6,004 research outputs found
On the width of the last scattering surface
We discuss the physical effects of some accelerated world models on the width
of the last scattering surface (LSS) of the cosmic microwave background
radiation (CMBR). The models considered in our analysis are X-matter (XCDM) and
a Chaplygin type gas. The redshift of the LSS does not depend on the kind of
dark energy (if XCDM of Chaplygin). Further, for a Chaplygin gas, the width of
the LSS is also only weakly dependent on the kind of scenario (if we have dark
energy plus cold dark matter or the unified picture).Comment: 10 pages, 1 figure, 2 tables, accepted to IJMP
Evolução da esquistossomose em uma zona hiperendêmica do estado de Minas Gerais: dois estudos seccionais
Two cross-sectional studies on schistosomiasis mansoni were done in Comercinho, Minas Gerais (Brazil), at an interval of 7 years. In 1974 and 1981 feces examinations (KATO-KATZ method) were done in 89 and 90% of the population (about 1,500 inhabitants) and clinical examinations were done in 78 and 92% of the patients who excreted Schistosoma mansoni eggs in the feces, respectively. The rate of infection by S. mansoni did not change (69.9% in 1974 and 70.4% in 1981), but the geometrical mean of eggs per gram of feces (431 ± 4 and 334 ± 4, respectively) and the rate of splenomegaly (11 and 7%, respectively) decreased significantly in 1981, when compared to 1974. This reduction was observed only in the central zones of the town (zones 1-2) where the rate of dwellings with piped water increased from 17 to 44%. In the surroundings (zones 3-4), where the proportion of houses with piped water did not change significantly between 1974 (10%) and 1981 (7%), the geometrical mean of S. mansoni eggs and the rate of splenomegaly did not change either.Dois estudos seccionais da esquistossomose mansoni foram desenvolvidos na cidade de Comercinho, Estado de Minas Gerais (Brasil), com intervalo de sete anos. Em 1974 e em 1981 foram feitos exames de fezes em, respectivamente, 89 e 90% da população da cidade (cerca de 1.500 habitantes) e exame clÃnico em, respectivamente, 78 e 92% dos pacientes que apresentavam ovos de S. mansoni nas fezes. O Ãndice de infecção pelo S. mansoni não se modificou durante o perÃodo analisado (69,9% em 1974 e 70,4% em 1981), mas a média geométrica de ovos por grama de fezes (431 ± 4 e 334 ± 4, respectivamente) e o Ãndice de esplenomegalia (11 e 7%, respectivamente) diminuÃram significativamente em 1981, quando comparado ao observado em 1974. Esta redução ocorreu exclusivamente nas zonas centrais da cidade (zonas 1-2), onde a percentagem de domicÃlios com água encanada aumentou de 17 para 44%. Na periferia (zonas 3-4), onde a porcentagem de domicÃlios com água encanada não mudou significativamente entre 1974 (10%) e 1981 (7%), a contagem de ovos de S. mansoni e o Ãndice de esplenomegalia também não sofreram modificações
Avaliação Nutricional de um Suplemento Alimentar
A escolha da nutrição mais adequada tem sido um tema estudado com grande interesse ao longo da história da humanidade tendo em conta a manutenção da Saúde, mas igualmente com outras finalidades como o atraso do envelhecimento ou outros benefÃcios.
O desafio colocado pela ingestão de frutos, vegetais, cereais, azeite e vinho aplicado pela intitulada Dieta Mediterrânica torna possÃvel o entendimento de paÃses com diversas etnias, culturas, economia e religiões, todos eles à volta do mar Mediterrâneo.
Por outro lado, o contÃnuo aparecimento de patologias como os acidentes vasculares cerebrais, o cancro e a aterosclerose podem ser de algum modo minimizadas pela ingestão de alguns compostos bioativos presentes nos alimentos, os chamados nutracêuticos e alimentos funcionais. O objetivo deste trabalho foi fazer uma revisão dos estudos publicados sobre os efeitos do licopeno na saúde humana, uma abordagem da respetiva quÃmica, fontes, biodisponibilidade e do potencial possÃvel papel e mecanismos desempenhado na prevenção de determinadas doenças crónicas e no cancro.
O licopeno é um dos antioxidantes mais potentes conhecidos, constituindo porventura o carotenóide mais importante presente na dieta, maioritariamente fornecido através do tomate e derivados. Atendendo a que o organismo humano não consegue sintetizar este composto de novo, este tem obrigatoriamente que ser fornecido pela dieta. No entanto, a sua biodisponibilidade pode ser afetada por inúmeros fatores tais como a forma de digestão da matriz alimentar, a temperatura de confecção, pela presença de outras gorduras no alimento, dosagem e outros compostos solúveis, incluindo os outros carotenóides. Esses fatores causam a libertação de licopeno a partir da matriz de alimentos e alteram assim a sua biodisponibilidade.info:eu-repo/semantics/publishedVersio
Fluid flow and structural numerical analysis of a cerebral aneurysm model
Intracranial aneurysms (IA) are dilations of the cerebral arteries and, in most cases, have no
symptoms. However, it is a very serious pathology, with a high mortality rate after rupture. Several
studies have been focused only on the hemodynamics of the flow within the IA. However, besides
the effect of the flow, the development and rupture of the IA are also associated with a combination
of other factors such as the wall mechanical behavior. Thus, the objective of this work was to
analyze, in addition to the flow behavior, the biomechanical behavior of the aneurysm wall. For
this, CFD simulations were performed for different Reynolds numbers (1, 100, 500 and 1000) and
for two different rheological models (Newtonian and Carreau). Subsequently, the pressure values of
the fluid simulations were exported to the structural simulations in order to qualitatively observe
the deformations, strains, normal stresses and shear stress generated in the channel wall. For the
structural simulations, a hyperelastic constitutive model (5-parameter Mooney–Rivlin) was used. The
results show that with the increase in the Reynolds number (Re), the recirculation phenomenon is
more pronounced, which is not seen for Re = 1. The higher the Re, the higher the strain, displacement,
normal and shear stresses values.The authors acknowledge the financial support from the project EXPL/EME-EME/0732/2021,
funded by the NORTE 2020 Portugal Regional Operational Programme, under the PORTUGAL
2020 Partnership Agreement, through the European Regional Development Fund (FEDER) and
by Fundação para a Ciência e Tecnologia (FCT). This work was also supported by Fundação para
a Ciência e a Tecnologia (FCT) under the strategic grants UIDB/04077/2020, UIDB/04436/2020,
UIDB/00319/2020 and UIDB/00532/2020. Andrews Souza and Violeta Carvalho also acknowledge
the financial support by FCT through the individual research grants 2021.07961.BD and
UI/BD/151028/2021, respectively.info:eu-repo/semantics/publishedVersio
Fusion activity and inactivation of influenza virus: Kinetics of low pH-induced fusion with cultured cells
The kinetics of fusion of influenza virus (A/PR/8/34) with human promyelocytic leukaemia (HL-60), human T lymphocytic leukaemia (CEM) and murine lymphoma (S49) cells were investigated. Fusion was demonstrated by electron microscopy, and monitored by fluorescence dequenching of octadecylrhodamine incorporated in the virus membrane. Rapid fusion was induced upon mild acidification of the medium. At pH 5, all virus particles were capable of fusing with the cells. The initial rate and the extent of fusion were maximal between pH 4.9 and 5.2 and declined sharply below and above this range. The rate constants of adhesion of influenza virus to cells or erythrocyte ghosts were large, indicating a diffusion-controlled process. The rate constants of fusion of the virus with cells were smaller than those found previously for fusion with various liposomes. Although preincubation of the virus at acidic pH in the absence of target membranes almost completely inactivated the virus in its ability to fuse with erythrocyte ghosts, it reduced the extent of fusion with cultured cells by only 20 to 40%. Kinetic analysis of fusion revealed a mode of inactivation of the virus bound to erythrocyte ghosts or suspension cells, below pH 5.4, different from that of the virus preincubated at low pH without target membranes
Cellulolytic ability of Penicillium strains isolated from soil of the Brazilian Atlantic forest
Penicillium spp. are capable of degrading plant wastes by producing large amounts
of enzymes such as cellulases. These form a complex capable of acting on cellulosic
materials and producing sugars with industrial interest (e.g., ethanol production).
Cellulases are also used for (a) pulp and paper industry (b) in the textile industry.
The aim of this study was to evaluate the cellulolytic capability of 17 strains
of Penicillium isolated from soil of the Brazilian Atlantic Forest and conserved
under mineral oil at the URM Culture Collection. All strains were re-grown from
mineral oil and re-identifiied. Each strain was grown in synthetic medium with
carboxymethylcellulose as the carbon source and incubated for 5 days at 28°C.
Strains were subjected to heat shock for 16h at 50°C. Thereafter, onto each colony
was added 5 ml of Congo red stain solution in Tris-HCl. After 30 min this solution
was removed and the cultures were washed and submerged under 0.1 M NaCl aqueous
solution for 5 min. Finally, an enzymatic index was calculated from the ratio
of the diameter of the halo around each colony to the diameter of the colony. All
of the 17 strains tested showed a halo of cellulose degradation, indicating enzyme
production. The enzymatic ratios varied between 0.2 (Penicillium brevicompactum
URM5994) and 3.3 (Penicillium glabrum URM6009). Thus, Penicillium glabrum
URM6009 is evaluated as a high producer of cellulase. It was selected for quantitative
production of this enzyme and additional studies are taking place in order to
verify potential industrial application for clarification of fruit juices
Nematodes Affecting Potato and Sustainable Practices for Their Management
Plant-parasitic nematodes are a significant factor limiting potato production and tuber quality in several regions where potato is produced. Overall, parasitic nematodes alone cause an estimated annual crop loss of $ 78 billion worldwide and an average crop yield loss of 10–15%. As a result, sustainable food production and food security are directly impacted by pests and diseases. Degrading land use with monocultures and unsustainable cropping practices have intensified problems associated with plant pathogens. Proper identification of nematode species and isolates is crucial to choose effective and sustainable management strategies for nematode infection. Several nematode species have been reported associated with potato. Among those, the potato cyst nematodes Globodera rostochiensis and G. pallida, the root-knot nematode Meloidogyne spp., the root lesion nematode Pratylenchus spp., the potato rot nematode Ditylenchus destructor and the false root-knot nematode Nacobbus aberrans are major species limiting potato yield and leading to poor tuber quality. Here, we report a literature review on the biology, symptoms, damage and control methods used for these nematode species
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