Born-Infeld magnetars: larger than classical toroidal magnetic fields and implications for gravitational-wave astronomy

Magnetars are neutron stars presenting bursts and outbursts of X- and soft-gamma rays that can be understood with the presence of very large magnetic fields. Thus, nonlinear electrodynamics should be taken into account for a more accurate description of such compact systems. We study that in the context of ideal magnetohydrodynamics and make a realization of our analysis to the case of the well-known Born-Infeld (BI) electromagnetism in order to come up with some of its astrophysical consequences. We focus here on toroidal magnetic fields as motivated by already known magnetars with low dipolar magnetic fields and their expected relevance in highly magnetized stars. We show that BI electrodynamics leads to larger toroidal magnetic fields when compared to Maxwell's electrodynamics. Hence, one should expect higher production of gravitational waves (GWs) and even more energetic giant flares from nonlinear stars. Given current constraints on BI's scale field, giant flare energetics and magnetic fields in magnetars, we also find that the maximum magnitude of magnetar ellipticities should be $10^{-6}-10^{-5}$. Besides, BI electrodynamics may lead to a maximum increase of order $10\%-20\%$ of the GW energy radiated from a magnetar when compared to Maxwell's, while much larger percentages may arise for other physically motivated scenarios. Thus, nonlinear theories of the electromagnetism might also be probed in the near future with the improvement of GW detectors.Comment: 8 pages, no figures, accepted for publication in The European Physical Journal C (EPJC

Evidence for 3XMM J185246.6+003317 as a massive magnetar with a low magnetic field

3XMM J185246.6+003317 is a transient magnetar located in the vicinity of the supernova remnant Kes\,79. So far, observations have only set upper limits to its surface magnetic field and spindown, and there is no estimate for its mass and radius. Using ray-tracing modelling and Bayesian inference for the analysis of several light curves spanning a period of around three weeks, we have found that it may be one of the most massive neutron stars to date. In addition, our analysis suggests a multipolar magnetic field structure with a subcritical field strength and a carbon atmosphere composition. Due to the time-resolution limitation of the available light curves, we estimate the surface magnetic field and the mass to be $\log_{10} (B/{\rm G}) = 11.89^{+0.19}_{-0.93}$ and $M=2.09^{+0.16}_{-0.09}$~$M_{\odot}$ at $1\sigma$ confidence level, while the radius is estimated to be $R=12.02^{+1.44}_{-1.42}$ km at $2\sigma$ confidence level. They were verified by simulations, i.e., data injections with known model parameters, and their subsequent recovery. The best-fitting model has three small hot spots, two of them in the southern hemisphere. These are, however, just first estimates and conclusions, based on a simple ray-tracing model with anisotropic emission; we also estimate the impact of modelling on the parameter uncertainties and the relevant phenomena on which to focus in more precise analyses. We interpret the above best-fitting results as due to accretion of supernova layers/interstellar medium onto 3XMM J185246.6+003317 leading to burying and a subsequent re-emergence of the magnetic field, and a carbon atmosphere being formed possibly due to hydrogen/helium diffusive nuclear burning. Finally, we briefly discuss some consequences of our findings for superdense matter constraints.Comment: 14 pages, 5 figures, 4 tables. Accepted for publication in Journal of High Energy Astrophysics (JHEAP

Diagnóstico da qualidade do solo sob cultivo de pêssego em agroecossistemas de base familiar

O objetivo do estudo foi diagnosticar a qualidade do solo utilizando indicadores químicos, físicos, e biológicos, em pomares de cinco propriedades agrícolas familiares produtoras de pêssego, localizadas em Pelotas, Território Zona Sul do Rio Grande do Sul. Os resultados mostram que as condições físicas dos solos analisados apresentam-se, em geral, com níveis adequados e próximos das condições encontradas nas áreas de vegetação nativa. Já as condições químicas sugerem, pelos desempenhos dos indicadores considerados, níveis adequados de fertilidade do solo, variando os mesmos entre médio a alto. No entanto, as condições biológicas dos solos estão abaixo dos níveis adequados, indicando que a qualidade dos solos estudados está aquém do nível desejado, tendo em vista que essas condições são fundamentais para que o solo possa exercer adequadamente suas funções no agroecossistema.This study was conducted in five family agroecosystems in Pelotas, located in the South Zone of Rio Grande do Sul state. The aim of this study was to elaborate a diagnosis of soil quality under peach cultivation through analysis of physical, chemical and biological soil indicators. The results show that the physical conditions are adequate and similar to the areas of native vegetation. The chemical conditions presented appropriate levels of soil fertility, ranging between medium to high levels. However, the soil biological conditions were below the adequate level. Thus, the soil quality of these agroecossystems was considered inadequate, decreasing the soil capacity to function satisfactorily.Facultad de Ciencias Agrarias y Forestale

Diagnóstico da qualidade do solo sob cultivo de pêssego em agroecossistemas de base familiar

O objetivo do estudo foi diagnosticar a qualidade do solo utilizando indicadores químicos, físicos, e biológicos, em pomares de cinco propriedades agrícolas familiares produtoras de pêssego, localizadas em Pelotas, Território Zona Sul do Rio Grande do Sul. Os resultados mostram que as condições físicas dos solos analisados apresentam-se, em geral, com níveis adequados e próximos das condições encontradas nas áreas de vegetação nativa. Já as condições químicas sugerem, pelos desempenhos dos indicadores considerados, níveis adequados de fertilidade do solo, variando os mesmos entre médio a alto. No entanto, as condições biológicas dos solos estão abaixo dos níveis adequados, indicando que a qualidade dos solos estudados está aquém do nível desejado, tendo em vista que essas condições são fundamentais para que o solo possa exercer adequadamente suas funções no agroecossistema.This study was conducted in five family agroecosystems in Pelotas, located in the South Zone of Rio Grande do Sul state. The aim of this study was to elaborate a diagnosis of soil quality under peach cultivation through analysis of physical, chemical and biological soil indicators. The results show that the physical conditions are adequate and similar to the areas of native vegetation. The chemical conditions presented appropriate levels of soil fertility, ranging between medium to high levels. However, the soil biological conditions were below the adequate level. Thus, the soil quality of these agroecossystems was considered inadequate, decreasing the soil capacity to function satisfactorily.Facultad de Ciencias Agrarias y Forestale

Diagnóstico da qualidade do solo sob cultivo de pêssego em agroecossistemas de base familiar

O objetivo do estudo foi diagnosticar a qualidade do solo utilizando indicadores químicos, físicos, e biológicos, em pomares de cinco propriedades agrícolas familiares produtoras de pêssego, localizadas em Pelotas, Território Zona Sul do Rio Grande do Sul. Os resultados mostram que as condições físicas dos solos analisados apresentam-se, em geral, com níveis adequados e próximos das condições encontradas nas áreas de vegetação nativa. Já as condições químicas sugerem, pelos desempenhos dos indicadores considerados, níveis adequados de fertilidade do solo, variando os mesmos entre médio a alto. No entanto, as condições biológicas dos solos estão abaixo dos níveis adequados, indicando que a qualidade dos solos estudados está aquém do nível desejado, tendo em vista que essas condições são fundamentais para que o solo possa exercer adequadamente suas funções no agroecossistema.This study was conducted in five family agroecosystems in Pelotas, located in the South Zone of Rio Grande do Sul state. The aim of this study was to elaborate a diagnosis of soil quality under peach cultivation through analysis of physical, chemical and biological soil indicators. The results show that the physical conditions are adequate and similar to the areas of native vegetation. The chemical conditions presented appropriate levels of soil fertility, ranging between medium to high levels. However, the soil biological conditions were below the adequate level. Thus, the soil quality of these agroecossystems was considered inadequate, decreasing the soil capacity to function satisfactorily.Facultad de Ciencias Agrarias y Forestale

Desmotivações no estudo da Química: Uma análise das causas a partir das percepções de estudantes do ensino médio.

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Venom alkaloids against Chagas disease parasite: search for effective therapies

Chagas disease is an important disease affecting millions of patients in the New World and is caused by a protozoan transmitted by haematophagous kissing bugs. It can be treated with drugs during the early acute phase; however, effective therapy against the chronic form of Chagas disease has yet to be discovered and developed. We herein tested the activity of solenopsin alkaloids extracted from two species of fire ants against the protozoan parasite Trypanosoma cruzi, the aetiologic agent of Chagas disease. Although IC50 determinations showed that solenopsins are more toxic to the parasite than benznidazole, the drug of choice for Chagas disease treatment, the ant alkaloids presented a lower selectivity index. As a result of exposure to the alkaloids, the parasites became swollen and rounded in shape, with hypertrophied contractile vacuoles and intense cytoplasmic vacuolization, possibly resulting in osmotic stress; no accumulation of multiple kinetoplasts and/or nuclei was detected. Overexpressing phosphatidylinositol 3-kinase—an enzyme essential for osmoregulation that is a known target of solenopsins in mammalian cells—did not prevent swelling and vacuolization, nor did it counteract the toxic effects of alkaloids on the parasites. Additional experimental results suggested that solenopsins induced a type of autophagic and programmed cell death in T. cruzi. Solenopsins also reduced the intracellular proliferation of T. cruzi amastigotes in infected macrophages in a concentration-dependent manner and demonstrated activity against Trypanosoma brucei rhodesiense bloodstream forms, which is another important aetiological kinetoplastid parasite. The results suggest the potential of solenopsins as novel natural drugs against neglected parasitic diseases caused by kinetoplastids.Fil: Silva, Rafael C. M. Costa. Universidade Federal do Rio de Janeiro; BrasilFil: Fox, Eduardo G. P.. Universidade Federal do Rio de Janeiro; Brasil. South China Agricultural University; ChinaFil: Gomes, Fabio M.. Universidade Federal do Rio de Janeiro; Brasil. National Institutes of Health; Estados UnidosFil: Feijó, Daniel F.. Universidade Federal do Rio de Janeiro; BrasilFil: Ramos, Isabela. Universidade Federal do Rio de Janeiro; BrasilFil: Koeller, Carolina M.. Universidade Federal do Rio de Janeiro; Brasil. University at Buffalo; Estados UnidosFil: Costa, Tatiana F. R.. Universidade Federal do Rio de Janeiro; BrasilFil: Rodrigues, Nathalia S.. Universidade Federal do Rio de Janeiro; BrasilFil: Lima, Ana P.. Universidade Federal do Rio de Janeiro; BrasilFil: Atella, Georgia C.. Universidade Federal do Rio de Janeiro; BrasilFil: Rocha de Miranda, Kildare. Universidade Federal do Rio de Janeiro; Brasil. Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Bioimagem; BrasilFil: Schoijet, Alejandra Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Alonso, Guillermo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: de Alcântara Machado, Ednildo. Universidade Federal do Rio de Janeiro; BrasilFil: Heise, Norton. Universidade Federal do Rio de Janeiro; Brasi

Rarity of monodominance in hyperdiverse Amazonian forests.

Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such "monodominant" forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tree Diversity Network (ATDN). Utilizing a simple defining metric of at least half of the trees ≥ 10 cm diameter belonging to one species, we found only a few occurrences of monodominance in Amazonia, and the phenomenon was not significantly linked to previously hypothesized life history traits such wood density, seed mass, ectomycorrhizal associations, or Rhizobium nodulation. In our analysis, coppicing (the formation of sprouts at the base of the tree or on roots) was the only trait significantly linked to monodominance. While at specific locales coppicing or ectomycorrhizal associations may confer a considerable advantage to a tree species and lead to its monodominance, very few species have these traits. Mining of the ATDN dataset suggests that monodominance is quite rare in Amazonia, and may be linked primarily to edaphic factors

Approach to Endoscopic Procedures: A Routine Protocol from a Quaternary University Referral Center Exclusively for Coronavirus Disease 2019 Patients

OBJECTIVES: The present coronavirus disease (COVID-19) pandemic has ushered in an unprecedented era of quality control that has necessitated advanced safety precautions and the need to ensure the adequate protection of healthcare professionals (HCPs). Endoscopy units, endoscopists, and other HCP may be at a significant risk for transmission of the virus. Given the immense burden on the healthcare system and surge in the number of patients with COVID-19, well-designed protocols and recommendations are needed. We aimed to systematically characterize our approach to endoscopic procedures in a quaternary university hospital setting and provide summary protocol recommendations. METHOD: This descriptive study details a COVID-19-specific protocol designed to minimize infection risks to patients and healthcare workers in the endoscopy unit. RESULTS: Our institution, located in Sa˜o Paulo, Brazil, includes a 900-bed hospital, with a 200-bed-specific intensive care unit exclusively designed for patients with moderate and severe COVID-19. We highlighted recommendations for infection prevention and control during endoscopic procedures, including appropriate triage and screening, outpatient management and procedural recommendations, role and usage of personal protective equipment (PPE), and role and procedural logistics involving COVID-19-positive patients. We also detailed hospital protocols for reprocessing endoscopes and cleaning rooms and also provided recommendations to minimize severe acute respiratory syndrome coronavirus 2 transmission. CONCLUSION: This COVID-19-specific administrative and clinical protocol can be replicated or adapted in multiple institutions and endoscopy units worldwide. Furthermore, the recommendations and summary protocol may improve patient and HCP safety in these trying times