 32%), and NO• (obtained inhibition = 18 %). Peroxidase activity inhibition was evaluated through the guaiacol oxidation reaction catalyzed by hemin, HRP and myeloperoxidase (MPO); data showed that ScEtOH at 10 &#956;g/mL led to 54 and 51% of inhibition, respectively, for the hemin and HRP systems. In the MPO system, ScEtOH promoted a 50% inhibition at 8.9 &#956;g/mL, whereas quercetin, a powerful MPO inhibitor, inhibited this system at 1.35 &#956;g/mL.<br>Espécies reativas do oxigênio (ERO) e radicais livres estão relacionados ao início ou à exacerbação de muitas doenças em organismos vivos; existindo portanto uma necessidade contínua por moléculas antioxidantes que inativem as ERO e radicais livres. Muitos estudos com extratos brutos de plantas têm demonstrado propriedades antioxidantes e seqüestradoras de radicais livres. Espécies de Salacia são utilizadas, em muitos países, como remédio tradicional contra certas doenças e por suas propriedades antiinflamatórias. Neste estudo, o extrato bruto etanólico da casca da raiz da Salacia campestris Walp (Hippocrateaceae) foi avaliado quanto à sua habilidade em seqüestrar radicais livres e espécies reativas do oxigênio; os resultados são expressos como porcentagem de inibição das espécies ativas. ScEtOH mostrou-se eficiente frente as espécies estudadas: radical DPPH (inibição obtida = 30%), ABTS•+ (IC50 = 1,8±0,8 &#956;g/mL), HOCl (IC50 = 1,7 ± 0,1 &#956;g/mL), O2•- (inibição obtida = 32%), and NO• (inibição obtida = 18%). A inibição da atividade peroxidásica foi avaliada através da oxidação do guaiacol catalisada pela hemina, HRP e mieloperoxidase (MPO); os dados mostram que 10 &#956;g/mL de ScEtOH promovem 54 e 51% de inibição, respectivamente para os sistemas da hemina e da HRP. No sistema da MPO, ScEtOH promoveu 50% de inibição na dose de 8,9 &#956;g/mL, enquanto a quercetina, um potente inibidor da MPO promoveu tal inibição com 1,35 &#956;g/mL