Neural computations of threat in the aftermath of combat trauma

© 2019, The Author(s), under exclusive licence to Springer Nature America, Inc. By combining computational, morphological, and functional analyses, this study relates latent markers of associative threat learning to overt post-traumatic stress disorder (PTSD) symptoms in combat veterans. Using reversal learning, we found that symptomatic veterans showed greater physiological adjustment to cues that did not predict what they had expected, indicating greater sensitivity to prediction errors for negative outcomes. This exaggerated weighting of prediction errors shapes the dynamic learning rate (associability) and value of threat predictive cues. The degree to which the striatum tracked the associability partially mediated the positive correlation between prediction-error weights and PTSD symptoms, suggesting that both increased prediction-error weights and decreased striatal tracking of associability independently contribute to PTSD symptoms. Furthermore, decreased neural tracking of value in the amygdala, in addition to smaller amygdala volume, independently corresponded to higher PTSD symptom severity. These results provide evidence for distinct neurocomputational contributions to PTSD symptoms

Therapists’ and non-therapists’ constructions of heterosex: A qualitative story completion study

© 2018 The British Psychological Society Objectives: Little research has examined the discourses that shape therapists’ sense-making around heterosex. This paper explores the discourses of sexuality and gender underpinning therapists’ and non-therapists’ responses to a sexual experimentation scenario in a heterosexual relationship. It also considers the value of the novel technique of story completion (SC), in which participants are asked to write a story in response to a hypothetical scenario, for qualitative psychology and psychotherapy research. Design: This research used a comparative SC design (Kitzinger & Powell,). Participants were sequentially presented with and invited to complete two story stems: one in which a male character suggested ‘trying something new’ to his female partner and one in which the female character made the suggestion. The stems were otherwise identical. Methods: A total of 100 SCs were written by 49 (28 female; 21 male) therapists and 51 (29 female; 22 male) non-therapists. Participants were recruited mainly via UK-based email lists and Facebook groups, and therapeutic training organizations, and the data were analysed using a feminist post-structuralist thematic analysis (Braun & Clarke,). Results: Both groups of participants drew on heteronormative discourses of sexuality and gender to make sense of the stem. Engaging in sexual experimentation was often depicted as a demonstration of being normal. In some stories written by women, sex was framed as a site for negotiating ‘equality’ and reciprocity in relationships. Therapists were more likely than non-therapists to frame ‘difficulties’ within relationships as opportunities for personal growth and increased emotional depth, and their stories included greater emotional complexity. Conclusion: These findings raise questions about practitioner training and whether it results in therapists drawing on narrow and restrictive discourses of heterosex in clinical practice. Practitioner points: Training on sexual issues is largely absent from non-specialist practitioner training courses, which potentially means therapists are ill-equipped to respond to clients’ anxiety about sexual issues. Evidence from this and other research indicates that therapists’ sense-making around heterosexual sexual relationships is underpinned by narrow and restrictive discourses that entrench traditional gender relations and limit sexual agency. Psychologists are increasingly taking up positions of clinical leadership and are looked to for models of best practice. Drawing on theorizations of sexual difficulties, and of anxieties about sexual practice, that challenge traditional gender and heteronorms, and the commodification and medicalization of sex, is important for effective psychological leadership relating to the treatment of sexual issues and the furthering of social justice agendas

Precision Pion-Proton Elastic Differential Cross Sections at Energies Spanning the Delta Resonance

A precision measurement of absolute pi+p and pi-p elastic differential cross sections at incident pion laboratory kinetic energies from T_pi= 141.15 to 267.3 MeV is described. Data were obtained detecting the scattered pion and recoil proton in coincidence at 12 laboratory pion angles from 55 to 155 degrees for pi+p, and six angles from 60 to 155 degrees for pi-p. Single arm measurements were also obtained for pi+p energies up to 218.1 MeV, with the scattered pi+ detected at six angles from 20 to 70 degrees. A flat-walled, super-cooled liquid hydrogen target as well as solid CH2 targets were used. The data are characterized by small uncertainties, ~1-2% statistical and ~1-1.5% normalization. The reliability of the cross section results was ensured by carrying out the measurements under a variety of experimental conditions to identify and quantify the sources of instrumental uncertainty. Our lowest and highest energy data are consistent with overlapping results from TRIUMF and LAMPF. In general, the Virginia Polytechnic Institute SM95 partial wave analysis solution describes our data well, but the older Karlsruhe-Helsinki PWA solution KH80 does not.Comment: 39 pages, 22 figures (some with quality reduced to satisfy ArXiv requirements. Contact M.M. Pavan for originals). Submitted to Physical Review

Terminal valuations, growth rates and the implied cost of capital

This article is published with open access at Springerlink.comWe develop a model based on the notion that prices lead earnings, allowing for a simultaneous estimation of the implied growth rate and the cost of equity capital for US industrial sectors. The major difference between our approach and that in prior literature is that ours avoids the necessity to make assumptions about terminal values and consequently about future growth rates. In fact, growth rates are an endogenous variable, which is estimated simultaneously with the implied cost of equity capital. Since we require only 1-year-ahead forecasts of earnings and no assumptions about dividend payouts, our methodology allows us to estimate ex ante aggregate growth and risk premia over a larger sample of firms than has previously been possible. Our estimate of the risk premium being between 3.1 and 3.9 % is at the lower end of recent estimates, reflecting the inclusion of these short-lived companies. Our estimate of the long run growth is from 4.2 to 4.7 %

Measurement of the Proton and Deuteron Spin Structure Functions g2 and Asymmetry A2

We have measured the spin structure functions g2p and g2d and the virtual photon asymmetries A2p and A2d over the kinematic range 0.02 < x < 0.8 and 1.0 < Q^2 < 30(GeV/c)^2 by scattering 38.8 GeV longitudinally polarized electrons from transversely polarized NH3 and 6LiD targets.The absolute value of A2 is significantly smaller than the sqrt{R} positivity limit over the measured range, while g2 is consistent with the twist-2 Wandzura-Wilczek calculation. We obtain results for the twist-3 reduced matrix elements d2p, d2d and d2n. The Burkhardt-Cottingham sum rule integral - int(g2(x)dx) is reported for the range 0.02 < x < 0.8.Comment: 12 pages, 4 figures, 1 tabl

Measurements of the Q2Q^2-Dependence of the Proton and Neutron Spin Structure Functions g1p and g1n

The structure functions g1p and g1n have been measured over the range 0.014 < x < 0.9 and 1 < Q2 < 40 GeV2 using deep-inelastic scattering of 48 GeV longitudinally polarized electrons from polarized protons and deuterons. We find that the Q2 dependence of g1p (g1n) at fixed x is very similar to that of the spin-averaged structure function F1p (F1n). From a NLO QCD fit to all available data we find $\Gamma_1^p - \Gamma_1^n =0.176 \pm 0.003 \pm 0.007$ at Q2=5 GeV2, in agreement with the Bjorken sum rule prediction of 0.182 \pm 0.005.Comment: 17 pages, 3 figures. Submitted to Physics Letters

Measurement of the Proton and Deuteron Spin Structure Function g_1 in the Resonance Region

We have measured the proton and deuteron spin structure functions g_1^p and g_1^d in the region of the nucleon resonances for W^2 < 5 GeV^2 and $Q^2\simeq 0.5$ and $Q^2\simeq 1.2$ GeV^2 by inelastically scattering 9.7 GeV polarized electrons off polarized $^{15}NH_3$ and $^{15}ND_3$ targets. We observe significant structure in g_1^p in the resonance region. We have used the present results, together with the deep-inelastic data at higher W^2, to extract $\Gamma(Q^2)\equiv\int_0^1 g_1(x,Q^2) dx$. This is the first information on the low-Q^2 evolution of Gamma toward the Gerasimov-Drell-Hearn limit at Q^2 = 0.Comment: 7 pages, 2 figure

Inside Organizations: Pricing, Politics, and Path Dependence

When economists have considered organizations, much attention has focused on the boundary of the firm, rather than its internal structures and processes. In contrast, this review sketches three approaches to the economic theory of internal organization—one substantially developed, another rapidly emerging, and a third on the horizon. The first approach (pricing) applies Pigou's prescription: If markets get prices wrong, then the economist's job is to fix the prices. The second approach (politics) considers environments where important actions inside organizations simply cannot be priced, so power and control become central. Finally, the third approach (path dependence) complements the first two by shifting attention from the between variance to the within. That is, rather than asking how organizations confronting different circumstances should choose different structures and processes, the focus here is on how path dependence can cause persistent performance differences among seemingly similar enterprises