Search results for "Linear regression"
showing 10 items of 375 documents
Relationship between Metabolic Fluxes and Sequence-Derived Properties of Enzymes
2014
Metabolic fluxes are key parameters of metabolic pathways being closely related to the kinetic properties of enzymes, thereby could be dependent on. This study examines possible relationships between the metabolic fluxes and the physical-chemical/structural features of enzymes from the yeast Saccharomyces cerevisiae glycolysis pathway. Metabolic fluxes were quantified by the COPASI tool using the kinetic models of Hynne and Teusink at varied concentrations of external glucose. The enzyme sequences were taken from the UniProtKB and the average amino acid (AA) properties were computed using the set of Georgiev’s uncorrelated scales that satisfy the VARIMAX criterion and specific AA indices th…
Application of Molecular Topology to the Prediction of the Reaction Yield and Anticancer Activity of Imidazole and Guanidine Derivatives
2013
In this study molecular topology based QSAR has been applied to predict the reaction yield and anticancer activity of 18 imidazole and guanidine derivatives. Four properties were evaluated, namely reaction yield, anti prostatic-cancer activity, anti breast-cancer activity and anti lung-cancer activity. The four models have been validated by both internal and cross validation, and also by randomness tests. The results obtained are in full agreement with the experimental results and confirm the precision, accuracy and robustness of the method followed. After carrying out a virtual screening upon such models, new imidazole and guanidine derivatives with potential anticancer activity are propos…
Species–area relationships in continuous vegetation: Evidence from Palaearctic grasslands
2019
Aim Species-area relationships (SARs) are fundamental scaling laws in ecology although their shape is still disputed. At larger areas, power laws best represent SARs. Yet, it remains unclear whether SARs follow other shapes at finer spatial grains in continuous vegetation. We asked which function describes SARs best at small grains and explored how sampling methodology or the environment influence SAR shape. Location Palaearctic grasslands and other non-forested habitats. Taxa Vascular plants, bryophytes and lichens. Methods We used the GrassPlot database, containing standardized vegetation-plot data from vascular plants, bryophytes and lichens spanning a wide range of grassland types throu…
Mortality and socioeconomic indicators in Spain 1962-1991
2000
Background: The study objectives were to describe the evolution of mortality and some socioeconomic indicators in the Spanish provinces (n=50) in order to quantify their association and assess the capability of these socioeconomic factors in explaining mortality levels in the Spanish provinces over the period 1962–1991. Methods: An ecological cross-sectional study was performed in order to assess the relationships between some socioeconomic indicators and mortality in Spain. Data on both-sexes, all-causes, age-adjusted mortality and infant mortality, gross national product per head, economically active population and unemployment rates, population density, state hospital functioning beds an…
Strategic and motivational factors as predictors of pre-service primary teachers's success in problem solving
2014
En este trabajo se presenta una investigación descriptiva que muestra las relaciones entre cinco factores motivacionales y estratégicos (planificación, estrategias cognitivas, autocontrol, esfuerzo y autoeficacia) y el rendimiento en la resolución de problemas. Se administró a 66 maestras y maestros de primaria en formación un cuadernillo con dos problemas (problema 1 y problema 2) y el test de O'Neil y Schacter. Los resultados de los análisis de regresión múltiple ponen de manifiesto que: a) planificación, esfuerzo y autoeficacia son predictores significativos de las puntuaciones de las puntuaciones del problema de estructura simple (problema 1); b) esfuerzo, autoeficacia y estrategias cog…
The Influence of Student Abilities and High School on Student Growth: A Case Study of Chinese National College Entrance Exam
2019
Enabled by available educational data and data mining techniques, educational data analysis has become a hot topic. Current researches mainly focus on the prediction of problems and performance rather than revealing the underlying causal relationships. Based on a unique exam data, we extracted the abilities of examinee from HSEE (High School Entrance Exam) based on the knowledge of educational experts, then we measured student growth from middle school to high school in total score and subject scores. We studied the impact of high school ranking and student abilities of HSEE on student growth by multiple linear regression model, in which high school ranking is divided into 5 levels, Level 1…
APROXIMACIÓN CONCEPTUAL Y PRÁCTICA A LOS MODELOS DE ECUACIONES ESTRUCTURALES
2017
En el presente trabajo se expone una aproximación conceptual y práctica a los Modelos de Ecuaciones Estructurales o Structural Equation Modeling (SEM). Los SEM están considerados entre las herramientas más potentes para el estudio de relaciones causales en datos no experimentales. Son una combinación del análisis factorial y la regresión múltiple y están compuestos por dos componentes: el modelo de medida y el modelo estructural. El modelo de medida describe la relación existente entre una serie de variables observables; mientras que en el modelo estructural se especifican las relaciones hipotetizadas entre las variables, es decir, se describen las relaciones entre las variables latentes me…
Authentication of extra virgin olive oils by Fourier-transform infrared spectroscopy
2010
Fourier-transform infrared spectroscopy (FTIR), followed by multivariate treatment of the spectral data, was used to classify vegetable oils according to their botanical origin, and also to establish the composition of binary mixtures of extra virgin olive oil (EVOO) with other low cost edible oils. Oil samples corresponding to five different botanical origins (EVOO, sunflower, corn, soybean and hazelnut) were used. The wavelength scale of the FTIR spectra of the oils was divided in 26 regions. The normalized absorbance peak areas within these regions were used as predictors. Classification of the oil samples according to their botanical origin was achieved by linear discriminant analysis (…
Use of electronic nose to determine defect percentage in oils. Comparison with sensory panel results
2010
Abstract An electronic nose based on an array of 6 metal oxide semiconductor sensors was used, jointly with linear discriminant analysis (LDA) and artificial neural network (ANN) method, to classify oils containing the five typical virgin olive oil (VOO) sensory defects (fusty, mouldy, muddy, rancid and winey). For this purpose, these defects, available as single standards of the International Olive Council, were added to refined sunflower oil. According to the LDA models and the ANN method, the defected samples were correctly classified. On the other hand, the electronic nose data was used to predict the defect percentage added to sunflower oil using multiple linear regression models. All …
Study on the financial performance of companies operating in the pharmaceutical industry in romania
2016
Abstract The study aims at determining the financial performance of companies in the pharmaceutical industry between 2009 and 2014 by means of the indicator of the financial return rate, using multiple linear regressions as research method. By analysing the evolution of the share of companies in the pharmaceutical industry based on the trend of the financial rate of return, we can estimate that the number of entities that resort to supporting the financial activities from loans and liabilities is growing in the period under analysis. This is due mainly to the liquidity crisis faced by entities, as a result of the high recovery duration of debts. Also, using the multiple linear regression we…