983 research outputs found
Disentangling the processes driving plant assemblages in mountain grasslands across spatial scales and environmental gradients
1. Habitat filtering and limiting similarity are well-documented ecological assembly processes that hierarchically filter species across spatial scales, from a regional pool to local assemblages. However, information on the effects of fine-scale spatial partitioning of species, working as an additional mechanism of coexistence, on community patterns, is much scarcer.
2. In this study, we quantified the importance of fine-scale spatial partitioning, relative to habitat filtering and limiting similarity, in structuring grassland communities in the western Swiss Alps. To do so, 298 vegetation plots (2 m × 2 m ) each with five nested subplots (20 cm × 20 cm) were used for trait based assembly tests (i.e. comparisons with several alternative null expectations), examining the observed plot and subplot level α-diversity (indicating habitat filtering and limiting similarity) and the between-subplot β-diversity of traits (indicating fine-scale spatial partitioning). We further assessed variations in the detected signatures of these assembly processes along a set of environmental gradients.
3. We found habitat filtering to be the dominating assembly process at the plot level with diminished effect at the subplot level, while limiting similarity prevailed at the subplot level with weaker average effect at the plot level. Plot-level limiting similarity was positively correlated with fine-scale partitioning suggesting that the trait divergence may result from a combination of competitive exclusion between functionally similar species and environmental micro-heterogeneities. Overall, signatures of assembly processes only marginally changed along environmental gradients but the observed trends were more prominent at the plot than at the subplot scale.
Synthesis: Our study emphasises the importance of considering multiple assembly processes and traits simultaneously across spatial scales and environmental gradients to understand the complex drivers of plant community composition
Advances in pre-treatment evaluation of pancreatic ductal adenocarcinoma: a narrative review
Background and Objective: Despite advances in the multidisciplinary management of pancreatic cancer, overall prognosis remains poor, due to early progression of the disease. There is a need to also take action in staging, to make it increasingly accurate and complete, to define the setting of the therapeutic strategy. This review was planned to update the current status of pre-treatment evaluation for pancreatic cancer. Methods: We conducted an extensive review, including relevant articles dealing with traditional imaging, functional imaging and minimally invasive surgical procedures before treatment for pancreatic cancer. We searched articles written in English only. Data in the PubMed database, published in the period between January 2000 and January 2022, were retrieved. Prospective observational studies, retrospective analyses and meta-analyses were reviewed and analysed. Key Content and Findings: Each imaging modality (endoscopic ultrasonography, endoscopic retrograde staging laparoscopy) has its own diagnostic advantages and limitations. The sensitivity, specificity and accuracy for each image set are reported. Data that support the increasing role of neoadjuvant therapy (radiotherapy and chemotherapy) and the meaning of a patient-tailored treatment selection, based on tumour staging, are also discussed. Conclusions: A multimodal pre-treatment workup should be searched as it improves staging accuracy, orienting patients with resectable tumors towards surgery, optimizing patient selection with locally advanced tumors to neoadjuvant or definite therapy and avoiding surgical resection or curative radiotherapy in those with metastatic disease
Evidence for a Low-Spin to Intermediate-Spin State Transition in LaCoO3
We present measurements of the magnetic susceptibility and of the thermal
expansion of a LaCoO single crystal. Both quantities show a strongly
anomalous temperature dependence. Our data are consistently described in terms
of a spin-state transition of the Co ions with increasing temperature
from a low-spin ground state to an intermediate-spin state without (100K -
500K) and with (>500K) orbital degeneracy. We attribute the lack of orbital
degeneracy up to 500K to (probably local) Jahn-Teller distortions of the
CoO octahedra. A strong reduction or disappearance of the Jahn-Teller
distortions seems to arise from the insulator-to-metal transition around 500 K.Comment: an error in the scaling factor of Eq.(4) and consequently 2 values of
table I have been corrected. The conclusions of the paper remain unchanged.
See also: C. Zobel et al. Phys. Rev. B 71, 019902 (2005) and J. Baier et al.
Phys. Rev. B 71, 014443 (2005
Gut microbiota-derived propionate reduces cancer cell proliferation in the liver
Peer reviewedPublisher PD
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Developing European conservation and mitigation tools for pollination services: approaches of the STEP (Status and Trends of European Pollinators) project
Pollinating insects form a key component of European biodiversity, and provide a vital ecosystem service to crops and wild plants. There is growing evidence of declines in both wild and domesticated pollinators, and parallel declines in plants relying upon them. The STEP project (Status and Trends of European Pollinators, 2010-2015, www.stepproject.net) is documenting critical elements in the nature and extent of these declines, examining key functional traits associated with pollination deficits, and developing a Red List for some European pollinator groups. Together these activities are laying the groundwork for future pollinator monitoring programmes. STEP is also assessing the relative importance of potential drivers of pollinator declines, including climate change, habitat loss and fragmentation, agrochemicals, pathogens, alien species, light pollution, and their interactions. We are measuring the ecological and economic impacts of declining pollinator services and floral resources, including effects on wild plant populations, crop production and human nutrition. STEP is reviewing existing and potential mitigation options, and providing novel tests of their effectiveness across Europe. Our work is building upon existing and newly developed datasets and models, complemented by spatially-replicated campaigns of field research to fill gaps in current knowledge. Findings are being integrated into a policy-relevant framework to create evidence-based decision support tools. STEP is establishing communication links to a wide range of stakeholders across Europe and beyond, including policy makers, beekeepers, farmers, academics and the general public. Taken together, the STEP research programme aims to improve our understanding of the nature, causes, consequences and potential mitigation of declines in pollination services at local, national, continental and global scales
Synchronization of multi-phase oscillators: An Axelrod-inspired model
Inspired by Axelrod's model of culture dissemination, we introduce and
analyze a model for a population of coupled oscillators where different levels
of synchronization can be assimilated to different degrees of cultural
organization. The state of each oscillator is represented by a set of phases,
and the interaction --which occurs between homologous phases-- is weighted by a
decreasing function of the distance between individual states. Both ordered
arrays and random networks are considered. We find that the transition between
synchronization and incoherent behaviour is mediated by a clustering regime
with rich organizational structure, where some of the phases of a given
oscillator can be synchronized to a certain cluster, while its other phases are
synchronized to different clusters.Comment: 6 pages, 5 figure
SHREC 2011: robust feature detection and description benchmark
Feature-based approaches have recently become very popular in computer vision
and image analysis applications, and are becoming a promising direction in
shape retrieval. SHREC'11 robust feature detection and description benchmark
simulates the feature detection and description stages of feature-based shape
retrieval algorithms. The benchmark tests the performance of shape feature
detectors and descriptors under a wide variety of transformations. The
benchmark allows evaluating how algorithms cope with certain classes of
transformations and strength of the transformations that can be dealt with. The
present paper is a report of the SHREC'11 robust feature detection and
description benchmark results.Comment: This is a full version of the SHREC'11 report published in 3DO
Variants Near MC4R Are Associated With Obesity and Influence Obesity-Related Quantitative Traits in a Population of Middle-Aged People: Studies of 14,940 Danes
OBJECTIVE— Variants downstream of the melanocortin-4 receptor gene (MC4R) have been reported to associate with obesity. We examined rs17782313, rs17700633, rs12970134, rs477181, rs502933, and rs4450508 near MC4R for association with obesity-related quantitative traits, obesity, and type 2 diabetes in Danish individuals
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