Search results for "Discriminant"
showing 10 items of 344 documents
Atom- and Bond-Based 2D TOMOCOMD-CARDD Approach and Ligand-Based Virtual Screening for the Drug Discovery of New Tyrosinase Inhibitors
2008
Two-dimensional atom- and bond-based TOMOCOMD-CARDD descriptors and linear discriminant analysis (LDA) are used in this report to perform a quantitative structure-activity relationship (QSAR) study of tyrosinase-inhibitory activity. A database of inhibitors of the enzyme is collected for this study, within 246 highly dissimilar molecules presenting antityrosinase activity. In total, 7 discriminant functions are obtained by using the whole set of atom- and bond-based 2D indices. All the LDA-based QSAR models show accuracies above 90% in the training set and values of the Matthews correlation coefficient (C) varying from 0.85 to 0.90. The external validation set shows globally good classifica…
On the classification of algebraic function fields of class number three
2012
AbstractLet F be an algebraic function field of one variable having a finite field Fq with q>2 elements as its field of constants. We determine all such fields for which the class number is three. More precisely, we show that, up to Fq-isomorphism, there are only 8 of such function fields. For q=2 the problem has been solved under the additional hypothesis that the function field is quadratic.
Milnor Number Equals Tjurina Number for Functions on Space Curves
2001
The equality of the Milnor number and Tjurina number for functions on space curve singularities, as conjectured recently by V. Goryunov, is proved. As a consequence, the discriminant in such a situation is a free divisor.
More on the Dimensionality of the GHQ-12: Competitive Confirmatory Models
2019
The General Health Questionnaire (GHQ) was designed to measure minor psychiatric morbidity by assessing normal ‘healthy’ functioning and the appearance of new, distressing symptoms. Among its versions, the 12-item is one of the most used. GHQ-12’s validity and reliability have been extensively tested in samples from different populations. In the Spanish version, studies have come to different conclusions, of one, two, and three-factor structures. This research aims to present additional evidence on the factorial validity of the Spanish version of the GHQ-12, using competitive confirmatory models. Three samples of workers (N= 525, 414 and 540) were used to test a set of substantive models pr…
Pharmacological distribution diagrams: a tool for de novo drug design.
1996
Abstract Discriminant analysis applied to SAR studies using topological descriptors allows us to plot frequency distribution diagrams: a function of the number of drugs within an interval of values of discriminant function vs. these values. We make use of these representations, pharmacological distribution diagrams (PDDs), in structurally heterogeneous groups where generally they adopt skewed Gaussian shapes or present several maxima. The maxima afford intervals of discrimianant function in which exists a good expectancy to find new active drugs. A set of β-blockers with contrasted activity has been selected to test the ability of PDDs as a visualizing technique, for the identification of n…
New antitrichomonal drug-like chemicals selected by bond (edge)-based TOMOCOMD-CARDD descriptors.
2008
Bond-based quadratic indices, new TOMOCOMD-CARDD molecular descriptors, and linear discriminant analysis (LDA) were used to discover novel lead trichomonacidals. The obtained LDA-based quantitative structure-activity relationships (QSAR) models, using nonstochastic and stochastic indices, were able to classify correctly 87.91% (87.50%) and 89.01% (84.38%) of the chemicals in training (test) sets, respectively. They showed large Matthews correlation coefficients of 0.75 (0.71) and 0.78 (0.65) for the training (test) sets, correspondingly. Later, both models were applied to the virtual screening of 21 chemicals to find new lead antitrichomonal agents. Predictions agreed with experimental resu…
Identification <i>In Silico</i> and <i>In Vitro</i> of Novel Trypanosomicidal Drug-like Compounds
2012
Atom-based bilinear indices and linear discriminant analysis are used to discover novel trypanosomicidal compounds. The obtained linear discriminant analysis-based quantitative structure–activity relationship models, using non-stochastic and stochastic indices, provide accuracies of 89.02% (85.11%) and 89.60% (88.30%) of the chemicals in the training (test) sets, respectively. Later, both models were applied to the virtual screening of 18 in-house synthesized compounds to find new pro-lead antitrypanosomal agents. The in vitro antitrypanosomal activity of this set against epimastigote forms of Trypanosoma cruzi is assayed. Predictions agree with experimental results to a great extent (16/18…
The Role of Individual and Relational Characteristics on Alcohol Consumption among Italian Adolescents: A Discriminant Function Analysis
2013
The aim of the present study was to explore the association between family functioning, coping strategies, peer influences and alcohol use among Italian adolescents. Nine hundred and sixty-three Italian adolescents, aged from 14 to 17 years, completed self-report measures assessing alcohol use, family functioning, and coping strategies. According to previous research, adolescents were categorized into non-drinkers, social, binge and heavy drinkers. Results showed that adolescents belonging to groups characterized by alcohol misuse differ in terms of coping strategies, family functioning dimensions, and typology of friends. In particular, heavy drinkers appeared to have more friends who drin…
Multiple morphological characters needed for field identification of cryptic long‐eared bat species around the Swiss Alps
2010
The identification of cryptic species may significantly change our view about their distribution, abundance, ecology and therefore conservation status. In the European Alps, molecular studies have revealed the existence of three sibling species of plecotine bats Plecotus auritus, Plecotus austriacus and, very recently, Plecotus macrobullaris. Knowledge of the ecological niche partitioning of cryptic species is a requisite to develop sound conservation policies. Yet, this requests the development of unambiguous identification methods easily applicable in the field. This study investigates the reliability of several morphological methods used for species recognition and proposes a new identif…
Correspondence between regional delineations and spatial patterns in macroinvertebrate assemblages of boreal headwater streams
2002
AbstractGeographical stratification may provide a useful framework for stream management programs, yet most studies testing the utility of such stratifications have been conducted in temperate regions. We studied the correspondence between regional delineations (5 ecoregions, 11 subecoregions), environmental characteristics, and benthic macroinvertebrate assemblages in 156 boreal headwater streams in Finland, using a combination of principal components analysis, nonmetric multidimensional scaling, and discriminant function analysis (DFA). Both stream characteristics and macroinvertebrate assemblage structure showed a closer correspondence to ecoregions than to subecoregions, a pattern partl…