A New Field Theoretic Approach to Criticality

A reorganized perturbation expansion with a propagator of soft infrared behavior is used to study the critical behavior of the mass gap. The condition of relativistic covariance fixes the form of the soft propagator. Finite approximants to the correlation critical exponent can be obtained in every order of the modified, soft perturbation expansion. Alternatively, a convergent series of exponents in large orders of the soft perturbation expansion is provided by the renormalization group in all spatial dimensions, $1\leq D\leq3$. The result of the $\epsilon$-expansion is recovered in the $D\rightarrow 3$ limit.Comment: 22 page

Neural spike train synchronization indices: Definitions, interpretations, and applications

A comparison of previously defined spike train synchronization indices is undertaken within a stochastic point process framework. The second-order cumulant density (covariance density) is shown to be common to all the indices. Simulation studies were used to investigate the sampling variability of a single index based on the second-order cumulant. The simulations used a paired motoneurone model and a paired regular spiking cortical neurone model. The sampling variability of spike trains generated under identical conditions from the paired motoneurone model varied from 50% to 160% of the estimated value. On theoretical grounds, and on the basis of simulated data a rate dependence is present in all synchronization indices. The application of coherence and pooled coherence estimates to the issue of synchronization indices is considered. This alternative frequency domain approach allows an arbitrary number of spike train pairs to be evaluated for statistically significant differences, and combined into a single population measure. The pooled coherence framework allows pooled time domain measures to be derived, application of this to the simulated data is illustrated. Data from the cortical neurone model is generated over a wide range of firing rates (1-250 spikes/s). The pooled coherence framework correctly characterizes the sampling variability as not significant over this wide operating range. The broader applicability of this approach to multielectrode array data is briefly discussed

Radiation induced zero-resistance states: a dressed electronic structure effect

Recent results on magnetoresistance in a two dimensional electron gas under crossed magnetic and microwave fields show a new class of oscillations, suggesting a new kind of zero-resistance states. A complete understanding of the effect is still lacking. We consider the problem from the point of view of the electronic structure dressed by photons due to a in plane linearly polarized ac field. The dramatic changes in the dressed electronic structure lead to a interpretation of the new magnetoresistance oscillations as a persistent-current like effect, induced by the radiation field.Comment: 5 pages, 5 figures, revtex4, changes in introduction and added reference

Selecting patients with nonischemic dilated cardiomyopathy for ICDs

No abstract available

Duals of nonabelian gauge theories in DD dimensions

The dual of an arbitrary $D$-dimensional nonabelian lattice gauge theory, obtained after character expansion and integration over the gauge group, is shown to be a {\em local} lattice theory in the eigenspace of the Casimir operators. For $D\leq4$ we also provide the explicit form of the action as a product of character expansion coefficients and Racah coefficients. The representation can be used to facilitate strong coupling expansions. Furthermore, the possibility of simulations, at weak coupling, in the dual representation, is also discussed

Simulation of Field Theories in Wavelet Representation

The field is expanded in a wavelet series and the wavelet coefficients are varied in a simulation of the 2D $\phi^4$ field theory. The drastically reduced autocorrelations result in a substantial decrease of computing requirements, compared to those in local Metropolis simulations. A large part of the improvement is shown to be the result of an additional freedom in the choice of the allowed range of change at the Metropolis update of wavelet components, namely the range can be optimized independently for all wavelet sizes.Comment: 10 pages, LaTeX with 8 figures, Swansea preprint SWAT/3

Exploring Durham University Physics exams with Large Language Models

The emergence of advanced Natural Language Processing (NLP) models like ChatGPT has raised concerns among universities regarding AI-driven exam completion. This paper provides a comprehensive evaluation of the proficiency of GPT-4 and GPT-3.5 in answering a set of 42 exam papers derived from 10 distinct physics courses, administered at Durham University over the span of 2018 to 2022, totalling 593 questions and 2504 available marks. These exams, spanning both undergraduate and postgraduate levels, include traditional pre-COVID and adaptive COVID-era formats. Questions from the years 2018-2020 were designed for pre-COVID in person adjudicated examinations whereas the 2021-2022 exams were set for varying COVID-adapted conditions including open-book conditions. To ensure a fair evaluation of AI performances, the exams completed by AI were assessed by the original exam markers. However, due to staffing constraints, only the aforementioned 593 out of the total 1280 questions were marked. GPT-4 and GPT-3.5 scored an average of 49.4\% and 38.6\%, respectively, suggesting only the weaker students would potential improve their marks if using AI. For exams from the pre-COVID era, the average scores for GPT-4 and GPT-3.5 were 50.8\% and 41.6\%, respectively. However, post-COVID, these dropped to 47.5\% and 33.6\%. Thus contrary to expectations, the change to less fact-based questions in the COVID era did not significantly impact AI performance for the state-of-the-art models such as GPT-4. These findings suggest that while current AI models struggle with university-level Physics questions, an improving trend is observable. The code used for automated AI completion is made publicly available for further research.Comment: 9 pages, 6 figure

On the use of low-cost computer peripherals for the assessment of motor dysfunction in Parkinson’s disease – Quantification of bradykinesia using target tracking tasks

The potential of computer games peripherals to measure the motor dysfunction in Parkinson’s diseases is assessed. Of particular interest is the quantification of bradykinesia. Previous studies used modified or custom haptic interfaces, here an unmodified force feedback joystick and steering wheel are used with a laptop. During testing an on screen cursor moves in response to movements of the peripheral, the user has to track a continuously moving target (pursuit tracking), or move to a predetermined target (step tracking). All tasks use movement in the horizontal axis, allowing use of joystick or steering wheel. Two pursuit tracking tasks are evaluated, pseudo random movement, and a swept frequency task. Two step tracking tasks are evaluated, movement between two or between two of five fixed targets. Thirteen patients and five controls took part on a weekly basis. Patients were assessed for bradykinesia at each session using standard clinical measures. A range of quantitative measures was developed to allow comparison between and within patients and controls using ANOVA. Both peripherals are capable of discriminating between controls and patients, and between patients with different levels of bradykinesia. Recommendations for test procedures and peripherals are given