Resampling technique applied to statistics of microsegregation characterization

Characterization of chemical heterogeneities at the dendrite scale is of practical importance for understanding phase transformation either during solidification or during subsequent solid-state treatment. Spot analysis with electron probe is definitely well-suited to investigate such heterogeneities at the micron scale that is relevant for most solidified products. However, very few has been done about the statistics of experimental solute distributions gained from such analyses when they are now more and more used for validating simulation data. There are two main sources generating discrepancies between estimated and actual solute distributions in an alloy: i) data sampling with a limited number of measurements to keep analysis within a reasonable time length; and ii) uncertainty linked to the measurement process, namely the physical noise that accompanies X-ray emission. Focusing on the first of these sources, a few 2-D composition images have been generated by phase field modelling of a Mg-Al alloy. These images were then used to obtain "true" solute distributions to which to compare coarse grid analyses as generally performed with a microanalyser. Resampling, i.e. generating several distributions by grid analyses with limited number of picked-up values, was then used to get statistics of estimates of solute distribution. The discussion of the present results deals first with estimating the average solute content and then focuses on the distribution in the primary phase

Exploring modularity in biological networks

Network theoretical approaches have shaped our understanding of many different kinds of biological modularity. This essay makes the case that to capture these contributions, it is useful to think about the role of network models in exploratory research. The overall point is that it is possible to provide a systematic analysis of the exploratory functions of network models in bioscientific research. Using two examples from molecular and developmental biology, I argue that often the same modelling approach can perform one or more exploratory functions, such as introducing new directions of research, offering a complementary set of concepts, methods and algorithms for individuating important features of natural phenomena, generating proofs of principle demonstrations and potential explanations for phenomena of interest and enlarging the scope of certain research agendas. This article is part of the theme issue 'Unifying the essential concepts of biological networks: biological insights and philosophical foundations'

Long-Term Potentiation: One Kind or Many?

Do neurobiologists aim to discover natural kinds? I address this question in this chapter via a critical analysis of classification practices operative across the 43-year history of research on long-term potentiation (LTP). I argue that this 43-year history supports the idea that the structure of scientific practice surrounding LTP research has remained an obstacle to the discovery of natural kinds

Dutch and German 3-year-olds’ representations of voicing alternations

The voicing contrast is neutralised syllable and word finally in Dutch and German, leading to alternations within the morphological paradigm (e.g. Dutch ‘bed(s)’, be[t] be[d]en, German ‘dog(s)’, Hun[t]-Hun[d]e). Despite structural similarity, language-specific morphological, phonological and lexical properties impact on the distribution of this alternation in the two languages. Previous acquisition research has focused on one language only, predominantly focusing on children’s production accuracy, concluding that alternations are not acquired until late in the acquisition process in either language. This paper adapts a perceptual method to investigate how voicing alternations are represented in the mental lexicon of Dutch and German 3-year-olds. Sensitivity to mispronunciations of voicing word-medially in plural forms was measured using a visual fixation procedure. Dutch children exhibited evidence of overgeneralising the voicing alternation, whereas German children consistently preferred the correct pronunciation to mispronunciations. Results indicate that the acquisition of voicing alternations is influenced by language-specific factors beyond the alternation itself

Contrasting responses of cluster roots formation induced by phosphorus and nitrogen supply in Embothrium coccineum populations from different geographical origin

Indexación: Scopus.Aims: Embothrium coccineum is a pioneer tree that produces cluster roots (CR) induced by phosphorus (P) or nitrogen (N) deficiency, but the role which both N and P play in CR formation for different E. coccineum populations is still unknown. We hypothesized that in E. coccineum, N influences the CR formation response, primarily induced by P limitation. However, this response depends on local adaptations to their specific conditions of geographic origin. Methods: Seedlings from three contrasting edaphoclimatic conditions (Northern, Central and Southern populations) were grown in hydroponic culture under high and low N supply and at five different P supply. Morphophysiological responses, including CR number, growth, biomass, P and N plant concentration, were studied. Results: Our results showed that at high N supply, CR formation was stimulated with increased P supply, but just until it reaches a maximum of 5 μM, above this concentration CR formation decreases. However, at low N supply, a constitutive response was observed regardless of P supply. Moreover, each of these responses depends on the populations. Conclusions: Our study suggests that N drives CR formation induced by P supply and that a differential response exists among E. coccineum populations, that could be related to their origin edaphoclimatic conditions. © 2020, Springer Nature Switzerland AG.https://link-springer-com.recursosbiblioteca.unab.cl/article/10.1007%2Fs11104-020-04622-

Simulating Food Web Dynamics along a Gradient: Quantifying Human Influence

Realistically parameterized and dynamically simulated food-webs are useful tool to explore the importance of the functional diversity of ecosystems, and in particular relations between the dynamics of species and the whole community. We present a stochastic dynamical food web simulation for the Kelian River (Borneo). The food web was constructed for six different locations, arrayed along a gradient of increasing human perturbation (mostly resulting from gold mining activities) along the river. Along the river, the relative importance of grazers, filterers and shredders decreases with increasing disturbance downstream, while predators become more dominant in governing eco-dynamics. Human activity led to increased turbidity and sedimentation which adversely impacts primary productivity. Since the main difference between the study sites was not the composition of the food webs (structure is quite similar) but the strengths of interactions and the abundance of the trophic groups, a dynamical simulation approach seemed to be useful to better explain human influence. In the pristine river (study site 1), when comparing a structural version of our model with the dynamical model we found that structurally central groups such as omnivores and carnivores were not the most important ones dynamically. Instead, primary consumers such as invertebrate grazers and shredders generated a greater dynamical response. Based on the dynamically most important groups, bottom-up control is replaced by the predominant top-down control regime as distance downstream and human disturbance increased. An important finding, potentially explaining the poor structure to dynamics relationship, is that indirect effects are at least as important as direct ones during the simulations. We suggest that our approach and this simulation framework could serve systems-based conservation efforts. Quantitative indicators on the relative importance of trophic groups and the mechanistic modeling of eco-dynamics could greatly contribute to understanding various aspects of functional diversity

A decadal view of biodiversity informatics: challenges and priorities

Biodiversity informatics plays a central enabling role in the research community's efforts to address scientific conservation and sustainability issues. Great strides have been made in the past decade establishing a framework for sharing data, where taxonomy and systematics has been perceived as the most prominent discipline involved. To some extent this is inevitable, given the use of species names as the pivot around which information is organised. To address the urgent questions around conservation, land-use, environmental change, sustainability, food security and ecosystem services that are facing Governments worldwide, we need to understand how the ecosystem works. So, we need a systems approach to understanding biodiversity that moves significantly beyond taxonomy and species observations. Such an approach needs to look at the whole system to address species interactions, both with their environment and with other species. It is clear that some barriers to progress are sociological, basically persuading people to use the technological solutions that are already available. This is best addressed by developing more effective systems that deliver immediate benefit to the user, hiding the majority of the technology behind simple user interfaces. An infrastructure should be a space in which activities take place and, as such, should be effectively invisible. This community consultation paper positions the role of biodiversity informatics, for the next decade, presenting the actions needed to link the various biodiversity infrastructures invisibly and to facilitate understanding that can support both business and policy-makers. The community considers the goal in biodiversity informatics to be full integration of the biodiversity research community, including citizens’ science, through a commonly-shared, sustainable e-infrastructure across all sub-disciplines that reliably serves science and society alike