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

False memories of childhood abuse

Are therapists to blame? Chris R. Brewin and Bernice Andrews consider the evidence in a controversial area

False Memories and Free Speech: Is Scientific Debate Being Suppressed?

Commentators have raised important points, including the relative contribution of false beliefs versus false memories and the issue of how findings in the laboratory can be generalized to the real world, which we have addressed here. However, some of the commentaries misrepresent what we said, make criticisms that are unfounded, or imply that our article should not have been published in Applied Cognitive Psychology. We relate these responses to a more general literature on the suppression of unwanted scientific findings and suggest that the study of false memory would be better served by more openness to alternative perspectives

Doing right by the eyewitness evidence: a response to Berkowitz et al

Berkowitz et al. (Berkowitz, S. R., Garrett, B. L., Fenn, K. M., & Loftus, E. F. (2020). Convicting with confidence? Why we should not over-rely on eyewitness confidence. Memory. https://doi.org/10.1080/09658211.2020.1849308) attribute to us the claim that “confidence trumps all”, and the few out-of-context quotations they selected can certainly be used to create that false impression. However, it is easily disproved, and we do so here. The notion that “confidence trumps all” is the mistake that the jurors made in the DNA exoneration cases, not a position that we have ever advocated

Slice Stretching Effects for Maximal Slicing of a Schwarzschild Black Hole

Slice stretching effects such as slice sucking and slice wrapping arise when foliating the extended Schwarzschild spacetime with maximal slices. For arbitrary spatial coordinates these effects can be quantified in the context of boundary conditions where the lapse arises as a linear combination of odd and even lapse. Favorable boundary conditions are then derived which make the overall slice stretching occur late in numerical simulations. Allowing the lapse to become negative, this requirement leads to lapse functions which approach at late times the odd lapse corresponding to the static Schwarzschild metric. Demanding in addition that a numerically favorable lapse remains non-negative, as result the average of odd and even lapse is obtained. At late times the lapse with zero gradient at the puncture arising for the puncture evolution is precisely of this form. Finally, analytic arguments are given on how slice stretching effects can be avoided. Here the excision technique and the working mechanism of the shift function are studied in detail.Comment: 16 pages, 4 figures, revised version including a study on how slice stretching can be avoided by using excision and/or shift

General Transformation Formulas for Fermi-Walker Coordinates

We calculate the transformation and inverse transformation, in the form of Taylor expansions, from arbitrary coordinates to Fermi-Walker coordinates in tubular neighborhoods of arbitrary timelike paths for general spacetimes. Explicit formulas for coefficients and the Jacobian matrix are given.Comment: 23 pages. Corrected typos in the last two equations. Accepted for publication in Classical and Quantum Gravit

Regge Calculus as a Fourth Order Method in Numerical Relativity

The convergence properties of numerical Regge calculus as an approximation to continuum vacuum General Relativity is studied, both analytically and numerically. The Regge equations are evaluated on continuum spacetimes by assigning squared geodesic distances in the continuum manifold to the squared edge lengths in the simplicial manifold. It is found analytically that, individually, the Regge equations converge to zero as the second power of the lattice spacing, but that an average over local Regge equations converges to zero as (at the very least) the third power of the lattice spacing. Numerical studies using analytic solutions to the Einstein equations show that these averages actually converge to zero as the fourth power of the lattice spacing.Comment: 14 pages, LaTeX, 8 figures mailed in separate file or email author directl

Prediction of posttraumatic stress disorder among adults in flood district

<p>Abstract</p> <p>Background</p> <p>Flood is one of the most common and severe forms of natural disasters. Posttraumatic stress disorder (PTSD) is a common disorder among victims of various disasters including flood. Early prediction for PTSD could benefit the prevention and treatment of PTSD. This study aimed to establish a prediction model for the occurrence of PTSD among adults in flood districts.</p> <p>Methods</p> <p>A cross-sectional survey was carried out in 2000 among individuals who were affected by the 1998 floods in Hunan, China. Multi-stage sampling was used to select subjects from the flood-affected areas. Data was collected through face-to-face interviews using a questionnaire. PTSD was diagnosed according to DSM-IV criteria. Study subjects were randomly divided into two groups: group 1 was used to establish the prediction model and group 2 was used to validate the model. We first used the logistic regression analysis to select predictive variables and then established a risk score predictive model. The validity of model was evaluated by using the model in group 2 and in all subjects. The area under the receiver operation characteristic (ROC) curve was calculated to evaluate the accuracy of the prediction model.</p> <p>Results</p> <p>A total of 2336 (9.2%) subjects were diagnosed as probable PTSD-positive individuals among a total of 25,478 study subjects. Seven independent predictive factors (age, gender, education, type of flood, severity of flood, flood experience, and the mental status before flood) were identified as key variables in a risk score model. The area under the ROC curve for the model was 0.853 in the validation data. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of this risk score model were 84.0%, 72.2%, 23.4%, and 97.8%, respectively, at a cut-off value of 67.5 in the validation data.</p> <p>Conclusions</p> <p>A simple risk score model can be used to predict PTSD among victims of flood.</p

A Pharmacogenomic and Protein Analysis of Human Lacrimal Fluid in Varying Age Groups

Proteins are large biological molecules located within all cells. They are considered the basic functional components of cells that allow them to operate appropriately. Genes consist of both DNA and RNA, and are the cellular components that code for the proteins. A biomarker is any cellular component that is an indication of a biological state. Therefore, genetic and protein biomarkers are specific genes and proteins, respectively, present in cells that indicate a specific biological state of a cell. Identification of proteins and genetic biomarkers in relative quantities has been found to reflect various disease states and age groups in humans. Comparisons of possible techniques for collecting lacrimal fluids from human subjects which could potentially be utilized in the design of the study