Search results for "Computer Science Applications"

Decremental 2- and 3-connectivity on planar graphs

1996

We study the problem of maintaining the 2-edge-, 2-vertex-, and 3-edge-connected components of a dynamic planar graph subject to edge deletions. The 2-edge-connected components can be maintained in a total ofO(n logn) time under any sequence of at mostO(n) deletions. This givesO(logn) amortized time per deletion. The 2-vertex- and 3-edge-connected components can be maintained in a total ofO(n log2n) time. This givesO(log2n) amortized time per deletion. The space required by all our data structures isO(n). All our time bounds improve previous bounds.

Prediction of Molecular Volume and Surface of Alkanes by Molecular Topology.

2003

Molecular volume and molecular surface are expressed as a function of topological degree in alkane graphs. This allows not only a straightforward approach to calculate such physicochemical magnitudes but also an interpretation of the role of the local vertex invariant (LOVI) or valence degree, delta, as well as the connectivity indices in the prediction of physicochemical properties. The interpretation is based on the concept of molecular accessibility (as introduced by Estrada, J. Phys. Chem. A 2002, 106, 9085) for which precise mathematical definitions are provided.

QSPR Modeling of Hydrocarbon Dipole Moments by Means of Correlation Weighting of Local Graph Invariants

2003

Hydrocarbon dipole moments are calculated by means of correlation weighting of local graph invariants within the context of QSPR theory. This sort of flexible topological descriptor is used for several parameters: local invariants of k th vertex in the labeled hydrogen filled graph extended connectivity of zero-, first- and second-orders, number of paths of length 2 at k th vertex and valence shell of the k th vertex. The models predict hydrocarbon dipole moments in a quite sensible way. The best model is that one based upon numbers of path length 2 correlation weighting.

Femtometer accuracy EXAFS measurements: Isotopic effect in the first, second and third coordination shells of germanium

2009

The analysis of the EXAFS signals from 70Ge and 76Ge has evidenced the low-temperature effect of isotopic mass difference on the amplitude of relative atomic vibrations. This effect is reflected in the difference of the Debye-Waller factors of the first three coordination shells, and on the difference of nearest-neighbour average interatomic distances, evaluated with femtometer accuracy. The experimental results are in agreement with theoretical expectations.

Unpacking the black‐box of students' visual attention in Mathematics and English classrooms: Empirical evidence using mini‐video recording gadgets

2020

ANID/PIA/Basal Funds for Centers of Excellence FB0003 Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) CONICYT FONDECYT 3170062

La ricostruzione tridimensionale e il restauro virtuale di una tomba etrusca dipinta dell’Etruria meridionale interna: la “Grotta Dipinta” di Pranzov…

2015

[EN] The paper concerns the 3D reconstruction and virtual restoration of a painted rock-cut chamber tombs located in the interior of Southern Etruria (Viterbo Province, Central Italy). The tomb was discovered in 1901 in a place named Pranzovico and it dates from the mid-fifth century BC; it has a cross plan with central atrium (decorated with paintings) and three chambers in which there are the rock-cut funerary beds. The paintings have been largely destroyed by illegal excavators in the days immediately following the discovery; during the 20th century it was damaged due to agricultural works in the surroundings and now it is partially filled up. Its 3D reconstruction is based on the scarce…

2019

Negative image-based (NIB) screening is a rigid molecular docking methodology that can also be employed in docking rescoring. During the NIB screening, a negative image is generated based on the target protein’s ligand-binding cavity by inverting its shape and electrostatics. The resulting NIB model is a drug-like entity or pseudo-ligand that is compared directly against ligand 3D conformers, as is done with a template compound in the ligand-based screening. This cavity-based rigid docking has been demonstrated to work with genuine drug targets in both benchmark testing and drug candidate/lead discovery. Firstly, the study explores in-depth the applicability of different ligand 3D conformer…

A Comparative Study of Nonlinear Machine Learning for the "In Silico" Depiction of Tyrosinase Inhibitory Activity from Molecular Structure.

2011

In the preset report, for the first time, support vector machine (SVM), artificial neural network (ANN), Baye- sian networks (BNs), k-nearest neighbor (k-NN) are applied and compared on two "in-house" datasets to describe the tyrosinase inhibitory activity from the molecular structure. The data set Data I is used for the identification of tyrosi- nase inhibitors (TIs) including 701 active and 728 inactive compounds. Data II consists of active chemicals for potency estimation of TIs. The 2D TOMOCOMD-CARDD atom-based quadratic indices are used as molecular descriptors. The de- rived models show rather encouraging results with the areas under the Receiver Operating Characteristic (AURC) curve …

Convolutional architectures for virtual screening

2020

Abstract Background A Virtual Screening algorithm has to adapt to the different stages of this process. Early screening needs to ensure that all bioactive compounds are ranked in the first positions despite of the number of false positives, while a second screening round is aimed at increasing the prediction accuracy. Results A novel CNN architecture is presented to this aim, which predicts bioactivity of candidate compounds on CDK1 using a combination of molecular fingerprints as their vector representation, and has been trained suitably to achieve good results as regards both enrichment factor and accuracy in different screening modes (98.55% accuracy in active-only selection, and 98.88% …

Improving structural similarity based virtual screening using background knowledge

2013

Background Virtual screening in the form of similarity rankings is often applied in the early drug discovery process to rank and prioritize compounds from a database. This similarity ranking can be achieved with structural similarity measures. However, their general nature can lead to insufficient performance in some application cases. In this paper, we provide a link between ranking-based virtual screening and fragment-based data mining methods. The inclusion of binding-relevant background knowledge into a structural similarity measure improves the quality of the similarity rankings. This background knowledge in the form of binding relevant substructures can either be derived by hand selec…