500 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
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 â€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)
Scaling of nestedness in complex networks
Nestedness characterizes the linkage pattern of networked systems, indicating
the likelihood that a node is linked to the nodes linked to the nodes with
larger degrees than it. Networks of mutualistic relationship between distinct
groups of species in ecological communities exhibit such nestedness, which is
known to support the network robustness. Despite such importance, quantitative
characteristics of nestedness is little understood. Here we take
graph-theoretic approach to derive the scaling properties of nestedness in
various model networks. Our results show how the heterogeneous connectivity
patterns enhance nestedness. Also we find that the nestedness of bipartite
networks depend sensitively on the fraction of different types of nodes,
causing nestedness to scale differently for nodes of different types.Comment: 9 pages, 4 figures, final versio
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 2009â2010 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 (Nâ=â21,075 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 (Cohenâs dâ=â.12), father (dâ=â.08), brothers (dâ=â.04) and sisters (dâ=â.06) are independently associated with later age at menarche. Living in a foster home (dâ=ââ.16), with âsomeone elseâ (dâ=ââ.11), stepmother (dâ=ââ.10) or stepfather (dâ=ââ.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 girlsâ 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
Impacts of Snow Darkening by Absorbing Aerosols on Eurasian Climate
The deposition of absorbing aerosols on snow surfaces reduces snow-albedo and allows snowpack to absorb more sunlight. This so-called snow darkening effect (SDE) accelerates snow melting and leads to surface warming in spring. To examine the impact of SDE on weather and climate during late spring and early summer, two sets of NASA GEOS-5 model simulations with and without SDE are conducted. Results show that SDE-induced surface heating is particularly pronounced in Eurasian regions where significant depositions of dust transported from the North African deserts, and black carbon from biomass burning from Asia and Europe occur. In these regions, the surface heating due to SDE increases surface skin temperature by 3-6 degrees Kelvin near the snowline in spring. Surface energy budget analysis indicates that SDE-induced excess heating is associated with a large increase in surface evaporation, subsequently leading to a significant reduction in soil moisture, and increased risks of drought and heat waves in late spring to early summer. Overall, we find that rainfall deficit combined with SDE-induced dry soil in spring provide favorable condition for summertime heat waves over large regions of Eurasia. Increased frequency of summer heat waves with SDE and the region of maximum increase in heat-wave frequency are found along the snow line, providing evidence that early snowmelt by SDE may increase the risks of extreme summer heat wave. Our results suggest that climate models that do not include SDE may significantly underestimate the effect of global warming over extra-tropical continental regions
Comparison of Acute Versus Subacute Coronary Angiography in Patients With NON-ST-Elevation Myocardial Infarction (from the NONSTEMI Trial)
Overexpression of SPARC gene in human gastric carcinoma and its clinicâpathologic significance
Vault changes after cyclopentolate instillation in eyes with posterior chamber phakic intraocular lens
Posterior chamber phakic intraocular lens (pIOL) implantation is a common option for correcting moderate-to-high ocular refractive defects. Because this pIOL is implanted on ciliary sulcus, the distance between the back surface of the pIOL and the anterior surface of the crystalline lens, that it is known as vault, should be measured in different conditions to ensure the technique's safety. Cyclopentolate is a drug that dilates the pupil and relaxes accommodation (cycloplegia). It is often used for different ocular examinations and for other medical purposes. However, there is no evidence of the effect of this drug on vault. This study quantified central vault changes associated with cyclopentolate instillation. We measured the vault under normal conditions (pre-cycloplegic instillation) and after instilling cyclopentolate on 39 eyes of 39 patients with implanted pIOL. Our results suggest that cyclopentolate instillation may induce changes to vault in eyes with implanted pIOL. These changes seem safe and are mainly associated with vault under normal conditions, but also with anterior chamber depth, pupillary diameter and pIOL size.- European Fund for Regional Development (FEDER) through the COMPETE Program and the Portuguese Foundation for Science and Technology (FCT) provided financial support in the framework of projects PTDC/SAU-BEB/098391/2008, PTDC/SAU-BEB/098392/2008 and the Strategic Project PEST-C/FIS/UI607/2011
Observation of Mott Transition in VO_2 Based Transistors
An abrupt Mott metal-insulator transition (MIT) rather than the continuous
Hubbard MIT near a critical on-site Coulomb energy U/U_c=1 is observed for the
first time in VO_2, a strongly correlated material, by inducing holes of about
0.018% into the conduction band. As a result, a discontinuous jump of the
density of states on the Fermi surface is observed and inhomogeneity inevitably
occurs. The gate effect in fabricated transistors is clear evidence that the
abrupt MIT is induced by the excitation of holes.Comment: 4 pages, 4 figure
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