Search results for "interactions."

Chasing Weak Forces: Hierarchically Assembled Helicates as a Probe for the Evaluation of the Energetics of Weak Interactions.

2017

London dispersion forces are the weakest interactions between molecules. Because of this, their influence on chemical processes is often low, but can definitely not be ignored, and even becomes important in cases of molecules with large contact surfaces. Hierarchically assembled dinuclear titanium(IV) helicates represent a rare example in which the direct observation of London dispersion forces is possible in solution even in the presence of strong cohesive solvent effects. Hereby, the dispersion forces do not unlimitedly support the formation of the dimeric complexes. Although they have some favorable enthalpic contribution to the dimerization of the monomeric complex units, large flexible…

Observed Fitness May Affect Niche Overlap in Competing Species via Selective Social Information Use

2013

Social information transmission is important because it enables horizontal spread of behaviors, not only between conspecifics but also between individuals of different species. Because interspecific social information use is expected to take place among species with similar resource needs, it may have major consequences for the emergence of local adaptations, resource sharing, and community organization. Social information use is expected to be selective, but the conditions promoting it in an interspecific context are not well known. Here, we experimentally test whether pied flycatchers (Ficedula hypoleuca) use the clutch size of great tits (Parus major) in determining the quality of the ob…

Engineering students' engagement with resources in an online learning environment

2018

International audience; This study explores engineering students' interactions with different resources in an online learning environment. The constituent resources of this environment involve MyMathLab which is an online interactive system for practicing mathematics, the tutorial videos, and the textbook. We conducted a qualitative case study to observe a small group of undergraduate engineering students interacting with the resources in a Calculus course. Employing the documentational approach to didactics, we identified several techniques while participants used resources to practice mathematics in MyMathLab environment. We discuss the pragmatic and epistemic value of the identified tech…

Parasite avoidance behaviours in aquatic environments

2018

Parasites, including macroparasites, protists, fungi, bacteria and viruses, can impose a heavy burden upon host animals. However, hosts are not without defences. One aspect of host defence, behavioural avoidance, has been studied in the terrestrial realm for over 50 years, but was first reported from the aquatic environment approximately 20 years ago. Evidence has mounted on the importance of parasite avoidance behaviours and it is increasingly apparent that there are core similarities in the function and benefit of this defence mechanism between terrestrial and aquatic systems. However, there are also stark differences driven by the unique biotic and abiotic characteristics of terrestrial …

Not just the sum of its parts : Geographic variation and nonadditive effects of pyrazines in the chemical defence of an aposematic moth

2022

Chemical defences often vary within and between populations both in quantity and quality, which is puzzling if prey survival is dependent on the strength of the defence. We investigated the within- and between-population variability in chemical defence of the wood tiger moth (Arctia plantaginis). The major components of its defences, SBMP (2-sec-butyl-3-methoxypyrazine) and IBMP (2-isobutyl-3-methoxypyrazine), are volatiles that deter bird attacks. We hypothesized that (1) variation in the chemical defences of male wood tiger moths reflects the local predation pressure; (2) observed differences in quantity and quality of defence among populations have a genetic basis; and (3) increasing con…

Antibacterial Activity of Positively and Negatively Charged Hematite (α-Fe2O3) Nanoparticles to Escherichia coli, Staphylococcus aureus and Vibrio fi…

2021

This research and work has been supported by the European Regional Development Fund within the Activity 1.1.1.2 “Post-doctoral Research Aid” of the Specific Aid Objective 1.1.1 (i.e., “to increase the research and innovative capacity of scientific institutions of Latvia and the ability to attract external financing, investing in human resources and infrastructure”) of the Operational Programme “Growth and Employment” (No. 1.1.1.2/VIAA/2/18/331).

Synthesis and Structure-Affinity Relationships of Spirocyclic Benzopyrans with Exocyclic Amino Moiety

2019

σ1 and/or σ2 receptors play a crucial role in pathological conditions such as pain, neurodegenerative disorders, and cancer. A set of spirocyclic cyclohexanes with diverse O-heterocycles and amino moieties (general structure III) was prepared and pharmacologically evaluated. In structure-activity relationships studies, the σ1 receptor affinity and σ1:σ2 selectivity were correlated with the stereochemistry, the kind and substitution pattern of the O-heterocycle, and the substituents at the exocyclic amino moiety. cis-configured 2-benzopyran cis-11b bearing a methoxy group and a tertiary cyclohexylmethylamino moiety showed the highest σ1 affinity ( Ki = 1.9 nM) of this series of compounds. In…

The challenges of GxE research: A rejoinder

2017

The question of Organic Unity in Flavour: The whole is not equal to the sum of the parts

2021

International audience

Sensitivity of bipartite network analyses to incomplete sampling and taxonomic uncertainty

2023

Bipartite network analysis is a powerful tool to study the processes structuring interactions in ecological communities. In applying the method, it is assumed that the sampled interactions provide an accurate representation of the actual community. However, acquiring a representative sample may be difficult as not all species are equally abundant or easily identifiable. Two potential sampling issues can compromise the conclusions of bipartite network analyses: failure to capture the full range of interactions (sampling completeness) and use of a taxonomic level higher than species to evaluate the network (taxonomic resolution). We asked how commonly used descriptors of bipartite antagonisti…