4,777 research outputs found
A FLAMINGOS Deep Near Infrared Imaging Survey of the Rosette Complex I: Identification and Distribution of the Embedded Population
We present the results of a deep near-infrared imaging survey of the Rosette
Complex. We studied the distribution of young embedded sources using a
variation of the Nearest Neighbor Method applied to a carefully selected sample
of near-infrared excess (NIRX) stars which trace the latest episode of star
formation in the complex. Our analysis confirmed the existence of seven
clusters previously detected in the molecular cloud, and identified four more
clusters across the complex. We determined that 60% of the young stars in the
complex and 86% of the stars within the molecular cloud are contained in
clusters, implying that the majority of stars in the Rosette formed in embedded
clusters. We compare the sizes, infrared excess fractions and average
extinction towards individual clusters to investigate their early evolution and
expansion. We found that the average infrared excess fraction of clusters
increases as a function of distance from NGC 2244, implying a temporal sequence
of star formation across the complex. This sequence appears to be primordial,
possibly resulting from the formation and evolution of the molecular cloud and
not from the interaction with the HII region.Comment: Accepted by Astrophysical Journa
Sward Structural Characteristics of Perennial Peanut Genotypes as Affected by Harvest Frequency
Despite the high potential of tropical forage species, herbage production, nutritive value and animal productivity in Brazilian livestock production systems are lower than what can be obtained from both a biological and operational point of view (Pedreira and Mello 2000, Da Silva and Sbrissia 2000). Even with these limitations, the livestock industry is often able to sustain high productivity levels (animal product per hectare) by using good animal genetics and supplementation. Reducing production costs, however, will likely depend on the identification and incorporation of a high-quality forage resource, in terms of both improving diet quality of grazing animals and sustaining pasture soil productivity. The search for economically viable and sustainable forage production alternatives has been the subject of a great deal of research in many parts of the world. Among the alternatives explored, the diversification of pastures by the introduction of forage legumes in traditional production systems has been suggested, mainly to improve soil chemical characteristics (increased nitrogen levels) and improve forage quality (Perez 2004, Valentim and Andrade 2004). Promising legume germplasm is available in the tropics, but before these materials are incorporated into commercial systems, they need to be evaluated for adaptation, productivity and persistence in specific micro-environments. In addition, interactions involving grazing management strategies and genotypes should be described and explained, so that their agronomic potential can be explored.
The aim of this study was to characterise sward structure of 4 perennial peanut genotypes subjected to 2 harvest management strategies, in south-eastern Brazil
Collaborative process design for waste management: co-constructing strategies with stakeholders
Funding Information: Thanks are due to all UrbanWINS project partners. Also, the authors acknowledge FCT - Foundation for Science and Technology (Portugal) through the strategic project UIDB/04292/2020 granted to MARE - Marine and Environmental Sciences Centre. And to NOVA School of Science and Technology - NOVA University Lisbon, to several other team members Ana Gomes, Pedro Santos and Mario Ramos Waste@nova team members that collaborate in several activities of the project, as well as to Prof. Joaquim Pina and Prof. Ana Silveira. The UrbanWINS project presented in this paper was funded by the European Union's Horizon 2020 research and innovation program under grant agreement no.690047.Waste management is currently facing multiple challenges worldwide. The population growth in urban areas and related environmental concerns have increased the need to promote urban sustainability, namely where urban waste is a challenge. Thus, research on efficient waste management to reduce resources overload and to develop more sustainable production and consumption is key. Having this in mind, modern society is now seeking for an active voice and to be part of the decision-making processes that directly affect citizens. Citizens need to play an active role on decision-making to co-construct action guidelines, aiming a higher implementation success for an effective and inclusive management of urban waste. In this sense, UrbanWINS project was developed to promote co-construction and implementation of pilot actions involving citizens. In this paper the authors described the framework developed, and reflect critically on the results achieved.publishersversionepub_ahead_of_prin
A simple prescription for simulating and characterizing gravitational arcs
Simple models of gravitational arcs are crucial to simulate large samples of
these objects with full control of the input parameters. These models also
provide crude and automated estimates of the shape and structure of the arcs,
which are necessary when trying to detect and characterize these objects on
massive wide area imaging surveys. We here present and explore the ArcEllipse,
a simple prescription to create objects with shape similar to gravitational
arcs. We also present PaintArcs, which is a code that couples this geometrical
form with a brightness distribution and adds the resulting object to images.
Finally, we introduce ArcFitting, which is a tool that fits ArcEllipses to
images of real gravitational arcs. We validate this fitting technique using
simulated arcs and apply it to CFHTLS and HST images of tangential arcs around
clusters of galaxies. Our simple ArcEllipse model for the arc, associated to a
S\'ersic profile for the source, recovers the total signal in real images
typically within 10%-30%. The ArcEllipse+S\'ersic models also automatically
recover visual estimates of length-to-width ratios of real arcs. Residual maps
between data and model images reveal the incidence of arc substructure. They
may thus be used as a diagnostic for arcs formed by the merging of multiple
images. The incidence of these substructures is the main factor preventing
ArcEllipse models from accurately describing real lensed systems.Comment: 12 pages, 11 figures, accepted for publication in A&
(Oligo)thienyl-imidazo-benzocrown ether derivatives : synthesis, photophysical studies and evaluation of their chemosensory properties
A series of novel (oligo)thienyl-imidazobenzocrown ethers were synthesised through a simple method and evaluated as fluorimetric chemosensors for transition metal cations. Interaction with Ni2+, Pd2+, and Hg2+ in ACN/DMSO solution (99:1) was studied by absorption and emission spectroscopy. Chemoselectivity studies in the presence of Na+ were also carried out and a fluorescence enhancement upon chelation (CHEF) effect was observed following Hg2+ complexation. Considering that most systems using fluorescence spectroscopy for detecting Hg2+ are based on the complexation enhancement of the fluorescence quenching (CHEQ) effect, the present work represents one of the few examples for sensing of Hg2+ based on a CHEF effect.Fundação para a Ciência e a Tecnologia (FCT) - PTDC/QUI/66250/2006, SFRH/BD/36396/2007, SRFH/BPD/72557/201
Sodium intake and metabolic syndrome: a systematic review
Estudos recentes mostram que restrições na ingestão de sódio podem aumentar a resistência à insulina (RI) e induzir alterações nas lipoproteínas séricas e em marcadores de inflamação semelhantes às encontradas na síndrome metabólica (SM). Realizou-se uma revisão sistemática da literatura sobre os efeitos da restrição do consumo de sódio sobre a SM ou a RI. Nove artigos foram incluídos na revisão. A restrição no consumo de sódio associou-se ao aumento da RI em dois artigos e a diminuição em três outros. Em sete dos nove artigos, a restrição na ingestão de sal determinou redução da pressão arterial e em dois artigos ocorreram efeitos adversos em marcadores da SM. A maioria dos estudos mostrou efeitos benéficos da restrição moderada de sódio da dieta associados ou não a outras modificações nutricionais ou ao aumento da atividade física. Novos estudos são necessários para avaliar os efeitos de reduções moderadas no consumo de sódio sobre a SM e a RI.Recent studies have shown that sodium intake restrictions may increase insulin resistance (IR) and induce changes on serum lipoproteins and on inflammation markers that are similar to those found in metabolic syndrome (MS). We performed a systematic review of literature regarding the effects of restricting sodium intake on MS or on IR. Nine articles were included in the review. Restriction of sodium consumption was associated with increase insulin resistance in two articles and with decrease in three others. In seven of nine articles, salt intake restriction determined blood pressure reduction, and in two articles adverse effects on markers of MS were found. Most studies showed beneficial effects of moderate sodium intake restriction, associated or not to others nutritional modifications or increased physical activity. Further studies are needed to evaluate the effects of moderate sodium consumption reductions on MS and IR
Theoretical priors in scalar-tensor cosmologies: Shift-symmetric Horndeski models
Attempts at constraining theories of late time accelerated expansion often
assume broad priors for the parameters in their phenomenological description.
Focusing on shift-symmetric scalar-tensor theories with standard gravitational
wave speed, we show how a more careful analysis of their dynamical evolution
leads to much narrower priors. In doing so, we propose a simple and accurate
parametrisation of these theories, capturing the redshift dependence of the
equation of state, , and the kinetic braiding parameter, , with only two parameters each, and derive their statistical
distribution (a.k.a. theoretical priors) that fit the cosmology of the
underlying model. We have considered two versions of the shift-symmetric model,
one where the energy density of dark energy is given solely by the scalar
field, and another where it also has a contribution from the cosmological
constant. By including current data, we show how theoretical priors can be used
to improve constraints by up to an order of magnitude. Moreover, we show that
shift-symmetric theories without a cosmological constant are observationally
viable. We work up to quartic order in first derivatives of the scalar in the
action and our results suggest this truncation is a good approximation to more
general shift-symmetric theories. This work establishes an actionable link
between phenomenological parameterisations and Lagrangian-based theories, the
two main approaches to test cosmological gravity and cosmic acceleration.Comment: 18 pages, 13 figures; Version as accepted in PRD - minor changes
Efficient green-emitting Tb3+-doped di-ureasil coating phosphors for near-UV excited light-emitting diodes
Light-emitting diodes (LEDs) are replacing conventional lighting sources, like incandescent and fluorescent lamps, due to their higher efficiency, lower energy consumption and environmental friendliness characteristics. Additional applications envisaging “engineered light” able to control the human circadian rhythm are now in place with emphases on green-emitting LEDs. In this work, transparent and flexible coatings based on organic–inorganic di-ureasil hybrids doped in-situ with a terbium (Tb3+) complex involving salicylic acid as ligands were synthesized. The materials are transparent, essentially amorphous and thermal stable up to 180 °C. Under near-UV excitation, bright green emission with high quantum yield (0.565 ± 0.057) and enhanced photostability are observed. Green-emitting prototypes were fabricated using a commercial near-UV-emitting LED (NUV-LED) combined with the Tb3+-doped di-ureasil coating showing narrow-band green emission with yellowish-green color coordinates (Commission Internationale de l'Éclairage, CIE 1931) of (0.329, 0.606) and high luminous efficacy (21.5 lm/W). This efficacy is the largest one reported for analogous prototypes formed by an NUV-LED coated with a green-emitting phosphor prepared under mild synthetic conditions (<100 °C), demonstrating that in-situ formation of carboxylate lanthanide-based complexes is an energy saving process with potential for solid-state lighting and backlight for flexible displays.publishe
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