1,518 research outputs found
Neutrino flux predictions for known Galactic microquasars
It has been proposed recently that Galactic microquasars may be prodigious
emitters of TeV neutrinos that can be detected by upcoming km^2 neutrino
telescopes. In this paper we consider a sample of identified microquasars and
microquasar candiates, for which available data enables rough determination of
the jet parameters. By employing the parameters inferred from radio
observations of various jet ejection events, we determine the neutrino fluxes
that should have been produced during these events by photopion production in
the jet. Despite the large uncertainties in our analysis, we demonstrate that
in several of the sources considered, the neutrino flux at Earth, produced in
events similar to those observed, would exceed the detection threshold of a
km^2 neutrino detector. The class of microquasars may contain also sources with
bulk Lorentz factors larger than those characteristic of the sample considered
here, directed along our line of sight. Such sources, which may be very
difficult to resolve at radio wavelengths and hence may be difficult to
identify as microqusar candidates, may emit neutrinos with fluxes significantly
larger than typically obtained in the present analysis. These sources may
eventually be identified through their neutrino and gamma-ray emission.Comment: 17 pages. Submitted to Ap
Preditores socio-demográficos, clínicos e de saúde oral auto-percebida nos idosos
Poster apresentado nas XXIV Jornadas Internacionais de Medicina Dentária do ISCSEM, 4-5 Março 2015, Egas Moniz, Caparica, Portugal
Morpholin-4-ium morpholine-4-carbodithioate
The title compound, C4H10NO+·C5H8NOS2
−, is built up of a morpholinium cation and a dithiocarbamate anion. In the crystal, two structurally independent formula units are linked via N—H⋯S hydrogen bonds, forming an inversion dimer, with graph-set motif R
4
4(12)
Análise comparativa de três métodos de correção atmosférica de imagens Landsat 5 - TM para obtenção de reflectância de superfície e NDVI.
The present study has compared three methods of atmospheric correction, two dark object subtraction (DOS) methods and one method based on the fourth component of the tasseled cap transformation (TC4), to obtain reflectance and NDVI values of Landsat 5 ? TM satellite images. For each atmospheric correction method, reflectance and NDVI values of five targets (crop/pasture, forest, straw, bare soil and water) were analyzed in three images (Landsat path-row 222-75). The study area is localized in the west of Sao Paulo State, Brazil. The images were acquired on 29/10/2009, 02/02/2010 and 26/06/2010 with solar zenith angles of 28°, 34° and 55°, correspondingly. The TC4 was the only method which eliminated the haze in the image, but it is not recommended if the objective is to obtain reflectance values. The DOS methods did not removed the image haze but performed reasonably to obtain reflectance values. For the visible bands, both DOS methods analyzed performed well. The DOS method which considered the atmospheric transmittance (DOS2), although more indicated to correct the infrared bands, it is dependent of the image solar zenith angle. The image acquired under a zenith angle of 55°, after been corrected using the DOS2 method, presented reflectance values overestimated. Without the atmospheric correction the NDVI of vegetation targets tended to be underestimated
Identificação e resistência a antibióticos de gêneros bacterianos presentes em surubins criados em tanques-rede.
O surubim é uma espécie apreciada pelo mercado consumidor, entretanto, seu cultivo intensivo em tanques-rede pode trazer problemas de sanidade devido ao estresse dos peixes, caso não sejam utilizadas boas práticas de manejo. Neste trabalho, objetivou-se identificar e verificar a resistência aos antibióticos de gêneros bacterianos isolados de Pseudoplatystoma sp. criados em tanques-rede de baixo volume
Classificação preliminar de pastagens degradadas em microbacias da região de Guararapes-SP.
Nos últimos anos, as técnicas de sensoriamento remoto tem sido fundamental para monitoramento e avaliação de fatores inerentes a dinâmica de uso e ocupação das terras. Este trabalho objetivou a realização de classificação preliminar de pastagens degradadas em três microbacias localizadas na região do município de Guararapes, SP. Para a área de estudo, utilizou-se uma imagem Landsat 5 ? TM do dia 02/02/10. Quatro níveis de degradação foram estipulados por meio da análise da cobertura vegetal da pastagem (CVP) tendo por base a relação entre NDVI do ponto e NDVI máximo e mínimo das áreas de pastagem. Além disso, para cada microbacia foram obtidos indicadores de degradação de pastagem (IDP). De forma preliminar, a metodologia mostrou-se satisfatória para diferenciação de três níveis de degradação. Conforme o IDP, as pastagens das microbacias foram classificadas como levemente degradadas. No entanto, estudos futuros são necessários para obtenção de série temporal do IDP para possível detecção de tendências positivas ou negativas no processo de degradação das pastagens.bitstream/item/26594/1/pastagens.pd
Procedimentos para o monitoramento populacional de Diaphorina Citri , vetor do Huanglongbing (HLB) dos citros.
Após o registro do agente etiológico do HLB, a bactéria Candidatus liberibacter spp. no Brasil em 2004, o inseto vetor Diaphorina citri (Hemiptera: Psyllidae) antes considerado uma praga secundária dos citros, ganhou o status de inseto-praga de grande importância
Classificação preliminar de pastagens degradadas em microbacias da região de Guararapes-SP.
Nos últimos anos, as técnicas de sensoriamento remoto tem sido fundamental para monitoramento e avaliação de fatores inerentes a dinâmica de uso e ocupação das terras. Este trabalho objetivou a realização de classificação preliminar de pastagens degradadas em três microbacias localizadas na região do município de Guararapes, SP. Para a área de estudo, utilizou-se uma imagem Landsat 5 ? TM do dia 02/02/10. Quatro níveis de degradação foram estipulados por meio da análise da cobertura vegetal da pastagem (CVP) tendo por base a relação entre NDVI do ponto e NDVI máximo e mínimo das áreas de pastagem. Além disso, para cada microbacia foram obtidos indicadores de degradação de pastagem (IDP). De forma preliminar, a metodologia mostrou-se satisfatória para diferenciação de três níveis de degradação. Conforme o IDP, as pastagens das microbacias foram classificadas como levemente degradadas. No entanto, estudos futuros são necessários para obtenção de série temporal do IDP para possível detecção de tendências positivas ou negativas no processo de degradação das pastagens
Green tea as a promising extract of active food packaging
Introduction: Tea is one of the most popular and frequently consumed beverages in the world
and its consumption dates back to more than 2000 years in China and then spread to other
areas including Japan and later on to Europe (Zhao et al., 2014). Green tea is produced from
Camellia sinensis (L.) Kuntze leaf infusion and is well known for its pleasant flavour and is
associated with positive health effects.
The biological activity of green tea is related with the considerable amount of catechins and
other phenolic compounds, in particular flavonols and phenolic acids, present in its
composition (Zhao et al., 2014). These phenolic compounds prevent the oxidative damage
through their antioxidant activity and also reduce the risk of cancer, cardiovascular and
neurodegenerative diseases (Lorenzo et al., 2014).
The process of oxidation is one of the most common mechanisms of degradation of foodstuffs
and it can alter food texture and colour, decrease nutritional quality, develop off-odours and
also produce possible toxic compounds. As a consequence, the shelf-life and commercial
acceptability of the food products decrease.
Currently, one of the major concerns of the consumers is the impact of food on health. In line
with this, food industry is trying to substitute synthetic additives by natural compounds. These
can be directly added to food or incorporated in food packaging with the aim of being
controlled released throughout the product shelf life. This concept is so-called Active
packaging and allows the packaging to positively interact with foods to increase food shelf-life.
This interaction can be due to the intended release of compounds from packaging to the foods
or to their headspace, or due to the scavenging of compounds by the packaging from the
packaged foods.
Due to the antioxidant capacity of green tea, its extract can be proposed as an alternative to
synthetic antioxidants (Giménez et al., 2013). In fact, it has already been applied in active food
packaging.
Material and Methods: The present review focuses on the application of green tea extract in
active packaging. In this regard, an extensive bibliographic research was carried out in order to
evaluate the polymers already used to incorporate green tea extract, as well as the mechanical
and barrier properties and efficiency of these packaging systems in contact with foods.
Results and Discussion: The chemical composition of tea leaves on active compounds with
antioxidant activity is well documented. Bioactive constituents of the tea leaves include
catechin gallates such as epigallocatechin gallate and gallocatechin gallate (López de Dicastillo
et al., 2011). However the levels of these compounds depend on many factors, such as the
edaphoclimatic conditions and drying conditions of the Camellia sinensis leaves. Moreover the
extraction and analysis methods can also have a great influence in their content.
Green tea extract has already been incorporated into different polymers. In fact, most of them
are edible such as proteic films from distilled dry beans (Yang et al., 2016), agar (Lacey et al.,
2014), chitosan (Siripatrawan et al., 2012; Siripatrawan et al., 2010) and gelatine (Hong et al
(2009).
Green tea extract (GTE) can offers protection against oxidation, significantly reducing rancidity
and thereby extending the shelf-life of packaged foods. Moreover the sensory analysis also
demonstrated that packaged food was unaffected by GTE (Carrizo et al., 2016).
According to Yang et al. (2016), the incorporation of the GTE did not alter the physical
properties of the films. According to Siripatrawan et al. (2010), the incorporation of GTE
improved the mechanical and water vapour barrier properties.
In general, GTE provides a very positive impact in the reduction of oxidation of all types of
food, from aqueous to fatty (López de Dicastillo et al., 2011), although most of the studies
selected meat (e.g. pork, pork sausages, pork loins), or fish products (e.g. fillets of hake, salted
sardines) to test the efficiency of the active films.
Conclusion: Green tea has great potential of application in active food packaging due to its
antioxidant capacity. Therefore, in the near future, is it possible that new food packaging
based on GTE will arise in the market. However, more studies are require to elucidate about
the concentrations of GTE that do not affect or affect positively the mechanical or barrier
properties of the packaging and that are effective as oxidation inhibitors of packaged foodsThis work was supported by the research project “Development of methodologies for the evaluation of polymeric food packaging components and determination of their structural and mechanical properties” (2016DAN 1289) funded by the National Institute of Health Dr Ricardo Jorge, I.P., Lisbon, Portugal.N/
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