Analysis Of Residual Distribution Research Articles

USE OF MACHINE LEARNING, FIXED AND MIXED MODELS FOR VOLUME ESTIMATION IN FLOODPLAIN FOREST IN THE AMAZON ESTUARY

The present study aimed to evaluate the performance of artificial neural networks (ANNs), support vector machines (SVM), and fixed and mixed models to estimate the volume of individual trees in an Amazonian estuary floodplain forest. The forest inventory was conducted in an area located in the district of Itatupã - Gurupá, Pará, Brazil. The Schumacher and Hall linear model was used in its fixed and mixed form to estimate the volume. A total of 240 ANNs and 32 SVM configurations were trained, with 4 variations of the input variables: diameter at breast height (D), commercial height (hm), diameter classes (CCD), commercial height classes (CChm),) and species (SP), with the volume (V) being the output variable. The ANNs were trained in the Neuro 4.0.6 software program, and the analyses of the fixed and mixed regression models and SVM were performed in the R software program. The AIC (Akaike’s Information Criterion) and BIC (Bayesian Information Criterion) information criteria were used for the regression models, while the following were used for comparisons of all models: correlation coefficient (rYŶ), bias, root mean squared error (RMSE), and residual distribution analysis. The best statistical metrics were obtained by the ANN of the RPROP- algorithm with D+hm+CCD+CChm inputs, with eight neurons in the hidden layer and hyperbolic tangent activation function, with 0.9827 of rYŶ RMSE of 0.2439, bias of 0.0080 and residual graphic distribution tending to homogeneity.

A Damping Modification Factor Prediction Model for Horizontal Displacement Spectrum from Shallow Crustal and Upper-Mantle Earthquakes in Japan Accounting for Site Conditions

ABSTRACT This article presents damping modification factors (DMFs) for the horizontal component of the strong-motion records generated by the shallow crustal and upper-mantle earthquakes in Japan. This model can be used to scale a 5% damped design spectrum that does not associate with a known magnitude and rupture distance to obtain a design spectrum with the desirable damping ratios. Our previous study suggested that the site effect on DMF was significant, and we used site class as the site-effect parameter. We used a quadratic function of damping ratio in a natural logarithm scale to model the effect of damping ratios and we used fourth-order polynomials of the natural logarithm spectral period to present the effect of the spectral period when the spectral period is over 0.06 s. The between-event, between-site, and within-site standard deviations can be described by the linear function of the damping ratio in a natural logarithm scale. The between-event standard deviations are smaller than the within-event standard deviations and the between-site standard deviations are less than the within-site ones at many spectral periods. Reasonable displacement spectra can be obtained by using the DMF model from this study to scale the 5% damped displacement spectra. The differences in the DMF values from the three types of earthquakes are moderate at many spectral periods and the predicted DMF values from this study are similar to those from other studies at some spectral periods, but the differences are considerable at the other spectral periods. The variation trend of the DMF values suggests that the predicted DMF values may reach the theoretic value of 1.0 at some spectral periods over 5.0 s. Residual distribution analysis suggested that the bilinear function of magnitude and fault-top depth can be used in a model for scenario earthquakes.

Analysis probes and statistical parameters affecting the OSL ages of mortar samples; a case study from Italy

Mortars stand among the very few materials that theoretically cannot be reused due to irreversible hardening processes. Among the various dating techniques, radiocarbon and Optically Stimulated Luminescence (OSL) struggle for being selected as the most robust and reliable dating technique for the specific material. The principle of mortar OSL dating depends on the bleaching of the quartz grains of the sandy aggregate while mixing and laying the mortar to daylight. Thus, the OSL ages strongly depend on the effective bleaching of the quartz. Here, we deal with OSL ages from the old Roman Theatre of Padua. Preliminary OSL results based on Single Aliquot Regeneration (SAR) protocol using three regenerated doses to multigrain (MG) quartz aliquots, indicated distributions of ED (Equivalent Dose) leading to significant mismatch of these results compared to the expected ages. The present work attempts to discuss the influence of various data analysis approaches such as (a) exclusion criteria like recycling ratio and recuperation values, (b) selection of the suitable region of interest in the signal's integral along with the correct background (late or early) subtraction technique and (c) appropriate statistical analysis by selecting the suitable age model (descriptive statistics, Central Age Model, Minimum Age Model) on the final distribution as well as both value and precision of the ED, enabling thus to obtain ages that are not only more accurate, but also closer to what was expected. Alternative statistical indicators of either the symmetry of the ED distributions (like skewness, kurtosis, etc) or the OSL signal itself (residual distribution analysis, kinetic parameters and percentage contribution of each OSL component to the overall signal) will be assessed in an effort to investigate possible correlations.

Adjustment of the Grass Fuel Moisture Code for Grasslands in Southern Brazil

Grasslands are one of the vegetation types most widely affected by wildfires in southern Brazil. It is a fire-dependent ecosystem and it is necessary to know the hourly fuel moisture variation for its management. The objective of this work is to fit Grass Fuel Moisture Code (GFMC) models to estimate the moisture content for the grassland of the State Park of Vila Velha, Paraná, Brazil. Data sampling to determine the hourly moisture content was performed during the winter of 2018 and divided into two campaigns of five days with stable weather conditions. Destructive samples were taken out for the sorption tests on climatic chambers to obtain the equilibrium moisture content and the time lag values. The fitted equilibrium moisture and time lag models were evaluated by residual distribution analysis, mean absolute error (MAE), root mean square error (RSME) and coefficient of determination (R2). The fitted model performed better than the original GFMC model due to the obtained MAE, RSME and R2 values. The results showed that the fitted GFMC model is better to predict the fine fuel moisture for the region.

Development and evaluation of the refined zenith tropospheric delay (ZTD) models

The tropospheric delay is a significant error source in Global Navigation Satellite System (GNSS) positioning and navigation. It is usually projected into zenith direction by using a mapping function. It is particularly important to establish a model that can provide stable and accurate Zenith Tropospheric Delay (ZTD). Because of the regional accuracy difference and poor stability of the traditional ZTD models, this paper proposed two methods to refine the Hopfield and Saastamoinen ZTD models. One is by adding annual and semi-annual periodic terms and the other is based on Back-Propagation Artificial Neutral Network (BP-ANN). Using 5-year data from 2011 to 2015 collected at 67 GNSS reference stations in China and its surrounding regions, the four refined models were constructed. The tropospheric products at these GNSS stations were derived from the site-wise Vienna Mapping Function 1 (VMP1). The spatial analysis, temporal analysis, and residual distribution analysis for all the six models were conducted using the data from 2016 to 2017. The results show that the refined models can effectively improve the accuracy compared with the traditional models. For the Hopfield model, the improvement for the Root Mean Square Error (RMSE) and bias reached 24.5/49.7 and 34.0/52.8 mm, respectively. These values became 8.8/26.7 and 14.7/28.8 mm when the Saastamoinen model was refined using the two methods. This exploration is conducive to GNSS navigation and positioning and GNSS meteorology by providing more accurate tropospheric prior information.

Deciphering human decision rules in motion discrimination

We investigated the eight decision rules for a same-different task, as summarized in Petrov (Psychonomic Bulletin & Review, 16(6), 1011–1025, 2009). These rules, including the differencing (DF) rule and the optimal independence rule, are all based on the standard model in signal detection theory. Each rule receives two stimulus values as inputs and uses one or two decision criteria. We proved that the false alarm rate p(F) ≤ 1/2 for four of the rules. We also conducted a same-different rating experiment on motion discrimination (n = 54), with 4∘ or 8∘ directional difference. We found that the human receiver operating characteristic (ROC) spanned its full range [0,1] in p(F), thus rejecting these four rules. The slope of the human Z-ROC was also < 1, further confirming that the independence rule was not used. We subsequently fitted in the four-dimensional (pAA, pAB, pBA, pBB) space the human data to the remaining four rules—DF and likelihood ratio rules, each with one or two criteria, where pXY = p(responding “different” given stimulus sequence XY). We found that, using residual distribution analysis, only the two criteria DF rule (DF2) could account for the human data.

Are models of volumetric production at the diametric distribution and total stand level mutually compatible?

The objective of this work was to compare estimates generated by a diametric distribution model and a total stand model against the pre-cut inventory. The model efficiency was also evaluated. Data were evaluated from 30 permanent sample plots in a Eucalyptus urophylla stand, comprising 24 sample plots used for model fitting, and six sample plots for validation. The volume of wood per hectare was estimated for different productive units (sites), using 7 years as the reference age. The model adjustment quality was verified by adjustment and precision statistics: the correlation between observed and predicted variables, root mean square error percentage, graphical analysis of residual distribution, and a frequency histogram for classes of relative errors and validation. Although the two-parameter Weibull probability density function adhered to the data for tree evolution in diameter classes for the reference age (7 years) in the different productivity classes, it generated imprecise estimates of the number of individuals. Consequently, it produced inaccurate volumetric production estimates. The total stand model provided reliable projections of production volumes in different productivity classes for both adjustment types, showing compatibility with the pre-cut inventory according to a Tukey test. In summary, the total stand model generated estimates that were compatible with the pre-cut inventory while the diametric distribution model did not.

Optimal esophageal balloon volume for accurate estimation of pleural pressure at end-expiration and end-inspiration: an in vitro bench experiment

BackgroundEsophageal pressure, used as a surrogate for pleural pressure, is commonly measured by air-filled balloon, and the accuracy of measurement depends on the proper balloon volume. It has been found that larger filling volume is required at higher surrounding pressure. In the present study, we determined the balloon pressure-volume relationship in a bench model simulating the pleural cavity during controlled ventilation. The aim was to confirm whether an optimal balloon volume range existed that could provide accurate measurement at both end-expiration and end-inspiration.MethodsWe investigated three esophageal balloons with different dimensions and materials: Cooper, SmartCath-G, and Microtek catheters. The balloon was introduced into a glass chamber simulating the pleural cavity and volume-controlled ventilation was initiated. The ventilator was set to obtain respective chamber pressures of 5 and 20 cmH2O during end-expiratory and end-inspiratory occlusion. Balloon was progressively inflated, and balloon pressure and chamber pressure were measured. Balloon transmural pressure was defined as the difference between balloon and chamber pressure. The balloon pressure-volume curve was fitted by sigmoid regression, and the minimal and maximal balloon volume accurately reflecting the surrounding pressure was estimated using the lower and upper inflection point of the fitted sigmoid curve. Balloon volumes at end-expiratory and end-inspiratory occlusion were explored, and the balloon volume range that provided accurate measurement at both phases was defined as the optimal filling volume.ResultsSigmoid regression of the balloon pressure-volume curve was justified by the dimensionless variable fitting and residual distribution analysis. All balloon transmural pressures were within ±1.0 cmH2O at the minimal and maximal balloon volumes. The minimal and maximal balloon volumes during end-inspiratory occlusion were significantly larger than those during end-expiratory occlusion, except for the minimal volume in Cooper catheter. Mean (±standard deviation) of optimal filling volume both suitable for end-expiratory and end-inspiratory measurement ranged 0.7 ± 0.0 to 1.7 ± 0.2 ml in Cooper, 1.9 ± 0.2 to 3.6 ± 0.3 ml in SmartCath-G, and 2.2 ± 0.2 to 4.6 ± 0.1 ml in Microtek catheter.ConclusionsIn each of the tested balloon, an optimal filling volume range was found that provided accurate measurement during both end-expiratory and end-inspiratory occlusion.

Desorption isotherms of Lactuca sativa seeds

ABSTRACT Lactuca sativa seeds are highly sensitive to climate conditions; thus, they should be stored securely to maintain their qualitative and quantitative characteristics. Studies on hygroscopicity aim to decrease possible changes in agricultural products under specific environmental conditions. Accordingly, this study aims to develop an appropriate mathematical model to represent the desorption isotherms of Lactuca sativa seeds. The hygroscopic equilibrium was achieved using a static-gravimetric method at temperatures of 10, 20, 30, 40 and 50 °C and water activity in the range 0.11-0.96. Six mathematical models were fitted to the experimental data of the equilibrium moisture content of Lactuca sativa seeds. The best model was chosen based on the determination coefficient (R2), magnitude of mean relative error (MRE), standard deviation of the estimate (SDE), and analysis of residue distribution. The modified Oswin model best represented the hygroscopicity of the Lactuca sativa seeds, with values of 8.02% and 0.55 for the MRE and SDE, respectively; moreover, the residual values were randomly distributed. The shape of the isotherms of the Lactuca sativa seeds estimated using the modified Oswin model is sigmoidal, which is characteristic of a type II curve.

Recognizing the Limited Applicability of Job Plots in Studying Host-Guest Interactions in Supramolecular Chemistry.

Continuous variation method, known as Job plot, is the most commonly applied method for the determination of stoichiometry of complex chemical entities for over 100 years. Although, the method was proven successful in the analysis of very stable metal-ligand complexes, we demonstrate that its use in supramolecular chemistry often provides false results. We support this statement with multiple simulations as well as cases studies of several real host-guest systems. We propose an alternative, general method relying on the analysis of residual distribution in titration data fitting. The latter method is more convenient compared to the Job plot and unlike it gives correct results in all real cases studied.

Effect of NaCl on the conformational stability of the thermophilic γ-glutamyltranspeptidase from Geobacillus thermodenitrificans: Implication for globular protein halotolerance

The transpeptidation activity of γ-glutamyltranspeptidase from Geobacillus thermodenitrificans (GthGT) is negligible and the enzyme is highly thermostable. Here we have examined the effect of concentrated NaCl solutions on structure, stability, dynamics and enzymatic activity of GthGT. The protein exhibited hydrolytic activity over a broad range of NaCl concentrations. Even at 4.0M NaCl, GthGT retained more than 90% of the initial activity and showed unaltered fluorescence emission, secondary structure and acrylamide quenching on tryptophan fluorescence. Furthermore, at 2.8M and 4.0M NaCl the temperature-induced unfolding profiles are dramatically changed with large (>20°C) positive shifts in the denaturation temperature. These features make GthGT an ideal system to be used in industrial processes that require high temperatures and high-salt environments. A general explanation of the NaCl effect by means of a statistical thermodynamic model is also provided, together with an analysis of residue distribution between protein surface and interior in 15 non-redundant families of halophilic and non-halophilic proteins. The results are in line with a comparative sequence and structural analysis between halophilic and non-halophilic γ-glutamyltranspeptidases which revealed that a major role in halotolerance should be played by solvent exposed negatively charged residues.

Kinetics of Coke Formation on a Fe-ZSM-5 Zeolite Catalyst in the One-Step Oxidation of Benzene to Phenol with N2O

The coking behavior of the Fe-ZSM-5 zeolite catalyst during the oxidation of benzene with N2O to phenol was studied in an isothermal fixed-bed reactor using thermogravimetry. The effect of reaction time and temperature as well as the molar ratio of reactants on coking was investigated. Based on information obtained from experiments and a gas chromatography-mass spectrometry analysis of the coke on the catalyst, we suggest a mechanism for coke formation. Results show that the formed coke mainly comes from the further oxidation of phenol, revealing that sequential deactivation occurs in the main reaction. Based on the suggested mechanism, a kinetic model for coke formation that describes coke deposition over the Fe-ZSM-5 zeolite catalyst was developed. A statistical test and a residual distribution analysis show that the kinetic model established here is in good agreement with the experimental data and is acceptable and reliable.

Hydration of the peptide backbone largely defines the thermodynamic propensity scale of residues at the C' position of the C-capping box of alpha-helices.

The C' position of the C-capping box is the second residue outside of the helix. Statistical analysis of residue distribution at the C' position in the alpha-helices' C-capping box showed that different amino acid residues occur with different probabilities, with the strongest preference being for glycine. To understand the physico-chemical basis for this preference, we studied the effects that 17 amino acid substitutions at the C' position in an alpha-helix of ubiquitin have on the stability of this protein. We determined the following rank order of amino acid residues at the C' position with respect to their effect on the stability: Gly>His>Asn>Arg>Lys>Gln>Ala>Phe>Met>Ser>Asp>Glu>Trp>Thr>Pro>Ile>Val. The effect of the amino acid substitutions on the structure also was evaluated by comparing the (1)H-(15)N heteronuclear sequential quantum correlation spectra and showed no significant changes in the structures of the most stable (Gly) and the least stable (Val) variants. The obtained changes in stability highly correlate (r = 0.85) with the statistical distribution of the residues at the C' position indicating that the measured thermodynamic propensities are unbiased by secondary interactions. We also found that the measured thermodynamic propensities correlate well with the amide hydrogen exchange data on short model peptides (r = 0.85) and the calculated hydration of the peptide backbone (r = 0.88). These results combined with the changes in enthalpy and entropy of unfolding of ubiquitin variants suggest that dehydration of the peptide backbone plays a significant role in defining the thermodynamic propensity scale at the C' position of the C-capping box in alpha-helices. This propensity scale is useful for protein secondary structure predictions and protein design.