On the nature of the interlayer magnetic interactions in biphase ferromagnetic films

We report on the nature of the interlayer magnetic interactions in NiFe/Cu/Co films. By probing the quasi-static and dynamic magnetic properties of biphase ferromagnetic films, with soft and hard ferromagnetic phases intermediated by a non-magnetic layer, we address aspects of the coupling between magnetic layers. Our results demonstrate the nature of the interlayer magnetic coupling in biphase films. We also disclose the asymmetric magnetoimpedance effect as a fingerprint of the nature of the magnetic interlayer interactions playing key role in the magnetization dynamics of the system. We revisit in literature data and ideas on the asymmetric magnetoimpedance and the nature of the magnetic interactions in biphase ferromagnetic systems. Then, we compare our findings with results for biphase ribbons and microwires. Our observations raise the fundamental similarities and differences in the asymmetric magnetoimpedance of these structures.

Magnetic nanoparticles hyperthermia in a non-adiabatic and radiating process

We investigate the magnetic nanoparticles hyperthermia in a non-adiabatic and radiating process through the calorimetric method. Specifically, we propose a theoretical approach to magnetic hyperthermia from a thermodynamic point of view. To test the robustness of the approach, we perform hyperthermia experiments and analyse the thermal behavior of magnetite and magnesium ferrite magnetic nanoparticles dispersed in water submitted to an alternating magnetic field. From our findings, besides estimating the specific loss power value from a non-adiabatic and radiating process, thus enhancing the accuracy in the determination of this quantity, we provide physical meaning to a parameter found in literature that still remained not fully understood, the effective thermal conductance, and bring to light how it can be obtained from experiment. In addition, we show our approach brings a correction to the estimated experimental results for specific loss power and effective thermal conductance, thus demonstrating the importance of the heat loss rate due to the thermal radiation in magnetic hyperthermia.

Individualized metacognitive therapy for delusions: A randomized controlled rater-blind study

BACKGROUND

Theory-driven interventions targeting specific factors that contribute to delusions are receiving increased interest. The present study aimed to assess the efficacy of individualized metacognitive therapy (MCT+), a short manualized intervention that addresses delusion-associated cognitive biases.

METHODS

92 patients with current or past delusions were randomized to receive 12 twice-weekly sessions of either MCT+ or a control intervention within a randomized controlled rater-blind design. Psychopathology and cognitive biases were assessed at baseline, 6 weeks and 6 months. ANCOVAs adjusted for baseline scores were used to assess differences between groups regarding outcome variables. Both per-protocol and intention-to-treat analyses were conducted.

RESULTS

At 6 weeks, there was a significant difference in favor of MCT+ regarding decrease in delusion severity and improvement of self-reflectiveness (medium effect size), and a trend-wise difference regarding probability thresholds to decision. These effects increased, when only patients attending a minimum of 4 therapy sessions were considered. Control group patients subsequently showed further improvement while patients in the MCT+ group remained stable, such that there were no differences between groups at the 6-month follow-up.

LIMITATIONS

Lower attendance rates in the control group possibly leading to unequal therapeutic effort; lower baseline delusion severity in the MCT+ group.

CONCLUSIONS

The result pattern suggests that MCT+ led to earlier improvement in delusions and cognitive biases compared to the control intervention. The absence of a long-term effect might reflect floor effects in the MCT+ group, but may also indicate the need for further measures to promote sustainability of MCT+ effects.

Universal temporal characteristics and vanishing of multifractality in Barkhausen avalanches

Barkhausen effect in ferromagnetic materials provides an excellent area for investigating scaling phenomena found in disordered systems exhibiting crackling noise. The critical dynamics is characterized by random pulses or avalanches with scale-invariant properties, power-law distributions, and universal features. However, the traditional Barkhausen avalanches statistics may not be sufficient to fully characterize the complex temporal correlation of the magnetic domain walls dynamics. Here we focus on the multifractal scenario to quantify the temporal scaling characteristics of Barkhausen avalanches in polycrystalline and amorphous ferromagnetic films with thicknesses from 50 to 1000 nm. We show that the multifractal properties are dependent on film thickness, although they seem to be insensitive to the structural character of the materials. Moreover, we observe for the first time the vanishing of the multifractality in the domain walls dynamics. As the thickness is reduced, the multifractal behavior gives place to a monofractal one over the entire range of time scales. This reorganization in the temporal scaling characteristics of Barkhausen avalanches is understood as a universal restructuring associated to the dimensional crossover, from three- to two-dimensional magnetization dynamics.

Subjective versus objective cognition: Evidence for poor metacognitive monitoring in schizophrenia

BACKGROUND

Patients with schizophrenia display a number of cognitive biases, particularly a tendency to jump to conclusions, which are implicated in the pathogenesis of the disorder. The present study contrasted the degree of objective reasoning biases with subjective cognitive insight. We expected that patients with schizophrenia would display greater objective than subjective impairment suggestive of poor metacognitive awareness.

METHODS

Patients with schizophrenia (n=140) and healthy controls (n=60) underwent a test battery encompassing a cognitive bias paradigm (beads task) as well as neurocognitive tests (story recall, trail-making tests). In addition, they were administered the Beck Cognitive Insight Scale (BCIS), a subjective measure of (meta)cognitive awareness.

RESULTS

Corroborating prior research on decision making, draws to decisions were significantly delayed in controls relative to patients, whereas the core jumping to conclusion parameter (i.e., decision after one or two pieces of information) bordered significance. Patients with schizophrenia showed a lowered decision threshold and impaired neurocognition relative to nonclinical controls. Despite poor cognitive performance and prior psychotic episodes, patients with schizophrenia showed similar scores on the self-confidence subscale of the BCIS and reported even higher levels of self-reflectiveness relative to healthy controls.

DISCUSSION

The study demonstrates that patients with schizophrenia show severe cognitive biases and neurocognitive deficits but display only partial awareness herein. Raising cognitive insight in a non-insulting fashion and elevating patients' corrigibility as well as willingness to consider others' feedback and advice may help to narrow this gap and improve psychiatric symptomatology.

Quantitative Scaling of Magnetic Avalanches

We provide the first quantitative comparison between Barkhausen noise experiments and recent predictions from the theory of avalanches for pinned interfaces, both in and beyond mean field. We study different classes of soft magnetic materials, including polycrystals and amorphous samples-which are characterized by long-range and short-range elasticity, respectively-both for thick and thin samples, i.e., with and without eddy currents. The temporal avalanche shape at fixed size as well as observables related to the joint distribution of sizes and durations are analyzed in detail. Both long-range and short-range samples with no eddy currents are fitted extremely well by the theoretical predictions. In particular, the short-range samples provide the first reliable test of the theory beyond mean field. The thick samples show systematic deviations from the scaling theory, providing unambiguous signatures for the presence of eddy currents.

Investigating the efficacy of an individualized metacognitive therapy program (MCT+) for psychosis: study protocol of a multi-center randomized controlled trial

BACKGROUND

Psychological interventions are increasingly recommended as adjunctive treatments for psychosis, but their implementation in clinical practice is still insufficient. The individualized metacognitive therapy program (MCT+; www.uke.de/mct_plus ) represents a low-threshold psychotherapeutic approach that synthesizes group metacognitive training (MCT) and cognitive behavioral therapy for psychosis, and addresses specific cognitive biases that are involved in the onset and maintenance of psychosis. It aims to "plant the seed of doubt" regarding rigid delusional convictions and to encourage patients to critically reflect, extend and change their approach to problem solving. Its second edition also puts more emphasis on affective symptoms. A recent meta-analysis of metacognitive interventions (MCT, MCT+) indicate small to moderate effects on positive symptoms and delusions, as well as high rates of acceptance. Nonetheless, no long-term studies of MCT+ involving large samples have been conducted.

METHODS

The goal of the present multi-center, observer-blind, parallel-group, randomized controlled trial is to compare the efficacy of MCT+ against an active control (cognitive remediation; MyBrainTraining(©)) in 328 patients with psychosis at three time points (baseline, immediately after intervention [6 weeks] and 6 months later). The primary outcome is change in psychosis symptoms over the 6-month follow-up period as assessed by the delusion subscale of the Psychotic Symptom Rating Scale. Secondary outcomes include jumping to conclusions, other positive symptoms of schizophrenia, depressive symptoms, self-esteem, quality of life, and cognitive insight. The study also seeks to elucidate mediating factors that promote versus impede symptom improvement across time.

DISCUSSION

This is the first multi-center randomized controlled trial to test the efficacy of individualized MCT+ in a large sample of patients with psychosis. The rationale for the trial, the design, and the strengths and limitations of the study are discussed.

TRIAL REGISTRATION

The trial is registered through the German Clinical Trials Register ( www.drks.de ) as DRKS00008001 . Registered 6 May 2015.

Sustained and "sleeper" effects of group metacognitive training for schizophrenia: a randomized clinical trial

IMPORTANCE

Cognitive interventions increasingly complement psychopharmacological treatment to enhance symptomatic and functional outcome in schizophrenia. Metacognitive training (MCT) is targeted at cognitive biases involved in the pathogenesis of delusions.

OBJECTIVE

To examine the long-term efficacy of group MCT for schizophrenia in order to explore whether previously established effects were sustained.

DESIGN, SETTING, AND PARTICIPANTS

A 2-center, randomized, controlled, assessor-blind, parallel group trial was conducted. A total of 150 inpatients or outpatients with DSM-IV diagnoses of schizophrenia spectrum disorders were enrolled. All patients were prescribed antipsychotic medication. The second follow-up assessment took place 3 years later after the intervention phase was terminated.

INTERVENTIONS

Group MCT targeting cognitive biases vs neuropsychological training (COGPACK). Patients received a maximum of 16 sessions.

MAIN OUTCOMES AND MEASURES

The primary outcome measure was a delusion score derived from the Positive and Negative Syndrome Scale (PANSS). The PANSS positive syndrome and total scores, the Psychotic Symptom Rating Scales, the jumping to conclusions bias, self-esteem, and quality of life served as secondary outcome measures.

RESULTS

The intention-to-treat analyses demonstrated that patients in the MCT group had significantly greater reductions in the core PANSS delusion score, after 3 years compared with the control group (η2partial = .037; P = .05). Among the secondary outcomes, the intention-to-treat analyses also demonstrated that patients in the MCT group had significantly greater reductions in the PANSS positive syndrome score (η2partial = .055; P = .02) and the Psychotic Symptom Rating Scales delusion score (η2partial = .109; P = .001). Significant group differences at the 3-year follow-up were also found on measures of self-esteem and quality of life, which did not distinguish groups at earlier assessment points. Attention was improved in the neuropsychological training group relative to the MCT group. The completion rate was 61.3% after 3 years.

CONCLUSIONS AND RELEVANCE

Metacognitive training demonstrated sustained effects in the reduction of delusions, which were over and above the effects of antipsychotic medication. Moreover, there were some unanticipated ("sleeper") effects as both self-esteem and quality of life were improved after 3 years. Effects on self-esteem and well-being were found even in the absence of an improvement on the jumping to conclusions bias.

TRIAL REGISTRATION

isrctn.org Identifier: ISRCTN95205723.

Statistical properties of Barkhausen noise in amorphous ferromagnetic films

We investigate the statistical properties of the Barkhausen noise in amorphous ferromagnetic films with thicknesses in the range between 100 and 1000 nm. From Barkhausen noise time series measured with the traditional inductive technique, we perform a wide statistical analysis and establish the scaling exponents τ,α,1/σνz, and ϑ. We also focus on the average shape of the avalanches, which gives further indications on the domain-wall dynamics. Based on experimental results, we group the amorphous films in a single universality class, characterized by scaling exponents τ=1.28±0.02,α=1.52±0.3, and 1/σνz=ϑ=1.83±0.03, values compatible with that obtained for several bulk amorphous magnetic materials. Besides, we verify that the avalanche shape depends on the universality class. By considering the theoretical models for the dynamics of a ferromagnetic domain wall driven by an external magnetic field through a disordered medium found in literature, we interpret the results and identify an experimental evidence that these amorphous films, within this thickness range, present a typical three-dimensional magnetic behavior with predominant short-range elastic interactions governing the domain-wall dynamics. Moreover, we provide experimental support for the validity of a general scaling form for the average avalanche shape for non-mean-field systems.

Predictors of early stable symptomatic remission after an exacerbation of schizophrenia: the significance of symptoms, neuropsychological performance and cognitive biases

Neuropsychological deficits and severity of initial psychopathology have been repeatedly associated with poor symptomatic outcomes in schizophrenia. The role of higher-order cognitive biases on symptomatic outcomes of the disorder has not yet been investigated. The present study aimed to assess the contribution of cognitive biases, psychopathology and neuropsychological deficits on the probability of achieving early symptomatic remission after a psychotic episode in patients with schizophrenia. Participants were 79 patients with a DSM-IV diagnosis of schizophrenia or schizoaffective disorder undergoing an acute psychotic episode, and 25 healthy controls. According to psychopathology assessments, patients were split into those who had achieved remission after an average follow-up interval of 7 months, and those who had not (NR). Patients who achieved remission exhibited higher premorbid IQ and better performance on the TMT-B, as well as lower baseline positive, disorganized and distress symptoms than NR patients. TMT-B performance and positive symptoms at baseline were the best predictors of remission. Cognitive biases and negative symptoms were not associated with later remission. The findings highlight the significance of initial symptom severity for at least short-term symptomatic outcomes and, thus, the importance of adequate symptomatic treatment and prevention of psychotic outbreaks in patients.

Complementary group Metacognitive Training (MCT) reduces delusional ideation in schizophrenia

BACKGROUND

Symptom reduction under antipsychotic agents is incomplete for most schizophrenia patients. In order to enhance outcome, cognitive approaches are increasingly adopted as add-on interventions. The present study aimed to determine the efficacy of group Metacognitive Training (MCT), which targets cognitive biases putatively involved in the pathogenesis of delusions.

METHODS

A two-center, randomized, assessor-blind, controlled trial between MCT group training and cognitive training was carried out (ISRCTN95205723). A total of 150 in- and outpatients with DSM diagnoses of schizophrenia spectrum disorders were enrolled. All patients were concurrently prescribed antipsychotic medication. Assessments were made at baseline, four weeks and six months later. The primary outcome was a delusion score derived from the Positive and Negative Syndrome Scale (PANSS). The Psychotic Symptom Rating Scales (PSYRATS) as well as cognitive measures served as secondary outcomes.

RESULTS

Completion at follow-up was 86%. According to intention-to-treat (ITT) analyses, patients in the MCT group showed significantly greater symptom reduction on the PANSS delusion subscore (follow-up), PANSS positive score (post-treatment) and PSYRATS delusion score (post-treatment and follow-up). Improvement on the PANSS positive scale at post-treatment and follow-up was positively correlated with the number of attended MCT sessions. No changes were seen for other psychopathological syndromes.

DISCUSSION

MCT, a low-intensity training aimed at enhancing patients' awareness of cognitive biases subserving paranoia, led to improvement in delusion symptoms relative to the control condition and over and above the effects of antipsychotic medication. This improvement was sustained at follow-up.

Predictors of performance improvements within a cognitive remediation program for schizophrenia

Cognitive impairment is regarded a core feature of schizophrenia and is associated with low psychosocial functioning. There is rich evidence that cognitive remediation can improve cognitive functions in patients with schizophrenia. However, little is known about what predicts individual remediation success. Some studies suggest that baseline cognitive impairment might be a limiting factor for training response. Aim of the current study was to further examine the role of cognitive and symptom variables as predictors of remediation success. We studied a total sample of 32 patients with schizophrenia and schizoaffective disorder who were engaged in a computer-based cognitive training program (CogPack). A pre-training test battery provided cognitive measures of selective attention, executive functioning, processing speed, verbal memory, and verbal intelligence along with measures for positive and negative symptoms. Training response was defined as improvement on training tasks. Correlation analyses revealed no significant relationship between any of the baseline cognitive or symptom measures and improvement rates. However, better baseline cognition was associated with a higher percentage of tasks with initial ceiling effects. We conclude that not carefully tailoring task difficulty to patients' cognitive abilities constitutes a much more severe threat to cognitive remediation success than cognitive impairment itself.

Beyond the usual suspects: positive attitudes towards positive symptoms is associated with medication noncompliance in psychosis

Antipsychotic medication represents the treatment of choice in psychosis according to clinical guidelines. Nevertheless, studies show that half to almost three-quarter of all patients discontinue medication with antipsychotics after some time, a fact which is traditionally ascribed to side-effects, mistrust against the clinician and poor illness insight. The present study investigated whether positive attitudes toward psychotic symptoms (ie, gain from illness) represent a further factor for medication noncompliance. An anonymous online survey was set up in order to prevent conservative response biases that likely emerge in a clinical setting. Following an iterative selection process, data from a total of 113 patients with a likely diagnosis of schizophrenia and a history of antipsychotic treatment were retained for the final analyses (80%). While side-effect profile and mistrust emerged as the most frequent reasons for drug discontinuation, 28% of the sample reported gain from illness (eg, missing voices, feeling of power) as a motive for noncompliance. At least every fourth patient reported the following reasons: stigma (31%), mistrust against the physician/therapist (31%), and rejection of medication in general (28%). Approximately every fifth patient had discontinued antipsychotic treatment because of forgetfulness. On average, patients provided 4 different explanations for noncompliance. Ambivalence toward symptoms and treatment should thoroughly be considered when planning treatment in psychosis. While antipsychotic medication represents the evidence-based cornerstone of the current treatment in schizophrenia, further research is needed on nonpharmacological interventions for noncompliant patients who are willing to undergo intervention but refuse pharmacotherapy.

Multifractality in domain wall dynamics of a ferromagnetic film

We investigate the multifractal properties in the dynamics of domain walls of a ferromagnetic film. We apply the Multifractal Detrended Fluctuation Analysis method in experimental Barkhausen noise time series measured in a 1000-nm-thick Permalloy film under different driving magnetic field frequencies, and calculate the fluctuation function F_{q}(s), generalized Hurst exponent h(q), multifractal scaling exponent τ(q), and the multifractal spectrum f(α). Based on this procedure, we provide experimental evidence of multifractality in the dynamics of domain walls in ferromagnetic films and identify a rich and strong multifractal behavior, revealed by the changes of the scaling properties of over the entire Barkhausen noise signal, independently of the driving magnetic field rate employed in the experiment.