419 research outputs found
Cosmological Bianchi Class A models in S\'aez-Ballester theory
We use the S\'aez-Ballester (SB) theory on anisotropic Bianchi Class A
cosmological model, with barotropic fluid and cosmological constant, using the
Hamilton or Hamilton-Jacobi approach. Contrary to claims in the specialized
literature, it is shown that the S\'aez-Ballester theory cannot provide a
realistic solution to the dark matter problem of Cosmology for the dust epoch,
without a fine tunning because the contribution of the scalar field in this
theory is equivalent to a stiff fluid (as can be seen from the energy--momentum
tensor for the scalar field), that evolves in a different way as the dust
component. To have similar contributions of the scalar component and the dust
component implies that their past values were fine tunned. So, we
reinterpreting this null result as an indication that dark matter plays a
central role in the formation of structures and galaxy evolution, having
measureable effects in the cosmic microwave bound radiation, and than this
formalism yield to this epoch as primigenius results. We do the mention that
this formalism was used recently in the so called K-essence theory applied to
dark energy problem, in place to the dark matter problem. Also, we include a
quantization procedure of the theory which can be simplified by reinterpreting
the theory in the Einstein frame, where the scalar field can be interpreted as
part of the matter content of the theory, and exact solutions to the
Wheeler-DeWitt equation are found, employing the Bianchi Class A cosmological
models.Comment: 24 pages; ISBN: 978-953-307-626-3, InTec
CUIQ. A theory of planned behavior questionnaire to measure cannabis use intentions amongst European teenagers
info:eu-repo/semantics/publishedVersio
Diversity and distribution of arbuscular mycorrhizal fungi along a land use gradient in Terceira Island (Azores)
More knowledge of community composition of arbuscular mycorrhizal (AM) fungi in ecosystems in relation to habitat type and land use intensity is needed. We studied AMF in 106 soil samples from pristine natural forests and a gradient of disturbance including semi-natural and intensively managed pastures of Terceira, Azores. Altogether, 42 spore morphotypes were detected from eight AMF families, revealing different fungal community structures among the three land use types. Spore density was highest in native forests and lowest in intensively managed pastures, but fungal richness was highest in semi-natural pastures and lowest in native forests. No significant difference occurred between intensively managed pastures and native forests. Members of Acaulosporaceae and Glomeraceae were dominant in native forests, while fungi from Gigasporaceae and Claroideoglomeraceae were most abundant in semi-natural and intensively managed pastures respectively, indicating family-based ecological preferences. Rarefaction analysis revealed that pastures supported more diverse AMF communities than native forests, because in high elevation pristine forests, a few rare species dominate. It is therefore likely that more species would be found with increasing survey effort. Further research is needed to clarify the influence of land use type on AMF diversity and distribution in remote islands, and the role of native AMF on soil ecosystem processes and the spread of exotic plants.This research was funded by Fundo Regional para a Ciência e Tecnologia–Governo dos Açores (M3.1.a/F/059/2016; M3.1.a/F/012/2016) and by the Development Grant (IF/00462/2013) from the Fundação para a Ciência e a Tecnologia (FCT) Portugal with national funds and co-funded by FEDER and COMPETE 2020 program. The Royal Botanic Garden Edinburgh (RBGE) is supported by the Scottish Government’s Rural and Environmental Science and Analytical Services Division.info:eu-repo/semantics/publishedVersio
Protein oxidation in muscle foods: a comprehensive review
Muscle foods and their products are a fundamental part of the human diet. The high protein
content found in muscle foods, as well as the high content of essential amino acids, provides an
appropriate composition to complete the nutritional requirements of humans. However, due to their
special composition, they are susceptible to oxidative degradation. In this sense, proteins are highly
susceptible to oxidative reactions. However, in contrast to lipid oxidation, which has been studied in
depth for decades, protein oxidation of muscle foods has been investigated much less. Moreover,
these reactions have an important influence on the quality of muscle foods, from physico-chemical,
techno-functional, and nutritional perspectives. In this regard, the loss of essential nutrients, the
impairment of texture, water-holding capacity, color and flavor, and the formation of toxic substances
are some of the direct consequences of protein oxidation. The loss of quality for muscle foods results
in consumer rejection and substantial levels of economic losses, and thus the control of oxidative
processes is of vital importance for the food industry. Nonetheless, the complexity of the reactions
involved in protein oxidation and the many different factors that influence these reactions make the
mechanisms of protein oxidation difficult to fully understand. Therefore, the present manuscript
reviews the fundamental mechanisms of protein oxidation, the most important oxidative reactions,
the main factors that influence protein oxidation, and the currently available analytical methods to
quantify compounds derived from protein oxidation reactions. Finally, the main effects of protein
oxidation on the quality of muscle foods, both from physico-chemical and nutritional points of view,
are also discussed.The authors thank GAIN (Axencia Galega de InnovaciĂłn) for supporting this
review (grant number IN607A2019/01). Some authors (R.D., M.P., P.E.S.M., and J.M.L.) are members
of the HealthyMeat network, funded by CYTED (ref. 119RT0568). The research leading to these results
was supported by MICINN supporting the RamĂłn y Cajal grant for M.A. Prieto (RYC-2017-22891); by
Xunta de Galicia for supporting the program EXCELENCIA-ED431F 2020/12; and the pre-doctoral
grants of P. Garcia-Oliveira (ED481A-2019/295) and M. Carpena (ED481A 2021/313). The authors
are grateful to the Ibero-American Program on Science and Technology (CYTED—AQUA-CIBUS,
P317RT0003) and to the Bio Based Industries Joint Undertaking (JU) under grant agreement No 888003
UP4HEALTH Project (H2020-BBI-JTI-2019). The JU receives support from the European Union’s
Horizon 2020 research and innovation program and the Bio Based Industries Consortium. The project
SYSTEMIC Knowledge hub on Nutrition and Food Security has received funding from national
research funding parties in Belgium (FWO), France (INRA), Germany (BLE), Italy (MIPAAF), Latvia
(IZM), Norway (RCN), Portugal (FCT), and Spain (AEI) in a joint action of JPI HDHL, JPI-OCEANS,
and FACCE-JPI launched in 2019 under the ERA-NET ERA-HDHL (n 696295).info:eu-repo/semantics/publishedVersio
Insulin resistance and carotid intima-media thickness mediate the association between resting-state heart rate variability and executive function: A path modelling study
Background: Research has linked high-frequency heart rate variability (HF-HRV) to cognitive function. The present study adopts a modern path modelling approach to understand potential causal pathways that may underpin this relationship. Methods: Here we examine the association between resting-state HF-HRV and executive function in a large sample of civil servants from Brazil (N = 8114) recruited for the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). HF-HRV was calculated from 10-min resting-state electrocardiograms. Executive function was assessed using the trail-making test (version B). Results and conclusions: Insulin resistance (a marker of type 2 diabetes mellitus) and carotid intima-media thickness (subclinical atherosclerosis) mediated the relationship between HRV and executive function in seriatim. A limitation of the present study is its cross-sectional design; therefore, conclusions must be confirmed in longitudinal study. Nevertheless, findings support that possibility that HRV provides a 'spark' that initiates a cascade of adverse downstream effects that subsequently leads to cognitive impairment.Fil: Kemp, Andrew H.. University of Sydney; Australia. Universidade de Sao Paulo; BrasilFil: RodrĂguez LĂłpez, Santiago. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba. Centro de Investigaciones y Estudios sobre Cultura y Sociedad. Universidad Nacional de CĂłrdoba. Centro de Investigaciones y Estudios sobre Cultura y Sociedad; Argentina. University of Sydney; Australia. Universidad AutĂłnoma de Madrid; EspañaFil: Passos, Valeria M. A.. Universidade Federal de Minas Gerais; BrasilFil: Bittencourt, Marcio S.. Universidade de Sao Paulo; BrasilFil: Dantas, Eduardo M.. University of Vale do SĂŁo Francisco; BrasilFil: Mill, JosĂ© G.. Universidade Federal do EspĂrito Santo; BrasilFil: Ribeiro, Antonio L. P.. Universidade Federal de Minas Gerais; BrasilFil: Thayer, Julian F.. Ohio State University; Estados UnidosFil: Bensenor, Isabela M.. Universidade de Sao Paulo; BrasilFil: Lotufo, Paulo A.. Universidade de Sao Paulo; Brasi
Paleoenvironmental implications of authigenic magnesian clay formation sequences in the Barra Velha formation (Santos Basin, Brazil)
The characterization of Mg-clays in rock samples (well P1) from the Barra Velha Formation (Early Cretaceous) allowed the establishment of mineral assemblages on the basis of their kerolite and Mg-smectite (stevensite and saponite) content. Kerolite-rich assemblages (A and B) rarely con-tain saponite. Assemblage B is composed of kerolite-stevensite mixed layers, while assemblage A consists of more than 95% kerolite. Mg-smectite-rich assemblages (C and CB) are made up of both Mg-smectites. The predominance of stevensite in the lower interval of the stratigraphic succession suggests evaporative conditions, higher salinity and pH, which would favor its authigenesis by neoformation. In the upper portion, the occurrence of thick kerolite-rich intervals suggests regular water inputs, contributing with a decreasing in salinity and pH, favoring the neoformation of kero-lite and later kerolite-stevensite mixed layering. The saponite would be the result of the transfor-mation from Al-smectite into Mg-smectite in a Mg2+ rich medium. The results indicate that lake hydrochemical processes would have allowed the establishment of a basic depositional sequence, from base to top, as follows: (i) initial lake expansion stage marked by the occurrence of saponite, (ii) later kerolite neoformation, (iii) formation of kerolite-stevensite mixed layer with increasing sa-linity, and (iv) neoformation of stevensite, marking a final stage of maximum salinity (evaporation) and alkalinity of the lak
Strong coupling of two interacting excitons confined in a nanocavity-quantum-dot system
We present a study of the strong coupling between radiation and matter,
considering a system of two quantum dots, which are in mutual interaction and
interacting with a single mode of light confined in a semiconductor nanocavity.
We take into account dissipative mechanisms such as the escape of the cavity
photons, decay of the quantum dot excitons by spontaneous emission, and
independent exciton pumping. It is shown that the mutual interaction between
the dots can be measured off-resonance, only if the strong coupling condition
is reached. Using the quantum regression theorem, a reasonable definition of
the dynamical coupling regimes is introduced in terms of the complex Rabi
frequency. Finally, the emission spectrum for relevant conditions is presented
and compared with the above definition, demonstrating that the interaction
between the excitons does not affect the Strong Coupling
Marine accidents in the Brazilian Amazon : the problems and challenges in the initiatives for their prevention focused on passenger ships
The Brazilian Amazon is part of one of the largest river systems in the world, in which the transport of cargo and passengers is commonplace. However, several accidents still occur to passenger ships, causing fatalities. Transportation occurs commonly in remote regions, where there are transport inequalities, and emergency assistance is hard to find. This can affect sustainability in communities with considerable levels of economic and social vulnerability. More information is needed about accidents involving inland transport in the Amazon, to identify the threats to ships and propose strategies for accident prevention. This paper addresses the main problems that long-distance passenger ships face in the Brazilian Amazon, presenting an integrated framework towards accident prevention. First, the present situation is characterized in terms of ship description, spatial distribution, and regulations that are applicable. Next, possible causes of passenger ship accidents are discussed, including topics of concern that should be considered in the Amazon waterways. Finally, measures to help minimize passenger ship accidents are proposed, and the social relevance is discussed. It was found that accidents in the Amazon are due to a combination of human and environmental factors. Stakeholders should strengthen the technical and legal training of ship operators. The use of new technologies for navigational aid and necessary maintenance of ships is suggested. Marine accident prevention initiatives should consider local conditions, such as environmental preservation, cultural respect, and difficulties related to navigation through the complex riverine system of the Amazon region
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