Gravitational traces of bumblebee gravity in metric-affine formalism

This work explores various manifestations of bumblebee gravity within the metric--affine formalism. We investigate the impact of Lorentz violation parameter, denoted as $X$, on the modification of the \textit{Hawking} temperature. Our calculations reveal that as $X$ increases, the values of the \textit{Hawking} temperature attenuate. To examine the behavior of massless scalar perturbations, specifically the \textit{quasinormal} modes, we employ the WKB method. The transmission and reflection coefficients are determined through our calculations. The outcomes indicate that a stronger Lorentz--violating parameter results in slower damping oscillations of gravitational waves. To comprehend the influence of the \textit{quasinormal} spectrum on time--dependent scattering phenomena, we present a detailed analysis of scalar perturbations in the time--domain solution. Additionally, we conduct an investigation on shadows, revealing that larger values of $X$ correspond to larger shadow radii. Lastly, we explore the concept of time delay within this framework.Comment: 29 pages and 7 figure

A BRIEF REVIEW ON THE ADVANTAGES, HINDRANCES AND ECONOMIC FEASIBILITY OF STIRLING ENGINES AS A DISTRIBUTED GENERATION SOURCE AND COGENERATION TECHNOLOGY

The present paper aims to provide a brief review of the potentiality and economic feasibility of the Stirling engine as a distributed generation source and cogeneration technology. Another objective was the determination of hindrances which may be preventing the feasibility of the Stirling technology. With these intentions, a research based on a combination of preselected keywords was performed at the Metasearch of CAPES (Brazil's Higher Education Coordination of Personnel Perfecting). No filters in relation to the research period or to particular geographical regions were employed, thus publications until 2017’s middle were included and the research was conducted on a global level. Next, the selection of papers which contained some of the keywords was made, consisting initially of the read of the publications’ abstracts. The remaining ones were then further explored and had their relevant information incorporated, according to the scope of this work. It is worth mentioning that other accredited sources which dealt with important aspects of the topic were also included. Furthermore, a table containing some examples of products concerning the application of the Stirling engine as a distributed generation and cogeneration technology is presented. Ultimately, it is concluded that the Stirling technology, despite its advantages and suitability regarding the proposed applications, is not yet commercially feasible, having currently only a minor presence in the market. This scenario can be attributed to the need for further research and technical development as well as cost reduction

Flebotomíneos (Diptera: Psychodidae) no Estado de Roraima. III. Listagem das espécies no Estado.

Are relationed the species of sand flies collected in the State of Roraima, Brasil

Adubação organo-mineral para a recuperação da produção de forragem em uma pastagem nativa degradada.

Resumo: A degradação do solo está geralmente associada às práticas inadequadas da agricultura e da pecuária, resultando na perda de matéria orgânica e na diminuição da disponibilidade de nutrientes, especialmente nitrogênio, fósforo e enxofre. Uma pesquisa foi conduzida, no período de 2003 a 2005, na região do Sertão Norte do Ceará, em uma área degradada pelo sobrepastejo, recoberta por um planossolo háplico, objetivando a recomposição de sua fertilidade e recuperação de sua cobertura forrageira e produtividade. Os tratamentos experimentais consistiram na aplicação de nitrogênio (300 kg/ha), fósforo (100 kg/ha), potássio (60 kg/ha) e de diferentes combinações destes nutrientes como parcelas principais e do esterco de cabra (5.000 kg/ha) como subparcela. Com base no incremento e na persistência da produção de fitomassa da parte aérea do estrato herbáceo, a adubação com fósforo se mostrou como uma técnica válida para recuperação da produtividade de pastagens degradadas, constituindo a combinação fósforo e potássio a mais recomendada. A adição de esterco de cabra não melhorou de imediato a produtividade de fitomassa porém, teve efeito positivo ao longo do tempo. [Mineral and organic fertilization as a tool to recover forage yield on a degraed native pasture]. Abstract: Soil degradation is generally associated with inadequate agriculture and livestock practices, resulting in organic matter losses, decreasing of nutrient availability, specially, N, P and K. A research was carried out, in a 2003-2005 period, in the "Sertão Norte" of Ceará region, in an area degraded by overgrazing. The are is covered by a haplic planossol and the objective of this trial was to evalnate, aiming the recovens of soil fertility, forage cover, and productivity. The experimental treatments consisted of the application of N (300 kg/ha), P (100 kg/ha),K(60 kg/ha) and different combinations of these nutrients, on the main plots, and goat manure 5000 Kg/ha on the subplots.Phosphorus fertilization showed to be a valid technique for the recuperation of degraded rangelands, and phosphorus-potassim is the best recommended combination. The addition of goat manure did not improve right away the phytomass production,however, it had a positive long-term effect

Brazilian solar saltworks - ancient uses and future possibilities

Coastal solar saltworks of Brazil are exploited for sea salt, which becomes progressively concentrated by evaporation. This study aimed to review the current and new potential uses of these systems, in order to provide more dynamic for this activity. The first evaporation ponds are also used for artisanal fisheries, ensuring the livelihood of many families. All the brine rich in secondary salts (bittern) can be widely used by the chemical industry, while the Brazil shows an incipient production of "flower of salt", a salt with distinct characteristics with higher market value than sodium chloride. On the other hand, the saltponds have a high potential for management and obtaining of large populations of Artemia spp., purifying the brine through the action as biological filter. This microcrustacean occurs naturally in intermediate salinity ponds, being commonly used in aquaculture. Species of microalgae and halobacteria found in the saltworks are employed for extraction of beta-carotene and glycerol, used in an extensive list of products with high commercial value. These ecosystems represent refuge zones for many species of migratory birds, becoming imperative to promote the conservation of these hypersaline wetlands

Influência da cultivar de tomateiro na ação de indutores de resistência sobre adultos de Bemisia tabaci biótipo B.

Este trabalho teve por objetivo determinar se o uso associado de cultivar e indutor de resistência a fitopatógenos pode ocasionar alta mortalidade de mosca branca.Resumo 153

Optimization of clavulanic acid production by Streptomyces daufpe 3060 by response surface methodology

Clavulanic acid is a β-lactam antibiotic which has a potent β-lactamase inhibiting activity. In order to optimize its production by the new isolate Streptomyces DAUFPE 3060, the influence of two independent variables, temperature and soybean flour concentration, on clavulanic acid and biomass concentrations was investigated in 250 mL-Erlenmeyers according to a 2² central composite design. To this purpose, temperature and soybean flour (SF) concentration were varied in the ranges 26-34°C and 10-50 g/L, respectively, and the results evaluated utilizing the Response Surface Methodology. The experimental maximum production of clavulanic acid (629 mg/L) was obtained at 32°C and 40 g/L SF after 48 h, while the maximum biomass concentration (3.9 g/L) at 30°C and 50 g/L soybean flour, respectively. These values are satisfactorily close to those (640 mg/L and 3.75 g/L, respectively) predicted by the model, thereby demonstrating the validity of the mathematical approach adopted in this study.Brazilian Research Funding InstitutionsCoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES