85 research outputs found
The Zel'dovich Approximation and the Relativistic Hamilton-Jacobi Equation
Beginning with a relativistic action principle for the irrotational flow of
collisionless matter, we compute higher order corrections to the Zel'dovich
approximation by deriving a nonlinear Hamilton-Jacobi equation for the velocity
potential. It is shown that the velocity of the field may always be derived
from a potential which however may be a multi-valued function of the space-time
coordinates. In the Newtonian limit, the results are nonlocal because one must
solve the Newton-Poisson equation. By considering the Hamilton-Jacobi equation
for general relativity, we set up gauge-invariant equations which respect
causality. A spatial gradient expansion leads to simple and useful results
which are local --- they require only derivatives of the initial gravitational
potential.Comment: 25 pages, DAMTP R94/6, ALBERTA THY/06-9
Lagrangian description of the fluid flow with vorticity in the relativistic cosmology
We develop the Lagrangian perturbation theory in the general relativistic
cosmology, which enables us to take into account the vortical effect of the
dust matter. Under the Lagrangian representation of the fluid flow, the
propagation equation for the vorticity as well as the density is exactly
solved. Based on this, the coupling between the density and vorticity is
clarified in a non-perturbative way. The relativistic correspondence to the
Lagrangian perturbation theory in the Newtonian cosmology is also emphasized.Comment: 14 pages (RevTeX); accepted for publication in Phys. Rev.
Long-wavelength iteration scheme and scalar-tensor gravity
Inhomogeneous and anisotropic cosmologies are modeled withing the framework
of scalar-tensor gravity theories. The inhomogeneities are calculated to
third-order in the so-called long-wavelength iteration scheme. We write the
solutions for general scalar coupling and discuss what happens to the
third-order terms when the scalar-tensor solution approaches at first-order the
general relativistic one. We work out in some detail the case of Brans-Dicke
coupling and determine the conditions for which the anisotropy and
inhomogeneity decay as time increases. The matter is taken to be that of
perfect fluid with a barotropic equation of state.Comment: 13 pages, requires REVTeX, submitted to Phys. Rev.
Adolescent self-control predicts midlife hallucinatory experiences:40-year follow-up of a national birth cohort
Associations between self-control in adolescence and adult mental health are unclear in the general population; to our knowledge, no study has investigated self-control in relation to psychotic-like symptoms
Diagnostic change 10 years after a first episode of psychosis
Background. A lack of an aetiologically based nosology classification has contributed to instability in psychiatric diag-noses over time. This study aimed to examine the diagnostic stability of psychosis diagnoses using data from an inci-dence sample of psychosis cases, followed up after 10 years and to examine those baseline variables which were associated with diagnostic change. Method. Data were examined from the ÆSOP and ÆSOP-10 studies, an incidence and follow-up study, respectively, of a population-based cohort of first-episode psychosis cases from two sites. Diagnosis was assigned using ICD-10 and DSM-IV-TR. Diagnostic change was examined using prospective and retrospective consistency. Baseline variables asso-ciated with change were examined using logistic regression and likelihood ratio tests. Results. Slightly more (59.6%) cases had the same baseline and lifetime ICD-10 diagnosis compared with DSM-IV-TR (55.3%), but prospective and retrospective consistency was similar. Schizophrenia, psychotic bipolar disorder and drug-induced psychosis were more prospectively consistent than other diagnoses. A substantial number of cases with other diagnoses at baseline (ICD-10, n = 61; DSM-IV-TR, n = 76) were classified as having schizophrenia at 10 years
Coordinate-free Solutions for Cosmological Superspace
Hamilton-Jacobi theory for general relativity provides an elegant covariant
formulation of the gravitational field. A general `coordinate-free' method of
integrating the functional Hamilton-Jacobi equation for gravity and matter is
described. This series approximation method represents a large generalization
of the spatial gradient expansion that had been employed earlier. Additional
solutions may be constructed using a nonlinear superposition principle. This
formalism may be applied to problems in cosmology.Comment: 11 pages, self-unpacking, uuencoded tex file, to be published in
Physical Review D (1997
Ten-year outcomes in first episode psychotic major depression patients compared with schizophrenia and bipolar patients.
We aimed to investigate long-term outcomes in psychotic major depression patients compared to schizophrenia and bipolar/manic psychosis patients, in an incidence sample, while accounting for diagnostic change. Based on Aetiology and Ethnicity in Schizophrenia and Other Psychoses (ÆSOP and ÆSOP-10), a first episode psychosis cohort was followed-up 10years after first presentation. The Schedules for Clinical Assessment in Neuropsychiatry, WHO Life Chart and Global Assessment of Functioning were used to assess clinical, social and service use outcomes. Seventy-two PMD patients, 218 schizophrenia patients and 70 psychotic bipolar disorder/mania patients were identified at baseline. Differences in outcome between PMD and bipolar patients based on baseline and lifetime diagnosis were minimal. Differences in clinical, social and service use outcomes between PMD and schizophrenia were more substantial with PMD patients showing better outcomes on most variables. However, there was some weak evidence (albeit not quite statistically significant at p<0.05) based on lifetime diagnoses that PMD patients were more likely to attempt suicide (OR 2.31, CI 0.98-5.42, p0.055) and self-harm (OR 2.34, CI 0.97-5.68, p0.060). PMD patients have better social and service use outcomes compared to people with schizophrenia, but may be more likely to attempt suicide or self-harm. This unique profile is important for clinicians to consider in any risk assessment.This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by Elsevier
Biological and psychosocial risk factors for psychotic major depression
AIMS: Few studies have investigated risk factors for psychotic major depression (PMD). We aimed to investigate the biological and psychosocial risk factors associated with PMD compared with other psychotic disorders. METHODS: Based on the aetiology and ethnicity in schizophrenia and other psychoses (ÆSOP) study, we used a case-control study to identify and recruit, at baseline and 10-year follow-up, all first episode cases of psychosis, presenting for the first time to specialist mental health services in defined catchment areas in the UK. Population-based controls were recruited from the same areas. Data were collected on: sociodemographics; social isolation; childhood adversity; life events; minor physical anomalies; and neurological soft signs. RESULTS: Living alone (aOR = 2.26, CI = 1.21-4.23), basic level qualification (aOR = 2.89, CI = 1.08-7.74), being unemployed (aOR = 2.12, CI = 1.13-3.96), having contact with friends less than monthly (aOR = 4.24, CI = 1.62-11.14), having no close confidants (aOR = 4.71, CI = 2.08-10.68), having experienced childhood adversity (aOR = 2.57, CI = 1.02-6.44), family history of mental illness (aOR = 10.68, CI = 5.06-22.52), family history of psychosis (aOR = 12.85, CI = 5.24-31.51), and having more neurological soft signs (aOR = 1.15, CI = 1.07-1.24) were all associated with a follow-up diagnosis of PMD and schizophrenia. Few variables associated with PMD were also associated with a diagnosis of bipolar disorder. Minor physical anomalies were associated with a follow-up diagnosis of schizophrenia and bipolar disorder, but not PMD. CONCLUSIONS: Risk factors associated with PMD appear to overlap with those for schizophrenia, but less so for bipolar disorder. Future work on the differential aetiology of PMD, from other psychoses is needed to find the 'specifier' between PMD and other psychoses. Future research on aetiology in PMD, and perhaps other psychoses, should account for diagnostic change.status: publishe
The Zel'dovich-type approximation for an inhomogeneous universe in general relativity: second-order solutions
The gravitational instability of inhomogeneities in the expanding universe is
studied by the relativistic second-order approximation. Using the tetrad
formalism we consider irrotational dust universes and get equations very
similar to those given in the Lagrangian perturbation theory in Newtonian
cosmology. Neglecting the cosmological constant and assuming a flat background
model we give the solutions of the nonlinear dynamics of cosmological
perturbations. We present the complete second-order solutions, which extend and
improve earlier works.Comment: 20 pages, LaTeX, no figure
Neurological Signs at the First Psychotic Episode as Correlates of Long-Term Outcome:Results From the AESOP-10 Study
Minor neurological signs are subtle deficits in sensory integration, motor coordination, and sequencing of complex motor acts present in excess in the early stages of psychosis. Still, it remains unclear whether at least some of these signs represent trait or state markers for psychosis and whether they are markers of long-term disease outcome of clinical utility. We examined the relationship between neurological function at illness onset assessed with the Neurological Evaluation Scale and subsequent illness course in 233 patients from AESOP-10 (Aetiology and Ethnicity in Schizophrenia and Other Psychoses), a 10-year follow-up study of a population-based cohort of individuals recruited at the time of their first episode of psychosis in the United Kingdom. In 56 of these patients, we also explored changes in neurological function over time. We included a group of 172 individuals without psychosis as controls. After 10 years, 147 (63%) patients had developed a non-remitting course of illness, and 86 (37%) a remitting course. Already at first presentation, patients who developed a non-remitting course had significantly more primary, motor coordination, and total signs than both remitting patients and healthy controls. While Motor Coordination signs did not change over time, rates of Primary, Sensory Integration, and Total signs increased, independently of illness course type. These findings suggest that motor coordination problems could be a useful early, quick, and easily detectable marker of subsequent clinical outcome. With other motor abnormalities, a measure of motor incoordination could contribute to the identification of the most vulnerable individuals, who could benefit from targeted and more assertive treatment approaches
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