Quantization of Integrable and Chaotic Three-Particle Fermi-Pasta-Ulam-Tsingou Models.

We study the transition from integrability to chaos for the three-particle Fermi-Pasta-Ulam-Tsingou (FPUT) model. We can show that both the quartic ß-FPUT model (α=0) and the cubic one (ß=0) are integrable by introducing an appropriate Fourier representation to express the nonlinear terms of the Hamiltonian. For generic values of α and ß, the model is non-integrable and displays a mixed phase space with both chaotic and regular trajectories. In the classical case, chaos is diagnosed by the investigation of Poincaré sections. In the quantum case, the level spacing statistics in the energy basis belongs to the Gaussian orthogonal ensemble in the chaotic regime, and crosses over to Poissonian behavior in the quasi-integrable low-energy limit. In the chaotic part of the spectrum, two generic observables obey the eigenstate thermalization hypothesis.

Tricritical point in the quantum Hamiltonian mean-field model.

Engineering long-range interactions in experimental platforms has been achieved with great success in a large variety of quantum systems in recent years. Inspired by this progress, we propose a generalization of the classical Hamiltonian mean-field model to fermionic particles. We study the phase diagram and thermodynamic properties of the model in the canonical ensemble for ferromagnetic interactions as a function of temperature and hopping. At zero temperature, small charge fluctuations drive the many-body system through a first-order quantum phase transition from an ordered to a disordered phase. At higher temperatures, the fluctuation-induced phase transition remains first order initially and switches to second-order only at a tricritical point. Our results offer an intriguing example of tricriticality in a quantum system with long-range couplings, which bears direct experimental relevance. The analysis is performed by exact diagonalization and mean-field theory.

Quantum Measurement Cooling.

Invasiveness of quantum measurements is a genuinely quantum mechanical feature that is not necessarily detrimental: Here we show how quantum measurements can be used to fuel a cooling engine. We illustrate quantum measurement cooling (QMC) by means of a prototypical two-stroke two-qubit engine which interacts with a measurement apparatus and two heat reservoirs at different temperatures. We show that feedback control is not necessary for operation while entanglement must be present in the measurement projectors. We quantify the probability that QMC occurs when the measurement basis is chosen randomly, and find that it can be very large as compared to the probability of extracting energy (heat engine operation), while remaining always smaller than the most useless operation, namely, dumping heat in both baths. These results show that QMC can be very robust to experimental noise. A possible low-temperature solid-state implementation that integrates circuit QED technology with circuit quantum thermodynamics technology is presented.

Impairment in Social Functioning differentiates youth meeting Ultra-High Risk for psychosis criteria from other mental health help-seekers: A validation of the Italian version of the Global Functioning: Social and Global Functioning: Role scales.

Social and occupational impairments are present in the schizophrenia prodrome, and poor social functioning predicts transition to psychosis in Ultra-High Risk (UHR) individuals. We aimed to: 1) validate the Italian version of the Global Functioning: Social (GF: S) and Global Functioning: Role (GF: S) scales; 2) evaluate their association with UHR criteria. Participants were 12-21-years-old (age, mean=15.2, standard deviation=2.1, male/female ratio=117/120) nonpsychotic help-seekers, meeting (N=39) or not (N=198) UHR criteria. Inter-rater reliability was excellent for both scales, which also showed good to excellent concurrent validity, as measured by correlation with Global Assessment of Functioning (GAF) scores. Furthermore, GF:S and GF: R were able to discriminate between UHRs and non-UHRs, with UHRs having lower current scores. After adjusting for current GAF scores, only current GF:S scores independently differentiated UHR from non-UHR (OR=1.33, 95%CI: 1.02-1.75, p=0.033). Finally, UHR participants showed a steeper decrease from highest GF:S and GF: R scores in the past year to their respective current scores, but not from highest past year GAF scores to current scores. GF:S/GS: R scores were not affected by age or sex. GF:S/GF: R are useful functional level and outcome measures, having the advantage over the GAF to not confound functioning with symptom severity. Additionally, the GF:S may be helpful in identifying UHR individuals.

The Italian version of the 92-item Prodromal Questionnaire: Concurrent validity with the SIPS and factor analysis in a sample of 258 outpatients aged 11-36years.

BACKGROUND: Current early screeners for psychosis-risk states have still to prove ability in identifying at-risk individuals. Among screeners, the 92-item Prodromal Questionnaire (PQ-92) is often used. We aimed to assess the validity of its Italian translation in a large Italian adolescent and young adult help-seeking sample. METHODS: We included all individuals aged 12-36years seeking help at psychiatric mental health services in a large semirural Roman area (534,600 population) who accepted to participate. Participants completed the Italian version of the PQ-92 and were subsequently assessed with the Structured Interview of Prodromal/Psychosis-Risk Syndromes (SIPS). We examined diagnostic accuracy (sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios) and content, concurrent, and convergent validity between PQ-92 and SIPS using Cronbach's alpha, Cohen's kappa, and Spearman's rho, respectively. We tested the validity of adopted cut-offs through Receiver Operating Characteristic (ROC) curves plotted against SIPS diagnoses and the instrument's factor-structure through Principal Component Analysis. RESULTS: PQ-92 showed high internal consistency, acceptable diagnostic accuracy and concurrent validity, and excellent convergent validity. ROC analyses pointed to scores of 18 on the Positive subscale and 36 on the total PQ-92 as best cut-offs. The Scree-test identified a four-factor solution as fitting best. CONCLUSIONS: Psychometric properties of Italian PQ-92 were satisfactory. Optimal cut-offs were confirmed at ≥18 on the positive subscale, but at ≥36 on the total scale was able to identify more SIPS-positive cases.

Self-reported attenuated psychotic-like experiences in help-seeking adolescents and their association with age, functioning and psychopathology.

OBJECTIVE: Self-rated attenuated psychotic-like experiences (APLEs) are increasingly used to screen for ultra-high-risk (UHR) across all ages. However, self-rated psychotic-like experiences (PLEs), in particular perception-related ones, were more frequent in children and adolescents, in which they possessed less clinical significance. We therefore explored the prevalence of different factors of APLEs in help-seeking adolescents, and their relationship with age, functioning and psychopathology. METHOD: As a part of the "Liberiamo il Futuro" project, help-seeking adolescents (N=171; 11-18 years, 53% male) were screened with the 92-item Prodromal Questionnaire (PQ-92). A factor analysis was performed on the PQ-92 positive items (i.e., APLEs) to identify different APLE-factors. These were assessed for their association with age, functioning and psychopathology using regression analyses. RESULTS: APLEs were very common in help-seeking adolescents, and formed four factors: "Conceptual Disorganization and Suspiciousness", "Perceptual Abnormalities", "Bizarre Experiences", and "Magical Ideation". Associations with age and functioning but not psychopathology were found for "Perceptual Abnormalities" that was significantly more severe in 11-12-year-olds, while "Conceptual Disorganization and Suspiciousness" was significantly related to psychopathology. CONCLUSION: In line with findings on PLEs, prevalence and clinical significance of APLEs, especially perception-related ones, might depend on age and thus neurodevelopmental stage, and may fall within the normal spectrum of experience during childhood. This should be considered when screening for UHR status in younger age groups.

Efficacy of add-on deep transcranial magnetic stimulation in comorbid alcohol dependence and dysthymic disorder: three case reports.

BACKGROUND: Craving for alcohol is associated with abnormal activation in the dorsolateral prefrontal cortex. Deep transcranial magnetic stimulation (dTMS) has shown promise in the treatment of depression. There are few treatment options for treatment-resistant dysthymic disorder comorbid with alcohol use disorder. OBJECTIVE: To investigate the possible anticraving efficacy of bilateral dorsolateral prefrontal cortex high-frequency dTMS in 3 patients with comorbid long-term DSM-IV-TR dysthymic disorder and alcohol use disorder. METHOD: Three patients with alcohol use disorder with dysthymic disorder in their detoxification phase (abstaining for > 1 month) underwent twenty 20-minute sessions of 20 Hz dTMS over the dorsolateral prefrontal cortex over 28 days between 2011 and 2012. Alcohol craving was rated with the Obsessive Compulsive Drinking Scale and depressive symptoms with the Hamilton Depression Rating Scale. RESULTS: All 3 patients responded unsatisfactorily to initial intravenous antidepressant and antianxiety combinations but responded after 10 dTMS sessions, improving on both anxiety-depressive symptoms and craving. This improvement enabled us to reduce antidepressant dosages after dTMS cycle completion. DISCUSSION: High-frequency bilateral dorsolateral prefrontal cortex dTMS with left prevalence was found to produce significant anticraving effects in alcohol use disorder comorbid with dysthymic disorder. The potential of dTMS for reducing craving in patients with substance use disorder deserves to be further investigated.

[Olanzapine in manic/mixed patients with or without substance abuse]. / Olanzapina in pazienti maniacali o misti con o senza abuso di sostanze.

AIM: To evaluate the efficacy of olanzapine in patients in their manic/mixed phase with or without comorbidity with substance abuse/dependence disorder. METHODS: In this observational, controlled, prospective study, 60 patients with a DSM-IV-TR diagnosis of bipolar disorder, manic/mixed episode (30 patients with and 30 patient without comorbidity with a substance abuse/dependence disorder) were treated with olanzapine, evaluated at discharge, and followed-up for 8 weeks. Efficacy of olanzapine was assessed by comparing the proportion of responders (an at least 50% drop in Young Mania Rating Scale [YMRS] score from baseline) and remitters (YMRS ≤ 12 and Hamilton Depression Rating Scale [HAM-D] ≤ 8) in both groups. Craving and days of abuse/use were assessed with Visual Analogue Scale (VAS) and Time-line Follow-Back (TLFB), respectively. RESULTS: Differences in response and remission percentages were statistically not significant at discharge and during follow-up. A reduction of days of abuse has been observed in the drug-abuse group, while craving was only slightly decreased. DISCUSSION: These results suggest that olanzapine is effective in both groups and its efficacy in reducing the days of abuse appears to be independent from its action on craving.

Risperidone-induced leukopenia: a case report and brief review of literature.

A Caucasian, male, young adult with recurrent agitated depression and suicidal ideation received lithium and oral olanzapine. His white blood cell count was normal at that time. Due to unsatisfactory response, he received 4 mg/day risperidone. While symptoms improved, leukopenia emerged, specifically directed towards neutrophils. Upon risperidone discontinuation, white blood cell count returned to reference values within 1 week. As symptom control was satisfactory, we attempted no risperidone rechallenge. Accurate blood testing must accompany atypical antipsychotic drug administration since blood dyscrasias are always possible with these drugs.