Real-time dynamics in the one-dimensional Hubbard model

We consider single-particle properties in the one-dimensional repulsive Hubbard model at commensurate fillings in the metallic phase. We determine the real-time evolution of the retarded Green's function by matrix-product state methods. We find that at sufficiently late times the numerical results are in good agreement with predictions of nonlinear Luttinger liquid theory. We argue that combining the two methods provides a way of determining the single-particle spectral function with very high frequency resolution.Comment: 10 pages, 6 figures. Minor edits from v1. Version as publishe

Statistical translation invariance protects a topological insulator from interactions

We investigate the effect of interactions on the stability of a disordered, two-dimensional topological insulator realized as an array of nanowires or chains of magnetic atoms on a superconducting substrate. The Majorana zero-energy modes present at the ends of the wires overlap, forming a dispersive edge mode with thermal conductance determined by the central charge $c$ of the low-energy effective field theory of the edge. We show numerically that, in the presence of disorder, the $c=1/2$ Majorana edge mode remains delocalized up to extremely strong attractive interactions, while repulsive interactions drive a transition to a $c=3/2$ edge phase localized by disorder. The absence of localization for strong attractive interactions is explained by a self-duality symmetry of the statistical ensemble of disorder configurations and of the edge interactions, originating from translation invariance on the length scale of the underlying mesoscopic array.Comment: 5+2 pages, 8 figure

Beam tests of an integrated prototype of the ATLAS Forward Proton detector

The ATLAS Forward Proton (AFP) detector is intended to measure protons scattered at small angles from the ATLAS interaction point. To this end, a combination of 3D Silicon pixel tracking modules and Quartz-Cherenkov time-of-flight (ToF) detectors is installed 210 m away from the interaction point at both sides of ATLAS. Beam tests with an AFP prototype detector combining tracking and timing sub-detectors and a common readout have been performed at the CERN-SPS test-beam facility in November 2014 and September 2015 to complete the system integration and to study the detector performance. The successful tracking-timing integration was demonstrated. Good tracker hit efficiencies above 99.9% at a sensor tilt of 14°, as foreseen for AFP, were observed. Spatial resolutions in the short pixel direction with 50 μm pitch of 5.5 ± 0.5 μm per pixel plane and of 2.8 ± 0.5 μm for the full four-plane tracker at 14° were found, largely surpassing the AFP requirement of 10 μm. The timing detector showed also good hit efficiencies above 99%, and a full-system time resolution of 35±6 ps was found for the ToF prototype detector with two Quartz bars in-line (half the final AFP size) without dedicated optimisation, fulfilling the requirements for initial low-luminosity AFP runs.Peer Reviewe

In and out and out again: The travails of Brazil as a security provider in Africa

The story of Brazil as a contemporary security actor in Africa can prove a peculiar one. Marked by quick gains and an equally quick recognition over a short period of time, it has also been followed by an equally quick turnaround which has led, as of 2020, to a visible disengagement on the ground. We explore the main travails in this domain, which have compromised much of the gains previously obtained throughout the continent. The chapter begins with a general balance of the progress achieved between 2003 and 2016, followed by the highlights of the recent downturn. We then analyze a specific sub-area, namely, the inroads carried out at the defence industry level, in order to showcase the promises and contradictions often associated to what the country has offered across the Atlantic. We conclude by presenting some opportunities for a new pickup of Brazilian interest in the middle and long run

Estudo de factores de virulência de culturas mistas de Candida albicans e Candida parapsilosis após adesão a uma superfície abiótica

Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Engenharia Clínica)Na cavidade oral, as espécies de Candida co-existem com outras espécies de Candida e/ou bactérias. Nos últimos anos as infecções causadas por Candida têm aumentado, sendo Candida albicans o fungo mais isolado. No entanto, outras espécies como Candida parapsilosis têm emergido como agente patogénico e colonizador de superfícies orais, nomeadamente próteses dentárias. O trabalho desenvolvido teve como objectivo estudar diferentes factores de virulência nomeadamente adesão, formação de biofilme (biomassa total e produção da matriz extracelular) e expressão de enzimas hidrolíticas de isolados clínicos orais de C. albicans e C. parapsilosis em sistemas de mono-espécie e de duas-espécies quando aderidos a uma superfície de poliestireno revestida com saliva artificial. Os isolados clínicos orais utilizados neste estudo foram isolados em condições diferentes: C. albicans AM e C. parapsilosis AM2 isolados de coinfecção e C. albicans AC e C. parapsilosis AD isolados de mono-infecção. Neste trabalho, quando as espécies isoladas em co-infecção foram separadas verificou-se que ao fim de 2h de adesão, C. parapsilosis AM2 é influenciado pela ausência de C. albicans AM, necessitando de mais tempo para se adaptar ao novo ambiente. Todavia, C. albicans AM ao fim de 2h tem capacidade de se adaptar a novos ambientes na ausência de C. parapsilosis AM2, quer num sistema de mono-espécie e quer num sistema de duas-espécies com a estirpe C. parapsilosis AD. Em biofilme simples, as estirpes de C. parapsilosis apresentaram maior expressão de factores de virulência do que as estirpes de C. albicans. Em biofilme misto, a expressão de factores de virulência foi menor do que o somatório da expressão de cada espécie em biofilme simples. Verificou-se ainda que o sistema de duasespécies formado pelas espécies isoladas em co-infecção produziu mais biomassa total e matriz extracelular. Nos biofilmes mistos formados por uma espécie isolada em co-infecção e a outra espécie isolada em mono-infecção não se detectou a produção de polissacáridos da matriz extracelular, apesar de cada uma das espécies produzirem polissacáridos em biofilme simples. Neste trabalho também se verificou que é durante a fase de adesão que as espécies de Candida apresentam maior actividade enzimática, salientando-se que nos sistemas de duasespécies, na presença de C. parapsilosis AM2, a actividade enzimática foi maior do que na presença de C. parapsilosis AD. Assim, neste trabalho evidenciou-se que a expressão de factores de virulência depende das condições em que as espécies foram isoladas (mono-infecção ou co-infecção), da estirpe, do tipo de sistema (mono-espécie ou duas-espécies). A compreensão dos mecanismos de interacção entre as duas espécies poderá contribuir para o desenvolvimento de estratégias mais eficazes no controlo destes patogénicos oportunistas.In the oral cavity, Candida species co-exist with other Candida spp. and/or bacteria. In recent years, infections caused by Candida spp. have increased and Candida albicans is the most common fungal isolated. However, Candida parapsilosis is emerging as pathogen and colonizing oral surfaces, such as dental prosthesis. This work aimed to study the ability of oral clinical isolates of C. albicans and C. parapsilosis to express virulence factors such as adhesion, biofilm formation (total biomass and biofilm matrix composition) and secretion of hydrolytic enzymes in systems of single-species and dual-species, after adhesion onto an artificial saliva polystyrene coated surface. The clinical isolates used in this study were isolated from different conditions: C. albicans AM and C. parapsilosis AM2 were isolated in co-infection and C. albicans AC and C. parapsilosis AD were isolated in single-infection. In this study, when species isolated in co-infection were separated, it was verified that after 2h of adhesion, C. parapsilosis AM2 was influenced by the absence of C. albicans AM, needing more time to adapt to the new environment. However, C. albicans AM after 2h of adhesion has the ability to adapt to a new environment in the absence of C. parapsilosis AM2, either in mono-specie system and in dual-species system with C. parapsilosis AD. In simple biofilm, strains of C. parapsilosis had higher expression of virulence factors than strains of C. albicans. In mixed biofilm, the expression of virulence factors was lower than the sum of the expression of each species in simple biofilm. It was also verified that dual-species system formed by species isolated in co-infection produced more total biomass and extracellular matrix. In mixed biofilms formed by the specie isolated in co-infection and other specie isolated in mono-infection the production of polysaccharides was not detected, although each species in simple biofilm produce polysaccharides. It was also found that during adhesion Candida species have higher enzyme activity. The dual-species systems with C. parapsilosis AM2 have higher enzymatic activity than the dualspecies systems with C. parapsilosis AD. Thus, this study showed that expression of virulence factors is dependent on the condition from which the strains were isolated (single or co-infection), strain, type of culture (monospecie or dual-specie). The understanding of the interaction mechanisms between these species may contribute to a better control of their pathogenicity

A novel strategy to incorporate coconut oil in dairy matrices

info:eu-repo/semantics/publishedVersio

The Interface and Control System of the Upgraded HVOpto/HVRemote Card of the TileCal

To comply with the increase in luminosity of the LHC (Large Hadron Collider) in the next decades, the electronics of the ATLAS (A Toroidal LHC Apparatus) experiment is being upgraded. Included in the upgrade is the interfacing and control electronics system of the HVOpto/HVRemote cards in the TileCal (Tile Calorimeter) detector, which provides high voltages to about 104 photomultipliers (PMTs). This paper presents the new interfacing architecture for the system and details the design of a prototype control board (HVRemote-Ctrl) used for test and validation of the new architecture. The tests evaluate the system multiplexing capabilities needed to monitor all the TileCal PMTs in real time. The communication channels involved, supported in Ethernet and SPI interfaces/protocols, have been fully tested. Some results from the tests already completed are presented

Estudo comparativo da artrodese posterolateral e PLIF no tratamento da espondilolistesis degenerativa grau I ou II ? análise de 124 casos

Objetivo: Posterior Lumbar Interbody Fusion (PLIF) ou artrodese posterolateral (APL) são técnicas cirúrgicas válidas na espondilolistese degenerativa. Alterações biomecânicas no nível adjacente à artrodese aceleram alterações degenerativas. Na literatura discute-se o tratamento adequado. Este estudo comparativo avalia clínica, taxa de fusão, complicações, alterações degenerativas e instabilidade no nível adjacente. Material e Métodos: Retrospectivamente foram analisadas espondilolisteses degenerativas grau I e II de Meyerding tratadas com PLIF ou APL de Janeiro 2000 a Dezembro 2010 num total de 124 doentes, 45 PLIF e 79 APL. Recorreu-se à escala visual analógica (VAS), Oswestry Disability Index (ODI) e Short Form-36 (SF-36). No PLIF foi determinada artrodese por estabelecimento de pontes ósseas estáveis. A instabilidade na APL foi definida quando osteolise adjacente aos parafusos, deslizamento ou angulação no nível da fusão. Resultados: O follow-up foi 4.5±2.7 e 3.9±2.6 anos (1-11 anos) no PLIF e APL, respectivamente. Ocorreu fusão em 93.3% no PLIF e 74.7% na APL (p=0.008). O PLIF apresenta superioridade no VAS pós-operatório (p=0.01) e variação geral (p=0.002). O ODI pós-operatório no PLIF foi menor (p<0.001) e 2.2% permanecem com disfunção severa comparativamente com 19% na APL. O PLIF é superior em escalas do SF-36: Função Física (p=0.034), Limitação Emocional (p=0.037), Função Social (p=0.05) e Saúde Geral (p=0.02). A taxa de complicações foi 4.4% no PLIF e 12.6% na APL (p=0.2). Ambas as técnicas desenvolveram doença do disco adjacente. Conclusões: Em ambos os grupos verifica-se melhoria da qualidade de vida, no entanto, a médio prazo o PLIF mostra superioridade. Instabilidade pré-operatória pode ser indicativa da eleição de PLIF

Red mud-based geopolymers with tailored alkali diffusion properties and pH buffering ability

This study develop novel porous red mud (RM) based geopolymers and evaluates their potential to ensure prolonged pH control. Several properties of the novel geopolymers were examined including buffering ability, alkalis leaching behaviour, mineralogical composition, microstructure and physical properties. Two experimental plans were defined to evaluate the influence of porosity and RM content on those properties. The pH values of the eluted water and geopolymers OH ions leaching have been determined over time showing that total OH ions and the leaching rate can be tailored by controlling the geopolymers porous structure and the availability of free alkaline species. The lower pH gradient over 28th d (1.64 pH units) was achieved by combining a 0.025 wt% pore forming agent (aluminium powder) with 45 wt% MK replacement by red mud. A high and prolonged buffer capacity was accomplished, proving that red mud-based geopolymers have potential to be applied as pH buffering material.This work was developed within the scope of the project CICECO-Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT Ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement.info:eu-repo/semantics/publishedVersio