Valence-bond theory of highly disordered quantum antiferromagnets

We present a large-N variational approach to describe the magnetism of insulating doped semiconductors based on a disorder-generalization of the resonating-valence-bond theory for quantum antiferromagnets. This method captures all the qualitative and even quantitative predictions of the strong-disorder renormalization group approach over the entire experimentally relevant temperature range. Finally, by mapping the problem on a hard-sphere fluid, we could provide an essentially exact analytic solution without any adjustable parameters.Comment: 5 pages, 3 eps figure

Implant surgery and oral anticoagulant therapy: case report

This work aims to assess the risks both thromboembolic that bleeding of a management protocol “non-conservative” in patients on oral anticoagulant therapy (OAT) to be undergoing implant surgery. We decided to take a surgical “non-conservative” protocol, to insert four implants in the aesthetic zone, without using flapless surgery and the surgical template. In accordance with the hematologist, the value of INR is lowered and warfarin was replaced with heparin low molecular weight, to have a better coagulation’s control. The modern guidelines impose a protocol of conservative management in patients with OAT, with minimally invasive surgery, flapless, and use of surgical template to reduce the risk of uncontrolled bleeding. This, thanks to the teamwork between dentist and hematologist, thanks to careful adjustment of INR and the use of local haemostatic agents, were not encountered any problems with bleeding or intra or postoperative. Surgical treatment of patients with OAT is a real problem for the oral surgeon, to treat every time in association with the hematologist. Applying this type of surgical procedure, different from today’s guidelines, in our experience there were no post-operative complications (bleeding or bleeding); osseointegration has not been compromised and the prosthetic rehabilitation was completed successfully

Digital work-flow

The project presents a clinical case in which the digital work-flow procedure was applied for a prosthetic rehabilitation in natural teeth and implants. Digital work-flow uses patient’s photo for the aesthetic’s planning, digital smile technology for the simulation of the final restoration and real time scanning to register the two arches. Than the scanning are sent to the laboratory that proceed with CAD-CAM production. Digital work-flow offers the opportunities to easily speak with laboratory and patients, gives better clinical results and demonstrated to be a less invasiveness method for the patient. Intra-oral scanner, digital smile design, preview using digital wax-up, CAD-CAM production, are new predictable opportunities for prosthetic team. This work-flow, compared with traditional methods, is faster, more precise and predictable

Supramolecular associations between atypical oxidative phosphorylation complexes of Euglena gracilis

In vivo associations of respiratory complexes forming higher supramolecular structures are generally accepted nowadays. Supercomplexes (SC) built by complexes I, III and IV and the so-called respirasome (I/III2/IV) have been described in mitochondria from several model organisms (yeasts, mammals and green plants), but information is scarce in other lineages. Here we studied the supramolecular associations between the complexes I, III, IV and V from the secondary photosynthetic flagellate Euglena gracilis with an approach that involves the extraction with several mild detergents followed by native electrophoresis. Despite the presence of atypical subunit composition and additional structural domains described in Euglena complexes I, IV and V, canonical associations into III2/IV, III2/IV2 SCs and I/III2/IV respirasome were observed together with two oligomeric forms of the ATP synthase (V2 and V4). Among them, III2/IV SC could be observed by electron microscopy. The respirasome was further purified by two-step liquid chromatography and showed in-vitro oxygen consumption independent of the addition of external cytochrome c

Stochastic background of gravitational waves

A continuous stochastic background of gravitational waves (GWs) for burst sources is produced if the mean time interval between the occurrence of bursts is smaller than the average time duration of a single burst at the emission, i.e., the so called duty cycle must be greater than one. To evaluate the background of GWs produced by an ensemble of sources, during their formation, for example, one needs to know the average energy flux emitted during the formation of a single object and the formation rate of such objects as well. In many cases the energy flux emitted during an event of production of GWs is not known in detail, only characteristic values for the dimensionless amplitude and frequencies are known. Here we present a shortcut to calculate stochastic backgrounds of GWs produced from cosmological sources. For this approach it is not necessary to know in detail the energy flux emitted at each frequency. Knowing the characteristic values for the ``lumped'' dimensionless amplitude and frequency we show that it is possible to calculate the stochastic background of GWs produced by an ensemble of sources.Comment: 6 pages, 4 eps figures, (Revtex) Latex. Physical Review D (in press

Scaling theory of two-dimensional metal-insulator transitions

We discuss the recently discovered two-dimensional metal-insulator transition in zero magnetic field in the light of the scaling theory of localization. We demonstrate that the observed symmetry relating conductivity and resistivity follows directly from the quantum critical behavior associated with such a transition. In addition, we show that very general scaling considerations imply that any disordered two dimensional metal is a perfect metal, but most likely not a Fermi liquid.Comment: 4 pages, no figures, REVTEX. Minor corrections adde

Neighborhood properties of complex networks

A concept of neighborhood in complex networks is addressed based on the criterion of the minimal number os steps to reach other vertices. This amounts to, starting from a given network $R_1$, generating a family of networks $R_\ell, \ell=2,3,...$ such that, the vertices that are $\ell$ steps apart in the original $R_1$, are only 1 step apart in $R_\ell$. The higher order networks are generated using Boolean operations among the adjacency matrices $M_\ell$ that represent $R_\ell$. The families originated by the well known linear and the Erd\"os-Renyi networks are found to be invariant, in the sense that the spectra of $M_\ell$ are the same, up to finite size effects. A further family originated from small world network is identified

Exact Thermodynamics of Disordered Impurities in Quantum Spin Chains

Exact results for the thermodynamic properties of ensembles of magnetic impurities with randomly distributed host-impurity couplings in the quantum antiferromagnetic Heisenberg model are presented. Exact calculations are done for arbitrary values of temperature and external magnetic field. We have shown that for strong disorder the quenching of the impurity moments is absent. For weak disorder the screening persists, but with the critical non-Fermi-liquid behaviors of the magnetic susceptibility and specific heat. A comparison with the disordered Kondo effect experiments in dirty metallic alloys is performed.Comment: 4 pages Late

Fault systems of Upper Triassic outcrops in Coimbra region

Poster apresentado ao VIII Congresso Nacional de Geologia, em Braga (9-16 de Julho 2010)A partir da análise estrutural dos sistemas de falhas em afloramentos do Triásico Superior localizados na região de Coimbra, na Bacia Lusitânica, foi possível definir famílias e sub-famílias de falhas. Este trabalho permitiu reconhecer que os acidentes tectónicos extensionais que afectaram os depósitos do Triásico nesta região, durante toda a evolução do contexto tectónico do Mesozóico foram sistematicamente reactivados nos regimes compressivos do final do Mesozóico e Cenozóico.From the structural analysis of the fault system in the Upper Triassic outcrops, located in the Coimbra region of the Lusitanian Basin, it was possible to define fault families and subfamilies. This recognizing that the extensional tectonic strutures that affected the Triassic deposits from this region, were systematically reactivated during the Late Mesozoic and Cenozoic compressive regimes

Variabilidade genética de isolados de Rhizoctonia solani, de parte aérea, analisadas por meio de marcadores RAPD.

Rhizoctonia solani é um fungo cosmopolita, com vasto número de hospedeiros, e causa importantes doenças na maioria das plantas cultivadas em todo o mundo. Diferentes técnicas têm sido utilizadas com o intuito de estudar a diversidade genética de R. solani. Dentre elas, os marcadores de DNA do tipo RAPD (Random Amplified Polymorphic DNA) constituem instrumentos para caracterizar e avaliar o germoplasma rapidamente e com eficiência. Em virtude da variabilidade existente nos sintomas produzidos por esse patógeno, o objetivo do presente trabalho é avaliar a variabilidade genética de 13 isolados de R. solani que induzem, na sua maioria, sintomas na parte aérea dos vegetais infectados, utilizando-se marcadores moleculares de DNA, do tipo RAPD. A análise molecular do DNA extraído dos isolados com o primers OPA1 e OPA2 permitiu visualizar 17 bandas polimórficas com tamanhos que variavam entre 800 a 1800 bp, gerando 100% de polimorfismo entre os 13 isolados estudados. A similaridade entre as amostras, estimada pelo coeficiente de Jaccard, foi de 21,71%, sendo gerado pelo método UPGMA um dendrograma que permitiu agrupar os isolados em 7 grupos principais. Com base nas avaliações realizadas, concluiu-se que há uma grande variabilidade molecular entre os isolados de R. solani analisado