Dissociation, trauma and the experience of visual hallucinations in post-traumatic stress disorder and schizophrenia

Dissociative behaviours and hallucinations are often reported in trauma-exposed people with schizophrenia spectrum disorders and post-traumatic stress disorder (PTSD). Auditory hallucinations are the most commonly reported type of hallucination, but often co-occur with experiences in other sensory modalities. The phenomenology and the neurobiological systems involved in visual experiences are not well characterised. Are these experiences similar in nature, content or severity among people with schizophrenia and/or PTSD? What are the neurobiological bases of these visual experiences and what is the role of dissociative behaviours in the formation of these experiences? A study by Wearne and colleagues in BJPsych Open aimed to characterise these phenomenological systems in groups of people with PTSD, schizophrenia or both (schizophrenia + PTSD)

Imaging dissociation in post-traumatic stress disorder

Symptom provocation paradigms have been successfully developed to identify the neural correlates associated with post-traumatic stress disorder (PTSD) symptoms, especially dissociative behaviours, but have critical limitations. Transiently stimulating the sympathetic nervous system and/or the hypothalamic-pituitary-adrenal (HPA) axis can enhance the stress response to symptom provocation and would help identify targets for personalised interventions

Analysing grouping of nucleotides in DNA sequences using lumped processes constructed from Markov chains

The most commonly used models for analysing local dependencies in DNA sequences are (high-order) Markov chains. Incorporating knowledge relative to the possible grouping of the nucleotides enables to define dedicated sub-classes of Markov chains. The problem of formulating lumpability hypotheses for a Markov chain is therefore addressed. In the classical approach to lumpability, this problem can be formulated as the determination of an appropriate state space (smaller than the original state space) such that the lumped chain defined on this state space retains the Markov property. We propose a different perspective on lumpability where the state space is fixed and the partitioning of this state space is represented by a one-to-many probabilistic function within a two-level stochastic process. Three nested classes of lumped processes can be defined in this way as sub-classes of first-order Markov chains. These lumped processes enable parsimonious reparameterizations of Markov chains that help to reveal relevant partitions of the state space. Characterizations of the lumped processes on the original transition probability matrix are derived. Different model selection methods relying either on hypothesis testing or on penalized log-likelihood criteria are presented as well as extensions to lumped processes constructed from high-order Markov chains. The relevance of the proposed approach to lumpability is illustrated by the analysis of DNA sequences. In particular, the use of lumped processes enables to highlight differences between intronic sequences and gene untranslated region sequences

Clone specific differences and dynamics of abiotic stress effects on the Daphnia pulex proteome

Daphnia pulex unterliegt in ihrem Habitat starken Futter- und Temperatur-Schwankungen. Veränderungen der Protein-Expression innerhalb des Proteoms während akutem Hunger-, Hitze- und kombiniertem Hunger- und Hitze-Stress wurden in dieser Arbeit in zwei unterschiedlichen D. pulex-Klonen durch 2D-Gelelektrophorese und Massenspektrometrie untersucht. Viele der bestimmten Protein-Isoformen waren nach Hunger- und/oder Hitze-Stress in beiden Klonen herauf- oder herunterregeguliert, wobei die Stärke der Expression und die regulatorischen Muster variierten. Glutathion-Transferasen, V-ATPase-Untereinheiten, Zytoskelett-Proteine und Chaperone waren signifikant heraufreguliert, Proteine für Proteolyse, Kohlenhydrat-Bindung oder Metabolismus waren herunterreguliert. Die Expression aller Proteine folgte spezifischen zeitlichen Mustern. Die Verfügbarkeit von Futter zeigten Klon-spezifische Unterschiede im Überleben, dem Gesamtproteingehalt und der Protein-Expression während akutem Hitze-Stress.Daphnia pulex is challenged by severe food and temperature changes in its habitat. To identify cellular adjustments in protein expression during acute starvation, heat-stress and the combination of both stress types; the proteomes of two D. pulex clones were studied by 2D gel electrophoresis and mass spectrometry. Several protein isoforms were up- or down-regulated in both clones during acute heat-stress and/or starvation. The expression varied in intensity and regulatory patterns between both clones. Glutathion transferases, V-ATPase subunits, cytoskeleton-proteins and chaperones were significantly up-regulated, proteins for proteolytic processes and carbohydrate binding or metabolism were down-regulated. The expression of all proteins followed specific temporal patterns. Availability of food resources revealed fundamental clone specific differences in survival, total protein content and protein expression during acute heat-stress

Dynanics of a vehicle-track coupling system at a rail joint

The dynamic behaviour at a rail joint is examined using a two-dimensional vehicle–track coupling model. The track system is described as a finite-length beam resting on a double-layer discrete viscous-elastic foundation. The vehicle is represented by a half car body and a single bogie. The influence of the number of layers considered, the number of elements between two sleepers, and the beam model is investigated. Parametric studies, both of the coupling model and the analytic formulae, are carried out in order to understand the influence of the main track and vehicle parameters on the P1 and P2 peak forces. Finally, the results in terms of P2 force from the proposed model are compared, not only with measured values but also with other simulated and analytical solutions. An excellent agreement between these values is foun

Automatic Learning Rate Maximization by On-Line Estimation of the Hessian's Eigenvectors

We propose a very simple, and well principled wayofcomputing the optimal step size in gradient descent algorithms. The on-line version is very efficient computationally, and is applicable to large backpropagation networks trained on large data sets. The main ingredient is a technique for estimating the principal eigenvalue(s) and eigenvector(s) of the objective function's second derivativematrix (Hessian), which does not require to even calculate the Hessian. Several other applications of this technique are proposed for speeding up learning, or for eliminating useless parameters

Cumulative sociodemographic disadvantage partially mediates associations between childhood trauma and schizotypy

Objectives: Risk for psychosis in the general population is characterized by a set of multidimensional traits that are referred to as schizotypy. Higher levels of schizotypy are associated with socioeconomic disadvantage and childhood trauma, just as these risk factors are associated with schizophrenia and bipolar disorder. Here, we set out to investigate whether cumulative sociodemographic disadvantage mediates associations between childhood trauma and schizotypy in adulthood. Methods: A sociodemographic cumulative risk (SDCR) score was derived from six risk indices spanning employment, education, income, socioeconomic status, marital, and living circumstances for 197 participants that included both healthy (n = 57) and clinical samples with schizophrenia or schizoaffective disorder (n = 65) or bipolar disorder (n = 75). A series of multiple linear regressions was used to examine the direct and indirect associations among childhood trauma (measured with the Childhood Trauma Questionnaire), the SDCR index, and levels of schizotypy (measured with the Schizotypal Personality Questionnaire). Results: Schizotypy was independently associated with trauma and the SDCR index. In addition, the SDCR index partially mediated associations between trauma and schizotypy. Conclusions: These findings in a mixed sample of healthy and clinical participants represent the full spectrum of schizotypy across health and illness and suggest that effects of childhood trauma on schizotypal personality organization may operate via cumulative socioeconomic disadvantage in adulthood. Practitioner points: The strong associations between trauma and schizotypy suggest that systematic health screening of children exposed to early life trauma may assist to identify those at risk of developing psychosis. Clinicians should pay attention to various indicators of sociodemographic disadvantage in patients prone to psychosis, in addition to any exposure to trauma during childhood