Particle-hole symmetry protects spin-valley blockade in graphene quantum dots.

Particle-hole symmetry plays an important role in the characterization of topological phases in solid-state systems1. It is found, for example, in free-fermion systems at half filling and it is closely related to the notion of antiparticles in relativistic field theories2. In the low-energy limit, graphene is a prime example of a gapless particle-hole symmetric system described by an effective Dirac equation3,4 in which topological phases can be understood by studying ways to open a gap by preserving (or breaking) symmetries5,6. An important example is the intrinsic Kane-Mele spin-orbit gap of graphene, which leads to a lifting of the spin-valley degeneracy and renders graphene a topological insulator in a quantum spin Hall phase7 while preserving particle-hole symmetry. Here we show that bilayer graphene allows the realization of electron-hole double quantum dots that exhibit near-perfect particle-hole symmetry, in which transport occurs via the creation and annihilation of single electron-hole pairs with opposite quantum numbers. Moreover, we show that particle-hole symmetric spin and valley textures lead to a protected single-particle spin-valley blockade. The latter will allow robust spin-to-charge and valley-to-charge conversion, which are essential for the operation of spin and valley qubits.

Observation of the Spin-Orbit Gap in Bilayer Graphene by One-Dimensional Ballistic Transport.

We report on measurements of quantized conductance in gate-defined quantum point contacts in bilayer graphene that allow the observation of subband splittings due to spin-orbit coupling. The size of this splitting can be tuned from 40 to 80 µeV by the displacement field. We assign this gate-tunable subband splitting to a gap induced by spin-orbit coupling of Kane-Mele type, enhanced by proximity effects due to the substrate. We show that this spin-orbit coupling gives rise to a complex pattern in low perpendicular magnetic fields, increasing the Zeeman splitting in one valley and suppressing it in the other one. In addition, we observe a spin polarized channel of 6e^{2}/h at high in-plane magnetic field and signatures of interaction effects at the crossings of spin-split subbands of opposite spins at finite magnetic field.

Weak Measurement Protocols for Majorana Bound State Identification.

We propose a continuous weak measurement protocol testing the nonlocality of Majorana bound states through current shot noise correlations. The experimental setup contains a topological superconductor island with three normal-conducting leads weakly coupled to different Majorana states. Putting one lead at finite voltage and measuring the shot noise correlations between the other two (grounded) leads, devices with true Majorana states are distinguished from those without by strong current correlations. The presence of true Majorana states manifests itself in unusually high noise levels or the near absence of noise, depending on the chosen device configuration. Monitoring the noise statistics amounts to a weak continuous measurement of the Majorana qubit and yields information similar to that of a full braiding protocol, but at much lower experimental effort. Our theory can be adapted to different platforms and should allow for the clear identification of Majorana states.

Breakdown of the Law of Reflection at a Disordered Graphene Edge.

The law of reflection states that smooth surfaces reflect waves specularly, thereby acting as a mirror. This law is insensitive to disorder as long as its length scale is smaller than the wavelength. Monolayer graphene exhibits a linear dispersion at low energies and consequently a diverging Fermi wavelength. We present proof that for a disordered graphene boundary, resonant scattering off disordered edge modes results in diffusive electron reflection even when the electron wavelength is much longer than the disorder correlation length. Using numerical quantum transport simulations, we demonstrate that this phenomenon can be observed as a nonlocal conductance dip in a magnetic focusing experiment.

[Milestones of Child Neuropsychiatry]. / Meilensteine der Kinderneuropsychiatrie.

The development of child and adolescent psychiatry took different pathways in East and West Germany after World War II. In East Germany, child and adolescent psychiatry put more emphasis on neurology as it was influenced by the foundation of the first chair and care unit in Rostock. Prof. Göllnitz, who held the chair for many years, established child and adolescent neuropsychiatry as a subject in its own right in research and health care and helped promoting it at other universities and medical academies.

CLOCK Genes and Circadian Rhythmicity in Alzheimer Disease.

Disturbed circadian rhythms with sleep problems and disrupted diurnal activity are often seen in patients suffering from Alzheimer disease (AD). Both endogenous CLOCK genes and external Zeitgeber are responsible for the maintenance of circadian rhythmicity in humans. Therefore, modifications of the internal CLOCK system and its interactions with exogenous factors might constitute the neurobiological basis for clinically observed disruptions in rhythmicity, which often have grave consequences for the quality of life of patients and their caregivers. Presently, more and more data are emerging demonstrating how alterations of the CLOCK gene system might contribute to the pathophysiology of AD and other forms of dementia. At the same time, the impact of neuropsychiatric medication on CLOCK gene expression is under investigation.

Effects of zuclopenthixol on aggressive disruptive behavior in adults with mental retardation--a 2-year follow-up on a withdrawal study.

INTRODUCTION: People with mental retardation often display aggressive behavior against themselves or others making care within institutions or foster families difficult. Due to a lack of viable alternatives, antipsychotics of the first and second generations are often used for long-term treatment despite the fact that only data about short-term treatment exist. METHODS: A short-time withdrawal trial of 12 weeks (n = 39) was extended at open label to 2 years. 31 patients received zuclopenthixol after the end of the withdrawal and were examined using the same instruments as in the withdrawal period (DAS, MOAS, CGI). RESULTS: Patients still treated with zuclopenthixol after 2 years (n = 21) benefitted, compared to the drop-outs (n = 10). Analyses of time trends revealed an early effect of zuclopenthixol which could not be enhanced afterwards. DISCUSSION: Zuclopenthixol proved to be safe and effective to keep a lower rate of aggressive behavior in adults with mental retardation also over a longer period of time.

Quantized conductance at the Majorana phase transition in a disordered superconducting wire.

Superconducting wires without time-reversal and spin-rotation symmetries can be driven into a topological phase that supports Majorana bound states. Direct detection of these zero-energy states is complicated by the proliferation of low-lying excitations in a disordered multimode wire. We show that the phase transition itself is signaled by a quantized thermal conductance and electrical shot noise power, irrespective of the degree of disorder. In a ring geometry, the phase transition is signaled by a period doubling of the magnetoconductance oscillations. These signatures directly follow from the identification of the sign of the determinant of the reflection matrix as a topological quantum number.

[Infanticide. Social and forensic aspects]. / Kindstötungen. Soziale und gutachterliche Aspekte.

Infanticides are not specifically classified in German criminal records. Thus, the number of infanticides varies depending on different sources of information. Reports from expert witnesses (n=48, 1980-2007) from the German regions around Munich and Rostock were analyzed retrospectively in order to identify sociodemographic, clinical and forensic characteristics of child murders. In 87.5% of the cases the victims were the natural children of which 25 were younger than 1 year old. Female offenders outnumbered male offenders by 3:1 and on average females were 8 years younger than males (26.5 years for females and 34.2 years for males). The motives included unwanted pregnancy/child, altruistic deeds, acute psychoses, child abuse (sexual abuse, neglect or negligence), drug or alcohol abuse, sadistic punishment of the child and revenge on partners. In 27 cases a restricted or exemption from criminal responsibility was acknowledged. About one third of the offenders consulted a physician before the crime. For an improvement in primary prevention, support networks should be integrated and sensitized to the problem.

A double-blind placebo-controlled discontinuation study of zuclopenthixol for the treatment of aggressive disruptive behaviours in adults with mental retardation - secondary parameter analyses.

INTRODUCTION: Earlier studies showed risperidone to be effective in the treatment of aggression and self-injurious behaviour in adults with mental retardation but also having adverse side effects. This study was conducted to evaluate the effects of zuclopenthixol withdrawal. METHODS: After open treatment with zuclopenthixol (n=49) responders were randomly assigned to continue (n=19) or discontinue (n=20) zuclopenthixol treatment during a 12-week double-blind, placebo-controlled period. Effects were measured using the Disability Assessment Schedule (DAS), improvement on the Clinical Global Impression Scale (CGI-I), and the Nurse's Observation Scale for Inpatient Evaluation (NOSIE). RESULTS: Ten patients (20%) discontinued the study due to insufficient therapeutic effect or adverse events in the open period. EFFICACY: The superiority of zuclopenthixol over placebo among all randomized patients was supported not only by primary efficacy measure but also by the comparisons of mean scores of all secondary efficacy measures tested in a step-down-procedure (DAS, p<0.001; CGI-I, p<0.002, NOSIE, p<0.005). SAFETY: In both groups, one patient discontinued (5%) for adverse events. Adverse events were generally mild or moderate in severity. DISCUSSION: Zuclopenthixol proved to be safe and effective to keep a low rate of aggressive behaviour in adults with mental retardation.

[Legal aspects of hyperkinetic disorders/ADHD]. / HKS/ADHS und rechtliche Aspekte.

With a prevalence of 2-6%, hyperkinetic disorders (F 90, ICD-10) and disturbances of activity and attention (F 90.0, ADHD, ICD-10) are among the psychiatric disorders most commonly diagnosed in children, adolescents, and adults. Children and adolescents diagnosed with ADHD suffer from hyperactivity and deficits in attention and impulse control. Adults usually have problems focusing on one goal, maintaining their attention, modulating emotions effectively, structuring their tasks, and controlling impulses and in executive functions. Legal implications derive from core symptoms and from treatment with stimulants governed by legislation on narcotics. This paper discusses juridical aspects of ADHD in connection with the administration of medication at school, trips abroad within and outside the Schengen area, driving, competitive sports, military service, the increased risk of delinquency, the individual capacity to incur criminal responsibility, developmental criteria for the ability to act responsibly, and modalities for withdrawal treatment or treatment during detention.

Effects of exchange symmetry on full counting statistics.

We study the full counting statistics for the transmission of two identical particles with positive or negative symmetry under exchange for the situation where the scattering depends on energy. We find that, in addition to the expected sensitivity of the noise and higher cumulants, the exchange symmetry has a huge effect on the average transmitted charge; for equal-spin exchange-correlated electrons, the average transmitted charge can be orders of magnitude larger than the corresponding value for independent electrons.

Long-acting methylphenidate has an effect on aggressive behavior in children with attention-deficit/hyperactivity disorder.

INTRODUCTION: Aggression is frequently observed in children and adolescents with attention-deficit/hyperactivity disorder (ADHD). The aim of this study was to assess the efficacy with regard to oppositional and aggressive behavior of a new long-acting methylphenidate preparation (Medikinet retard, MPH-MR), with equal portions of the immediate-release and the sustained-release active substance, and especially to look at correlations between either teacher or parent assessment of aggression and ADHD sub-symptomatology. METHODS: Eighty five children and adolescents (6-16 years) were investigated in a double-blind, randomized, clinical trial over 5 weeks under a treatment with MPH-MR using symptom checklists for ADHD, oppositional-defiant and conduct disorder according to the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV). RESULTS: A total of 64.9% of the children showed oppositional defiant disorder/conduct disorder (ODD/CD) symptoms. A statistically significant effect was found in the group treated with MPH (verum-group). On the basis of Cohen's criteria, high effects were found for aggressive symptoms in school (d = 1.0), but not in the afternoon (d = 0.4). There were also lower effect sizes for more severe aggressive symptoms. We found characteristic correlations between ODD/CD symptoms and the ADHD subscale hyperactivity/impulsivity compared to the subscale inattention. CONCLUSIONS: Long-acting MPH is effective in the treatment of oppositional-defiant and aggressive behavior, especially concerning milder symptoms. The expected correlation between impulsivity and aggressiveness could be confirmed.

Using qubits to measure fidelity in mesoscopic systems.

We point out the similarities in the definition of the "fidelity" of a quantum system and the generating function determining the full counting statistics of charge transport through a quantum wire and suggest to use flux or charge qubits for their measurement. As an application we use the notion of fidelity within a first-quantized formalism in order to derive new results and insights on the generating function of the full counting statistics.

[Possibilities and limits of treatment of aggressive behavior in patients with mental retardation with risperidone]. / Möglichkeiten und Grenzen der Behandlung aggressiven Verhaltens bei Menschen mit geistiger Behinderung mit Risperidon.

Despite definite indication for psychopharmacologic intervention, severe and persistent symptoms of aggressive and self-injurious behaviour still remain a therapeutic challenge. As recent research has demonstrated, not only the dopaminergic and serotonergic but also the endogenous opiate system plays a role in the pathogenesis of self-injurious behaviour. Nevertheless, the efficacy of classical neuroleptics as well as opiate antagonists is questioned. In open and controlled studies, the administration of the atypical neuroleptic risperidone (a serotonin 2A-dopamine D2 antagonist) was associated with a long-term effect in reducing self-injuries. In our clinical trial, 20 mentally retarded adults presenting with severe self-injurious and aggressive behaviour were administered risperidone over a follow-up period of 35 months. Clinical efficacy was measured with the Disability Assessment Schedule (DAS), conducted in a home for people with mental retardation. In 17 patients, a significant reduction in self-injurious behaviour is shown. Besides, there was a significant overall clinical improvement in behaviour.

[Child and adolescent psychiatric aspects of expertising on children suffering from impediments in learning or mental perceptien]. / Kinder- und jugendpsychiatrische Aspekte der Begutachtung von Kindern mit Lernstörungen oder geistiger Behinderung.

Based on the efforts by the legislator to standardize the law for disabled persons and to simplify the accesses to appropriate assistance, procedures of expert reports are exemplarily presented from the aspect of child and adolescent psychiatry. Obliged to the principle of the two aspects for constituting a claim (which is first to set up a diagnosis and then to evaluate the existent or imminent handicap, both serving as the basis for the claim), etiological models, diagnostic - including developmental psychological - and therapeutic approaches in underlying psychiatric disorders of learning difficulties such as attention deficit hyperactivity disorders, pervasive developmental disorders, specific developmental disorders in learning abilities, and mental retardation are described as the participation in social life is either at risk or already affected. With regard these descriptions it is readily recognizable that child and adolescent neuropsychiatry has not only to provide professional competence in cases of appraisal question formulations concerning special assistance in early childhood, determination of special educational needs, and creation of plans for auxilliary interventions, but should also be employed regularly.

[Psychopharmacological therapy of self-injurious behavior in mentally retarded individuals]. / Psychopharmakotherapie des selbstverletzenden Verhaltens bei Menschen mit geistiger Behinderung.

Neurobiological research has implicated the dopamine and serotonin system in the pathogenesis of self-injurious behavior. The efficacy of antipsychotic drugs has been questioned. Opened and controlled investigations have shown risperidone is effective for reducing self-injurious behaviour in mentally retardation. We report about 3 mentally retarded patients which were given open-label risperidone for 12 weeks. They participated in a detailed assessment of behaviour symptoms at baseline and the repetitive behaviour was weekly rated with the disability assessment schedule (DAS). All three patients responded.

[Television behavior of a pediatric and adolescent psychiatric patient population]. / Das Fernsehverhalten einer kinder- und jugendpsychiatrischen Inanspruchnahmepopulation.

Television viewing is a common phenomen influencing everyday life of children. A questionnaire on the use of television was administered to 97 children aged from 5 to 19 years, and their parents. On an average, children spend 2 to 5 hours daily viewing television. Their parents accept this amount of time. Adolescents watch more TV than younger children. The social background was not related to the amount of time spent viewing television. Children with behavior disorders (F90-92) spend the same time watching television like children without behavior problems. 1/3 of the children owned their own television set using it more often. Nearly 50% like programs with violent and aggressive themes.

[Quantitative evaluation of motor activity of children with hyperkinetic syndrome]. / Ocena ilosciowa aktywnosci ruchowej dzieci z zespolem hiperkinetycznym.

Quantitative assessment of children's motor activity is necessary to objective classification of children according to their motor activity. The authors of the study made a quantitative assessment of motor activity of 55 boys in the age from 8-12, with normal IQ, using motor-scopic-motor-metric method. Global motor activity was assessed together with the activity of the head, trunk, and limbs, in such testing situations as sitting, standing, lying, and reading. It was found out that quiet children make 6.4 movements per minute, and hyperkinetic children make 21.4 movements per minute. Assessment of motor activity of upper limbs (arms, hands, fingers) is a sufficient factor to assess motor activity of children and verify their hyperkinetic syndrome. In such conditions 3.1 movements per minute is a borderline for quiet children and 6.4 movements per minute for hyperkinetic children. It was found out that the growing-up process leads to lessening of motor activity, especially in hyperexcitable children.