Spiral Waves in Chaotic Systems

Spiral waves are investigated in chemical systems whose underlying spatially-homogeneous dynamics is governed by a deterministic chaotic attractor. We show how the local periodic behavior in the vicinity of a spiral defect is transformed to chaotic dynamics far from the defect. The transformation occurs by a type of period doubling as the distance from the defect increases. The change in character of the dynamics is described in terms of the phase space flow on closed curves surrounding the defect.Comment: latex file with three postscript figures to appear in Physical review Letter

Towards a genome-wide transcriptogram: the Saccharomyces cerevisiae case

A genome modular classification that associates cellular processes to modules could lead to a method to quantify the differences in gene expression levels in different cellular stages or conditions: the transcriptogram, a powerful tool for assessing cell performance, would be at hand. Here we present a computational method to order genes on a line that clusters strongly interacting genes, defining functional modules associated with gene ontology terms. The starting point is a list of genes and a matrix specifying their interactions, available at large gene interaction databases. Considering the Saccharomyces cerevisiae genome we produced a succession of plots of gene transcription levels for a fermentation process. These plots discriminate the fermentation stage the cell is going through and may be regarded as the first versions of a transcriptogram. This method is useful for extracting information from cell stimuli/responses experiments, and may be applied with diagnostic purposes to different organisms

The ICD-11 and DSM-5-TR prolonged grief criteria: Validation of the Traumatic Grief Inventory-Self Report Plus using exploratory factor analysis and item response theory

More recently, the prolonged grief disorder (PGD) has been recognized as a mental health disorder following bereavement, which is distinct from depression and PTSD. However, the number and proposed symptom items vary across the ICD-11 and the DSM-5-TR criteria for PG. The Traumatic Grief Inventory-Self Report Plus (TGI-SR+), which is an updated version of the TGI-SR, is currently the only robust instrument that assesses PG according to the ICD-11 and DSM-5-TR criteria. For research and clinical use among French-speaking countries, the forward-backward procedure was applied to translate the TGI-SR+ into French language. Exploratory factor analysis and parallel analysis converged towards a two-dimensional structure for the TGI-SR+, representing adaptation difficulties and traumatic separation distress. However, items mapping onto ICD-11 and DSM-5-TR criteria for PG represented a one-dimensional structure. Findings based on item response theory method provided strong evidence for discriminative characteristics of the items. The internal reliability was excellent for the TGI-SR+ (McDonald's ω = 0.97) and ICD-11 and DSM-5-TR criteria for PGD (McDonald's ω = 0.95). We also demonstrated a very high temporal stability for the TGI-SR+ total score (ICC =.91, p < 0.0001) and ICD-11 PGD and DSM-5-TR PGD (ICC = 0.90, and ICC = 0.88, ps < 0.0001, respectively). The concurrent validity of the instrument was also demonstrated, such that the TGI-SR+ total score and all combinations were positively and significantly associated with the levels of depression, anxiety and post-traumatic stress symptoms. However, the effect sizes were moderate. We conclude that for research and clinical use among French bereaved populations, the TGI-SR+ is a sound tool with very good psychometric properties

The ICD-11 and DSM-5-TR prolonged grief criteria: Validation of the Traumatic Grief Inventory-Self Report Plus using exploratory factor analysis and item response theory

More recently, the prolonged grief disorder (PGD) has been recognized as a mental health disorder following bereavement, which is distinct from depression and PTSD. However, the number and proposed symptom items vary across the ICD-11 and the DSM-5-TR criteria for PG. The Traumatic Grief Inventory-Self Report Plus (TGI-SR+), which is an updated version of the TGI-SR, is currently the only robust instrument that assesses PG according to the ICD-11 and DSM-5-TR criteria. For research and clinical use among French-speaking countries, the forward-backward procedure was applied to translate the TGI-SR+ into French language. Exploratory factor analysis and parallel analysis converged towards a two-dimensional structure for the TGI-SR+, representing adaptation difficulties and traumatic separation distress. However, items mapping onto ICD-11 and DSM-5-TR criteria for PG represented a one-dimensional structure. Findings based on item response theory method provided strong evidence for discriminative characteristics of the items. The internal reliability was excellent for the TGI-SR+ (McDonald's ω = 0.97) and ICD-11 and DSM-5-TR criteria for PGD (McDonald's ω = 0.95). We also demonstrated a very high temporal stability for the TGI-SR+ total score (ICC =.91, p < 0.0001) and ICD-11 PGD and DSM-5-TR PGD (ICC = 0.90, and ICC = 0.88, ps < 0.0001, respectively). The concurrent validity of the instrument was also demonstrated, such that the TGI-SR+ total score and all combinations were positively and significantly associated with the levels of depression, anxiety and post-traumatic stress symptoms. However, the effect sizes were moderate. We conclude that for research and clinical use among French bereaved populations, the TGI-SR+ is a sound tool with very good psychometric properties