271 research outputs found

    Finding a Spherically Symmetric Cosmology from Observations in Observational Coordinates -- Advantages and Challenges

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    One of the continuing challenges in cosmology has been to determine the large-scale space-time metric from observations with a minimum of assumptions -- without, for instance, assuming that the universe is almost Friedmann-Lema\^{i}tre-Robertson-Walker (FLRW). If we are lucky enough this would be a way of demonstrating that our universe is FLRW, instead of presupposing it or simply showing that the observations are consistent with FLRW. Showing how to do this within the more general spherically symmetric, inhomogeneous space-time framework takes us a long way towards fulfilling this goal. In recent work researchers have shown how this can be done both in the traditional Lema\^{i}tre-Tolman-Bondi (LTB) 3 + 1 coordinate framework, and in the observational coordinate (OC) framework. In this paper we investigate the stability of solutions, and the use of data in the OC field equations including their time evolution and compare both approaches with respect to the singularity problem at the maximum of the angular-diameter distance, the stability of solutions, and the use of data in the field equations. This allows a more detailed account and assessment of the OC integration procedure, and enables a comparison of the relative advantages of the two equivalent solution frameworks. Both formulations and integration procedures should, in principle, lead to the same results. However, as we show in this paper, the OC procedure manifests certain advantages, particularly in the avoidance of coordinate singularities at the maximum of the angular-diameter distance, and in the stability of the solutions obtained. This particular feature is what allows us to do the best fitting of the data to smooth data functions and the possibility of constructing analytic solutions to the field equations.Comment: 31 page

    Flight-call as species-specific signal in South American parrots and the effect of species relatedness in call similarity

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    Vocal communication is fundamental to regulate the social interactions in most gregarious species especially after dispersal movements for foraging or predator escape. A species common acoustic signal may be beneficial to group members and is especially critical in species that disperse large distances like parrots. In this study, we investigated whether parrots flight-calls carry species-specific characteristics and tested its variability within and across species. We also assessed the hypothesis of relationship between similarity in species flight-calls and phylogeny. We studied the flight-calls of 10 parrot species all occurring in Cerrado habitat in central Brazil. Our results show that, spectrum wise, there is not a discrete spectral partition between species flight-calls. Flight-calls are conservative within most of the species. Both spectral and temporal dimensions contribute to the difference between species. The species specificity of the calls was confirmed by cross correlation approach. Nevertheless, we found a difference in the call variability with some species exhibiting stereotyped calls (e.g. Amazona aestiva) while others exhibited variable calls (Brotogeris chiriri), suggesting that the function of the flight-call may differ between species, from conveying species signatures to more specific information like group or individual signature. As expected, closely related species have more similar calls. These results show that parrots flight-calls have species-specific characteristics. In some species, these calls can potentially be used in the maintenance of the group or could code other type of information, suggesting that flight-calls may play different roles depending of the species life history.FCT - Fundação para a Ciência e Tecnologiainfo:eu-repo/semantics/publishedVersio

    The Lemaitre Model and the Generalisation of the Cosmic Mass

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    We consider the spherically symmetric metric with a comoving perfect fluid and non-zero pressure -- the Lemaitre metric -- and present it in the form of a calculational algorithm. We use it to review the definition of mass, and to look at the apparent horizon relations on the observer's past null cone. We show that the introduction of pressure makes it difficult to separate the mass from other physical parameters in an invariant way. Under the usual mass definition, the apparent horizon relation, that relates the diameter distance to the cosmic mass, remains the same as in the Lemaitre-Tolman case.Comment: latex, 16 pages, Revision has minor changes due to referee's comments

    Designing surgical clothing and drapes according to the new technical standards

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    Hospitals will continue to be the largest consumers of disposables, because of the diverse range of procedures they provide. Favourable growth is forecast for nonwovens. Increasing concern over contamination and nosocomial infections will boost the demand for consumables and disposables surgical gowns and drapes. But, until now neither the manufacturers nor the end users of surgical gowns and drapes could agree on standards. So, a mandatory European standard is being developed to establish basic requirements and test methods for disposable and reusable materials used for surgical gowns and drapes. Once this standard has been adopted, the continued use of cotton textiles and conventional cotton-polyester mixed textiles will become questionable.(undefined

    Meat quality of lambs fed different saltbush hay (Atriplex nummularia) levels

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    Climate changes have increased soil and water salinity, compromising animal produc- tion especially in dry areas where scientists have become more interested in halophyte plants, like saltbush. The effects of saltbush hay levels (30, 40, 50 and 60%) were evaluated based on physical-chemical, nutritional and sensory parameters of Santa Ine^s lamb meat. Thirty-two 8-month-old castrated Santa Ine^s lambs, with initial weights of 22±1.97 kg were used; they were slaughtered after 60 days in the feedlot. The pH, colour, moisture, protein and cholesterol contents did not differ among treatments. Panelists observed a greater inten- sity of lamb smell and flavour (P=0.0035) in the meat of animals that received more con- centrate in the diet. An increase in the inclu- sion of saltbush increased ash percentage (P=0.0232), total saturated (P=0.0035) and polyunsaturated (P=0.0287) fatty acids and reduced the lipids (P=0.0055) and the n-6:n-3 ratio (P=0.0058) of the meat. Therefore, salt- bush hay can be used as a feeding resource in regions with problems of water and soil salini- ty because it does not impair the physical- chemical, nutritional and sensory quality of sheep meat

    New In Vitro studies on the bioprofile of Genista tenera antihyperglycemic extract

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    The inhibition of a-glucosidase and glucose-6-phosphatase, two enzymes involved in the carbohydrate metabolism, is an important target to control glycaemia on individuals with type 2 diabetes. In this work we report for the first time the inhibition of both enzymes by the antihyperglycemic n-butanol extract from Genista tenera (Fabaceae). This extract decreased a-glucosidase and glucose-6-phosphatase activities to 0.97 and 80.25 %, respectively, being more effective than acarbose, and phlorizin, the positive controls, which reduced enzymes activities only to 17.39 and 96.06 %. Once inflammation and oxidative stress are related to diabetic impairments, the anti-inflammatory activity of the extract was also evaluated, through its inhibitory activity over COX-1 enzyme (47.5 % inhibition). Moreover, after induction of oxidative stress by UV radiation, the viability of irradiated rat liver hepatoma cells exposed to the extract was significantly higher (67.82 %) than that promoted by ascorbic acid, the positive control (45.05 %). In addition, the stability of the extract under gastrointestinal conditions was evaluated by HPLC–DAD-ESI–MS/MS. Flavonoid diglycosides were identified as the main constituents of the extract, and no alterations in the chemical composition nor in the antioxidant activity were observed after in vitro digestion with artificial gastric and pancreatic juices.Fundação para a Ciência e a Tecnologia e Comissão Europeiainfo:eu-repo/semantics/publishedVersio

    Diversity and Genetic Relationship of Free-Range Chickens from the Northeast Region of Brazil

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    In this study, we aimed to evaluate the genetic diversity within and among chicken breeds from the northeast region of Brazil (states of Bahia and Piauí) using microsatellite markers. In addition, we assessed the identity and genetic relationships of chickens from Europe, Africa, and South America, as well as their influence on the formation of the Brazilian breeds. A total of 25 microsatellite markers and a panel containing 886 samples from 20 breeds (including the Brazilian chickens) were used in this study. Different statistical parameters were used to estimate the genetic diversity and relationship among the genetic groups studied. Our study indicates that the Brazilian Creole chickens have high genetic variability. The results show that chickens reared in the states of Bahia and Piauí could have originated from different ancestors. The Brazilian breeds studied have an evolutionary relationship with chickens from Portugal, Nigeria, Chile, and Spain. Our results will contribute directly to the conservation and recognition of Brazilian Creole chicken breeds and provide a solid basis for the demonstration of their genetic identity and genetic conservation of American Creole chicken populations

    Oral treatment with Saccharomyces cerevisiae strain UFMG 905 modulates immune responses and interferes with signal pathways involved in the activation of inflammation in a murine model of typhoid fever

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    AbstractSalmonella spp. are Gram-negative, facultative, intracellular pathogens that cause several diarrheal diseases ranging from self-limiting gastroenteritis to typhoid fever. Previous results from our laboratory showed that Saccharomyces cerevisiae strain UFMG 905 isolated from ‘cachaça’ production presented probiotic properties due to its ability to protect against experimental infection with Salmonella enterica serovar Typhimurium. In this study, the effects of oral treatment with S. cerevisiae 905 were evaluated at the immunological level in a murine model of typhoid fever. Treatment with S. cerevisiae 905 inhibited weight loss and increased survival rate after Salmonella challenge. Immunological data demonstrated that S. cerevisiae 905 decreased levels of proinflammatory cytokines and modulated the activation of mitogen-activated protein kinases (p38 and JNK, but not ERK1/2), NF-κB and AP-1, signaling pathways which are involved in the transcriptional activation of proinflammatory mediators. Experiments in germ-free mice revealed that probiotic effects were due, at least in part, to the binding of Salmonella to the yeast. In conclusion, S. cerevisiae 905 acts as a potential new biotherapy against S. Typhimurium infection due to its ability to bind bacteria and modulate signaling pathways involved in the activation of inflammation in a murine model of typhoid fever

    Caracterização e Análise dos Processos Produtivos em Empresas Agro-Alimentares

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    Através de um diagnóstico inicial baseado na análise do conhecimento, informação existente, recolha de informação e medição de parâmetros num conjunto de empresas (60) dos subsetores dos produtos cárneos, hortofrutícolas, lácteos e panificação apresenta-se através do presente relatório a caracterização dos processos e atividades produtivas em empresas do setor agroalimentar. Executando uma análise técnica ao estado da arte, através do estudo da organização das atividades produtivas, nível tecnológico e tendências no desenvolvimento de produtos, permite-se de acordo com a informação disponível realizar uma comparação das empresas em análise com a performance da indústria, globalmente, por região ou setor de atividade. Verifica-se através da análise ao presente relatório, quais os fatores que permitem a criação de valor no setor agroindustrial de uma forma contínua para a cadeia de valor organizacional. Por outro lado, entre os diversos pontos a melhorar, considerando as organizações em análise, destaca-se a cultura de inovação e a digitalização dos processos de produção (Indústria 4.0). Pretende-se, com a aplicação prática do conhecimento gerado pelo presente relatório, a criação de ferramentas que constituam soluções para a melhoria da gestão da produção que promovam a introdução de métodos de inovação na cultura e performance organizacional de forma a tornar as organizações do setor competitivas e com impacto nos mercados internacionais

    Caracterização e Análise Energética de Empresas Agro-Alimentares

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    Através de um diagnóstico inicial baseado na análise do conhecimento, informação existente, recolha de informação e medição de parâmetros num conjunto de 60 empresas dos subsetores dos produtos cárneos, hortofrutícolas, lácteos e panificação, o presente relatório apresenta os resultados da caracterização energética em empresas do setor agroalimentar. Executando uma análise técnica ao estado da arte, através do estudo da organização, de acordo com a informação disponível, é realizada uma comparação das empresas em análise com a performance da indústria, globalmente, por região ou setor de atividade. Verifica-se, através da análise ao presente relatório, quais os fatores que permitem a criação de valor no setor agroindustrial de uma forma contínua para a cadeia de valor organizacional. Por outro lado, entre os diversos pontos a melhorar, considerando as organizações em análise, destaca-se a cultura de inovação e a digitalização dos processos de produção (Indústria 4.0). Pretende-se, com a aplicação prática do conhecimento gerado pelo presente relatório, a criação de ferramentas que constituam soluções para a melhoria da gestão da produção que promovam a introdução de métodos de inovação na cultura e performance organizacional de forma a tornar as organizações do setor competitivas e com impacto nos mercados internacionais
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