Singularity, complexity, and quasi--integrability of rational mappings

We investigate global properties of the mappings entering the description of symmetries of integrable spin and vertex models, by exploiting their nature of birational transformations of projective spaces. We give an algorithmic analysis of the structure of invariants of such mappings. We discuss some characteristic conditions for their (quasi)--integrability, and in particular its links with their singularities (in the 2--plane). Finally, we describe some of their properties {\it qua\/} dynamical systems, making contact with Arnol'd's notion of complexity, and exemplify remarkable behaviours.Comment: Latex file. 17 pages. To appear in CM

Baxterization, dynamical systems, and the symmetries of integrability

We resolve the `baxterization' problem with the help of the automorphism group of the Yang-Baxter (resp. star-triangle, tetrahedron, \dots) equations. This infinite group of symmetries is realized as a non-linear (birational) Coxeter group acting on matrices, and exists as such, {\em beyond the narrow context of strict integrability}. It yields among other things an unexpected elliptic parametrization of the non-integrable sixteen-vertex model. It provides us with a class of discrete dynamical systems, and we address some related problems, such as characterizing the complexity of iterations.Comment: 25 pages, Latex file (epsf style). WARNING: Postscript figures are BIG (600kB compressed, 4.3MB uncompressed). If necessary request hardcopy to [email protected] and give your postal mail addres

Associations of plasma leptin to clinical manifestations in reproductive aged female patients with panic disorder

Preclinical studies suggest the implication of the adipocyte hormone leptin in anxiety and fear processes. We explored for potential differences regarding plasma leptin, cortisol and the ratio leptin/Body Mass Index (BMI) between 27 medication-free female patients with Panic Disorder (PD) and 42 age-matched female controls, and for potential associations between plasma leptin and psychometric evaluations including number of panic attacks during last week, Clinical Global Impression-Severity of Illness (CGI-S) and Symptoms Checklist-90-Revised (SCL-90-R). Cortisol levels showed no differences between patients and controls, or correlations to leptin or to any clinical features. Both groups demonstrated a strong positive correlation between leptin and BMI and similar leptin and leptin/BMI, despite patients’ lower BMI. However, patients –but not controls- demonstrated significant negative correlations of leptin to the ‘somatization’, ‘anxiety’, and ‘phobic anxiety’ SCL-90-R subscales. Moreover, there was a significant negative correlation of leptin and of leptin/BMI ratio to the number of panic attacks during last week, while higher CGI-S was associated with lower leptin/BMI ratio. Our results, limited to PD female patients, suggest that lower leptin serum levels are significantly associated with greater severity of psychopathological manifestations, including number of panic attacks, symptoms of somatization, anxiety and phobic anxiety and overall clinical presentation. © 2017 Elsevier Ireland Lt

Associations of plasma testosterone with clinical manifestations in acute panic disorder

The probable implication of testosterone in the neurobiology of anxiety disorders, and particularly panic disorder (PD), is poorly studied. We explored for potential differences concerning testosterone (T) plasma levels and the ratio testosterone/cortisol (T/C) between medication-free, consecutively-referred patients with acute exacerbation of PD comorbid with agoraphobia (PDA) (N = 40; females = 24; age = 31.4 ± 7.1 years) and healthy controls (N = 80; females = 48; matched for age). Moreover, we investigated for potential associations of T levels and T/C ratio with the severity of acute PDA psychopathology in the patients of the sample. Psychometric measures included panic attacks’ number during last three weeks (PA-21days), the Agoraphobic Cognitions Questionnaire (ACQ) and the Hamilton Anxiety Rating Scale (HARS). Male patients –but not female ones- demonstrated significantly lower T levels compared to controls. Moreover, in male patients, a significant inverse association emerged between T/C ratio and PA-21days, so that lower T/C ratio is associated with significantly more panic attacks. On the contrary, female patients demonstrated significant positive associations: (a) between T levels and PDA-related pathological cognitions (ACQ); (b) between the T/C ratio and both PA-21days and anxiety symptoms’ severity (HARS). The results of the study suggest that testosterone is significantly associated to the severity of clinical manifestations of acute panic disorder, although in a different fashion concerning the two genders. © 2018 Elsevier Lt

Psychoticism in patients with panic disorder with or without comorbid agoraphobia

Objective: A few case-reports have previously described transient psychotic-like symptoms in non-psychotic patients with panic disorder (PD). We aimed to systematically explore whether PD patients without any current or past psychosis can be differentiated according to the severity of ‘psychoticism’ as a dimension, comprising clinical features such as psychotic-like experiences, increased social alienation, hostility and suspiciousness. Methods: Sample included 35 (female = 26) medication-free, non-psychotic patients consecutively referred from our Department’s Outpatient Clinic for acute symptoms of DSM-5 PD with (PDA; N = 29) or without concurrent agoraphobia. Psychometric measures included the Symptom Checklist–90–Revised (SCL-90-R), Agoraphobic Cognitions Questionnaire (ACQ), Body Sensations Questionnaire (BSQ), and panic attacks during last 21 days PA-21d. Results: Multiple regression analysis (forward stepwise) revealed that, among all SCL-90-R subscales, the psychoticism-subscale was most significantly associated with panic-related beliefs included in the ACQ, while significant associations emerged between the paranoid ideation-subscale and the ACQ and BSQ measures. Moreover, significant correlations emerged between the SCL-90-R psychoticism-subscale and all three measures of PD symptoms (ACQ, BSQ, PA-21d) and between the SCL-90-R paranoid ideation-subscale and both the ACQ and BSQ. Conclusions: This significant association between levels of psychoticism and severity of panic symptoms may reflect a more severe subtype of PD. © 2017 Informa UK Limited, trading as Taylor & Francis Group

Pituitary-adrenal axis hormones in early-onset versus late-onset panic disorder

Objective: It has been hypothesised that early-onset panic disorder (PD) may constitute a biologically distinct subtype of PD, but the few relevant data are inconclusive. We systematically explored for potential psychopathological and hormonal differences between early-onset (age at onset ≤ 27 years) versus late-onset PD, in consecutively-referred, medication-free, acutely-ill PD outpatients, moreover without comorbid mental disorders except agoraphobia (N = 54; age = 32.3 ± 7.5 years; early-onset = 27; females = 38). Methods: Hormones assessed (plasma levels) included adrenocorticotropic hormone (ACTH), cortisol and dehydroepiandrosterone sulphate (DHEAS). Psychopathological measures included panic attacks’ number during last three weeks, the Agoraphobic Cognitions and the Body Sensations Questionnaires and the Hamilton Anxiety Rating Scale. Results: Early-onset PD patients–compared to their late-onset counterparts–had longer duration of the disease. The two onset-groups demonstrated similar panic and anxiety symptoms and similar ratios of smokers/never-smokers. However, early-onset patients demonstrated significantly greater ACTH and DHEAS levels and higher (marginally significant) cortisol levels than the late-onset patients. Moreover, in the early-onset patients only, significant positive correlations emerged between ACTH levels and the severity of both panic and anxiety symptomatology. Conclusions: These findings suggest that the two onset-groups demonstrate significant differences in the hypothalamic-pituitary-adrenal axis functioning, at least when acutely-ill.Key points Early-onset panic disorder (EOPD) may differ biologically from late-onset PD (LOPD). EOPD was correlated with greater adrenocorticotropic hormone (ACTH) plasma levels. EOPD was correlated with greater dehydroepiandrosterone sulphate plasma levels. In EOPD only, ACTH levels were positively correlated with panic and anxiety symptoms. © 2020 Informa UK Limited, trading as Taylor & Francis Group

Stress Hormones as Predictors of Response to Cognitive Behavior Therapy in Panic Disorder

Objective: Data regarding the potential association between the outcome of psychotherapy of panic disorder (PD) and biological parameters are few. In 21 (16 females) consecutively referred, medication-free, acutely ill PD outpatients, without comorbidities, except agoraphobia, we systematically explored for potential neuroendocrine and clinical correlates of response to a brief cognitive behavior therapy (CBT). Methods: Cortisol and adrenocorticotropic hormone (ACTH) basal plasma levels were measured. Measures of psychopathology: (a) Symptom Checklist-90-Revised (SCL-90-R), (b) Clinical Global Impressions-Improvement (CGI-I) Scale, (c) Agoraphobic Cognitions Questionnaire (ACQ), and (d) Mobility Inventory (MI)-alone subscale. Results: Nonresponders to CBT (CGI-I >2; N = 6) - as compared to the responders (CGI-I ≤2; N = 15) - demonstrated significantly higher cortisol and ACTH basal plasma concentrations. These differences were much stronger when only female patients (nonresponders = 4; responders = 12) were taken into consideration. Regarding psychopathology, nonresponders to CBT suffered from more severe agoraphobia (MI-alone) at baseline. On the contrary, more intense manifestations of anger (SCL-90-R) at baseline were associated with a better treatment outcome. Response to CBT was associated with significant reductions in all SCL-90-R subscales, more pronounced for "phobic anxiety"and "anxiety"subscales. Conclusions: This study suggests that in acutely ill, medication-free PD patients, response to CBT may be associated with certain hormonal and clinical parameters at baseline. © 202

Gender related differences on the EEG during a simulated mobile phone signal

The present study investigated the gender-related influence of electromagnetic fields (EMF), similar to that emitted by mobile phones, on brain activity. Ten women and nine men performed a short memory task (Wechsler test), both without (baseline) and with exposure to a 900 MHz signal. The EEG energy of the total waveform and the α, β, δ and θ rhythms were calculated from the recordings of 15 scalp electrodes. Baseline EEG energy of males was greater than that of females, while exposure to EMF decreased EEG energy of males and increased that of females. Memory performance was invariant to EMF exposure and gender influences. These findings indicate that EMF may exert a gender-related influence on brain activity. © 2004 Lippincott Williams & Wilkins