Is the Regge Calculus a consistent approximation to General Relativity?

We will ask the question of whether or not the Regge calculus (and two related simplicial formulations) is a consistent approximation to General Relativity. Our criteria will be based on the behaviour of residual errors in the discrete equations when evaluated on solutions of the Einstein equations. We will show that for generic simplicial lattices the residual errors can not be used to distinguish metrics which are solutions of Einstein's equations from those that are not. We will conclude that either the Regge calculus is an inconsistent approximation to General Relativity or that it is incorrect to use residual errors in the discrete equations as a criteria to judge the discrete equations.Comment: 27 pages, plain TeX, very belated update to match journal articl

Fast algorithms for computing defects and their derivatives in the Regge calculus

Any practical attempt to solve the Regge equations, these being a large system of non-linear algebraic equations, will almost certainly employ a Newton-Raphson like scheme. In such cases it is essential that efficient algorithms be used when computing the defect angles and their derivatives with respect to the leg-lengths. The purpose of this paper is to present details of such an algorithm.Comment: 38 pages, 10 figure

Identity – A critical but neglected construct in cognitive-behaviour therapy

In cognitive-behaviour therapy attention paid to the self and identity has primarily involved self-representations (the Me-Self) rather than how the self is experienced (the I-Self). Within the I-Self experiences vary on a continuum from pre-reflective consciousness (raw experienced perceptions and states of being) to self-awareness (permitting reflection on and evaluation of subjective experience). There is considerable evidence that the I-Self is affected in many if not all disorders, and I review illustrative studies of OCD, eating disorders, body dysmorphic disorder, PTSD, and personality disorder. These indicate that patients often experience themselves as being defective in various ways, or as having an unstable or contradictory I-Self. Recognition of this neglected aspect of patients' experience has major implications for assessment and treatment. For example, acknowledgment that their sense of self may fluctuate dramatically from moment to moment, may be fragmented, or may consist of a sense of emptiness, may help to build a more empathic therapeutic relationship. If frightening or distressing pre-reflective experiences are the cause of avoidance or other maladaptive coping strategies, conscious attention paid to them in therapy may help to better integrate the I-Self and Me-Self, restoring a sense of predictability and control

Inaccuracy in the Scientific Record and Open Postpublication Critique

There is growing evidence that the published psychological literature is marred by multiple errors and inaccuracies and often fails to reflect the changing nature of the knowledge base. At least four types of error are common—citation error, methodological error, statistical error, and interpretation error. In the face of the apparent inevitability of these inaccuracies, core scientific values such as openness and transparency require that correction mechanisms are readily available. In this article, I reviewed standard mechanisms in psychology journals and found them to have limitations. The effects of more widely enabling open postpublication critique in the same journal in addition to conventional peer review are considered. This mechanism is well established in medicine and the life sciences but rare in psychology and may assist psychological science to correct itself

A simple expression for the ADM mass

We show by an almost elementary calculation that the ADM mass of an asymptotically flat space can be computed as a limit involving a rate of change of area of a closed 2-surface. The result is essentially the same as that given by Brown and York. We will prove this result in two ways, first by direct calculation from the original formula as given by Arnowitt, Deser and Misner and second as a corollary of an earlier result by Brewin for the case of simplicial spaces.Comment: 9 pages, 1 figur

Long term stable integration of a maximally sliced Schwarzschild black hole using a smooth lattice method

We will present results of a numerical integration of a maximally sliced Schwarzschild black hole using a smooth lattice method. The results show no signs of any instability forming during the evolutions to t=1000m. The principle features of our method are i) the use of a lattice to record the geometry, ii) the use of local Riemann normal coordinates to apply the 1+1 ADM equations to the lattice and iii) the use of the Bianchi identities to assist in the computation of the curvatures. No other special techniques are used. The evolution is unconstrained and the ADM equations are used in their standard form.Comment: 47 pages including 26 figures, plain TeX, also available at http://www.maths.monash.edu.au/~leo/preprint

Regaining Consensus on the Reliability of Memory

In the last 20 years, the consensus about memory being essentially reliable has been neglected in favor of an emphasis on the malleability and unreliability of memory and on the public’s supposed unawareness of this. Three claims in particular have underpinned this popular perspective: that the confidence people have in their memory is weakly related to its accuracy, that false memories of fictitious childhood events can be easily implanted, and that the public wrongly sees memory as being like a video camera. New research has clarified that all three claims rest on shaky foundations, suggesting there is no reason to abandon the old consensus about memory being malleable but essentially reliable

The memory and identity theory of ICD-11 complex posttraumatic stress disorder

The 11th version of the International Classification of Diseases (ICD-11) includes complex posttraumatic stress disorder (CPTSD) as a separate diagnostic entity alongside posttraumatic stress disorder (PTSD). ICD-11 CPTSD is defined by six sets of symptoms, three that are shared with PTSD (reexperiencing in the here and now, avoidance, and sense of current threat) and three (affective dysregulation, negative self-concept, and disturbances in relationships) representing pervasive "disturbances in self-organization" (DSO). There is considerable evidence supporting the construct validity of ICD-11 CPTSD, but no theoretical account of its development has thus far been presented. A theory is needed to explain several phenomena that are especially relevant to ICD-11 CPTSD such as the role played by prolonged and repeated trauma exposure, the functional independence between PTSD and DSO symptoms, and diagnostic heterogeneity following trauma exposure. The memory and identity theory of ICD-11 CPTSD states that single and multiple trauma exposure occur in a context of individual vulnerability which interact to give rise to intrusive, sensation-based traumatic memories and negative identities which, together, produce the PTSD and DSO symptoms that define ICD-11 CPTSD. The model emphasizes that the two major and related causal processes of intrusive memories and negative identities exist on a continuum from prereflective experience to full self-awareness. Theoretically derived implications for the assessment and treatment of ICD-11 CPTSD are discussed, as well as areas for future research and model testing. (PsycInfo Database Record (c) 2023 APA, all rights reserved)

The Role of Intrusive Imagery in Hoarding Disorder

Despite the incidence of trauma in the histories of people with Hoarding Disorder (HD), reexperiencing symptoms, namely intrusive images, have not been investigated in the condition. To address this, 27 individuals who met DSM-5 criteria for HD and 28 community controls (CCs) were interviewed about (a) their everyday experiences of intrusive imagery, and (b) the unexpected images they experience when discarding high- and low-value possessions. Compared to CCs, everyday images described by the HD group were more frequent, had a greater negative valence, and were associated with greater interference in everyday life and attempts to avoid the imagery. With regard to discard-related imagery, a MANOVA followed up with mixed ANOVAs showed that HD participants reported more negative experiences of intrusive imagery in comparison with CCs during recent episodes of discarding objects of low subjective value. However, HD and CC participants both experienced positive imagery when discarding high-value objects. CC participants reported greater avoidance of imagery in the high-value object condition, but imagery-avoidance did not change between conditions for HD participants. The findings are discussed, particularly in relation to the potential of imagery-based interventions for HD