Attention, predictive learning, and the inverse base-rate effect: Evidence from event-related potentials

We report the first electrophysiological investigation of the inverse base-rate effect (IBRE), a robust non-rational bias in predictive learning. In the IBRE, participants learn that one pair of symptoms (AB) predicts a frequently occurring disease, whilst an overlapping pair of symptoms (AC) predicts a rarely occurring disease. Participants subsequently infer that BC predicts the rare disease, a non-rational decision made in opposition to the underlying base rates of the two diseases. Error-driven attention theories of learning state that the IBRE occurs because C attracts more attention than B. On the basis of this account we predicted and observed the occurrence of brain potentials associated with visual attention: a posterior Selection Negativity, and a concurrent anterior Selection Positivity, for C vs. B in a post-training test phase. Error-driven attention theories further predict no Selection Negativity, Selection Positivity or IBRE, for control symptoms matched on frequency to B and C, but for which there was no shared symptom (A) during training. These predictions were also confirmed, and this confirmation discounts alternative explanations of the IBRE based on the relative novelty of B and C. Further, we observed higher response accuracy for B alone than for C alone; this dissociation of response accuracy (B>C) from attentional allocation (C>B) discounts the possibility that the observed attentional difference was caused by the difference in response accuracy

Fundamental properties of a microwave induced argon plasma

The behaviour of a microwave excited electrodeless argon discharge is investigated at pressures between 0.02 and 6.00 mbar. Spectroscopic measurements of twenty one emission lines of the argon I spectrum and seven lines of the argon II spectrum are combined with microwave impedance and Langmuir probe measurements. The population densities of some seventeen levels of the argon atom are evaluated and the results analysed in terms of a collisional-radiative recombination model due to Fujimoto. The atomic system is shown to be in the saturation phase above the 5p level and the population coefficients for seven levels of the argon atom are determined. Values of ion density and electron temperature are derived from probe measurements. The former are compared with values of electron density derived from impedance measurements and it is shown that the condition of electrical neutrality is not valid in this plasma. Ion loss to the walls of the discharge tube is demonstrated to be a major contributor to the non-neutrality of the plasma. The effect of a double Maxwellian distribution of electrons upon the double floating probe characteristics is investigated. A pair of equations is derived to describe the characteristic under this condition and the results are shown to fit an observed, but previously undescribed, form of characteristic. The behaviour of the characteristic for different ratios of electron temperature and electron density of the two distributions is examined and it is shown that careful consideration must be given to the interpretation of double floating probe characteristics to avoid ambiguous results. The effect of microwave power on the population densities of the argon atom and ion, the electron temperature and the electron and ion densities is examined. It is shown that power and pressure are not independent variables and the consequences of this for the analysis of the data is discussed

Optimal design of a toroidal field magnet system and cost of electricity implications for a tokamak using high temperature superconductors

The potential for reducing the Cost of Electricity (CoE) by using High Temperature Superconductors (HTS) in the Toroidal Field (TF) coils of a fusion tokamak power plant has been investigated using a new HTS module in the PROCESS systems code. We report the CoE and the design of HTS tokamaks that have been optimised by minimising the major radius of the plasma. Potential future improvements in both the superconducting properties and the structural materials for TF coils operating at 4.8 K and 30 K are considered. Increasing the critical current density by a factor of 10 (with a commensurate reduction in costs kA−1 m−1) results in a CoE 4.4% less than equivalent tokamaks using current low temperature superconductors (LTS). If the yield strength of the TF casing material is increased by 40% to 1400 MPa, the CoE is further reduced by 3.4%. Implementing both improvements and operating the TF coils at 4.8 K leads to CoE of 19.1 (10.1) €cent kW−1 h−1 for a 500 MW (1.5 GW) HTS reactor compared to 20.7 (11.1) €cent kW−1 h−1 for an LTS reactor (2013 costs). Operating the HTS TF coils at 30 K with both improvements, gives a similar CoE for HTS and LTS tokamaks

Development of the Variable Dexterity Test: construction, reliability and validity

Background/Aims: This article introduces a dexterity test designed to assess individual types of dexterity used to carry out activities of daily living (ADL). The Variable Dexterity Test (VDT) was developed as part of a wider study, the broader aim being to fully understand dexterity and its effect on human-product interaction during ADL. This was done with a view to improve occupational therapy methods when assessing dexterity and general hand function. Methods: The control group consisted of 24 healthy participants. Estimates of reliability and validity were evaluated in this pilot study. Inter-rater and test-retest reliability were assessed using a one-way ANOVA. The validity of the test was estimated by correlating participants’ VDT scores with their proficiency to complete four ADL task actions and a standardised dexterity test (Purdue Pegboard Test). Results: The test produced consistent results among the control group with both a single assessor (test‑retest reliability) and multiple assessors (inter‑rater reliability). High correlations between participants’ VDT scores and proficiency to perform ADL were found for most of the subtests. There was also a high correlation between participants’ scores from the Purdue Pegboard Test and the VDT. Conclusions: The VDT proved to be a flexible, reliable and valid tool that assesses dexterity based on ability to carry out ADL. Validity and reliability estimates show encouraging values, which recognises that the VDT can be used as an accurate method to assess more than one type of dexterity.</p

The effect of testing environment on small punch creep

Small punch creep testing (SPCT) is currently experiencing a resurgence of interest as a small-scale testing technique (SSTT) for a wide range of uses, including testing in-service components and materials with limited availability. SPCT is particularly pertinent for the fusion community since it is difficult to irradiate large volumes of material due to the high damage levels required and relatively low number of available facilities. An important aspect of the SPCT development that still requires investigation is the effect of the testing environment, which has been shown to impact the creep properties of materials when using standard testing techniques. This paper investigates the effect of using an air or an argon environment on the SPCT behaviour of the leading European fusion reactor material Eurofer97 at 550°C. The test environment was found to impact on the small punch creep behaviour: testing in an argon environment significantly increased time to failure and deflection at failure by a factor of approximately 30 and 7%, respectively. The test environment also appeared to affect the behaviour of the test via oxidation of the punch head which should be an important consideration in future testing

Incidence of hyperoxia in trauma patients receiving pre-hospital emergency anaesthesia:results of a 5-year retrospective analysis

Abstract Background Previous studies have demonstrated an association between hyperoxia and increased mortality in various patient groups. Critically unwell and injured patients are routinely given high concentration oxygen in the pre-hospital phase of care. We aim to investigate the incidence of hyperoxia in major trauma patients receiving pre-hospital emergency anesthesia (PHEA) in the pre-hospital setting and determine factors that may help guide clinicians with pre-hospital oxygen administration in these patients. Methods A retrospective cohort study was performed of all patients who received PHEA by a single helicopter emergency medical service (HEMS) between 1 October 2014 and 1 May 2019 and who were subsequently transferred to one major trauma centre (MTC). Patient and treatment factors were collected from the electronic patient records of the HEMS service and the MTC. Hyperoxia was defined as a PaO2 > 16 kPA on the first arterial blood gas analysis upon arrival in the MTC. Results On arrival in the MTC, the majority of the patients (90/147, 61.2%) had severe hyperoxia, whereas 30 patients (20.4%) had mild hyperoxia and 26 patients (19.7%) had normoxia. Only 1 patient (0.7%) had hypoxia. The median PaO2 on the first arterial blood gas analysis (ABGA) after HEMS handover was 36.7 [IQR 18.5–52.2] kPa, with a range of 7.0–86.0 kPa. SpO2 pulse oximetry readings before handover were independently associated with the presence of hyperoxia. An SpO2 ≥ 97% was associated with a significantly increased odds of hyperoxia (OR 3.99 [1.58–10.08]), and had a sensitivity of 86.7% [79.1–92.4], a specificity of 37.9% [20.7–57.8], a positive predictive value of 84.5% [70.2–87.9] and a negative predictive value of 42.3% [27.4–58.7] for the presence of hyperoxemia. Conclusion Trauma patients who have undergone PHEA often have profound hyperoxemia upon arrival at hospital. In the pre-hospital setting, where arterial blood gas analysis is not readily available a titrated approach to oxygen therapy should be considered to reduce the incidence of potentially harmful tissue hyperoxia