613 research outputs found
Interspecific competition underlying mutualistic networks
The architecture of bipartite networks linking two classes of constituents is
affected by the interactions within each class. For the bipartite networks
representing the mutualistic relationship between pollinating animals and
plants, it has been known that their degree distributions are broad but often
deviate from power-law form, more significantly for plants than animals. Here
we consider a model for the evolution of the mutualistic networks and find that
their topology is strongly dependent on the asymmetry and non-linearity of the
preferential selection of mutualistic partners. Real-world mutualistic networks
analyzed in the framework of the model show that a new animal species
determines its partners not only by their attractiveness but also as a result
of the competition with pre-existing animals, which leads to the
stretched-exponential degree distributions of plant species.Comment: 5 pages, 3 figures, accepted version in PR
Influence of Oxygen content on the electrochemical behavior of Ta1-xOx coatings
In this study, Ta1-xOx coatings were deposited by reactive magnetron sputtering aiming at the
enhancement of the electrochemical stability stainless steel 316L. The coatings were produced using
variable oxygen content in order to determine its influence on the films morphological features and corrosion resistance. Structural and morphological characteristics were correlated with the corrosion
behavior in artificial saliva. Potentiodynamic and electrochemical impedance spectroscopy tests were
complemented with X-ray photoelectron spectroscopy to determine the electrochemical behavior of the
coatings. The results reveal a more protective behavior of the coatings as the oxygen amount increases in
the films, as well as pitting inhibition in the coated stainless steel, independently of the
film composition.
A synergetic effect between Ta2O5 and phosphate-based passive layers is suggested as the protective
mechanisms of the coatings; while the more active electrochemical behavior of low oxygen content
films is evidenced as a consequence of the metallic tantalum on the surface with a more open morphology and
larger density of defects on the surface.This research is sponsored by FEDER funds through the program COMPETE – Programa Operacional Factores de Competitividade – by national funds through FCT – Fundação para a Ciência e a Tecnologia , in the framework of the Strategic Projects PEST-C/FIS/UI607/2013, and PEst-C/EME/UI0285/2013, and with a PhD fellowship SFRH/BD/98199/2013.
The authors thank the financial support by IAPMEI funds through QREN – Implantes dentários inteligentes – SMARTDENT, Projeto Vale Inovação n. 2012/24005 and by MCTI/CNPQ N 16/2012 TECNOLOGIAS INOVADORAS NA PRODUÇÃO, PROTOTIPAGEM E/OU AUMENTO DE ESCALA EM NANOTECNOLO-
GIA – Desenvolvimento de Titânio e Liga de Titânio Nano-estruturados com Tratamentos de Superfície para Aplicação em Implantes Ósseos
Coronary Atherosclerosis Phenotypes in Focal and Diffuse Disease.
The interplay between coronary hemodynamics and plaque characteristics remains poorly understood.
The aim of this study was to compare atherosclerotic plaque phenotypes between focal and diffuse coronary artery disease (CAD) defined by coronary hemodynamics.
This multicenter, prospective, single-arm study was conducted in 5 countries. Patients with functionally significant lesions based on an invasive fractional flow reserve ≤0.80 were included. Plaque analysis was performed by using coronary computed tomography angiography and optical coherence tomography. CAD patterns were assessed using motorized fractional flow reserve pullbacks and quantified by pullback pressure gradient (PPG). Focal and diffuse CAD was defined according to the median PPG value.
A total of 117 patients (120 vessels) were included. The median PPG was 0.66 (IQR: 0.54-0.75). According to coronary computed tomography angiography analysis, plaque burden was higher in patients with focal CAD (87% ± 8% focal vs 82% ± 10% diffuse; P = 0.003). Calcifications were significantly more prevalent in patients with diffuse CAD (Agatston score per vessel: 51 [IQR: 11-204] focal vs 158 [IQR: 52-341] diffuse; P = 0.024). According to optical coherence tomography analysis, patients with focal CAD had a significantly higher prevalence of circumferential lipid-rich plaque (37% focal vs 4% diffuse; P = 0.001) and thin-cap fibroatheroma (TCFA) (47% focal vs 10% diffuse; P = 0.002). Focal disease defined by PPG predicted the presence of TCFA with an area under the curve of 0.73 (95% CI: 0.58-0.87).
Atherosclerotic plaque phenotypes associate with intracoronary hemodynamics. Focal CAD had a higher plaque burden and was predominantly lipid-rich with a high prevalence of TCFA, whereas calcifications were more prevalent in diffuse CAD. (Precise Percutaneous Coronary Intervention Plan [P3]; NCT03782688)
Family composition and age at menarche: findings from the international Health Behaviour in School-Aged Children Study
This research was funded by The University of St Andrews and NHS Health Scotland.Background Early menarche has been associated with father absence, stepfather presence and adverse health consequences in later life. This article assesses the association of different family compositions with the age at menarche. Pathways are explored which may explain any association between family characteristics and pubertal timing. Methods Cross-sectional, international data on the age at menarche, family structure and covariates (age, psychosomatic complaints, media consumption, physical activity) were collected from the 2009–2010 Health Behaviour in School-aged Children (HBSC) survey. The sample focuses on 15-year old girls comprising 36,175 individuals across 40 countries in Europe and North America (N = 21,075 for age at menarche). The study examined the association of different family characteristics with age at menarche. Regression and path analyses were applied incorporating multilevel techniques to adjust for the nested nature of data within countries. Results Living with mother (Cohen’s d = .12), father (d = .08), brothers (d = .04) and sisters (d = .06) are independently associated with later age at menarche. Living in a foster home (d = −.16), with ‘someone else’ (d = −.11), stepmother (d = −.10) or stepfather (d = −.06) was associated with earlier menarche. Path models show that up to 89% of these effects can be explained through lifestyle and psychological variables. Conclusions Earlier menarche is reported amongst those with living conditions other than a family consisting of two biological parents. This can partly be explained by girls’ higher Body Mass Index in these families which is a biological determinant of early menarche. Lower physical activity and elevated psychosomatic complaints were also more often found in girls in these family environments.Publisher PDFPeer reviewe
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