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22
result(s) for
"environmental explanatory variables"
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Bulbous perennials precisely detect the length of winter and adjust flowering dates
2020
In order to identify the most relevant environmental parameters that regulate flowering time of bulbous perennials, first flowering dates of 329 taxa over 33 yr are correlated with monthly and daily mean values of 16 environmental parameters (such as insolation, precipitation, temperature, soil water content, etc.) spanning at least 1 yr back from flowering.
A machine learning algorithm is deployed to identify the best explanatory parameters because the problem is strongly prone to overfitting for traditional methods: if the number of parameters is the same or greater than the number of observations, then a linear model can perfectly fit the dependent variable (observations).
Surprisingly, the best proxy of flowering date fluctuations is the daily snow depth anomaly, which cannot be a signal itself, however it should be related to some integrated temperature signal. Moreover, daily snow depth anomaly as proxy performs much better than mean soil temperature preceding the flowering, the best monthly explanatory parameter.
Our findings support the existence of complicated temperature sensing mechanisms operating on different timescales, which is a prerequisite to precisely observe the length and severity of the winter season and translate for example, ‘lack of snow’ information to meaningful internal signals related to phenophases.
Journal Article
Key environmental and production factors for understanding variation in switchgrass chemical attributes
by
Payne, Courtney
,
Wolfrum, Ed
,
Crawford, Jamie
in
Agricultural production
,
Alternative energy sources
,
bioenergy
2022
Switchgrass (Panicum virgatum L.) is a promising feedstock for bioenergy and bioproducts; however, its inherent variability in chemical attributes creates challenges for uniform conversion efficiencies and product quality. It is necessary to understand the range of variation and factors (i.e., field management, environmental) influencing chemical attributes for process improvement and risk assessment. The objectives of this study were to (1) examine the impact of nitrogen fertilizer application rate, year, and location on switchgrass chemical attributes, (2) examine the relationships among chemical attributes, weather and soil data, and (3) develop models to predict chemical attributes using environmental factors. Switchgrass samples from a field study spanning four locations including upland cultivars, one location including a lowland cultivar, and between three and six harvest years were assessed for glucan, xylan, lignin, volatiles, carbon, nitrogen, and ash concentrations. Using variance estimation, location/cultivar, nitrogen application rate, and year explained 65%–96% of the variation for switchgrass chemical attributes. Location/cultivar × year interaction was a significant factor for all chemical attributes indicating environmental‐based influences. Nitrogen rate was less influential. Production variables and environmental conditions occurring during the switchgrass field trials were used to successfully predict chemical attributes using linear regression models. Upland switchgrass results highlight the complexity in plant responses to growing conditions because all production and environmental variables had strong relationships with one or more chemical attributes. Lowland switchgrass was limited to observations of year‐to‐year environmental variability and nitrogen application rate. All explanatory variable categories were important for lowland switchgrass models but stand age and precipitation relationships were particularly strong. The relationships found in this study can be used to understand spatial and temporal variation in switchgrass chemical attributes. The ability to predict chemical attributes critical for conversion processes in a geospatial/temporal manner would provide state‐of‐the‐art knowledge for risk assessment in the bioenergy and bioproducts industry. Switchgrass is a promising feedstock for bioenergy and bioproducts. Chemical attributes were assessed for switchgrass from a field study spanning five locations and up to six harvest years. Production variables and environmental conditions occurring during the switchgrass field trials were used to successfully predict chemical attributes using linear regression models. The relationships found in this study can be used to understand spatial and temporal variation in switchgrass chemical attributes. The ability to predict chemical attributes critical for conversion processes in a geospatial/temporal manner would provide state‐of‐the‐art knowledge for risk assessment in the bioenergy and bioproducts industry.
Journal Article
Forward selection of explanatory variables
by
Legendre, Pierre
,
Borcard, Daniel
,
Blanchet, F. Guillaume
in
Analysis
,
Animal and plant ecology
,
Animal, plant and microbial ecology
2008
This paper proposes a new way of using forward selection of explanatory variables in regression or canonical redundancy analysis. The classical forward selection method presents two problems: a highly inflated Type I error and an overestimation of the amount of explained variance. Correcting these problems will greatly improve the performance of this very useful method in ecological modeling. To prevent the first problem, we propose a two-step procedure. First, a global test using all explanatory variables is carried out. If, and only if, the global test is significant, one can proceed with forward selection. To prevent overestimation of the explained variance, the forward selection has to be carried out with two stopping criteria: (1) the usual alpha significance level and (2) the adjusted coefficient of multiple determination ($R_{a}^{2}$) calculated using all explanatory variables. When forward selection identifies a variable that brings one or the other criterion over the fixed threshold, that variable is rejected, and the procedure is stopped. This improved method is validated by simulations involving univariate and multivariate response data. An ecological example is presented using data from the Bryce Canyon National Park, Utah, USA.
Journal Article
Land use land cover change in the African Great Lakes Region: a spatial–temporal analysis and future predictions
by
Tonini, Marj
,
Guzha, Alphonce C.
,
Mariethoz, Gregoire
in
Agricultural land
,
Agriculture
,
Atmospheric Protection/Air Quality Control/Air Pollution
2024
The African Great Lakes Region has experienced substantial land use land cover change (LULCC) over the last decades, driven by a complex interplay of various factors. However, a comprehensive analysis exploring the relationships between LULCC, and its explanatory variables remains unexplored. This study focused on the Lake Kivu catchment in Rwanda, analysing LULCC from 1990 to 2020, identifying major variables, and predicting future LULC scenarios under different development trajectories. Image classification was conducted in Google Earth Engine using random forest classifier, by incorporating seasonal composites Landsat images, spectral indices, and topographic features, to enhance discrimination and capture seasonal variations. The results demonstrated an overall accuracy exceeding 83%. Historical analysis revealed significant changes, including forest loss (26.6 to 18.7%) and agricultural land expansion (27.7 to 43%) in the 1990–2000 decade, attributed to political conflicts and population movements. Forest recovery (24.8% by 2020) was observed in subsequent decades, driven by Rwanda’s sustainable development initiatives. A Multi-Layer Perceptron neural network from Land Change Modeler predicted distinct 2030 and 2050 LULC scenarios based on natural, socio-economic variables, and historical transitions. Analysis of explanatory variables highlighted the significant role of proximity to urban centers, population density, and terrain in LULCC. Predictions indicate distinct trajectories influenced by demographic and socio-economic trends. The study recommends adopting the Green Growth Economy scenario aligned with ongoing conservation measures. The findings contribute to identifying opportunities for land restoration and conservation efforts, promoting the preservation of Lake Kivu catchment’s ecological integrity, in alignment with national and global goals.
Graphical Abstract
Journal Article
Forecast generation model of municipal solid waste using multiple linear regression
by
Araiza-Aguilar, J A
,
Rojas-Valencia, M N
,
Aguilar-Vera, R A
in
Demographic variables
,
Demographics
,
explanatory variables
2020
The objective of this study was to develop a forecast model to determine the rate of generation of municipal solid waste in the municipalities of the Cuenca del Cañón del Sumidero, Chiapas, Mexico. Multiple linear regression was used with social and demographic explanatory variables. The compiled database consisted of 9 variables with 118 specific data per variable, which were analyzed using a multicollinearity test to select the most important ones. Initially, different regression models were generated, but only 2 of them were considered useful, because they used few predictors that were statistically significant. The most important variables to predict the rate of waste generation in the study area were the population of each municipality, the migration and the population density. Although other variables, such as daily per capita income and average schooling are very important, they do not seem to have an effect on the response variable in this study. The model with the highest parsimony resulted in an adjusted coefficient of 0.975, an average absolute percentage error of 7.70, an average absolute deviation of 0.16 and an average root square error of 0.19, showing a high influence on the phenomenon studied and a good predictive capacity.
Journal Article
The Influence of Individual Set-Pieces in Elite Rink Hockey Match Outcomes
by
Hileno, Raúl
,
Trabal, Guillem
,
Fort-Vanmeerhaeghe, Azahara
in
Athletic Performance
,
Business metrics
,
Hockey
2021
The main objective of this study was to analyze the influence of individual set-pieces (Free Direct Hits and Penalties) in elite rink hockey match outcomes in different game situations. A sample of 161 matches played between high-standard teams during ten consecutive seasons (2009–2010 to 2018–2019) were analyzed using a binary logistic regression. The full evaluated model was composed of an explanatory variable (set-pieces scored) and five potential confounding and interaction variables (match location, match level, match importance, extra time, and balanced score). However, the final model only included one significant interaction variable (balanced score). The results showed that scoring more individual set-pieces than the opponent was associated with victory (OR = 6.1; 95% CI: 3.7, 10.0) and was more relevant in unbalanced matches (OR = 19.5; 95% CI: 8.6, 44.3) than in balanced matches (OR = 2.3; 95% CI: 1.2, 4.5). These findings indicate that individual set-pieces are strongly associated with match outcomes in matches played between high-standard teams. Therefore, it is important for teams to excel in this aspect, and it is suggested that these data can encourage coaches to reinforce the systematic practice of individual set-pieces in their training programs. Additionally, it is suggested that teams have specialist players in this kind of action to mainly participate in these specific match moments.
Journal Article
An Explanatory Model of Sexual Satisfaction in Adults with a Same-Sex Partner: An Analysis Based on Gender Differences
by
Calvillo, Cristóbal
,
Sánchez-Fuentes, María del Mar
,
Sierra, Juan Carlos
in
Adjustment
,
Adult
,
Anxiety
2020
This study aimed to develop an explanatory model of sexual satisfaction in same-sex attracted individuals with a partner, based on personal and interpersonal variables. The participants were 410 men (mean age = 29.24, SD = 9.84) and 410 women (mean age = 29, SD = 8.57) who maintained a relationship with another person of the same sex. Internalized homophobia was considered as a personal variable, and as interpersonal variables, the dimensions of attachment (anxiety and avoidance), sexual functioning, dyadic adjustment, relationship satisfaction, the components of the Interpersonal Exchange Model of Sexual Satisfaction, the number of sexual costs and the number of sexual rewards were considered. The degree to which sexual satisfaction was related to these variables was examined separately, for both men and women, through multiple linear regression models within the framework of structural equation models. The results indicated that sexual satisfaction is associated in a negative sense with internalized homophobia, the number of sexual costs, anxiety, and avoidance, and in a positive sense with the remaining variables. Relational variables were more relevant in the explanation of sexual satisfaction. The clinical implications are discussed.
Journal Article
Short-Term Urban Water Demand Prediction Considering Weather Factors
by
Mawada Abdellatif
,
Zubaidi, Salah L
,
Alkhaddar, Rafid M
in
Algorithms
,
Artificial neural networks
,
Computer simulation
2018
Accurate and reliable forecasting plays a key role in the planning and designing of municipal water supply infrastructures. Recent studies related to water demand prediction have shown that water demand is driven by weather variables, but the results do not clearly show to what extent. The principal aim of this research was to better understand the effects of weather variables on water demand. Additionally, it aimed to offer an appropriate and reliable technique to predict municipal water demand by using the Gravitational Search Algorithm (GSA) and Backtracking Search Algorithm (BSA) with Artificial Neural Network (ANN). Moreover, eight weather factors were adopted to evaluate their impact on the water demand. The principal findings of this research are that the hybrid GSA-ANN (Agent = 40) model is superior in terms of fitness function (based on RMSE) for yearly and seasonal phases. In addition, it is evidently clear from the findings that the GSA-ANN model has the ability to simulate both seasonal and yearly patterns for daily data water consumption.
Journal Article
Probabilistic assessment of the earthquake-induced soil liquefaction hazard at national scale: macrozonation of the Italian territory
2023
Seismic soil liquefaction is one of the most relevant phenomena of ground failure that may induce disastrous consequences on structures, infrastructures and the environment. This article presents the first probabilistic zonation for liquefaction hazard at national scale, carried out with reference to Italy. Macrozonation is the geospatial identification of areas in a national territory that, in case of an earthquake, may be affected by phenomena associated to soil liquefaction by using a probabilistic approach. Zonation of a large territory for earthquake-induced liquefaction hazard seems to be, at least at a first glance, an unachievable goal, since liquefaction occurs at a very local scale. In this study, the strategy for macrozoning consists in combining and processing geospatial predictors, which represent both ground susceptibility to liquefaction and expected seismic loading. A database was built for the Italian territory including the explanatory variables adopted as proxies for soil density, degree of saturation and ground motion intensity. This database represents the starting point for the application of a geospatial methodology based on logistic regression for assessing the liquefaction hazard in Italy. The outcomes are macrozonation charts computed for three return periods (i.e. 475, 975 and 2475 years) with a spatial resolution on the order of 500 m. The mapping was validated by superimposing historical liquefaction and then compared with the coarser charts recently delivered for Europe. Despite their intrinsic limitations, national scale maps of liquefaction hazard may support decision-makers, civil protection agencies, insurance and re-insurance companies to fund zonation projects at regional or even at urban/suburban scale.
Journal Article
Health Related Values and Preferences Regarding Meat Intake: A Cross-Sectional Mixed-Methods Study
by
Santero, Marilina
,
Bala, Malgorzata M.
,
Rabassa, Montserrat
in
Cancer
,
Cross-sectional studies
,
Dietary guidelines
2021
Background. In addition to social and environmental determinants, people’s values and preferences determine daily food choices. This study evaluated adults’ values and preferences regarding unprocessed red meat (URM) and processed meat (PM) and their willingness to change their consumption in the face of possible undesirable health consequences. Methods. A cross-sectional mixed-methods study including a quantitative assessment through an online survey, a qualitative inquiry through semi-structured interviews, and a follow-up assessment through a telephone survey. We performed descriptive statistics, logistic regressions, and thematic analysis. Results. Of 304 participants, over 75% were unwilling to stop their consumption of either URM or PM, and of those unwilling to stop, over 80% were also unwilling to reduce. Men were less likely to stop meat intake than women (odds ratios < 0.4). From the semi-structured interviews, we identified three main themes: the social and/or family context of meat consumption, health- and non-health-related concerns about meat, and uncertainty of the evidence. At three months, 63% of participants reported no changes in meat intake. Conclusions. When informed about the cancer incidence and mortality risks of meat consumption, most respondents would not reduce their intake. Public health and clinical nutrition guidelines should ensure that their recommendations are consistent with population values and preferences.
Journal Article