scholarly journals Annual Population Dynamics and Their Influencing Factors for an Endangered Submerged Macrophyte (Ottelia cordata)

2021 ◽  
Vol 9 ◽  
Author(s):  
Yichun Shen ◽  
Jinrui Lei ◽  
Xiqiang Song ◽  
Mingxun Ren
Keyword(s):  
Growth Rate ◽  
Population Dynamics ◽  
Sex Ratio ◽  
Leaf Area ◽  
Water Depth ◽  
Habitat Types ◽  
Mixed Effect ◽  
Mixed Effect Models ◽  
Demographic Traits ◽  
Linear Mixed Effect Models

Due to wetland loss, Ottelia cordata (O. cordata, Wallich) Dandy has been categorized as an endangered species on the List of Key Protected Wild Plants in China. Quantifying the relative importance of demographic (i.e., growth, survival, and reproduction) and habitat preference traits on the population dynamics (abundance) of O. cordata could guide how to develop the best recovery strategies of O. cordata, yet currently, there are no studies that investigate this. By monitoring monthly changes in O. cordata abundance and demographic traits (plant height, leaf area, flower sex ratio, and seed number) that were highly correlated with growth rate, photosynthetic rate, and water depth, we identified several relationships. Linear mixed-effect models and variance partition quantified the specific effects of four demographic traits and water depth on O. cordata abundance in three habitat types (paddyfield, stream, and spring). The linear mixed-effect models indicate that among the four demographic traits, height could be significantly positively correlated to abundance in all three habitat types. In contrast, other three traits (leaf area, sex ratio, and seed numbers) were non-significantly associated with abundance across each habitat. Height was determined by water depth, so water depth rather than photosynthetic rate and reproduction rate may promote the development and recovery of O. cordata populations. Variance partition results showed that water depth mediated the positive influence of growth rate on the abundance of O. cordata in the living habitats (paddyfield and spring). In contrast, water depth but not growth rate determined the abundance of O. cordata in the living habitat (stream). However, water depth had a significantly negative impact on the abundance of O. cordata in stream habitats, likely because all of the streams were shallow. Altogether, in the short term for avoiding the potential harm or even extinction of O. cordata, keeping appropriate water depth or transplanting O. cordata to spring should be an effective strategy because the water is not only deep enough but also clear in spring habitats. Additionally, water turbidity was shown to affect the density of O. cordata growth, wherein O. cordata was sparsely distributed when turbidity was high. Therefore, in the long run, to make the population gradually recovery, it will be necessary to restore the degraded wetland. This could be accomplished by reducing water pollution and removing sludge to reduce turbidity and increase hydrological connectivity.

Association of fine particulate matter with glucose and lipid metabolism: a longitudinal study in young adults

2021 ◽  
pp. oemed-2020-107039
Author(s):  
Jingyi Qin ◽  
Wei Xia ◽  
Gaodao Liang ◽  
Shunqing Xu ◽  
Xiuge Zhao ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Lipid Metabolism ◽  
Longitudinal Study ◽  
Fine Particulate Matter ◽  
Healthy Adults ◽  
Mixed Effect ◽  
Glucose And Lipid Metabolism ◽  
Mixed Effect Models ◽  
Fine Particulate ◽  
Linear Mixed Effect Models

ObjectivesThis study aimed to evaluate whether PM2.5 exposure in a highly polluted area (>100 µg/m3) affects glucose and lipid metabolism in healthy adults.MethodsWe recruited 110 healthy adults in Baoding city, Hebei, China, and followed them up between 2017 and 2018. Personal air samplers were used to monitor personal PM2.5 levels. Eight glucose and lipid metabolism parameters were quantified. We performed the linear mixed-effect models to investigate the relationships between PM2.5 and glucose and lipid metabolism parameters. Stratified analyses were further performed according to sex and body mass index (BMI).ResultsThe concentration of PM2.5 was the highest in spring, with a median of 232 μg/m3 and the lowest in autumn (139 μg/m3). After adjusting for potential confounders, we found that for each twofold increase in PM2.5, the median of insulin concentration decreased by 5.89% (95% CI −10.91% to −0.58%; p<0.05), and ox-LDL increased by 6.43% (95% CI 2.21% to 10.82%; p<0.05). Stratified analyses indicated that the associations were more pronounced in females, overweight and obese participants.ConclusionsExposure to high PM2.5 may have deleterious effects on glucose and lipid metabolism. Females, overweight and obese participants are more vulnerable.

scholarly journals Changes in the biomass of scots pine (Pinus sylvestris L.) trees in Europe since 1940

2021 ◽  
pp. 6-22
Author(s):  
А.В. Лебедев ◽  
В.В. Кузьмичев
Keyword(s):  
Wood Density ◽  
Scots Pine ◽  
Wood Properties ◽  
Mixed Effect ◽  
Pine Tree ◽  
Mixed Effect Models ◽  
The Face ◽  
Long Term Trends ◽  
Linear Mixed Effect Models

Сосна обыкновенная является одной из основных лесообразующих пород Европы, а ее древесина находит широкое применение в лесопромышленном комплексе. При оценке углерододепонирующих функций считается, что конверсионные коэффициенты являются константными по времени. Последние исследования показывают, что происходящие климатические изменения оказывают существенное влияние на прирост древесины и ее свойства. Цель данного исследования – выявление долговременных тенденций в изменении биомассы фракций деревьев сосны обыкновенной в Европе, происходящих с 1940 г. Для проверки гипотезы о влиянии календарного года на биомассу фракций деревьев проводился регрессионный анализ с применением линейных моделей смешанных эффектов. Проведенный статистический анализ позволил выявить достоверное влияние (при p < 0,05) календарного года только на биомассу стволов в коре. Наиболее сильно изменения проявляются для деревьев в молодняках и средневозрастных насаждениях, где происходит формирование наибольшего радиального прироста. Для крупномерных стволов, согласно результатам моделирования, снижение биомассы стволов в коре не прослеживается. В ближайшие десятилетия в результате продолжающихся климатических изменений процесс снижения биомассы и плотности древесины крупномерных стволов должен усилиться. Выявленные изменения биомассы сопровождаются снижением плотности древесины, что происходит в результате увеличения в структуре годичного прироста более рыхлой и менее плотной ранней древесины. Таким образом, в условиях ускоряющихся темпов роста древесных растений объемы стволов и запасы древесины не должны напрямую пересчитываться в депонированный углерод с учетом исторических значений конверсионных коэффициентов. Это также следует учитывать при мониторинге, моделировании и использовании углерода и биомассы в лесах в условиях глобальных изменений. Scots pine is one of the main forest-forming species in Europe, and its wood is widely used in the timber industry. When evaluating carbon-depositing functions, the conversion rations are assumed to be constant over time. Recent studies show that the ongoing climatic changes have a significant impact on the growth of trees and wood properties. Therefore, the purpose of this study is to identify long-term trends in the change in the biomass of Scots pine tree fractions in Europe since 1940. To test the hypothesis about the influence of the calendar year on the biomass of tree fractions, regression analysis was performed using linear mixed-effect models. The performed statistically analysis made it possible to reveal a significant effect (p < 0.05) of the calendar year only on the biomass of the trunks in the bark. The changes are most pronounced for trees in young and middle-aged stands, where the formation of the greatest radial growth occurs. For large-sized trunks, according to the simulation results, the biomass of the stems in the bark is not traced. In the coming decades, as a result of ongoing climate change, the decline in biomass and wood density of largesized stems should intensify. The revealed changes in biomass are accompanied by a decrease in wood density, which occurs as a result of an increase in the structure of the annual growth of looser and less dense early wood. Thus, in the context of accelerating growth rates of woody plants, the volume of trunks and wood stock should not be directly converted into deposited carbon, considering the historical values of conversion rations. This should also be considered when monitoring, modeling and using carbon and biomass in forests in the face of global change.

scholarly journals The role of incubator classification on performance of incubators in Kenya.

2021 ◽  
Vol 10 (6) ◽  
pp. 256-267
Author(s):  
Miriti Jane Kinya ◽  
Kenneth Lawrance Wanjau ◽  
Nyagweth Ebenezer Odeyo
Keyword(s):  
Fixed Effects ◽  
Selection Criteria ◽  
Primary Data ◽  
Cross Sectional ◽  
Mixed Effect ◽  
Study Objective ◽  
Mixed Effect Models ◽  
Random Slopes ◽  
Linear Mixed Effect Models

The study sought to assess the importance of classifying incubators based on the programs offered for optimum performance. Client selection criteria were assessed through three constructs namely: models that fit program goals, uniqueness of ideas, and standard selection tool. A mixed cross-sectional and causal design was adopted and a census was carried out targeting all the 51 incubators. Primary data was collected with an incubator program as a grouping/ cluster variable yielding a multilevel data structure with incubator centres nested in programs. Linear mixed effect models were fitted using Stata to assess the study objective taking into account the fixed effects for the incubator centre level (level-1) and random effects for the program level (level-2). The uniqueness of ideas was found to have a significant fixed effect on performance at level one while at level two, the study found significant random intercepts of incubator centre performance across the programs. Models that match program goals and standard selection tools were also found to have significant random slopes as level two random covariates in the model. Based on the findings of significant random slopes, the study concluded that incubator classification is key for client selection criteria and enhances incubator performance.

scholarly journals Relationship between β-amyloid and structural network topology in decedents without dementia

Neurology ◽  
2020 ◽  
Vol 95 (5) ◽  
pp. e532-e544
Author(s):  
Laura E. Jonkman ◽  
Martijn D. Steenwijk ◽  
Nicky Boesen ◽  
Annemieke J.M. Rozemuller ◽  
Frederik Barkhof ◽  
...  
Keyword(s):  
Network Topology ◽  
Pathologic Change ◽  
Mixed Effect ◽  
Linear Mixed Effect ◽  
Local Efficiency ◽  
Mixed Effect Models ◽  
Global Efficiency ◽  
Structural Network ◽  
Β Amyloid ◽  
Linear Mixed Effect Models

ObjectiveTo investigate the association between β-amyloid (Aβ) load and postmortem structural network topology in decedents without dementia.MethodsFourteen decedents (mean age at death 72.6 ± 7.2 years) without known clinical diagnosis of neurodegenerative disease and meeting pathology criteria only for no or low Alzheimer disease (AD) pathologic change were selected from the Normal Aging Brain Collection Amsterdam database. In situ brain MRI included 3D T1-weighted images for anatomical registration and diffusion tensor imaging for probabilistic tractography with subsequent structural network construction. Network topologic measures of centrality (degree), integration (global efficiency), and segregation (clustering and local efficiency) were calculated. Tissue sections from 12 cortical regions were sampled and immunostained for Aβ and hyperphosphorylated tau (p-tau), and histopathologic burden was determined. Linear mixed effect models were used to assess the relationship between Aβ and p-tau load and network topologic measures.ResultsAβ was present in 79% of cases and predominantly consisted of diffuse plaques; p-tau was sparsely present. Linear mixed effect models showed independent negative associations between Aβ load and global efficiency (β = −0.83 × 10−3, p = 0.014), degree (β = −0.47, p = 0.034), and clustering (β = −0.55 × 10−2, p = 0.043). A positive association was present between Aβ load and local efficiency (β = 3.16 × 10−3, p = 0.035). Regionally, these results were significant in the posterior cingulate cortex (PCC) for degree (β = −2.22, p < 0.001) and local efficiency (β = 1.01 × 10−2, p = 0.014) and precuneus for clustering (β = −0.91 × 10−2, p = 0.017). There was no relationship between p-tau and network topology.ConclusionThis study in deceased adults with AD-related pathologic change provides evidence for a relationship among early Aβ accumulation, predominantly of the diffuse type, and structural network topology, specifically of the PCC and precuneus.

scholarly journals Modelling subject-specific childhood growth using linear mixed-effect models with cubic regression splines

2016 ◽  
Vol 13 (1) ◽  
Author(s):  
Laura M. Grajeda ◽  
Andrada Ivanescu ◽  
Mayuko Saito ◽  
Ciprian Crainiceanu ◽  
Devan Jaganath ◽  
...  
Keyword(s):  
Regression Splines ◽  
Mixed Effect ◽  
Childhood Growth ◽  
Linear Mixed Effect ◽  
Mixed Effect Models ◽  
Subject Specific ◽  
Linear Mixed Effect Models

Snails on oceanic islands: testing the general dynamic model of oceanic island biogeography using linear mixed effect models

2012 ◽  
Vol 40 (1) ◽  
pp. 117-130 ◽  
Author(s):  
Robert A. D. Cameron ◽  
Kostas A. Triantis ◽  
Christine E. Parent ◽  
François Guilhaumon ◽  
María R. Alonso ◽  
...  
Keyword(s):  
Dynamic Model ◽  
Island Biogeography ◽  
Oceanic Islands ◽  
Oceanic Island ◽  
Mixed Effect ◽  
Linear Mixed Effect ◽  
Mixed Effect Models ◽  
Linear Mixed Effect Models ◽  
General Dynamic

scholarly journals Mate Availability and Sexual Disgust

2020 ◽  
Author(s):  
Courtney L. Crosby ◽  
Patrick Durkee ◽  
Anna Sedlacek ◽  
David M. Buss
Keyword(s):  
Mate Choice ◽  
Mate Selection ◽  
Local Environment ◽  
Relationship Status ◽  
Mixed Effect ◽  
Mate Availability ◽  
Mixed Effect Models ◽  
Sexual Disgust ◽  
Linear Mixed Effect Models

Objective: One of the factors that sexual disgust should be calibrated to is the size of the mating pool. Previous research provides evidence that low mate availability affects perceptions related to mate choice. However, methodological shortcomings leave the role of sexual disgust in facilitating mate selection unclear. We will examine whether perceptions of mate availability explain variance in levels of sexual disgust towards potential mates.Methods: Participants (N = 1,000) will rate how sexually disgusting they find 60 potential mates that have previously been rated on attractiveness by a separate group of raters. We will measure participants’ perceptions of mate availability in their local environment, self-perceived attractiveness and mate value, and relevant control variables (e.g., age, relationship status). Results: We will use linear mixed effect models to examine (1) the association between sexual disgust towards potential mates and perceived mate availability; (2) the sex difference in sexual disgust; (3) the association between targets’ attractiveness and raters’ sexual disgust; and (4) whether perceived mate availability moderates the association between sexual disgust and targets’ attractiveness. Conclusions: This study will test perceptions of mate availability as an input into the calibration of sexual disgust. The results will clarify the magnitude of mate availability perceptions on mate choice.

scholarly journals Age Polyethism in Atta sexdens (Linnaeus) (Hymenoptera: Formicidae)

Sociobiology ◽  
2020 ◽  
Vol 67 (4) ◽  
pp. 508
Author(s):  
Fabrícia Gonçalves Lacerda ◽  
Leandro Sousa-Souto ◽  
Terezinha Maria Castro Della Lucia ◽  
Danival José De Souza
Keyword(s):  
Block Design ◽  
Distinct Pattern ◽  
Foraging Activity ◽  
Fungus Garden ◽  
Age Polyethism ◽  
Atta Sexdens ◽  
Mixed Effect ◽  
Mixed Effect Models ◽  
Laboratory Colonies ◽  
Linear Mixed Effect Models

This study aimed to verify age polyethism occurrence in medium-sized (cephalic capsule = 2.3 ± 0.21 mm) and small-sized (cc = 1.4 ± 0.10 mm) workers from Atta sexdens (Linnaeus) colonies. Four laboratory colonies were used, and they were maintained at 25 ± 2 °C, with 75 ± 3% relative humidity and a 12-hour photoperiod. Workers from these colonies were marked after their emergence and observed throughout their lifetime to determine which tasks they performed. The number of ants performing each activity was analyzed using linear mixed-effect models (LME), considering the temporal effect and the block design (colonies). We found that fungal garden maintenance tasks were frequent for both sizes, but their occurrence decreased significantly from the ninth week. The foraging activity occurred gradually in both sizes, with stabilization in the number of workers from the fourth week onwards and declined in the last three weeks of lifespan. Waste management tasks occurred throughout life but were more frequent during the first two weeks of life, in both medium and small workers. Therefore, age polyethism may be related to all activities; however, foraging tasks presented a distinct pattern compared to tasks in the fungus garden and refuse dump, where younger ants were more frequently observed.

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