Critical fluctuations in the spin-orbit Mott insulator Sr3Ir2O7.

X-ray magnetic critical scattering measurements and specific heat measurements were performed on the perovskite iridate [Formula: see text]. We find that the magnetic interactions close to the Néel temperature [Formula: see text] are three-dimensional. This contrasts with previous studies which suggest two-dimensional behaviour like Sr2IrO4. Violation of the Harris criterion ([Formula: see text]) means that weak disorder becomes relevant. This leads a rounding of the antiferromagnetic phase transition at [Formula: see text], and modifies the critical exponents relative to the clean system. Specifically, we determine that the critical behaviour of [Formula: see text] is representative of the diluted 3D Ising universality class.

Collapse of the Mott Gap and Emergence of a Nodal Liquid in Lightly Doped Sr(2)IrO(4).

We report angle resolved photoemission experiments on the electron doped Heisenberg antiferromagnet (Sr(1-x)La(x))(2)IrO(4). For a doping level of x=0.05, we find an unusual metallic state with coherent nodal excitations and an antinodal pseudogap bearing strong similarities with underdoped cuprates. This state emerges from a rapid collapse of the Mott gap with doping resulting in a large underlying Fermi surface that is backfolded by a (π,π) reciprocal lattice vector which we attribute to the intrinsic structural distortion of Sr(2)IrO(4).

Coherent quasiparticles with a small fermi surface in lightly doped Sr(3)Ir(2)O(7).

We characterize the electron doping evolution of (Sr_{1-x}La_{x})_{3}Ir_{2}O_{7} by means of angle-resolved photoemission. Concomitant with the metal insulator transition around x≈0.05 we find the emergence of coherent quasiparticle states forming a closed small Fermi surface of volume 3x/2, where x is the independently measured La concentration. The quasiparticle weight Z remains large along the entire Fermi surface, consistent with the moderate renormalization of the low-energy dispersion, and no pseudogap is observed. This indicates a conventional, weakly correlated Fermi liquid state with a momentum independent residue Z≈0.5 in lightly doped Sr_{3}Ir_{2}O_{7}.

The epidemiology of depersonalisation and derealisation. A systematic review.

BACKGROUND: Symptoms of depersonalisation (DP) and derealisation (DR) are increasingly recognised in both clinical and non-clinical settings, but their importance and underlying pathophysiology is only now being addressed. METHODS: This paper is a systematic review of the current state of knowledge about the prevalence of depersonalisation and derealisation using computerised databases and citation searches. All potential studies were examined and numerical data included. Three categories of study are reviewed: questionnaire and interview surveys of selected student and non-clinical samples; population-based community surveys using standardised diagnostic interviews; and clinical surveys of depersonalisation/derealisation symptoms occurring within inpatients with psychiatric disorders. In addition, we present newly analysed data of the prevalence of depersonalisation/derealisation from five large population-based studies. RESULTS: Epidemiological surveys demonstrate that transient symptoms of depersonalisation/derealisation in the general population are common, with a lifetime prevalence rate of between 26 and 74% and between 31 and 66% at the time of a traumatic event. Community surveys employing standardised diagnostic interviews reveal rates of between 1.2 and 1.7 % for one month prevalence in a UK sample and a 2.4% current prevalence rate in a Canadian sample. Current prevalence rates in samples of consecutive inpatient admissions are reported between 1 and 16%, although screening measures employed may have resulted in these being an underestimate. Prevalence rates in clinical samples of specific psychiatric disorders vary between 30% of war veterans with PTSD and 60% of those with unipolar depression. There is a high prevalence within panic disorder with rates varying from 7.8 to 82.6%. DISCUSSION: DP and DR symptoms are common in normal and psychiatric populations, but prevalence estimates are hampered by inconsistent definitions and the use of variable time-frames. Population-based surveys using diagnostic interviews yield prevalence rates of clinically significant DP/DR in the region of 1-2%. Surveys of clinical populations in which common screening and assessment instruments were used also yield consistently high prevalence rates. The use of reliable diagnostic assessments and rating scales is needed. The relationship between DP/DR and certain other psychiatric disorders (e. g. panic) suggests possible common pathophysiological or aetiological factors.

Depersonalisation disorder: a cognitive-behavioural conceptualisation.

Depersonalisation (DP) and derealisation (DR) are subjective experiences of unreality in, respectively, one's sense of self and the outside world. These experiences occur on a continuum from transient episodes that are frequently reported in healthy individuals under certain situational conditions to a chronic psychiatric disorder that causes considerable distress (depersonalisation disorder, DPD). Despite the relatively high rates of reporting these symptoms, little research has been conducted into psychological treatments for this disorder. We suggest that there is compelling evidence to link DPD with the anxiety disorders, particularly panic. This paper proposes that it is the catastrophic appraisal of the normally transient symptoms of DP/DR that results in the development of a chronic disorder. We suggest that if DP/DR symptoms are misinterpreted as indicative of severe mental illness or brain dysfunction, a vicious cycle of increasing anxiety and consequently increased DP/DR symptoms will result. Moreover, cognitive and behavioural responses to symptoms such as specific avoidances, 'safety behaviours' and cognitive biases serve to maintain the disorder by increasing awareness of the symptoms, heightening the perceived threat and preventing disconfirmation of the catastrophic misinterpretations. A coherent model facilitates the development of potentially effective cognitive and behavioural interventions.