Nonlinear Hall Effects in Strained Twisted Bilayer WSe2_2

Recently, it has been pointed out that the twisting of bilayer WSe$_2$ would generate topologically non-trivial flat bands near the Fermi energy. In this work, we show that twisted bilayer WSe$_2$ (tWSe$_2$) with uniaxial strain exhibits a large nonlinear Hall (NLH) response due to the non-trivial Berry curvatures of the flat bands. Moreover, the NLH effect is greatly enhanced near the topological phase transition point which can be tuned by a vertical displacement field. Importantly, the nonlinear Hall signal changes sign across the topological phase transition point and provides a way to identify the topological phase transition and probe the topological properties of the flat bands. The strong enhancement and high tunability of the NLH effect near the topological phase transition point renders tWSe$_2$ and related moire materials new platforms for rectification and second harmonic generations.Comment: 5 pages, 3 figures. Comments are welcom

ENT care of children and adolescents in the Brazilian public healthy system in three different municipalities

The data base of ENT care in the Brazilian public health system (Sistema Unico de Saude - SUS) will help organize public health programs. AIM: The following items were investigated in patients aged up to 17 years attended in public health system outpatient units in the city of Mariana, in the ENT screening unit, UNIFESP-EPM, and in CISMISEL: 1) The main otorhinolaryngological diagnoses; 2) The most frequently required exams, drugs, and surgical procedures and their indications; 3) The jobs of parents; the number of siblings; and 4) A statistical analysis and comparison of data in each location. MATERIAL AND METHODS: We undertook a prospective study and a statistical analysis of variables that were gathered during the first visit. RESULTS: The age, the parents' salary, the number of siblings aged below 18 years, the presence of rhinitis, ears diseases, the exams, drugs and otological surgeries that were indicated were all statistically significant. CONCLUSION: The most common diagnosis was mouth breathing. The most common surgery was adenotonsillectomy. The most frequently requested exam was a lateral cranial radiograph. The number of unemployed parents, their poor salaries, and the number of siblings make if difficult for these patients to be treated in any facility other than the public heath system.A criação de um banco de dados sobre as demandas otorrinolaringológicas no SUS poderá fornecer informações para organizar estratégias de saúde e criar ou otimizar recursos do governo ou privados. OBJETIVOS: Determinar em pacientes até 17 anos de idade: 1) As principais doenças otorrinolaringológicas diagnosticadas; 2) Exames complementares mais solicitados; 3) Medicamentos mais prescritos; 4) Procedimentos ambulatoriais realizados e as indicações cirúrgicas; 5) Estado empregatício dos pais e o número de irmãos dependentes; 6) Comparar e analisar estatisticamente os dados nos locais estudados. MATERIAL E MÉTODO: Estudo prospectivo e análise estatística das variáveis obtidas nas primeiras-consultas na Policlínica de Mariana, na sede Consórcio Intermunicipal de Saúde da Microrregião de Sete Lagoas e na Triagem da Otorrinolaringologia da UNIFESP-EPM. RESULTADOS: Há diferenças estatisticamente significativas quanto às variáveis idade, média salarial dos pais empregados, número de irmãos até 17 anos, rinite, doenças otológicas, exames solicitados, prescrições e indicações de cirurgias micro-otológicas. CONCLUSÕES: O diagnóstico mais encontrado foi respiração oral. O exame complementar e a cirurgia mais indicados foram a radiografia de cavum e a adenoamigdalectomia. O nível de desemprego, a baixa média salarial e o número de dependentes na família dificultam tratamentos que não estejam disponíveis na rede pública de saúde.Hospital João XXIIIInstituto de Otorrinolaringologia de Minas GeraisUNIFESP-EPM Departamento de Otorrinolaringologia e Cirurgia de Cabeça e PescoçoUNIFESP-EPM Programa de Pós-Graduação em Otorrinolaringologia e Cirurgia de Cabeça e PescoçoUNIFESP, EPM, Depto. de Otorrinolaringologia e Cirurgia de Cabeça e PescoçoUNIFESP, EPM Programa de Pós-Graduação em Otorrinolaringologia e Cirurgia de Cabeça e PescoçoSciEL

An integrated gene regulatory network controls stem cell proliferation in teeth.

Epithelial stem cells reside in specific niches that regulate their self-renewal and differentiation, and are responsible for the continuous regeneration of tissues such as hair, skin, and gut. Although the regenerative potential of mammalian teeth is limited, mouse incisors grow continuously throughout life and contain stem cells at their proximal ends in the cervical loops. In the labial cervical loop, the epithelial stem cells proliferate and migrate along the labial surface, differentiating into enamel-forming ameloblasts. In contrast, the lingual cervical loop contains fewer proliferating stem cells, and the lingual incisor surface lacks ameloblasts and enamel. Here we have used a combination of mouse mutant analyses, organ culture experiments, and expression studies to identify the key signaling molecules that regulate stem cell proliferation in the rodent incisor stem cell niche, and to elucidate their role in the generation of the intrinsic asymmetry of the incisors. We show that epithelial stem cell proliferation in the cervical loops is controlled by an integrated gene regulatory network consisting of Activin, bone morphogenetic protein (BMP), fibroblast growth factor (FGF), and Follistatin within the incisor stem cell niche. Mesenchymal FGF3 stimulates epithelial stem cell proliferation, and BMP4 represses Fgf3 expression. In turn, Activin, which is strongly expressed in labial mesenchyme, inhibits the repressive effect of BMP4 and restricts Fgf3 expression to labial dental mesenchyme, resulting in increased stem cell proliferation and a large, labial stem cell niche. Follistatin limits the number of lingual stem cells, further contributing to the characteristic asymmetry of mouse incisors, and on the basis of our findings, we suggest a model in which Follistatin antagonizes the activity of Activin. These results show how the spatially restricted and balanced effects of specific components of a signaling network can regulate stem cell proliferation in the niche and account for asymmetric organogenesis. Subtle variations in this or related regulatory networks may explain the different regenerative capacities of various organs and animal species

Myoepithelioma of minor salivary gland on the base of the tongue: a case report

This study reports a case of myoepithelioma of minor salivary gland on the base of the tongue of a 58 year-old patient. This theme is discussed because it is a rare tumor, and in this case, it was located in an uncommon position. The diagnosis was given by the pathologic and immunohistochemical study of the excised tumor. The course is usually benign, and the cure is possible if it is completely excised.Os autores apresentam um caso de mioepitelioma de glândula salivar menor, localizado na base da língua de uma paciente de 58 anos. O mioepitelioma é um tumor pouco freqüente, de evolução benigna, sendo possível obter-se a cura através da excisão cirúrgica completa da lesão. Neste caso, apresentou-se numa posição bastante incomum, a base da língua. Foi realizada a exérese da lesão, com margens de segurança, e a paciente está assintomática e sem recidiva local depois de 6 meses de acompanhamento pós-operatório. O diagnóstico foi obtido através do estudo anatomopatológico e imuno-histoquímico da peça.Universidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina (EPM)Universidade Federal de São Paulo (UNIFESP), Escola Paulista de Medicina (EPM) Departamento de Otorrinolaringologia e Distúrbios da Comunicação HumanaUNIFESP, EPM, Depto. de Otorrinolaringologia e Distúrbios da Comunicação HumanaSciEL

Higher-Order Nonlinear Anomalous Hall Effects Induced by Berry Curvature Multipoles

In recent years, it has been shown that Berry curvature monopoles and dipoles play essential roles in the anomalous Hall effect and the nonlinear Hall effect respectively. In this work, we demonstrate that Berry curvature multipoles (the higher moments of Berry curvatures at the Fermi energy) can induce higher-order nonlinear anomalous Hall (NLAH) effect. Specifically, an AC Hall voltage perpendicular to the current direction emerges, where the frequency is an integer multiple of the frequency of the applied current. Importantly, by analyzing the symmetry properties of all the 3D and 2D magnetic point groups, we note that the quadrupole, hexapole and even higher Berry curvature moments can cause the leading-order frequency multiplication in certain materials. To provide concrete examples, we point out that the third-order NLAH voltage can be the leading-order Hall response in certain antiferromagnets due to Berry curvature quadrupoles, and the fourth-order NLAH voltage can be the leading response in the surface states of topological insulators induced by Berry curvature hexapoles. Our results are established by symmetry analysis, effective Hamiltonian and first-principles calculations. Other materials which support the higher-order NLAH effect are further proposed, including 2D antiferromagnets and ferromagnets, Weyl semimetals and twisted bilayer graphene near the quantum anomalous Hall phase.Comment: 17 pages, 5 figure

Development of a Method for Measuring Carbon Balance in Chemical Sequestration of CO2

Anthropogenic CO2 released from fossil fuel combustion is a primary greenhouse gas which contributes to “global warming.” It is estimated that stationary power generation contributes over one-third of total CO2 emissions. Reducing CO2 in the atmosphere can be accomplished either by decreasing the rate at which CO2 is emitted into the atmosphere or by increasing the rate at which it is removed from it. Extensive research has been conducted on determining a fast and inexpensive method to sequester carbon dioxide. These methods can be classified into two categories, CO2 fixation by natural sink process for CO2, or direct CO2 sequestration by artificial processes. In direct sequestration, CO2 produced from sources such as coal-fired power plants, would be captured from the exhausted gases. CO2 from a combustion exhaust gas is absorbed with an aqueous ammonia solution through scrubbing. The captured CO2 is then used to synthesize ammonium bicarbonate (ABC or NH4HCO3), an economical source of nitrogen fertilizer. In this work, we studied the carbon distribution after fertilizer is synthesized from CO2. The synthesized fertilizer in laboratory is used as a “CO2 carrier” to “transport” CO2 from the atmosphere to crops. After biological assimilation and metabolism in crops treated with ABC, a considerable amount of the carbon source is absorbed by the plants with increased biomass production. The majority of the unused carbon source percolates into the soil as carbonates, such as calcium carbonate (CaCO3) and magnesium carbonate (MgCO3). These carbonates are environmentally benign. As insoluble salts, they are found in normal rocks and can be stored safely and permanently in soil. This investigation mainly focuses on the carbon distribution after the synthesized fertilizer is applied to soil. Quantitative examination of carbon distribution in an ecosystem is a challenging task since the carbon in the soil may come from various sources. Therefore synthesized 14C tagged NH4HCO3 (ABC) was used. Products of ammonium bicarbonate (ABC) or long-term effect ammonium bicarbonate (LEABC) were tagged with 14C when they were synthesized in the laboratory. An indoor greenhouse was built and wheat was chosen as the plant to study in this ecosystem. The investigated ecosystem consists of plant (wheat), soils with three different pH values (alkaline, neutral and acid), and three types of underground water (different Ca2+ and Mg2+ concentrations). After biological assimilation and metabolism in wheat receiving ABC or LEABC, it was found that a considerable amount (up to 10%) of the carbon source is absorbed by the wheat with increased biomass production. The majority of the unused carbon source (up to 76%) percolated into the soil as carbonates, such as environmentally benign calcium carbonate (CaCO3). Generally speaking, alkaline soil has a higher capability to capture and store carbon. For the same soil, there is no apparent difference in carbon capturing capability between ABC fertilizer and LEABC fertilizer. These findings answer the question how carbon is distributed after synthesized fertilizer is applied into the ecosystem. In addition, a separate post-experiment on fertilizer carbon forms that exist in the soil was made. It was found that the up to 88% of the trapped carbon exists in the form of insoluble salts (i.e., CaCO3) in alkaline soils. This indicates that alkaline soil has a greater potential for storing carbon after the use of the synthesized fertilizer from exhausted CO2

Chirped pulse Raman amplification in warm plasma: towards controlling saturation

Stimulated Raman backscattering in plasma is potentially an efficient method of amplifying laser pulses to reach exawatt powers because plasma is fully broken down and withstands extremely high electric fields. Plasma also has unique nonlinear optical properties that allow simultaneous compression of optical pulses to ultra-short durations. However, current measured efficiencies are limited to several percent. Here we investigate Raman amplification of short duration seed pulses with different chirp rates using a chirped pump pulse in a preformed plasma waveguide. We identify electron trapping and wavebreaking as the main saturation mechanisms, which lead to spectral broadening and gain saturation when the seed reaches several millijoules for durations of 10's - 100's fs for 250 ps, 800 nm chirped pump pulses. We show that this prevents access to the nonlinear regime and limits the efficiency, and interpret the experimental results using slowly-varying-amplitude, current-averaged particle-in-cell simulations. We also propose methods for achieving higher efficiencies.close0