Why Do Delusions Persist?

Delusions are bizarre and distressing beliefs that characterize certain mental illnesses. They arise without clear reasons and are remarkably persistent. Recent models of delusions, drawing on a neuroscientific understanding of learning, focus on how delusions might emerge from abnormal experience. We believe that these models can be extended to help us understand why delusions persist. We consider prediction error, the mismatch between expectancy and experience, to be central. Surprising events demand a change in our expectancies. This involves making what we have learned labile, updating and binding the memory anew: a process of memory reconsolidation. We argue that, under the influence of excessive prediction error, delusional beliefs are repeatedly reconsolidated, strengthening them so that they persist, apparently impervious to contradiction

Contribution of walking to school to individual and population moderate-vigorous intensity physical activity

PURPOSE: This study estimated the contribution of walking to/from school to objectively measured daily moderate-vigorous intensity physical activity (MVPA) in individuals and populations. METHODS: MEDLINE, PsycINFO and SPORTDiscus were systematically searched up to February 2015. Two reviewers independently screened titles/abstracts/full-text articles, and assessed study quality. RESULTS: Of 2430 records, 116 were eligible for full-text screening. Twelve studies met the inclusion criteria of reporting objectively obtained measures of MVPA (total and while walking to/from school) in children and adolescents. The weighted mean MVPA accumulated in walking to and from school was 17 minutes per day in primary school pupils (9 samples, n=3422) and 13 minutes per day in high school pupils (4 samples, n=2600). Pooled analysis suggested that walking to and from school contributed 23% and 36% of MVPA on schooldays in primary school age children and high school pupils, respectively. All included studies were of high methodological quality. CONCLUSIONS: Walking to and from school makes a meaningful contribution to individual schoolday MVPA for active commuters in western countries. Since schooldays represent only around half of all days, and prevalence of walking to school is low in many countries, the contribution of walking to school to population MVPA is probably low

Particle-In-Cell/Monte Carlo Simulation of Ion Back Bombardment in Photoinjectors

In this paper, we report on studies of ion back bombardment in high average current dc and rf photoinjectors using a particle-in-cell/Monte Carlo method. Using H{sub 2} ion as an example, we observed that the ion density and energy deposition on the photocathode in rf guns are order of magnitude lower than that in a dc gun. A higher rf frequency helps mitigate the ion back bombardment of the cathode in rf guns

Electron Sources for Future Lightsources, Summary and Conclusions for the Activities during FLS 2012

This paper summarizes the discussions, presentations, and activity of the Future Light Sources Workshop 2012 (FLS 2012) working group dedicated to Electron Sources. The focus of the working group was to discuss concepts and technologies that might enable much higher peak and average brightness from electron beam sources. Furthermore the working group was asked to consider methods to greatly improve the robustness of operation and lower the costs of providing electrons.Comment: 11 pages, 7 figures, summary paper from working group Future Light Sources 2012 Workshop at Newport News, Virginia, USA (http://www.jlab.org/conferences/FLS2012/

Illusions and Delusions: Relating Experimentally-Induced False Memories to Anomalous Experiences and Ideas

The salience hypothesis of psychosis rests on a simple but profound observation that subtle alterations in the way that we perceive and experience stimuli have important consequences for how important these stimuli become for us, how much they draw our attention, how they embed themselves in our memory and, ultimately, how they shape our beliefs. We put forward the idea that a classical memory illusion – the Deese–Roediger–McDermott (DRM) effect – offers a useful way of exploring processes related to such aberrant belief formation. The illusion occurs when, as a consequence of its relationship to previous stimuli, a stimulus that has not previously been presented is falsely remembered. Such illusory familiarity is thought to be generated by the surprising fluency with which the stimulus is processed. In this respect, the illusion relates directly to the salience hypothesis and may share common cognitive underpinnings with aberrations of perception and attribution that are found in psychosis. In this paper, we explore the theoretical importance of this experimentally-induced illusion in relation to the salience model of psychosis. We present data showing that, in healthy volunteers, the illusion relates directly to self reported anomalies of experience and magical thinking. We discuss this finding in terms of the salience hypothesis and of a broader Bayesian framework of perception and cognition which emphasizes the salience both of predictable and unpredictable experiences

Contribution of walking to school to individual and population moderate-vigorous intensity physical activity:Systematic review and meta-analysis

Purpose: This study estimated the contribution of walking to/from school to objectively measured daily moderate-vigorous intensity physical activity (MVPA) in individuals and populations. Methods: MEDLINE, PsycINFO and SPORTDiscus were systematically searched up to February 2015. Two reviewers independently screened titles/abstracts/full-text articles, and assessed study quality. Results: Of 2430 records, 129 were eligible for full-text screening. Twelve studies met the inclusion criteria of reporting objectively obtained measures of MVPA (total and while walking to/from school) in children and adolescents. The weighted mean MVPA accumulated in walking to and from school was 17 min/day in primary school pupils (9 samples, n = 3422) and 13 min/day in high school pupils (4 samples, n = 2600). Pooled analysis suggested that walking to and from school contributed 23% and 36% of MVPA on schooldays in primary school age children and high school pupils, respectively. All included studies were of high methodological quality. Conclusions: Walking to and from school makes a meaningful contribution to individual schoolday MVPA for active commuters in western countries. Since schooldays represent only around half of all days, and prevalence of walking to school is low in many countries, the contribution of walking to school to population MVPA is probably low

Intercomparison of long-term sea surface temperature analyses using the GHRSST Multi-Product Ensemble (GMPE) system

Six global, gridded, gap-free, daily sea surface temperature (SST) analyses covering a period of at least 20 years have been intercompared: ESA SST CCI anal- ysis long-term product v1.0, MyOcean OSTIA reanalysis v1.0, CMC 0.2 degree, AVHRR ONLY Daily 1/4 degree OISST v2.0, HadISST2.1.0.0 and MGDSST. A seventh SST product of the ensemble median of all six has also been produced using the GMPE (Group for High Resolution SST Multi-Product Ensemble) sys- tem. Validation against independent near-surface Argo data, a long timeseries of moored buoy data from the tropics and anomalies to the GMPE median have been used to examine the temporal and spatial homogeneity of the analyses. A comparison of the feature resolution of the analyses has also been undertaken. A summary of relative strengths and weaknesses of the SST datasets is presented, intended to help users to make an informed choice of which analysis is most suitable for their proposed application