Relativistic confinement of neutral fermions with a trigonometric tangent potential

The problem of neutral fermions subject to a pseudoscalar potential is investigated. Apart from the solutions for $E=\pm mc^{2}$, the problem is mapped into the Sturm-Liouville equation. The case of a singular trigonometric tangent potential ($\sim \mathrm{tan} \gamma x$) is exactly solved and the complete set of solutions is discussed in some detail. It is revealed that this intrinsically relativistic and true confining potential is able to localize fermions into a region of space arbitrarily small without the menace of particle-antiparticle production.Comment: 12 page

Cervical nodular fasciitis in a 10-year-old girl: a case report of a rare condition

Nodular fasciitis (NF) is a benign fibroblastic proliferation that usually involves  superficial fascia in the subcutaneous tissue or muscle. The rapid growth, high  cellularity and mitotic activity can simulate sarcoma. Thus, as clinical and morphologic characteristics are similar to those of malignant tumours, this entity is often  misdiagnosed, with a few cases described in the literature. We present a case of nodular fasciitis involving the retropharynx and hypopharynx of a 10-year-old girl and discuss the importance of considering this rare diagnosis in different soft tissue masses.Keywords: excisional biopsy, histology, nodular fasciiti

Explorando la regeneración de la mordenita en la reacción de carbonilación de dimetiléter

Dimethyl ether carbonylation (DME) to produce methyl acetate (MA) over mordenite catalysts is attracting much attention because of its high selectivity. However, acidic mordenite suffers from a fast deactivation (coking) that has not been properly studied. In the present work, we study the regeneration of the catalyst in several cycles aiming to help the future industrial application of mordenite catalysts in MA production. Both diluted and pure air have been successfully tested for the regeneration of the catalyst. The results show that 1) there is no negative effect after several regeneration cycles and 2) there is a slight improvement of catalyst productivity after the first regeneration cycle. A possible explanation to these results, which is highlighted in this work, is that the catalyst structure is not affected during regeneration while there is an initial migration of Al from the mordenite structure to extra-framework positions.Ministerio de Economía y Competitividad, BIOTER project, Proyecto I+D Retos ENE2012-31598Ministerio de Economía y Competitividad, Universidad de Sevilla, Juan de la Cierva IJCI-2017-3283

Intrasellar Chondroid Chordoma: A Case Report

Chordomas are tumors derived from cells that are remnants of the notochord, particularly from its proximal and distal extremes, they are mainly midline and represent approximately 1% of all malignant bone tumors and 0.1 to 0.2% of intracranial neoplasms. Chordomas involving the sellar region are rare. Herein, we describe a 57-year-old male patient presenting with a history of retro-orbital headache, progressive loss of vision, and clinical features of hypopituitarism, for over 2 months. During evaluation, the CT scan revealed a large contrast-enhancing intrasellar tumor with a 3.6-cm largest diameter. The patient underwent transsphenoidal partial resection of the tumor, and histological examination was consistent with the diagnosis of chondroid chordoma. Although chordomas are rare, they may be considered to constitute a differential diagnostic of pituitary adenomas, especially if a calcified intrasellar tumor with bone erosion is diagnosed

Insect repellents: recommendations for use in children

OBJETIVO: Apresentar uma revisão bibliográfica sobre o uso de repelentes de insetos em crianças, com ênfase especial na proteção contra mosquitos. FONTES DE DADOS: Realizou-se uma pesquisa bibliográfica nas bases de dados Pubmed e Lilacs, cujos artigos incluíam produtos comercialmente disponíveis no Brasil. Foram selecionados artigos publicados nos últimos dez anos em língua inglesa ou portuguesa, referentes a crianças, obtidos com as seguintes palavras-chave: "insect repellents", "children", "mosquitoes", "N,N-dietil-metatoluamida (DEET)". SÍNTESE DOS DADOS: Entre os repelentes tópicos, DEET, icaridina e óleo natural de eucalipto-limão apresentam, em concentrações adequadas, perfil de segurança favorável e são eficazes na prevenção de picadas de mosquitos em crianças e adultos. Em geral, são indicados para crianças acima de dois anos de idade. Medidas físicas são fundamentais para proteger lactentes jovens, especialmente menores de seis meses, com destaque para o uso de telas com permetrina. CONCLUSÕES: Os mosquitos são vetores de doenças infectoparasitárias que acometem, anualmente, milhões de pessoas no mundo e causam milhares de mortes. O combate aos mosquitos inclui medidas ambientais e de proteção individual. O uso de repelentes tópicos para proteção individual da criança exige cuidados específicos e conhecimento quanto ao produto ideal para cada idade, especialmente quando consideradas sua eficácia e segurança.OBJECTIVE: To present a literature review about the use of insect repellents on children, highlighting the protection against mosquitoes. DATA SOURCES: Pubmed and Lilacs databases were searched for articles in English and Portuguese published in the last ten years with the following key-words: "insect repellents", "children", "mosquitoes", "N,N-dietil-metatoluamida (DEET)". DATA SYNTHESIS: Concerning topical repellents, DEET, icaridine and natural oil of lemon eucalyptus are effective to prevent mosquito bites in children and adults and have favorable safety profile when used in appropriate concentration. They are generally recommended for children older than two years-old. Physical barriers are essential for infant protection, especially if they are six months old or less, with special interest in the permethrin-treated nets. CONCLUSIONS: Mosquitoes are vectors of a variety of infectious and parasitic diseases which annually affect millions of people and cause thousands of deaths worldwide. The combat to mosquitoes includes individual and environmental measures. Topic repellents for children's individual protection demand specific handling attention and knowledge about the ideal product for each age, especially regarding their efficacy and safety

Two-bands superconductivity with intra- and interband pairing for synthetic superlattices

We consider a model for superconductivity in a two-band superconductor, having an anisotropic electronic structure made of two partially overlapping bands with a first hole-like and a second electron-like fermi surface. In this pairing scenario, driven by the interplay between interband $V_{i,j}$ and intraband $V_{i,i}$ pairing terms, we have solved the two gap equations at the critical temperature $T = T_c$ and calculate $T_c$ and the chemical potential $\mu$ as a function of the number of carriers $n$ for various values of pairing interactions, $V_{1,1}$, $V_{2,2}$, and $V_{1,2}$. The results show the complexity of the physics of condensates with multiple order parameters with the chemical potential near band edges.Comment: 6 pages, 2 figure

History of the Spanish demersal fishery in the Atlantic and Mediterranean Seas

Long fisheries time series allow the review of baselines and inform our knowledge of past events that have conditioned the recent history of the stocks. In this study, we investigated trends in fisheries landings data for the most representative Atlantic and Mediterranean demersal fisheries off the Spanish Iberian Peninsula and the Balearic Islands (1933–1986). The aim was to analyse the evolution of demersal species exploitation and detect changes in landings and fishing tactics. Ten species were selected, which included teleosts, crustaceans, and cephalopods. Results indicated a decrease in Landings Per Unit of Capacity (LPUC) in six of the species examined. While in the Atlantic the process of substitution or incorporation of new species to the fisheries occurs progressively, in the Mediterranean this incorporation occurs simultaneously for many of the species. Four main fishing tactics (landing pattern obtained from the classification analysis of landings per species) were identified. Geographically nearby and connected regions developed similar fishing tactics to each other, and also changed over time. While the fleets from isolated regions were more specialized, and only carrying out one fishing tactic during the study period. Improvements in LPUC with the implementation of new technology and legislative and management measures were not observed.Postprint2,27

Atomically thin boron nitride: a tunnelling barrier for graphene devices

We investigate the electronic properties of heterostructures based on ultrathin hexagonal boron nitride (h-BN) crystalline layers sandwiched between two layers of graphene as well as other conducting materials (graphite, gold). The tunnel conductance depends exponentially on the number of h-BN atomic layers, down to a monolayer thickness. Exponential behaviour of I-V characteristics for graphene/BN/graphene and graphite/BN/graphite devices is determined mainly by the changes in the density of states with bias voltage in the electrodes. Conductive atomic force microscopy scans across h-BN terraces of different thickness reveal a high level of uniformity in the tunnel current. Our results demonstrate that atomically thin h-BN acts as a defect-free dielectric with a high breakdown field; it offers great potential for applications in tunnel devices and in field-effect transistors with a high carrier density in the conducting channel.Comment: 7 pages, 5 figure