522 research outputs found
Uniqueness and Non-uniqueness in the Einstein Constraints
The conformal thin sandwich (CTS) equations are a set of four of the Einstein
equations, which generalize the Laplace-Poisson equation of Newton's theory. We
examine numerically solutions of the CTS equations describing perturbed
Minkowski space, and find only one solution. However, we find {\em two}
distinct solutions, one even containing a black hole, when the lapse is
determined by a fifth elliptic equation through specification of the mean
curvature. While the relationship of the two systems and their solutions is a
fundamental property of general relativity, this fairly simple example of an
elliptic system with non-unique solutions is also of broader interest.Comment: 4 pages, 4 figures; abstract and introduction rewritte
The Errors of Karen Franklin's Pretextuality
In her recent article, Hebephilia: Quintessence of Diagnostic Pretextuality (published in Behavioral Sciences and the Law, 2010), Karen Franklin expands on her previous argument that psychologists and psychiatrists should not diagnose as abnormal hebephilia, the sexual preference for early pubescent children. She supports her argument with a series of claims about the contents of the empirical literature and the scientists who produced it. The present document provides fact-checking of those claims, revealing that Franklin's conclusions are based largely on demonstrable falsehoods
Asymptotically Hyperbolic Non Constant Mean Curvature Solutions of the Einstein Constraint Equations
We describe how the iterative technique used by Isenberg and Moncrief to
verify the existence of large sets of non constant mean curvature solutions of
the Einstein constraints on closed manifolds can be adapted to verify the
existence of large sets of asymptotically hyperbolic non constant mean
curvature solutions of the Einstein constraints.Comment: 19 pages, TeX, no figure
Absorption spectrum in the wings of the potassium second resonance doublet broadened by helium
We have measured the reduced absorption coefficients occurring in the wings
of the potassium 4S-5P doublet lines at 404.414 nm and at 404.720 nm broadened
by helium gas at pressures of several hundred Torr. At the experimental
temperature of 900 K, we have detected a shoulder-like broadening feature on
the blue wing of the doublet which is relatively flat between 401.8 nm and
402.8 nm and which drops off rapidly for shorter wavelengths, corresponding to
absorption from the X doublet Sigma+ state to the C doublet Sigma+ state of the
K-He quasimolecule. The accurate measurements of the line profiles in the
present work will sharply constrain future calculations of potential energy
surfaces and transition dipole moments correlating to the asymptotes He-K(5p),
He-K(5s), and He-K(3d).Comment: 2 figure
Recovery of surface reflectance spectra and evaluation of the optical depth of aerosols in the near-IR using a Monte-Carlo approach: Application to the OMEGA observations of high latitude regions of Mars
We present a model of radiative transfer through atmospheric particles based
on Monte Carlo methods. This model can be used to analyze and remove the
contribution of aerosols in remote sensing observations. We have developed a
method to quantify the contribution of atmospheric dust in near-IR spectra of
the Martian surface obtained by the OMEGA imaging spectrometer on board Mars
Express. Using observations in the nadir pointing mode with significant
differences in solar incidence angles, we can infer the optical depth of
atmospheric dust, and we can retrieve the surface reflectance spectra free of
aerosol contribution. Martian airborne dust properties are discussed and
constrained from previous studies and OMEGA data. We have tested our method on
a region at 90{\deg}E and 77{\deg}N extensively covered by OMEGA, where
significant variations of the albedo of ice patches in the visible have been
reported. The consistency between reflectance spectra of ice-covered and
ice-free regions recovered at different incidence angles validates our
approach. The optical depth of aerosols varies by a factor 3 in this region
during the summer of Martian year 27. The observed brightening of ice patches
does not result from frost deposition but from a decrease in the dust
contamination of surface ice and (to a lower extent) from a decrease in the
optical thickness of atmospheric dust. Our Monte Carlo-based model can be
applied to recover the spectral reflectance characteristics of the surface from
OMEGA spectral imaging data when the optical thickness of aerosols can be
evaluated. It could prove useful for processing image cubes from the Compact
Reconnaissance Imaging Spectrometer for Mars (CRISM) on board the Mars
Reconnaissance Orbiter (MRO)
Sexual Attraction to Others: A Comparison of Two Models of Alloerotic Responding in Men
The penile response profiles of homosexual and heterosexual pedophiles, hebephiles, and teleiophiles to laboratory stimuli depicting male and female children and adults may be conceptualized as a series of overlapping stimulus generalization gradients. This study used such profile data to compare two models of alloerotic responding (sexual responding to other people) in men. The first model was based on the notion that men respond to a potential sexual object as a compound stimulus made up of an age component and a gender component. The second model was based on the notion that men respond to a potential sexual object as a gestalt, which they evaluate in terms of global similarity to other potential sexual objects. The analytic strategy was to compare the accuracy of these models in predicting a man’s penile response to each of his less arousing (nonpreferred) stimulus categories from his response to his most arousing (preferred) stimulus category. Both models based their predictions on the degree of dissimilarity between the preferred stimulus category and a given nonpreferred stimulus category, but each model used its own measure of dissimilarity. According to the first model (“summation model”), penile response should vary inversely as the sum of stimulus differences on separate dimensions of age and gender. According to the second model (“bipolar model”), penile response should vary inversely as the distance between stimulus categories on a single, bipolar dimension of morphological similarity—a dimension on which children are located near the middle, and adult men and women are located at opposite ends. The subjects were 2,278 male patients referred to a specialty clinic for phallometric assessment of their erotic preferences. Comparisons of goodness of fit to the observed data favored the unidimensional bipolar model
In their own words: what bothers children online?
In an open-ended survey question to European 9- to 16-year-olds, some 10,000 children reported a range of risks that concern them on the internet. Pornography (named by 22% of children who mentioned risks), conduct risk such as cyber-bullying (19%) and violent content (18%) were at the top of children’s concerns. The priority given to violent content is noteworthy insofar as this receives less attention than sexual content or bullying in awareness-raising initiatives. Many children express shock and disgust on witnessing violent, aggressive or gory online content, especially that which graphically depicts realistic violence against vulnerable victims, including from the news. Video-sharing websites such as YouTube were primary sources of violent and pornographic content. The findings discussed in relation to children’s fear responses to screen media and the implications for the public policy agenda on internet safety are identified
Modulation of emotional appraisal by false physiological feedback during fMRI
BACKGROUND
James and Lange proposed that emotions are the perception of physiological reactions. Two-level theories of emotion extend this model to suggest that cognitive interpretations of physiological changes shape self-reported emotions. Correspondingly false physiological feedback of evoked or tonic bodily responses can alter emotional attributions. Moreover, anxiety states are proposed to arise from detection of mismatch between actual and anticipated states of physiological arousal. However, the neural underpinnings of these phenomena previously have not been examined.
METHODOLOGY/PRINCIPAL FINDINGS
We undertook a functional brain imaging (fMRI) experiment to investigate how both primary and second-order levels of physiological (viscerosensory) representation impact on the processing of external emotional cues. 12 participants were scanned while judging face stimuli during both exercise and non-exercise conditions in the context of true and false auditory feedback of tonic heart rate. We observed that the perceived emotional intensity/salience of neutral faces was enhanced by false feedback of increased heart rate. Regional changes in neural activity corresponding to this behavioural interaction were observed within included right anterior insula, bilateral mid insula, and amygdala. In addition, right anterior insula activity was enhanced during by asynchronous relative to synchronous cardiac feedback even with no change in perceived or actual heart rate suggesting this region serves as a comparator to detect physiological mismatches. Finally, BOLD activity within right anterior insula and amygdala predicted the corresponding changes in perceived intensity ratings at both a group and an individual level.
CONCLUSIONS/SIGNIFICANCE
Our findings identify the neural substrates supporting behavioural effects of false physiological feedback, and highlight mechanisms that underlie subjective anxiety states, including the importance of the right anterior insula in guiding second-order "cognitive" representations of bodily arousal state
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