Search results for "Linear regression"

Optimization of ultrasound-assisted extraction of phenolic compounds from grapefruit (Citrus paradisiMacf.) leaves via D-optimal design and artificia…

2018

The extraction of phenolic compounds from grapefruit leaves assisted by ultrasound-assisted extraction (UAE) was optimized using response surface methodology (RSM) by means of D-optimal experimental design and artificial neural network (ANN). For this purpose, five numerical factors were selected: ethanol concentration (0-50%), extraction time (15-60 min), extraction temperature (25-50 °C), solid:liquid ratio (50-100 g L-1 ) and calorimetric energy density of ultrasound (0.25-0.50 kW L-1 ), whereas ultrasound probe horn diameter (13 or 19 mm) was chosen as categorical factor.; Results: The optimized experimental conditions yielded by RSM were: 10.80% for ethanol concentration; 58.52 min for…

Oral health-related quality of life after dental treatment in patients with intellectual disability

2020

Background The influence of dental treatment on oral health-related quality of life (OHRQOL) has rarely been evaluated in patients with intellectual disability (ID) through validated questionnaires. The aim of this study was to estimate the changes on OHRQOL in patients with ID after the implementation of an institutional dental treatment program under general anesthesia using the Franciscan Hospital for Children Oral Health-Related Quality of Life questionnaire (FHCOHRQOL-Q). Material and Methods A prospective longitudinal study was conducted on 85 patients (mean age=24.85 years) classified according to DSM-V whose parents/caregivers completed the FHC-OHRQOL-Q. We analyzed the changes in t…

2016

Purpose The use of new headless compression screws (HCSs) for scaphoid fixation is growing, but the nonunion rate has remained constant. The aim of this study was to compare the stability of fixation resulting from four modern HCSs using a simulated fracture model to determine the optimal screw design(s). Methods We tested 40 fresh-frozen cadaver scaphoids treated with the Acumed Acutrak 2 mini (AA), the KLS Martin HBS2 midi (MH), the Stryker TwinFix (ST) and the Synthes HCS 3.0 with a long thread (SH). The bones with simulated fractures and implanted screws were loaded uniaxially into flexion for 2000 cycles with a constant bending moment of 800 Nmm. The angulation of the fracture fragment…

Evaluation of the validity of the Bolton Index using cone-beam computed tomography (CBCT)

2012

Aims: To evaluate the reliability and reproducibility of calculating the Bolton Index using cone-beam computed tomography (CBCT), and to compare this with measurements obtained using the 2D Digital Method. Material and Methods: Traditional study models were obtained from 50 patients, which were then digitized in order to be able to measure them using the Digital Method. Likewise, CBCTs of those same patients were undertaken using the Dental Picasso Master 3D® and the images obtained were then analysed using the InVivoDental programme. Results: By determining the regression lines for both measurement methods, as well as the difference between both of their values, the two methods are shown t…

Assessment of the rate of force development scaling factor for the hip muscles

2014

Introduction: The aim of this study was to evaluate test feasibility, validity, and reproducibility of the rate of force development scaling factor (RFD-SF) for the hip muscles. Methods: Feasibility was assessed as the testing compliance, validity as the ability to compute the RFD-SF from a linear regression, and reproducibility with a test–retest design in 20 healthy subjects. Reliability and agreement (reproducibility) were evaluated using intraclass correlation coefficient (ICC3,1) and percent standard error of measurement (SEM), respectively. Results: The RFD-SF testing protocol was completed successfully by all subjects, although the analysis had to be modified for hip rotators. Reliab…

Identification for a general class of LPV Models

2000

Abstract In this paper we consider the problem of identifying discrete-time Linear Parameter Varying (LPV) models of non-linear or time-varying systems. LPV models are considered for their connection with the industrial practice of gain-scheduling. We assume that inputs, outputs and the scheduling parameters are measured, and a form of the functional dependence of the coefficients on the parameters is known. We show how the identification problem can be reduced to a linear regression so that a Least Mean Square identification algorithm can be reformulated. Conditions on the persistency of excitation in terms of the inputs and parameter trajectories are given to ensure the consistency of the…

Identification of linear parameter varying models

2003

We consider the problem of identifying discrete-time linear parameter varying models of nonlinear or time-varying systems. We assume that inputs, outputs and the scheduling parameters are measured, and a form of the functional dependence of the coefficients on the parameters. We show how the identification problem can be reduced to a linear regression, and we give conditions on persistency of excitation in terms of the inputs and parameter trajectories.

A density functional study of flavonoid compounds with anti-HIV activity.

2005

Abstract Quantum chemical calculations at the DFT/B3LYP theory level, with the 6-31G* basis set, was employed to calculate a set of molecular properties of 26 flavonoid compounds with anti-HIV activity. The correlation between biological activity and structural properties was obtained by using the multiple linear regression method. The model obtained showed not only statistical significance but also predictive ability. We demonstrate in this paper that the anti-HIV activity of compounds can be related with the molecular hydrophobicity (ClogP), the electronegativity ( χ ) and the charges on some key atoms, while that the toxicity can be related with the electronic affinities (EA), ClogP and …

Prediction of Aquatic Toxicity of Benzene Derivatives to Tetrahymena pyriformis According to OECD Principles

2016

Background: Many QSAR studies have been developed to predict acute toxicity over several biomarkers like Pimephales promelas, Daphnia magna and Tetrahymena pyriformis. Regardless of the progress made in this field there are still some gaps to be resolved such as the prediction of aquatic toxicity over the protozoan T. pyriformis still lack a QSAR study focused in accomplish the OECD principles. Methods: Atom-based quadratic indices are used to obtain quantitative structure-activity relationship (QSAR) models for the prediction of aquatic toxicity. Our models agree with the principles required by the OECD for QSAR models to regulatory purposes. The database employed consists of 392 substitut…

Correlation of pharmacological properties of a group of beta-blocker agents by molecular topology.

1995

Abstract The molecular connectivity method has been applied to the study of pharmacological properties, among which are found the angor treatment dose, α-distribution half-life and intravenous LD50 in mouse, of a group of β-blocker agents, verifying its application in the prediction of theoretic values for said pharmacological properties. To do this, the obtained multiple regression functions of the corresponding connectivity indices were used in relation with the experimental values of the properties, which are accompanied by the statistical parameters used in their selection criteria, as well as the corresponding random and cross-validation studies of said functions, which corroborate the…