Density and size-dependent bioturbation effects of the infaunal polychaete Nephtys incisa on sediment biogeochemistry and solute exchange

2021 ◽  
Vol 79 (4) ◽  
pp. 181-220
Author(s):  
Emma Michaud ◽  
Robert C. Aller ◽  
Qingzhi Zhu ◽  
Christina Heilbrun ◽  
Georges Stora
Keyword(s):  
Activity Patterns ◽  
Single Species ◽  
Size Classes ◽  
Size Dependent ◽  
Sediment Biogeochemistry ◽  
Reactive Solutes ◽  
Reaction Coupling ◽  
Chemical Cycling ◽  
The Impact ◽  
Net Fluxes

The impact of bioturbation on the geochemistry of aquatic sediments is known to depend on the benthic infauna species that are present. However, burrowing and activity patterns of each species may also change during the different stages of a life cycle. In this study, we examined the effects of four size classes of the polychaete Nephtys incisa on burrow networks and sediment biogeochemistry. In our experimental aquaria, the total biovolume (~ biomass) of Nephtys was kept constant, but different age classes were introduced, so the size and abundance varied between treatments. Despite differences in the geometry of burrow networks (due to varying density and size of burrows as revealed by X-radiography), the transport of nonreactive solutes (Br–) showed little difference between treatments. In contrast, the depth distribution of reactive solutes (Fe2+, Mn2+, TPO3– 4, TCO2, O2, pH) depended on oxidized sediment volumes and on spatial micro-heterogeneity related to burrowing patterns. Net fluxes of O2, TCO2, and NO– 3 fluxes were strongly affected by age-dependent burrowing patterns. Carbonate dissolution and remineralization rates (reflected by TCO 2fluxes) were enhanced as the size of individuals increased. NO– 3fluxes showed progressive change from dominance of nitrification (release) to denitrification (uptake) as burrow densities decreased with larger individuals. We conclude that different age-size classes of a single species at identical biovolume affect biogeo- chemical cycling differently, due to changes in burrow sizes and burrow densities. Because of redox reaction coupling associated with burrow geometries (Fe2+, Mn2+ oxidation patterns), similar magnitudes of nonlocal transport may be a misleading indicator of biogenic impacts. Our observations demonstrate that biogeochemical impacts must be evaluated in the context of size (age-) specific traits and population densities rather than biomass or biovolume alone.

scholarly journals Analysing the impact of the COVID-19 outbreak on everyday travel behaviour in Germany and potential implications for future travel patterns

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Viktoriya Kolarova ◽  
Christine Eisenmann ◽  
Claudia Nobis ◽  
Christian Winkler ◽  
Barbara Lenz
Keyword(s):  
Public Transport ◽  
Online Survey ◽  
Adult Population ◽  
Activity Patterns ◽  
Age Groups ◽  
Travel Behaviour ◽  
German Population ◽  
Travel Patterns ◽  
Home Office ◽  
The Impact

Abstract Introduction The global Coronavirus (COVID-19) pandemic is having a great impact on all areas of the everyday life, including travel behaviour. Various measures that focus on restricting social contacts have been implemented in order to reduce the spread of the virus. Understanding how daily activities and travel behaviour change during such global crisis and the reasons behind is crucial for developing suitable strategies for similar future events and analysing potential mid- and long-term impacts. Methods In order to provide empirical insights into changes in travel behaviour during the first Coronavirus-related lockdown in 2020 for Germany, an online survey with a relative representative sample for the German population was conducted a week after the start of the nationwide contact ban. The data was analysed performing descriptive and inferential statistical analyses. Results and Discussion The results suggest in general an increase in car use and decrease in public transport use as well as more negative perception of public transport as a transport alternative during the pandemic. Regarding activity-related travel patterns, the findings show firstly, that the majority of people go less frequent shopping; simultaneously, an increase in online shopping can be seen and characteristics of this group were analysed. Secondly, half of the adult population still left their home for leisure or to run errands; young adults were more active than all other age groups. Thirdly, the majority of the working population still went to work; one out of four people worked in home-office. Lastly, potential implications for travel behaviour and activity patterns as well as policy measures are discussed.

Data and visual displays in the Journal of Ecology 1996–2016

2020 ◽  
pp. 147387162098012
Author(s):  
Alon Friedman
Keyword(s):  
Best Practices ◽  
Pearson Correlation ◽  
Single Species ◽  
Data Type ◽  
Reliability Test ◽  
Visual Displays ◽  
Domain Type ◽  
Academic Publications ◽  
The Creation ◽  
The Impact

Scholars in scientific disciplines face unique challenges in the creation of visualizations, especially in publications that require insights derived from analyses to be visually displayed. The literature on visualizations describes different techniques and best practices for the creation of graphs. However, these techniques have not been used to evaluate the impact of visualizations in academic publications. In the field of ecology, as in other scientific fields, graphs are an essential part of journal articles. Little is known about the connections between the kind of data presented and domain in which the researchers conducted their study that together produces the visual graphics. This study focused on articles published in the Journal of Ecology between 1996 and 2016 to explore possible connections between data type, domain, and visualization type. Specifically, this study asked three questions: How many of the graphics published between 1996 and 2016 follow a particular set of recommendations for best practices? What can Pearson correlations reveal about the relationships between type of data, domain of study, and visual displays? Can the findings be examined through an inter-reliability test lens? Out of the 20,080 visualizations assessed, 54% included unnecessary graphical elements in the early part of the study (1996–2010). The most common type of data was univariate (35%) and it was often displayed using line graphs. Twenty-one percent of the articles in the period studied could be categorized under the domain type “single species.” Pearson correlation analysis showed that data type and domain type was positively correlated ( r = 0.08; p ≤ 0.05). Cohen’s kappa for the reliability test was 0.86, suggesting good agreement between the two categories. This study provides evidence that data type and domain types are equally important in determining the type of visualizations found in scientific journals.

R&D Heterogeneity and the Impact of R&D Subsidies*

2021 ◽  
Author(s):  
Sigurd M⊘lster Galaasen ◽  
Alfonso Irarrazabal
Keyword(s):  
Economic Impact ◽  
Growth Model ◽  
Relative Size ◽  
Schumpeterian Growth ◽  
Size Dependent ◽  
Investment Growth ◽  
The Impact ◽  
D Investment ◽  
Model Fits

Abstract This paper studies the determinants of R&D heterogeneity and the economic impact of R&D subsidies. We estimate a Schumpeterian growth model featuring firms with heterogeneous innovation efficiencies. The model fits well the R&D investment distribution, and the frequency and relative size of R&D performers. Using the model we study the impact of a Norwegian R&D reform targeting firms with R&D spending below a certain threshold. The size-dependent subsidy increases aggregate R&D investment by 11.7%, but reduces growth and welfare. In contrast, a uniform subsidy stimulates investment, growth and welfare.

scholarly journals Nonlocal and Size-Dependent Dielectric Function for Plasmonic Nanoparticles

2019 ◽  
Vol 9 (15) ◽  
pp. 3083
Author(s):  
Kai-Jian Huang ◽  
Shui-Jie Qin ◽  
Zheng-Ping Zhang ◽  
Zhao Ding ◽  
Zhong-Chen Bai
Keyword(s):  
Metallic Nanoparticles ◽  
High Efficiency ◽  
Finite Size ◽  
Plasmonic Nanostructures ◽  
Accurate Analysis ◽  
Finite Size Effects ◽  
Size Dependent ◽  
Quantum Size ◽  
The Impact ◽  
Electron Energy Loss

We develop a theoretical approach to investigate the impact that nonlocal and finite-size effects have on the dielectric response of plasmonic nanostructures. Through simulations, comprehensive comparisons of the electron energy loss spectroscopy (EELS) and the optical performance are discussed for a gold spherical dimer system in terms of different dielectric models. Our study offers a paradigm of high efficiency compatible dielectric theoretical framework for accounting the metallic nanoparticles behavior combining local, nonlocal and size-dependent effects in broader energy and size ranges. The results of accurate analysis and simulation for these effects unveil the weight and the evolution of both surface and bulk plasmons vibrational mechanisms, which are important for further understanding the electrodynamics properties of structures at the nanoscale. Particularly, our method can be extended to other plasmonic nanostructures where quantum-size or strongly interacting effects are likely to play an important role.

scholarly journals Influence Model of User Behavior Characteristics on Information Dissemination

2016 ◽  
Vol 11 (2) ◽  
pp. 209 ◽  
Author(s):  
Shao Chun Han ◽  
Yun Liu ◽  
Hui Ling Chen ◽  
Zhen Jiang Zhang
Keyword(s):  
Human Behavior ◽  
Information Diffusion ◽  
Statistical Physics ◽  
Information Dissemination ◽  
User Behavior ◽  
Activity Patterns ◽  
Propagation Model ◽  
Propagation Time ◽  
Behavior Characteristics ◽  
The Impact

Quantitative analysis on human behavior, especially mining and modeling temporal and spatial regularities, is a common focus of statistical physics and complexity sciences. The in-depth understanding of human behavior helps in explaining many complex socioeconomic phenomena, and in finding applications in public opinion monitoring, disease control, transportation system design, calling center services, information recommendation. In this paper,we study the impact of human activity patterns on information diffusion. Using SIR propagation model and empirical data, conduct quantitative research on the impact of user behavior on information dissemination. It is found that when the exponent is small, user behavioral characteristics have features of many new dissemination nodes, fast information dissemination, but information continued propagation time is short, with limited influence; when the exponent is big, there are fewer new dissemination nodes, but will expand the scope of information dissemination and extend information dissemination duration; it is also found that for group behaviors, the power-law characteristic a greater impact on the speed of information dissemination than individual behaviors. This study provides a reference to better understand influence of social networking user behavior characteristics on information dissemination and kinetic effect.

scholarly journals Localisation determines the optimal noise rate for quantum transport

2021 ◽  
Author(s):  
Alexandre Coates ◽  
Brendon W Lovett ◽  
Erik Gauger
Keyword(s):  
Energy Transport ◽  
Optimal Transport ◽  
Detailed Balance ◽  
Finite Size ◽  
Temperature Limit ◽  
Transport Efficiency ◽  
Size Dependent ◽  
Noise Rate ◽  
Pure Dephasing ◽  
The Impact

Abstract Environmental noise plays a key role in determining the efficiency of transport in quantum systems. However, disorder and localisation alter the impact of such noise on energy transport. To provide a deeper understanding of this relationship we perform a systematic study of the connection between eigenstate localisation and the optimal dephasing rate in 1D chains. The effects of energy gradients and disorder on chains of various lengths are evaluated and we demonstrate how optimal transport efficiency is determined by both size-independent, as well as size-dependent factors. By discussing how size-dependent influences emerge from finite size effects we establish when these effects are suppressed, and show that a simple power law captures the interplay between size-dependent and size-independent responses. Moving beyond phenomenological pure dephasing, we implement a finite temperature Bloch-Redfield model that captures detailed balance. We show that the relationship between localisation and optimal environmental coupling strength continues to apply at intermediate and high temperature but breaks down in the low temperature limit.

scholarly journals An evaluation of the interpretability and predictive performance of the BayesR model for genomic prediction

2020 ◽  
Author(s):  
Fanny Mollandin ◽  
Andrea Rau ◽  
Pascal Croiseau
Keyword(s):  
Linkage Disequilibrium ◽  
Qtl Mapping ◽  
Effect Size ◽  
Genomic Prediction ◽  
Simulated Data ◽  
Predictive Performance ◽  
Real Data ◽  
Sliding Windows ◽  
Size Classes ◽  
The Impact

ABSTRACTTechnological advances and decreasing costs have led to the rise of increasingly dense genotyping data, making feasible the identification of potential causal markers. Custom genotyping chips, which combine medium-density genotypes with a custom genotype panel, can capitalize on these candidates to potentially yield improved accuracy and interpretability in genomic prediction. A particularly promising model to this end is BayesR, which divides markers into four effect size classes. BayesR has been shown to yield accurate predictions and promise for quantitative trait loci (QTL) mapping in real data applications, but an extensive benchmarking in simulated data is currently lacking. Based on a set of real genotypes, we generated simulated data under a variety of genetic architectures, phenotype heritabilities, and we evaluated the impact of excluding or including causal markers among the genotypes. We define several statistical criteria for QTL mapping, including several based on sliding windows to account for linkage disequilibrium. We compare and contrast these statistics and their ability to accurately prioritize known causal markers. Overall, we confirm the strong predictive performance for BayesR in moderately to highly heritable traits, particularly for 50k custom data. In cases of low heritability or weak linkage disequilibrium with the causal marker in 50k genotypes, QTL mapping is a challenge, regardless of the criterion used. BayesR is a promising approach to simultaneously obtain accurate predictions and interpretable classifications of SNPs into effect size classes. We illustrated the performance of BayesR in a variety of simulation scenarios, and compared the advantages and limitations of each.

scholarly journals Assessing the suitability of non-invasive methods to monitorinterspecific interactions and breeding biology of the South Georgian diving petrel (Pelecanoides georgicus)

2020 ◽  
Author(s):  
Johannes Fischer ◽  
I Debski ◽  
GA Taylor ◽  
Heiko Wittmer
Keyword(s):  
Small Body ◽  
Activity Patterns ◽  
Breeding Biology ◽  
The South ◽  
Detection Rates ◽  
Seabird Species ◽  
Remote Cameras ◽  
The Impact ◽  
Diving Petrel ◽  
Rfid Readers

© The Ornithological Society of New Zealand Inc. We assessed the impact of interspecific interactions on the breeding success of the South Georgian diving petrel (Pelecanoides georgicus; SGDP), a Nationally Critical seabird species, by monitoring 20 burrows at Codfish Island (Whenua Hou), with remote cameras. Additionally, we tested the utility of remote cameras to study the breeding biology and activity patterns of the SGDP by pairing 5 remote cameras with RFID readers. We recorded 7 different species at SGDP burrow entrances. The common diving petrel (P. urinatrix) likely caused two monitored burrows to fail. These results suggest that remote cameras are useful tools to study such interactions. However, the cameras had extremely low SGDP detection rates (mean = 10.86%; se = 7.62%) when compared to RFID readers. These low detection rates may be explained by the small body size and the speed at which SGDPs enter/leave burrows. Therefore, remote cameras, or at least the model and setup we used, appear unsuitable to study breeding biology and activity patterns in this seabird species.

scholarly journals What Happens When People with Depression Gather Online?

2021 ◽  
Vol 18 (16) ◽  
pp. 8762
Author(s):  
Xuening Wang ◽  
Xianyun Tian ◽  
Xuwei Pan ◽  
Dongxu Wei ◽  
Qi Qi
Keyword(s):  
Online Community ◽  
Mental Disease ◽  
Activity Patterns ◽  
Comparison Analysis ◽  
The Impact

Depression is a common mental disease that impacts people of all ages and backgrounds. To meet needs that cannot otherwise be met, people with depression or who tend to suffer from depression often gather in online depression communities. However, since joining a depression community exposes members to the depression of others, the impact of such communities is not entirely clear. This study therefore explored what happens when people with depression gather in Sina Weibo’s Depression Super Topic online community. Through website crawling, postings from Depression Super Topic were compared with postings from members’ regular timelines with respect to themes, emotions disclosed, activity patterns, and the number of likes and comments. Topics of distilled postings covering support, regulations, emotions and life sharing, and initiating discussions were then coded. From comparison analysis, it was found that postings in the Depression Super Topic community received more comments and disclosed more emotions than regular timelines and that members were more active in the community at night. This study offers a picture of what occurs when people with depression gather online, which helps better understand their issues and therefore provide more targeted support.

scholarly journals Aminophosphine Reduction Mechanisms and the Synthesis of Indium Phosphide Nanomaterials

2021 ◽  
Author(s):  
◽  
Geoffry Laufersky
Keyword(s):  
Indium Phosphide ◽  
Density Functional ◽  
Large Scale ◽  
Visible Spectrum ◽  
Size Dependent ◽  
Reduction Mechanisms ◽  
Highly Sensitive ◽  
Dependent Absorption ◽  
Entire Visible Spectrum ◽  
The Impact

<p>Indium phosphide (InP) nanomaterials are attractive for countless technological applications due to their well-placed band gap energies. The quantum confinement of these semiconductors can give rise to size-dependent absorption and emission features throughout the entire visible spectrum. Therefore, InP materials can be employed as low-toxicity fluorophores that can be implemented in high value avenues such as biological probes, lighting applications, and lasing technologies. However, large scale development of these quantum dots (QDs) has been stymied by the lack of affordable and safe phosphorus precursors. Syntheses have largely been restricted to the use of dangerous chemicals such as tris(trimethylsilyl)phosphine ((TMS)₃P), which is costly and highly sensitive to oxygen and water. Recently, less-hazardous tris(dialkylamino)phosphines have been introduced to produce InP QDs on par with those utilizing (TMS)₃P. However, a poor understanding of the reaction mechanics has resulted in difficulties tuning and optimizing this method.  In this work, density functional theory (DFT) is used to identify the mechanism of this aminophosphine precursor conversion. This understanding is then implemented to design an improved InP QD synthesis, allowing for the production of high-quality materials outside of glovebox conditions. Time is spent understanding the impact of different precursor salts on the reaction mechanisms and discerning their subsequent effects on nanoparticle size and quality. The motivation of this work is to formulate safer and less technical indium phosphide quantum dot syntheses to foster non-specialist and industrial implementation of these materials.</p>

Sign in / Sign up

Export Citation Format

Share Document