826 research outputs found
Medicago spp. as potential sources of bioactive isoflavones: Characterization according to phylogenetic and phenologic factors
A high variety of plant species are often proposed as potential natural sources of specific bioactive components, with emphasis in phenolic compounds. However, the ability to produce a determined phytochemical might be variable, even among species with close phylogeny. Furthermore, the metabolic dynamics vary greatly according to phenologic factors. Herein, it was verified whether isoflavone production in Medicago spp. is more associated with phylogenetic or phenologic determinants, to define the optimal productive conditions. Isoflavone profiles were characterized in field-grown Medicago species in three phenologic stages. Isoflavones were extracted by matrix solid-phase dispersion method and analyzed using high-performance liquid chromatography coupled with a diode-array detector. The obtained data were evaluated by a generalized linear model (GLM) and linear discriminant analysis (LDA). Formononetin, genistein and irilone were the most abundant isoflavones, reaching values higher than those present in acknowledged plant sources like soy or red clover. Outputs from GLM and LDA indicate that the phylogenetic factors are the most defining criteria. This study promotes Medicago spp. as potential isoflavone sources, particularly because the effects of these compounds are highly dependent on their type and concentration, with potential application as foodstuff, feedstuff, or in the nutraceutical and pharmaceutica l industry.Visnevschi-Necrasov and João C.M. Barreira are grateful to ‘‘FCT
– Fundação para a Ciência e a Tecnologia’’ for their Grants
(SFRH/BD/31734/2006 and SFRH/BPD/72802/2010, respectively).
S.C. Cunha is grateful to ‘‘POPH-QREN – Tipologia 4.2, Fundo
Social Europeu e Fundo Nacional MCTES’’.info:eu-repo/semantics/publishedVersio
Phylogenetic insights on the isoflavone profile variations in Fabaceae spp.: Assessment through PCA and LDA
Legumes (Fabaceae) are important crops, known as sources of food, feed for livestock and raw materials for industry. Their ability to capture atmospheric nitrogen during symbiotic processes with soil bacteria reduces the need for expensive chemical fertilizers, improving soil and water quality. Several Fabaceae species are acknowledged for the high levels of secondary metabolites. Isoflavones are among the most well-known examples of these compounds, being recognized for their several types of biological activity. Herein, isoflavone profiles were characterized in nine species of four Fabaceae genera (Biserrula, Lotus, Ornithopus and Scorpiurus). Plants were harvested in the late flower physiological stage to prevent biased results due to naturally occurring variations along the vegetative cycle. Isoflavones were extracted using matrix solid-phase dispersion and analyzed by high performance liquid chromatography/diode-array detection. The detected profiles revealed significant differences, inclusively among species belonging to the same genus, indicating that other factors besides the genotypic features contribute to the expression of these phenolic compounds. The classification of the results by principal component analysis placed species belonging to the same genus in different clustering groups, proving this latter assumption. However, the detected profiles proved to be characteristic of the assayed, as it was proved by the applied linear discriminant analysis.info:eu-repo/semantics/publishedVersio
Spin evolution of Earth-sized exoplanets, including atmospheric tides and core-mantle friction
Planets with masses between 0.1 and 10M(circle plus) are believed to host dense atmospheres. These atmospheres can play an important role on the planet's spin evolution, since thermal atmospheric tides, driven by the host star, may counterbalance gravitational tides. In this work, we study the long-term spin evolution of Earth-sized exoplanets. We generalize previous works by including the effect of eccentric orbits and obliquity. We show that under the effect of tides and core-mantle friction, the obliquity of the planets evolves either to 0 degrees or 180 degrees. The rotation of these planets is also expected to evolve into a very restricted number of equilibrium configurations. In general, none of these equilibria is synchronous with the orbital mean motion. The role of thermal atmospheric tides becomes more important for Earth-sized planets in the habitable zones of their systems; so they cannot be neglected when we search for their potential habitability
Advances in isoflavone profile characterisation using matrix solid-phase dispersion coupled to HPLC/DAD in medicago species
Analytical methods used in phytochemistry analysis are limited by the sample preparation step, which should ideally be fast, accurate, ecofriendly and achievable using low quantities of the sample. Matrix solid-phase dispersion (MSPD) may be a good alternative for combining extraction and purification procedures, thereby reducing the indicated limitations. Objective-Applying an MSPD extraction procedure coupled to high-performance liquid chromatography diode-array detection (HPLC/DAD) as an alternative methodology to evaluate isoflavone profiles. Methods-Isoflavone profiles were determined for the leaves of nine species of Medicago in the late flower phenological stage (one or more nodes with 50% open flowers, no seed pods). Extraction was performed following MSPD, and isoflavone profiles were characterised using HPLC/DAD. The quantified amounts were compared with previous results in different species commonly recognised as good sources of isoflavones. Results-Formononetin was the major isoflavone in most species, except M. polymorpha and M. truncatula. The isoflavone amounts were significantly different among the assayed species, with M. orbicularis and M. arabica as the major isoflavone sources, while M. rigidula presented the lowest contents. Furthermore, the detected differences allow electing the best species as a primary source of a specific isoflavone. Conclusion-The MSPD allowed good extraction efficiency, reproducibility and recovery. Some of the species showed relevant isoflavone contents, even when compared with acknowledged plant sources such as soy or red clover. To the best of our knowledge the results presented are reported for the first time in these species.T. Visnevschi-Necrasov and João C.M. Barreira are grateful to ‘FCT -
Fundação para a Ciência e a Tecnologia’ for their grants (BD/
31734/2006 and SFRH/BPD/72802/2010, respectively). S.C. Cunha
is grateful to ‘POPH-QREN - Tipologia 4.2, Fundo Social Europeu
e Fundo Nacional MCTES’.info:eu-repo/semantics/publishedVersio
De Sitter Gravity and Liouville Theory
We show that the spectrum of conical defects in three-dimensional de Sitter
space is in one-to-one correspondence with the spectrum of vertex operators in
Liouville conformal field theory. The classical conformal dimensions of vertex
operators are equal to the masses of the classical point particles in dS_3 that
cause the conical defect. The quantum dimensions instead are shown to coincide
with the mass of the Kerr-dS_3 solution computed with the Brown-York stress
tensor. Therefore classical de Sitter gravity encodes the quantum properties of
Liouville theory. The equality of the gravitational and the Liouville stress
tensor provides a further check of this correspondence. The Seiberg bound for
vertex operators translates on the bulk side into an upper mass bound for
classical point particles. Bulk solutions with cosmological event horizons
correspond to microscopic Liouville states, whereas those without horizons
correspond to macroscopic (normalizable) states. We also comment on recent
criticism by Dyson, Lindesay and Susskind, and point out that the
contradictions found by these authors may be resolved if the dual CFT is not
able to capture the thermal nature of de Sitter space. Indeed we find that on
the CFT side, de Sitter entropy is merely Liouville momentum, and thus has no
statistical interpretation in this approach.Comment: 22 pages, LateX2e; added references for section 1 and section 2;
corrected typos; improved discussion in section
Cardy-Verlinde Formula and Achucarro-Ortiz Black Hole
In this paper it is shown that the entropy of the black hole horizon in the
Achucarro-Ortiz spacetime, which is the most general two-dimensional black hole
derived from the three-dimensional rotating BTZ black hole, can be described by
the Cardy-Verlinde formula. The latter is supposed to be an entropy formula of
conformal field theory in any dimension.Comment: 10 pages, LaTeX, v2: minor changes, references added, to appear in
Phys. Rev.
Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector
A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results
Measurement of D*+/- meson production in jets from pp collisions at sqrt(s) = 7 TeV with the ATLAS detector
This paper reports a measurement of D*+/- meson production in jets from
proton-proton collisions at a center-of-mass energy of sqrt(s) = 7 TeV at the
CERN Large Hadron Collider. The measurement is based on a data sample recorded
with the ATLAS detector with an integrated luminosity of 0.30 pb^-1 for jets
with transverse momentum between 25 and 70 GeV in the pseudorapidity range
|eta| < 2.5. D*+/- mesons found in jets are fully reconstructed in the decay
chain: D*+ -> D0pi+, D0 -> K-pi+, and its charge conjugate. The production rate
is found to be N(D*+/-)/N(jet) = 0.025 +/- 0.001(stat.) +/- 0.004(syst.) for
D*+/- mesons that carry a fraction z of the jet momentum in the range 0.3 < z <
1. Monte Carlo predictions fail to describe the data at small values of z, and
this is most marked at low jet transverse momentum.Comment: 10 pages plus author list (22 pages total), 5 figures, 1 table,
matches published version in Physical Review
The Milky Way Bulge: Observed properties and a comparison to external galaxies
The Milky Way bulge offers a unique opportunity to investigate in detail the
role that different processes such as dynamical instabilities, hierarchical
merging, and dissipational collapse may have played in the history of the
Galaxy formation and evolution based on its resolved stellar population
properties. Large observation programmes and surveys of the bulge are providing
for the first time a look into the global view of the Milky Way bulge that can
be compared with the bulges of other galaxies, and be used as a template for
detailed comparison with models. The Milky Way has been shown to have a
box/peanut (B/P) bulge and recent evidence seems to suggest the presence of an
additional spheroidal component. In this review we summarise the global
chemical abundances, kinematics and structural properties that allow us to
disentangle these multiple components and provide constraints to understand
their origin. The investigation of both detailed and global properties of the
bulge now provide us with the opportunity to characterise the bulge as observed
in models, and to place the mixed component bulge scenario in the general
context of external galaxies. When writing this review, we considered the
perspectives of researchers working with the Milky Way and researchers working
with external galaxies. It is an attempt to approach both communities for a
fruitful exchange of ideas.Comment: Review article to appear in "Galactic Bulges", Editors: Laurikainen
E., Peletier R., Gadotti D., Springer Publishing. 36 pages, 10 figure
Search for supersymmetry in final states with jets, missing transverse momentum and one isolated lepton in sqrt{s} = 7 TeV pp collisions using 1 fb-1 of ATLAS data
We present an update of a search for supersymmetry in final states containing
jets, missing transverse momentum, and one isolated electron or muon, using
1.04 fb^-1 of proton-proton collision data at sqrt{s} = 7 TeV recorded by the
ATLAS experiment at the LHC in the first half of 2011. The analysis is carried
out in four distinct signal regions with either three or four jets and
variations on the (missing) transverse momentum cuts, resulting in optimized
limits for various supersymmetry models. No excess above the standard model
background expectation is observed. Limits are set on the visible cross-section
of new physics within the kinematic requirements of the search. The results are
interpreted as limits on the parameters of the minimal supergravity framework,
limits on cross-sections of simplified models with specific squark and gluino
decay modes, and limits on parameters of a model with bilinear R-parity
violation.Comment: 18 pages plus author list (30 pages total), 9 figures, 4 tables,
final version to appear in Physical Review
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