498 research outputs found
Spectral characterization of families of split graphs
An upper bound for the sum of the squares of the entries of the principal eigenvector corresponding to a vertex subset inducing a k-regular subgraph is introduced and applied to the determination of an upper bound on the order of such induced subgraphs. Furthermore, for some connected graphs we establish a lower bound for the sum of squares of the entries of the principal eigenvector corresponding to the vertices of an independent set. Moreover, a spectral characterization of families of split
graphs, involving its index and the entries of the principal eigenvector corresponding
to the vertices of the maximum independent set is given. In particular, the complete
split graph case is highlighted
Relations between (κ, τ)-regular sets and star complements
Let G be a finite graph with an eigenvalue μ of multiplicity m. A set X of m vertices in G is called a star set for μ in G if μ is not an eigenvalue of the star complement G\X which is the subgraph of G induced by vertices not in X. A vertex subset of a graph
is (k ,t)-regular if it induces a k -regular subgraph and every vertex not in the subset has t neighbors in it. We investigate the graphs having a (k,t)-regular set which induces a star complement for some eigenvalue. A survey of known results is provided and new properties for these graphs are deduced. Several particular graphs where these properties stand out are presented as examples
Persistence and Variation in the Distribution of Bottom-trawl Fish Assemblages over the Flemish Cap
The aim of this study is to test the variability of the assemblages defined in the Flemish Cap area.
Data from 951 bottom hauls were analysed, covering depths between 126 and 740 m in the years
1995–2002. The fish fauna in Flemish Cap appears distributed in a persistent structural zonation
defined in three assemblages. The first three factors of a Principal Component Analysis explained
the 78.4% of the variance in distribution species, and they are consistent with the results of a cluster
analysis. The three characteristic assemblages show a temporal persistence, but some changes appear
in this period, for instance: displacements of the assemblages limits towards shallower waters, and
some changes in relative position of the dominant species in each assemblage. These changes can be
related with the constant decrease of the biomass of the main demersal fish species like Atlantic cod
and American plaice. The species of Genus Sebastes appear as dominant fish species in the area
Missing energy in black hole production and decay at the Large Hadron Collider
Black holes could be produced at the Large Hadron Collider in TeV-scale
gravity scenarios. We discuss missing energy mechanisms in black hole
production and decay in large extra-dimensional models. In particular, we
examine how graviton emission into the bulk could give the black hole enough
recoil to leave the brane. Such a perturbation would cause an abrupt
termination in Hawking emission and result in large missing-energy signatures.Comment: addressed reviewer comments and updated reference
Adherence to the planetary health diet index and obesity indicators in the Brazilian longitudinal study of adult health (ELSA-Brasil)
The EAT-Lancet Commission has proposed a model diet to improve the health of human beings and that of the planet. Recently, we proposed the Planetary Health Diet Index (PHDI) to assess adherence of the population to this model diet. In this study, we aimed to evaluate adherence to the PHDI and obesity outcomes using baseline data from 14, 515 participants in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). The dietary data were assessed using a 114-item FFQ. Body mass index (BMI) and waist circumference (WC) were both used continuously and cat-egorized. Linear and multinomial regression models adjusted for potential confounding factors were performed to assess the relationship between adherence to PHDI and outcomes. An inverse association was observed between adherence to PHDI and obesity indicators. Individuals with high adherence to the PHDI had lower BMI (ß-0.50 95% CI-0.73:-0.27) and WC (ß-1.70 95% CI-2.28:-1.12) values. They were also 24% less likely to be overweight (OR 0.76 95% CI 0.67:0.85) or obese (OR 0.76 95% CI 0.65:0.88), and they were 14% and 27% less likely to have increased WC (OR 0.86 95% CI 0.75:0.98) or substantially increased WC (OR 0.73 95% CI 0.64:0.83) than those with lower adherence. Our results showed that higher adherence to the PHDI may decrease obesity in-dicators. © 2021 by the authors. Licensee MDPI, Basel, Switzerland
Tributyltin in crustacean tissues: Analytical performance and validation of method
The hermit crab Clibanarius vittatus is a typical organism from intertidal regions being considered as a good bioindicator of tributyltin presence at these environments. Thus this study presents the analytical performance and validation method for TBT quantification in tissues of C. vittatus by gas chromatography with pulsed flame photometric detector (GC-PFPD) after extraction with an apolar solvent (toluene) and Grignard derivatization. The limits of detection of the method (LOD) were 2.0 and 2.8 ng g -1 for TBT and DBT (dibutyltin), respectively, and its limits of quantification (LOQ) were 6.6 and 8.9 ng g-1 for TBT and DBT, respectively. The method was applied to samples from Santos Estuary, São Paulo State, Brazil. TBT and DBT concentrations ranged from 26.7 to 175.0 ng g -1 and from 46.2 to 156.0 ng g -1, respectively. These concentrations are worrisome since toxic effects (such as endocrine disruption) have been reported for other organisms even under lower levels of registred at this study. © 2012 Sociedade Brasileira de Química
Scalar Synchrotron Radiation in the Schwarzschild-anti-de Sitter Geometry
We present a complete relativistic analysis for the scalar radiation emitted
by a particle in circular orbit around a Schwarzschild-anti-de Sitter black
hole. If the black hole is large, then the radiation is concentrated in narrow
angles- high multipolar distribution- i.e., the radiation is synchrotronic.
However, small black holes exhibit a totally different behavior: in the small
black hole regime, the radiation is concentrated in low multipoles. There is a
transition mass at , where is the AdS radius. This behavior is
new, it is not present in asymptotically flat spacetimes.Comment: 13 pages, 6 figures, published version. References adde
Androgens and low density lipoprotein-cholesterol interplay in modulating prostate cancer cell fate and metabolism
Background: Androgens, the known drivers of prostate cancer (PCa), have been indicated as important metabolic regulators with a relevant role in stimulating lipid metabolism. Also, the relationship between obesity and the aggressiveness of PCa has been established. However, it is unknown if the androgenic hormonal environment may alter the response of PCa cells to lipid availability. Purpose: The present study evaluated the effect of 5 alpha-dihydrotestosterone (DHT) in regulating lipid metabolism, and the interplay between this hormone and low-density lipoprotein (LDL)-cholesterol in modulating PCa cells fate.Methods: Non-neoplastic and neoplastic PCa cells were treated with 10 nM DHT, and the expression of fatty acids transporter, fatty acid synthase (FASN), and carnitine palmitoyltransferase 1A (CPT1A) evaluated. PCa cells were also exposed to LDL (100 mu g/ml) in the presence or absence of DHT.Results: Treatment with DHT upregulated the expression of FASN and CPT1A in androgen-sensitive PCa cells. In contrast, LDL supplementation suppressed FASN expression regardless of the presence of DHT, whereas aug-menting CPT1A levels. Our results also showed that LDL-cholesterol increased PCa cells viability, proliferation, and migration dependently on the presence of DHT. Moreover, LDL and DHT synergistically enhanced the accumulation of lipid droplets in PCa cells.Conclusions: The obtained results show that androgens deregulate lipid metabolism and enhance the effects of LDL increasing PCa cells viability, proliferation and migration. The present findings support clinical data linking obesity with PCa and first implicate androgens in this relationship. Also, they sustain the application of phar-macological approaches targeting cholesterol availability and androgens signaling simultaneously.info:eu-repo/semantics/publishedVersio
Signatures of black holes at the LHC
Signatures of black hole events at CERN's Large Hadron Collider are
discussed. Event simulations are carried out with the Fortran Monte Carlo
generator CATFISH. Inelasticity effects, exact field emissivities, color and
charge conservation, corrections to semiclassical black hole evaporation,
gravitational energy loss at formation and possibility of a black hole remnant
are included in the analysis.Comment: 13 pages, 7 figure
Regularisation Techniques for the Radiative Corrections of Wilson lines and Kaluza-Klein states
Within an effective field theory framework we compute the most general
structure of the one-loop corrections to the 4D gauge couplings in one- and
two-dimensional orbifold compactifications with non-vanishing constant gauge
background (Wilson lines). Although such models are non-renormalisable, we keep
the analysis general by considering the one-loop corrections in three
regularisation schemes: dimensional regularisation (DR), Zeta-function
regularisation (ZR) and proper-time cut-off regularisation (PT). The relations
among the results obtained in these schemes are carefully addressed. With
minimal re-definitions of the parameters involved, the results obtained for the
radiative corrections can be applied to most orbifold compactifications with
one or two compact dimensions. The link with string theory is discussed. We
mention a possible implication for the gauge couplings unification in such
models.Comment: 37 pages, 1 Figure, LaTeX; minor correction
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