Psychological Coping and Resilience to COVID-19 in Mexico, Evidence From a National Sample.

We report the effect of COVID-19 confinement on some psychological variables associated with mental health: Stress perception, types of coping strategies during crises, and some components related to resilience. A national sample of the Mexican population was considered in a total of 2775 people whose ages ranged from 15 years and older. Questionnaires that met the psychometric criteria (reliability and validity) to be used in Latino samples were used.

Understanding topological symmetry: a heuristic approach to its determination.

An algorithm based on heuristic rules for topological symmetry perception of organic structures having heteroatoms, multiple bonds, and any kind of cycle, and configuration, is presented. This algorithm identifies topological symmetry planes and sets of equivalent atoms in the structure, named symmetry atom groups (SAGs). This approach avoids both the need to explore the entire graph automorphism groups, and to encompass cycle determination, resulting in a very effective computer processing.

Algorithm for exhaustive and nonredundant organic stereoisomer generation.

Generation of organic stereoisomers with R/S, Z/E, and/or M/P configurations that may contain heteroatoms, multiple bonds, and any kind of cycle (isolated, spiro, condensed, and nested) is described. Inputs for processing are molecular structures in a N_tuple format resident on an automatic (canonical) or manual (non canonical) generated file which are processed by doing internal molecular graph construction, a weighted bipartite tree construction for all atoms and bonds to detect stereocenters, and symmetrical atom groups (SAG) with some specific SAG parameters that constitute a novel way for redundancy elimination of meso structures. Finally, determination of ligand CIP priorities allows for writing the output N_tuples with stereoisomer description.