3,466 research outputs found

    Complementary effects of species abundances and ecological neighborhood on the occurrence of fruit-frugivore interactions

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    Species interactions are traditionally seen as the outcome of both ecological and evolutionary mechanisms. Among them, the two most frequently studied are the neutral role of species abundances in determining encounter probability and the deterministic role of species identity (traits and evolutionary history) in determining the compatibility of interacting species. Nevertheless, the occurrence of pairwise interactions also depends on the spatio-temporal context imposed by the ecological neighborhood (i.e., the indirect effect of other local species sharing traits and interaction potential with the focal ones). Although a few studies have begun to examine neighborhood effects on community interactions, these have not incorporated neighborhood structure as a complementary driver of pairwise interactions within an integrative approach. Here we describe the spatial structure of pairwise interactions between three fleshy-fruited tree species and six frugivorous thrush species within the same locality of the Cantabrian Range (Iberian Peninsula). Using a spatio-temporally fine-grained dataset sampled during 3 years, we aimed to detect spatial patterns of interactions and to evaluate their concordance across years. We also evaluated the simultaneous roles played by species abundance, species identity and the ecological neighborhood in determining the pairwise interaction frequencies based on fruit removal. Our results showed that the abundances of fruit and bird species involved in plant-frugivore interactions, and the spatial patterns of these interactions, varied among years, and this was mainly due to different fruiting landscapes responding to masting events of distinct plant species. Despite high interannual differences in species abundances and pairwise interaction frequencies, the main mechanisms underpinning the occurrence of pairwise interactions remained constant. Most of the variability in pairwise interactions was always explained by interacting fruit and bird species' abundances. Ecological neighborhood, characterized as the net quantity of forest cover, heterospecific fruit crops, and heterospecific bird abundances in the immediate surroundings, also affected pairwise interaction frequency through its indirect effects on the abundance of interacting bird species. Our results highlight the prevalence of neutral forces in highly generalized plant-frugivore assemblages as well as the influence of indirect interactions (competition and/or facilitation with other local species) as another important driver to consider when predicting pairwise interactions

    Novel Bayesian Networks for Genomic Prediction of Developmental Traits in Biomass Sorghum.

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    The ability to connect genetic information between traits over time allow Bayesian networks to offer a powerful probabilistic framework to construct genomic prediction models. In this study, we phenotyped a diversity panel of 869 biomass sorghum (Sorghum bicolor (L.) Moench) lines, which had been genotyped with 100,435 SNP markers, for plant height (PH) with biweekly measurements from 30 to 120 days after planting (DAP) and for end-of-season dry biomass yield (DBY) in four environments. We evaluated five genomic prediction models: Bayesian network (BN), Pleiotropic Bayesian network (PBN), Dynamic Bayesian network (DBN), multi-trait GBLUP (MTr-GBLUP), and multi-time GBLUP (MTi-GBLUP) models. In fivefold cross-validation, prediction accuracies ranged from 0.46 (PBN) to 0.49 (MTr-GBLUP) for DBY and from 0.47 (DBN, DAP120) to 0.75 (MTi-GBLUP, DAP60) for PH. Forward-chaining cross-validation further improved prediction accuracies of the DBN, MTi-GBLUP and MTr-GBLUP models for PH (training slice: 30-45 DAP) by 36.4-52.4% relative to the BN and PBN models. Coincidence indices (target: biomass, secondary: PH) and a coincidence index based on lines (PH time series) showed that the ranking of lines by PH changed minimally after 45 DAP. These results suggest a two-level indirect selection method for PH at harvest (first-level target trait) and DBY (second-level target trait) could be conducted earlier in the season based on ranking of lines by PH at 45 DAP (secondary trait). With the advance of high-throughput phenotyping technologies, our proposed two-level indirect selection framework could be valuable for enhancing genetic gain per unit of time when selecting on developmental traits

    Surface topography of hydroxyapatite affects ROS17/2.8 cells response

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    Hydroxyapatite (HA) has been used in orthopedic, dental, and maxillofacial surgery as a bone substitute. The aim of this investigation was to study the effect of surface topography produced by the presence of microporosity on cell response, evaluating: cell attachment, cell morphology, cell proliferation, total protein content, and alkaline phosphatase (ALP) activity. HA discs with different percentages of microporosity (< 5%, 15%, and 30%) were confected by means of the combination of uniaxial powder pressing and different sintering conditions. ROS17/2.8 cells were cultured on HA discs. For the evaluation of attachment, cells were cultured for two hours. Cell morphology was evaluated after seven days. After seven and fourteen days, cell proliferation, total protein content, and ALP activity were measured. Data were compared by means of ANOVA and Duncan’s multiple range test, when appropriate. Cell attachment (p = 0.11) and total protein content (p = 0.31) were not affected by surface topography. Proliferation after 7 and 14 days (p = 0.0007 and p = 0.003, respectively), and ALP activity (p = 0.0007) were both significantly decreased by the most irregular surface (HA30). These results suggest that initial cell events were not affected by surface topography, while surfaces with more regular topography, as those present in HA with 15% or less of microporosity, favored intermediary and final events such as cell proliferation and ALP activity

    Impact of inhaled corticosteroids on growth in children with asthma: systematic review and meta-analysis

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    Background: Long-term inhaled corticosteroids (ICS) may reduce growth velocity and final height of children with asthma. We aimed to evaluate the association between ICS use of >12 months and growth. Methods: We initially searched MEDLINE and EMBASE in July 2013, followed by a PubMed search updated to December 2014. We selected RCTs and controlled observational studies of ICS use in patients with asthma. We conducted random effects meta-analysis of mean differences in growth velocity (cm/year) or final height (cm) between groups. Heterogeneity was assessed using the I2 statistic. Results: We found 23 relevant studies (twenty RCTs and three observational studies) after screening 1882 hits. Meta-analysis of 16 RCTs showed that ICS use significantly reduced growth velocity at one year follow-up (mean difference -0.48 cm/year (95% CI -0.66 to -0.29)). There was evidence of a dose-response effect in three RCTs. Final adult height showed a mean reduction of -1.20 cm (95% CI -1.90 cm to -0.50 cm) with budesonide versus placebo in a high quality RCT. Meta-analysis of two lower quality observational studies revealed uncertainty in the association between ICS use and final adult height, pooled mean difference -0.85 cm (95% CI -3.35 to 1.65). Conclusion: Use of ICS for >12 months in children with asthma has a limited impact on annual growth velocity. In ICS users, there is a slight reduction of about a centimeter in final adult height, which when interpreted in the context of average adult height in England (175 cm for men and 161 cm for women), represents a 0.7% reduction compared to non-ICS users

    A ferroelectric memristor

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    Memristors are continuously tunable resistors that emulate synapses. Conceptualized in the 1970s, they traditionally operate by voltage-induced displacements of matter, but the mechanism remains controversial. Purely electronic memristors have recently emerged based on well-established physical phenomena with albeit modest resistance changes. Here we demonstrate that voltage-controlled domain configurations in ferroelectric tunnel barriers yield memristive behaviour with resistance variations exceeding two orders of magnitude and a 10 ns operation speed. Using models of ferroelectric-domain nucleation and growth we explain the quasi-continuous resistance variations and derive a simple analytical expression for the memristive effect. Our results suggest new opportunities for ferroelectrics as the hardware basis of future neuromorphic computational architectures

    The Maximal U(1)LU(1)_L Inverse Seesaw from d=5d=5 Operator and Oscillating Asymmetric Sneutrino Dark Matter

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    The maximal U(1)LU(1)_L supersymmetric inverse seesaw mechanism (MLLSIS) provides a natural way to relate asymmetric dark matter (ADM) with neutrino physics. In this paper we point out that, MLLSIS is a natural outcome if one dynamically realizes the inverse seesaw mechanism in the next-to minimal supersymmetric standard model (NMSSM) via the dimension-five operator (N)2S2/M∗(N)^2S^2/M_*, with SS the NMSSM singlet developing TeV scale VEV; it slightly violates lepton number due to the suppression by the fundamental scale M∗M_*, thus preserving U(1)LU(1)_L maximally. The resulting sneutrino is a distinguishable ADM candidate, oscillating and favored to have weak scale mass. A fairly large annihilating cross section of such a heavy ADM is available due to the presence of singlet.Comment: journal versio

    Strain-Driven Mn-Reorganization in Overlithiated LixMn2O4 Epitaxial Thin-Film Electrodes

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    Lithium manganate LixMn2O4 (LMO) is a lithium ion cathode that suffers from the widely observed but poorly understood phenomenon of capacity loss due to Mn dissolution during electrochemical cycling. Here, operando X-ray reflectivity (low- and high-angle) is used to study the structure and morphology of epitaxial LMO (111) thin film cathodes undergoing lithium insertion and extraction to understand the inter-relationships between biaxial strain and Mn-dissolution. The initially strain-relieved LiMn2O4 films generate in-plane tensile and compressive strains for delithiated (x 1) charge states, respectively. The results reveal reversible Li insertion into LMO with no measurable Mn-loss for 0 1) reveals Mn loss from LMO along with dramatic changes in the intensity of the (111) Bragg peak that cannot be explained by Li stoichiometry. These results reveal a partially reversible site reorganization of Mn ions within the LMO film that is not seen in bulk reactions and indicates a transition in Mn-layer stoichiometry from 3:1 to 2:2 in alternating cation planes. Density functional theory calculations confirm that compressive strains (at x = 2) stabilize LMO structures with 2:2 Mn site distributions, therefore providing new insights into the role of lattice strain in the stability of LMO

    Considering the influence of coronary motion on artery-specific biomechanics using fluid-structure interaction simulation

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    The endothelium in the coronary arteries is subject to wall shear stress and vessel wall strain, which influences the biology of the arterial wall. This study presents vessel-specific fluid-structure interaction (FSI) models of three coronary arteries, using directly measured experimental geometries and boundary conditions. FSI models are used to provide a more physiologically complete representation of vessel biomechanics, and have been extended to include coronary bending to investigate its effect on shear and strain. FSI both without- and with-bending resulted in significant changes in all computed shear stress metrics compared to CFD (p = 0.0001). Inclusion of bending within the FSI model produced highly significant changes in Time Averaged Wall Shear Stress (TAWSS) + 9.8% LAD, + 8.8% LCx, - 2.0% RCA; Oscillatory Shear Index (OSI) + 208% LAD, 0% LCx, + 2600% RCA; and transverse wall Shear Stress (tSS) + 180% LAD, + 150% LCx and + 200% RCA (all p < 0.0001). Vessel wall strain was homogenous in all directions without-bending but became highly anisotropic under bending. Changes in median cyclic strain magnitude were seen for all three vessels in every direction. Changes shown in the magnitude and distribution of shear stress and wall strain suggest that bending should be considered on a vessel-specific basis in analyses of coronary artery biomechanics

    MiniBooNE and LSND data: non-standard neutrino interactions in a (3+1) scheme versus (3+2) oscillations

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    The recently observed event excess in MiniBooNE anti-neutrino data is in agreement with the LSND evidence for electron anti-neutrino appearance. We propose an explanation of these data in terms of a (3+1) scheme with a sterile neutrino including non-standard neutrino interactions (NSI) at neutrino production and detection. The interference between oscillations and NSI provides a source for CP violation which we use to reconcile different results from neutrino and anti-neutrino data. Our best fit results imply NSI at the level of a few percent relative to the standard weak interaction, in agreement with current bounds. We compare the quality of the NSI fit to the one obtained within the (3+1) and (3+2) pure oscillation frameworks. We also briefly comment on using NSI (in an effective two-flavour framework) to address a possible difference in neutrino and anti-neutrino results from the MINOS experiment.Comment: 28 pages, 9 figures, discussion improved, new appendix added, conclusions unchange
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