Almost periodic Schrödinger operators along interval exchange transformations

AbstractIt is shown that Schrödinger operators, with potentials along the shift embedding of irreducible interval exchange transformations in a dense set, have pure singular continuous spectrum for Lebesgue almost all points of the interval. Such potentials are natural generalizations of the Sturmian case

The Highest Geomagnetic Storms of the Solar Cycle Observed at Ground Level

We report two ground-level observations, of geomagnetic storms of different origins; they are among the highest geomagnetic storms, in the solar Cycle 24. The first is St. Patrick’s Day storm on March 17, 2015, originated by the impact on Earth’s atmosphere of coronal mass ejections (CMEs), the storm reaching the condition of G4 (severe) level, in the NOAA geomagnetic scale. The second included the major geomagnetic storm whose origin is attributed to the interaction with the Earth of a High-Speed Stream (HSS) ahead of a positive polarity coronal hole on October 7, 2015. This storm reached the condition G3 (strong) level. We give emphasis to observations detected by the New-Tupi muon telescopes, located at sea level in Brazil (22.53° S, 43.13° W). We present a study of these observations in correlation with observations reported by multipoint space-based measurements, such as the ACE at Lagrange Point L1 and the geostationary GOES weather satellite, including two global geomagnetic indices and several ground-based detectors. Some considerations on the influence of these geomagnetic storms in the Earth weather are reported

Electromagnetic dual Einstein-Maxwell-scalar models

Electromagnetic duality is discussed in the context of Einstein-Maxwell-scalar (EMS) models including axionic-type couplings. This family of models introduces two non-minimal coupling functions $f(\phi)$ and $g(\phi)$, depending on a real scalar field $\phi$. Interpreting the scalar field as a medium, one naturally defines constitutive relations as in relativistic non-linear electrodynamics. Requiring these constitutive relations to be invariant under the $SO(2)$ electromagnetic duality rotations of Maxwell's theory, defines 1-parameter, closed $\textit{duality orbits}$ in the space of EMS models, connecting different electromagnetic fields in "dual" models with different coupling functions, but leaving both the scalar field and the spacetime geometry invariant. This mapping works as a solution generating technique, extending any given solution of a specific model to a (different) solution for any of the dual models along the whole duality orbit. We illustrate this technique by considering the duality orbits seeded by specific EMS models wherein solitonic and black hole solutions are known. For dilatonic models, specific rotations are equivalent to $S$-duality.Comment: 18 pages, 1 figur

Silk bilayer scaffolds can induce fast integration with subchondral bone and support cartilage repair

Publicado em : J Tissue Eng Regen Med 2014; 8 (Suppl. 1)Introduction: Osteochondral defect (OCD) regeneration presents major challenges in orthopedics. Since healing of cartilage and bone should be simultaneously considered, ideal scaffolds should be those that can mimic both tissues properties. In this study, bilayered silk and silk-nano calcium phosphate (Silk/Silk-NanoCaP) scaffolds with tailored mechanical properties were developed for OCD tissue engineering application. Materials and methods: Aqueous silk solution (16%) was prepared.1 Nano calcium phosphate particles (16%) were synthesized in the silk solution (Silk-NanoCaP).2 The bony layer was prepared by addition of NaCl particles (500–1000 lm) into the Silk-NanoCaP suspension. After drying for 2 days and salt-leaching overnight, silk solution was added on top of the bony layer using the same procedure to produce the chondral layer. The !nal scaffolds were evaluated through in vitro culture of rabbit bone marrow stromal cells (RBMSCs) for 2 weeks, and in vivo implantation in a rabbit knee OCD for 4 weeks. Results: The RBMSCs cultured in the scaffolds presented increasing viability from day 1 to day 7 by MTS assay. Good adhesion and migration of the RBMSCs in the scaffolds were achieved, as observed under the scanning electron microscope. Cell proliferation was observed from day 7 to day 14 as determined by DNA quanti!cation. The bony layer induced higher alkaline phosphatase level as compared to the chondral layer, in osteogenic condition. Histological analysis (H&E) showed that the bilayered scaffolds integrated well with the host tissue, after 4 weeks of implantation in a critical size OC defect (Fig. 1). Abundant new bone formation was detected in the Silk-NanoCaP layer. Cartilage regeneration occurred in the silk layer. Discussion and conclusions: The bilayered scaffolds favored the attachment, proliferation, and differentiation of RBMSCs. The bony layer of the bilayered scaffolds possessed osteoconductive properties. The bilayered scaffolds were biocompatible in vitro and in vivo. These scaffolds also induced both subchondral bone regeneration and supported cartilage regeneration, thus showing great promise in OCD regeneration. Acknowledgments: The authors thank FCT projects Tissue2Tissue and OsteoCart, and the FP7 Programme POLARIS. Yan LP was awarded a FCT PhD scholarship. Investigador FCT program (IF/00423/2012) and (IF/00411/2013) are also greatly acknowledged. Disclosure: The authors declare that there is no con"ict of interest

Avaliação do uso do óxido nítrico no tratamento da hipertensão pulmonar persistente do recém-nascido: uma metanálise

OBJECTIVES: To evaluate the use of inhaled nitric oxide (NO) in the management of persistent pulmonary hypertension of the newborn. METHODS: Computerized bibliographic search on MEDLINE, CURRENT CONTENTS and LILACS covering the period from January 1990 to March 1998; review of references of all papers found on the subject. Only randomized clinical trials evaluating nitric oxide and conventional treatment were included. OUTCOMES STUDIED: death, requirement for extracorporeal membrane oxygenation (ECMO), systemic oxygenation, complications at the central nervous system and development of chronic pulmonary disease. The methodologic quality of the studies was evaluated by a quality score system, on a scale of 13 points. RESULTS: For infants without congenital diaphragmatic hernia, inhaled NO did not change mortality (typical odds ratio: 1.04; 95% CI: 0.6 to 1.8); the need for ECMO was reduced (relative risk: 0.73; 95% CI: 0.60 to 0.90), and the oxygenation was improved (PaO2 by a mean of 53.3 mm Hg; 95% CI: 44.8 to 61.4; oxygenation index by a mean of -12.2; 95% CI: -14.1 to -9.9). For infants with congenital diaphragmatic hernia, mortality, requirement for ECMO, and oxygenation were not changed. For all infants, central nervous system complications and incidence of chronic pulmonary disease did not change. CONCLUSIONS: Inhaled NO improves oxygenation and reduces requirement for ECMO only in newborns with persistent pulmonary hypertension who do not have diaphragmatic hernia. The risk of complications of the central nervous system and chronic pulmonary disease were not affected by inhaled NO.OBJETIVOS: Avaliar o papel do óxido nítrico inalatório no tratamento da hipertensão pulmonar persistente do recém-nascido. MATERIAL E MÉTODO: Busca bibliográfica informatizada para janeiro de 1990 a março de 1998 (MEDLINE, CURRENT CONTENTS e LILACS) complementada manualmente. Apenas ensaios clínicos controlados e randomizados foram selecionados. INTERVENÇÃO: tratamento com óxido nítrico inalatório comparado com tratamento convencional. DESFECHOS: morte, necessidade de ECMO, oxigenação sistêmica, complicações em sistema nervoso central e doença pulmonar crônica. Qualidade metodológica: critério de escores, sendo treze a pontuação máxima. RESULTADOS: Nos não portadores de hérnia diafragmática o óxido nítrico inalatório não reduziu a mortalidade, OR: 1,04 (IC 95%: 0,59 a 1,82), mas diminuiu a necessidade de indicação de ECMO, RR: 0,73 (IC 95%: 0,6 a 0,9) e melhorou a oxigenação sistêmica, diferença média ponderada (DMP) para PaO2 em 30 e 60min: 53,18 (IC 95%: 44,8 a 61,4) e DMP para IO em 30 e 60min: -12,17 (IC 95%: -14,4 a -9,9). Nos portadores de hérnia diafragmática, não houve melhora da oxigenação arterial, nem redução da mortalidade ou da necessidade de ECMO, RR: 1,17 (IC 95%: 0,97 a 1,41). A incidência de complicações neurológicas e de doença pulmonar foram semelhantes para os dois grupos

Chemical composition and minerals in pyrite ash of an abandoned sulphuric acid production plant

The extraction of sulphur produces a hematite-rich waste, known as roasted pyrite ash, which contains significant amounts of environmentally sensitive elements in variable concentrations and modes of occurrence. Whilst the mineralogy of roasted pyrite ash associated with iron or copper mining has been studied, as this is the main source of sulphur worldwide, the mineralogy, and more importantly, the characterization of submicron, ultrafine and nanoparticles, in coal-derived roasted pyrite ash remain to be resolved. In this work we provide essential data on the chemical composition and nanomineralogical assemblage of roasted pyrite ash. XRD, HR-TEM and FE-SEM were used to identify a large variety of minerals of anthropogenic origin. These phases result from highly complex chemical reactions occurring during the processing of coal pyrite of southern Brazil for sulphur extraction and further manufacture of sulphuric acid. Iron-rich submicron, ultrafine and nanoparticles within the ash may contain high proportions of toxic elements such as As, Se, U, among others. A number of elements, such as As, Cr, Cu, Co, La, Mn, Ni, Pb, Sb, Se, Sr, Ti, Zn, and Zr, were found to be present in individual nanoparticles and submicron, ultrafine and nanominerals (e.g. oxides, sulphates, clays) in concentrations of up to 5%. The study of nanominerals in roasted pyrite ash from coal rejects is important to develop an understanding on the nature of this by-product, and to assess the interaction between emitted nanominerals, ultra-fine particles, and atmospheric gases, rain or body fluids, and thus to evaluate the environmental and health impacts of pyrite ash materials

Ocorrência de xenótimo em amostras aluvionares da região centro-leste de Portugal, Zona Centro Ibérica-Zona de Ossa Morena

Foi identificado, possivelmente pela primeira vez em Portugal, xenótimo aluvionar em concentrados de bateia colhidos numa campanha de prospecção de terras raras desenvolvida pelo ex-IGM no centro-leste deste país. O xenótimo ocorre em grãos sub-rolados de dimensão média =250um, em concentrações mais significativas em Nisa, Stº António das Areias e Marvão. A geologia regional e o cortejo mineral das amostras sugerem proveniência do xenótimo dos maciços graníticos de Penamacor e Nisa e ainda das Arcoses da Beira Baixa e níveis de cascalheiras plio-plistocénicas com intercalações argilo-arenosas

Development and application of a microsurfacing mix design method to assess the influence of the emulsion type

Microsurfacing asphalt mixtures are a preventive maintenance technology comprising the application of a slurry (produced with a modified asphalt emulsion), aggregate, filler, and water on top of an existing pavement at ambient temperature. Although it is a widely used technology, further studies on the mix design procedures are necessary to ensure an adequate composition. Thus, this study contributes to developing an improved mix design procedure for microsurfacing asphalt mixtures. Different mixtures were prepared, and the influence of the type and amount of asphalt emulsion and the amount of added water and filler (cement) on the characteristics of the mixture were evaluated. Two preliminary tests, referred to as the “pizza test” and the “ball test”, were proposed to determine the initial proportions of added water and cement in the mixture, respectively. Then, consistency, cohesion, and shaking abrasion tests were performed to determine the optimum content of each component and evaluate their influence on the mixture characteristics. The results showed that these tests are essential to optimize the mix composition, even though it was found that the mix design of microsurfacings is a complex task because the mixture is a system with chemical interactions strongly influenced by its composition.This research was funded by Fundação para a Ciência e a Tecnologia through a Ph.D. grant (number 2021.08004.BD). This work was also partly financed by FCT/MCTES through national funds (PIDDAC) under the R&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE), reference UIDB/04029/2020, and under the Associate Laboratory Advanced Production and Intelligent Systems ARISE, reference LA/P/0112/2020

Low-temperature performance of polymer-modified binders in stone mastic asphalts

When temperatures drop to significantly low levels, road pavements are subjected to thermally-induced stresses, resulting in the appearance of thermal cracking, among other distresses. In these situations, polymers can be used as asphalt binder modifiers to improve certain asphalt binder properties, such as elastic recovery, cohesion, and ductility. Polymers also minimize some of the problems of asphalt mixtures, such as thermal and fatigue cracking and permanent deformation. This work’s objective was to study the behavior of asphalt mixtures at low temperatures, mainly when using modified binders. Thus, three binders were selected and tested: a standard 50/70 penetration grade bitumen and two polymer-modified binders (PMB), obtained by adding, respectively, 2.5% and 5.0% of styrene–butadiene–styrene (SBS) in the 50/70 pen grade bitumen. Then, the PMBs were incorporated into stone mastic asphalt mixtures (namely SMA 11), which were subjected to low-temperature mechanical tests based on the most recent European Standards. The asphalt binders and mixtures evaluated in this work were tested for thermal cracking resistance, creep, elastic recovery, cohesive strength, and ductility strength. Overall, it is concluded that the studied asphalt mixtures with PMB, with just 2.5% SBS, performed adequately at low temperatures down to −20 °C.This research was funded by FCT/MCTES through national funds (PIDDAC) under the R&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE), under reference code UIDB/04029/2020