A quasi-static approximation is studied of linearised nonhomogeneous anisotropic compressible thermoelasticity on a non-compact region. Differential inequalities are constructed which under ...appropriate conditions lead to algebraic spatial growth and decay estimates for various cross-sectional and volume measures of the temperature, displacement and their spatial gradients.
Developmental dyscalculia is a specific learning disorder that persists over lifetime and can have an enormous impact on personal, health-related, and professional aspects of life. Despite its ...central importance, the origin both at the cognitive and neural level is not yet well understood. Several classification schemas of dyscalculia have been proposed, sometimes together with an associated deficit at the neural level. However, these explanations are (a) not providing an exhaustive framework that is at levels with the observed complexity of developmental dyscalculia at the behavioral level and (b) are largely mono-causal approaches focusing on gray matter deficits. We suggest that number processing is instead the result of context-dependent interaction of two anatomically largely separate, distributed but overlapping networks that function/cooperate in a closely integrated fashion. The proposed two-network framework (TNF) is the result of a series of studies in adults on the neural correlates underlying magnitude processing and arithmetic fact retrieval, which comprised neurofunctional imaging of various numerical tasks, the application of probabilistic fiber tracking to obtain well-defined connections, and the validation and modification of these results using disconnectome mapping in acute stroke patients. Emerged from data in adults, it represents the endpoint of the acquisition and use of mathematical competencies in adults. Yet, we argue that its main characteristics should already emerge earlier during development. Based on this TNF, we develop a classification schema of phenomenological subtypes and their underlying neural origin that we evaluate against existing propositions and the available empirical data.
A tradeoff between growth and reproduction, often inferred from an inverse correlation between these two variables, is a fundamental paradigm of life-history evolution. Oak species provide a unique ...test of this relationship because different species mature acorns either in the year of pollination or in the year after pollination. This difference allows for an interspecific comparison testing whether the apparent tradeoff is causal or the result of confounding factors influencing growth and reproduction independently. Based on 13 years of data on five California oak species, we found significant negative correlations between radial growth and seed production in the three species that produce acorns the same year in which pollination occurs, but not in two species that mature acorns the year after pollination. Rainfall, which correlates positively with radial growth and correlates negatively with acorn production (based on the year of pollination), appears to be driving this pattern. We conclude that the observed negative correlations are not causal, but rather a consequence of growth and reproduction being dependent, in opposite ways, on environmental conditions. Thus, contrary to the current consensus, growth and reproduction in these species are apparently largely independent of each other. In contrast, tradeoffs between current and future reproduction appear to be much more important in the life-history evolution of these long-lived plants. We also conclude that a negative correlation does not necessarily imply a causal mechanism and should not be used as the only evidence supporting a tradeoff.
Alien plant species regularly and simultaneously invade agricultural landscapes and ecosystems; however, the effects of co-invasion on crop production and native biodiversity have rarely been ...studied. Secondary metabolites produced by alien plants may be allelopathic; if they enter the soil, they may be transported by agricultural activities, negatively affecting crop yield and biodiversity. It is unknown whether substances from different alien species in combination have a greater impact on crops and wild plants than if they are from only one of the alien species. In this study, we used a set of common garden experiments to test the hypothesis that mixed extracts from two common invasive species have synergistic effects on crops and weeds (defined as all non-crop plants) in European agricultural fields compared to single-species extracts. We found that both the combined and individual extracts had detrimental effects on the seed germination, seedling growth, biomass, and photosynthetic performance of both crops and weeds. We found that the negative effect of mixed extracts was not additive and that crop plants were more strongly affected by invasive species extracts than the weeds. Our results are important for managing invasive species in unique ecosystems on agricultural land and preventing economic losses in yield production.
Connective tissue growth factor, also known as CCN2, is a cysteine-rich matricellular protein involved in the control of biological processes, such as cell proliferation, differentiation, adhesion ...and angiogenesis, as well as multiple pathologies, such as tumor development and tissue fibrosis. Here, we describe the molecular and biological characteristics of CTGF, its regulation and various functions in the spectrum of development and regeneration to fibrosis. We further outline the preclinical and clinical studies concerning compounds targeting CTGF in various pathologies with the focus on heart, lung, liver, kidney and solid organ transplantation. Finally, we address the advances and pitfalls of translational fibrosis research and provide suggestions to move towards a better management of fibrosis.
•The structure, regulation and roles of CTGF in (patho)physiologies are described.•Results of studies on CTGF inhibition in various diseases and models are provided.•The role of CTGF as a marker and therapeutic target is reviewed.
Abandoned agricultural fields (old fields) are thought to accumulate soil organic matter (SOM) after cultivation cessation. However, most research on old fields soil carbon (C) and nitrogen (N) ...sequestration has focused on the surface (10 or 30 cm depth) and overlooked their dynamics below 30 cm. This study quantified C and N stock change in both the surface and subsurface with repeated inventories over 13 years. We conducted repeated soil surveys in 8 old fields that form a 64-year chronosequence at Cedar Creek Ecosystem Science Reserve (CCESR), Minnesota in 2001 and 2014. On average, soil C and N accumulated by 16.5 ± 14.5 g C m
−2
y
−1
and 1.0 ± 1.1 g N m
−2
y
−1
in the surface (0–20 cm). In contrast, we found soil C and N decreased by 78.9 ± 26.3 g C m
−2
y
−1
and 12.9 ± 2.42 g N m
−2
y
−1
in the subsurface (20–100 cm). The C and N losses in the subsurface soil were correlated with low deep root biomass; the majority of roots are located in the top 20 cm of soil. Such root distribution may be attributed to the continuing dominance of nonnative and shallow-rooted C3 grasses and the lack of legumes after field abandonment. This study shows that agriculture has a long legacy effect after abandonment on subsurface soil C and N. Some abandoned agricultural fields can continue to lose C and N because surface C and N accumulation does not offset the ongoing deeper soil C and N losses.
A leadless intracardiac transcatheter pacing system has been designed to avoid the need for a pacemaker pocket and transvenous lead.
In a prospective multicenter study without controls, a ...transcatheter pacemaker was implanted in patients who had guideline-based indications for ventricular pacing. The analysis of the primary end points began when 300 patients reached 6 months of follow-up. The primary safety end point was freedom from system-related or procedure-related major complications. The primary efficacy end point was the percentage of patients with low and stable pacing capture thresholds at 6 months (≤2.0 V at a pulse width of 0.24 msec and an increase of ≤1.5 V from the time of implantation). The safety and efficacy end points were evaluated against performance goals (based on historical data) of 83% and 80%, respectively. We also performed a post hoc analysis in which the rates of major complications were compared with those in a control cohort of 2667 patients with transvenous pacemakers from six previously published studies.
The device was successfully implanted in 719 of 725 patients (99.2%). The Kaplan-Meier estimate of the rate of the primary safety end point was 96.0% (95% confidence interval CI, 93.9 to 97.3; P<0.001 for the comparison with the safety performance goal of 83%); there were 28 major complications in 25 of 725 patients, and no dislodgements. The rate of the primary efficacy end point was 98.3% (95% CI, 96.1 to 99.5; P<0.001 for the comparison with the efficacy performance goal of 80%) among 292 of 297 patients with paired 6-month data. Although there were 28 major complications in 25 patients, patients with transcatheter pacemakers had significantly fewer major complications than did the control patients (hazard ratio, 0.49; 95% CI, 0.33 to 0.75; P=0.001).
In this historical comparison study, the transcatheter pacemaker met the prespecified safety and efficacy goals; it had a safety profile similar to that of a transvenous system while providing low and stable pacing thresholds. (Funded by Medtronic; Micra Transcatheter Pacing Study ClinicalTrials.gov number, NCT02004873.).
The Eurasian steppe is an important vegetation type characterized by cold, arid and nitrogen poor conditions. At the Eastern edge, including in the Songnen grassland, the vegetation is dominated by ...Leymus chinensis (henceforth L. chinensis) and is increasing threatened by elevated anthropogenic nitrogen deposition. L. chinensis is a perennial grass that mainly reproduces vegetatively and its sexual reproduction is limited. However, sexual reproduction plays an important role influencing colonization after large disturbances. To develop an understanding of how elevated nitrogen deposition changes the plant community structure and functioning we need a better understanding how sexual reproduction of L. chinensis changes with nitrogen enrichment. Here we report on a field experiment where we added 10 g N m
yr
and examined changes in seed traits, seed germination and early seedling growth.
Nitrogen addition increased seed production by 79%, contributing to this seed increases were a 28% increase in flowering plant density, a 40% increase in seed number per plant and a 11% increase in seed weight. Seed size increased with a 42% increase in large seeds and a 49% decrease in the smallest seed size category. Seed germination success improved by 10% for small seeds and 18% for large seeds. Combined, the increased in seed production and improved seed quality doubled the potential seed germination. Subsequent seedling above and below-ground biomass also significantly increased.
All aspects of L. chinensis sexual reproduction increased with nitrogen addition. Thus, L. chinensis competitive ability may increase when atmospheric nitrogen deposition increases, which may further reduce overall plant diversity in the low diversity Songnen grasslands.
Soil stores approximately twice as much carbon as the atmosphere and fluctuations in the size of the soil carbon pool directly influence climate conditions. We used the Nutrient Network global change ...experiment to examine how anthropogenic nutrient enrichment might influence grassland soil carbon storage at a global scale. In isolation, enrichment of nitrogen and phosphorous had minimal impacts on soil carbon storage. However, when these nutrients were added in combination with potassium and micronutrients, soil carbon stocks changed considerably, with an average increase of 0.04 KgCm−2 year−1 (standard deviation 0.18 KgCm−2 year−1). These effects did not correlate with changes in primary productivity, suggesting that soil carbon decomposition may have been restricted. Although nutrient enrichment caused soil carbon gains most dry, sandy regions, considerable absolute losses of soil carbon may occur in high‐latitude regions that store the majority of the world's soil carbon. These mechanistic insights into the sensitivity of grassland carbon stocks to nutrient enrichment can facilitate biochemical modelling efforts to project carbon cycling under future climate scenarios.
“Old fields” are ecosystems that have been previously managed and subsequently abandoned, usually from agricultural use. These systems are classic testing grounds for hypotheses about community ...assembly. However, old field succession can be difficult to predict: seemingly similar fields often diverge in terms of species composition and environmental conditions.
Here, we test the relative roles of contingency and stochasticity in driving vegetative successional dynamics. We draw on three decades of surveys in 24 old fields at the Cedar Creek Ecosystem Science Reserve (Minnesota, USA), and focus on five drivers that are known to shape local plant communities: soil fertility, fire, climate, competition, and demography. These drivers can contribute to contingency when they act consistently across fields and years (e.g., soil nitrogen accumulation, experimental fire regimes, or average climate), or to stochasticity when their effects are variable (e.g., annual variations in weather, or colonization and mortality events).
We proceed in two steps. First, we fit regressions estimating abundance, colonization, and mortality for eight major functional groups in relation to these five drivers. We then use these regressions to parameterize a series of metacommunity simulation models, and test whether observed levels of stochasticity and variation in the drivers are sufficient to explain successional divergence.
All drivers were significantly associated with plant species abundances, colonization, and mortality. Contingent factors strongly altered predicted successional trajectories. However, replicate simulations with similar conditions followed similar successional trajectories, suggesting that stochastic processes did not lead to divergence. This robustness of successional dynamics may be explained by compensatory trade‐offs. For example, species that were abundant late in succession typically suffered from low colonization rates and high mortality rates early in succession.
Synthesis. Average successional dynamics among old fields at Cedar Creek follow largely consistent trends. Though dynamics of individual fields vary, much of this variation can be explained by contingent factors. Stochastic processes appear not to be sufficiently strong to create divergent successional trajectories among fields with similar sets of drivers. Our results therefore suggest that divergence among successional trajectories in chronosequences may be the result of predictable contingent factors, rather than unpredictable stochastic fluctuations.
Average successional dynamics among old fields at Cedar Creek follow largely consistent trends. Though dynamics of individual fields vary, much of this variation can be explained by contingent factors. For example, regular burning (left half of picture) can lead to reduced leaf litter and changes in plant species abundances relative to unburned fields (right half of picture). In contrast, stochastic processes appear not to be sufficiently strong to create divergent successional trajectories among fields with similar sets of drivers. Our results suggest that divergence among successional trajectories in chronosequences may be the result of predictable contingent factors, rather than unpredictable stochastic fluctuations. Photo credit: Adam Clark, April 2017. Field 5 at Cedar Creek.
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