Analytic Detection Thresholds for Measurements of Linearly Polarized Intensity Using Rotation Measure Synthesis

A fully analytic statistical formalism does not yet exist to describe radio-wavelength measurements of linearly polarized intensity that are produced using rotation measure synthesis. In this work we extend the analytic formalism for standard linear polarization, namely that describing measurements of the quadrature sum of Stokes Q and U intensities, to the rotation measure synthesis environment. We derive the probability density function and expectation value for Faraday-space polarization measurements for both the case where true underlying polarized emission is present within unresolved Faraday components, and for the limiting case where no such emission is present. We then derive relationships to quantify the statistical significance of linear polarization measurements in terms of standard Gaussian statistics. The formalism developed in this work will be useful for setting signal-to-noise ratio detection thresholds for measurements of linear polarization, for the analysis of polarized sources potentially exhibiting multiple Faraday components, and for the development of polarization debiasing schemes.Comment: 14 pages, 6 figures, accepted for publication in MNRA

A role for eyebrows in regulating the visibility of eye gaze direction

The human eye is unique amongst those of primates in having white sclera against which the dark iris is clearly visible. This high-contrast structure makes the gaze direction of a human potentially easily perceptible to others. For a social creature such as a human, the ability to perceive the direction of another’s gaze may be very useful, since gaze usually signals attention. We report data showing that the accuracy of gaze deviation detection is independent of viewing distance up to a certain critical distance, beyond which it collapses. This is, of itself, surprising since most visual tasks are performed better at closer viewing distances. Our data also show that the critical distance, but not accuracy, is affected by the position of the eyebrows so that lowering the eyebrows reduces the critical distance. These findings show that mechanisms exist by which humans could expand or restrict the availability of their gaze direction to others. A way to regulate the availability of the gaze-direction signal could be an advantage. We show that an interpretation of eyebrow function in these terms provides a novel explanation for several well-known eyebrow actions, including the eyebrow flash

Hybrid video quality prediction: reviewing video quality measurement for widening application scope

A tremendous number of objective video quality measurement algorithms have been developed during the last two decades. Most of them either measure a very limited aspect of the perceived video quality or they measure broad ranges of quality with limited prediction accuracy. This paper lists several perceptual artifacts that may be computationally measured in an isolated algorithm and some of the modeling approaches that have been proposed to predict the resulting quality from those algorithms. These algorithms usually have a very limited application scope but have been verified carefully. The paper continues with a review of some standardized and well-known video quality measurement algorithms that are meant for a wide range of applications, thus have a larger scope. Their individual artifacts prediction accuracy is usually lower but some of them were validated to perform sufficiently well for standardization. Several difficulties and shortcomings in developing a general purpose model with high prediction performance are identified such as a common objective quality scale or the behavior of individual indicators when confronted with stimuli that are out of their prediction scope. The paper concludes with a systematic framework approach to tackle the development of a hybrid video quality measurement in a joint research collaboration.Polish National Centre for Research and Development (NCRD) SP/I/1/77065/10, Swedish Governmental Agency for Innovation Systems (Vinnova

Are Reports of Psychological Stress Higher in Occupational Studies? A Systematic Review across Occupational and Population Based Studies

This study was funded by the UK Ministry of Defence (MoD)

What are adult psychiatric inpatients' experience of seclusion: A systematic review of qualitative studies

Introduction There is limited understanding of patients' seclusion experience. A 2013 systematic review provides some insight; however, more knowledge is required in order to improve patient care. This is a systematic review of qualitative research into the patient experience of seclusion. The qualitative focus enables the phenomena to be the central focus. Question "What are adult psychiatric inpatients' experience of seclusion?" and "What is the quality of the applicable research?" Method Electronic searches for qualitative research published between 2006 and 2017 were undertaken. Data were excluded if it was not explicitly related to seclusion. Research was appraised using three standardized appraisal criterion. Themes were generated through thematic synthesis. Results Eight papers met inclusion criteria; four had been translated into English. Four themes were identified: "feeling vulnerable," "feeling neglected and abused," "disconnecting" and "seclusion is dangerous to mental health." Participants felt vulnerable and without control. They experienced staff and room as neglectful and abusive. Participants mentally disconnected. The experience threatened participants' mental health. Discussion Participants' experience is an amalgamation of interpersonal experience and the environment. Disconnecting may be a coping strategy. Implications for practice The findings have implications for seclusion practice, staff training and clinical supervision. Specific attention needs to be paid to the staff-patient interaction

Temporal Integration of Movement: The Time-Course of Motion Streaks Revealed by Masking

Temporal integration in the visual system causes fast-moving objects to leave oriented ‘motion streaks’ in their wake, which could be used to facilitate motion direction perception. Temporal integration is thought to occur over 100 ms in early cortex, although this has never been tested for motion streaks. Here we compare the ability of fast-moving (‘streaky’) and slow-moving fields of dots to mask briefly flashed gratings either parallel or orthogonal to the motion trajectory. Gratings were presented at various asynchronies relative to motion onset (from to ms) to sample the time-course of the accumulating streaks. Predictions were that masking would be strongest for the fast parallel condition, and would be weak at early asynchronies and strengthen over time as integration rendered the translating dots more streaky and grating-like. The asynchrony where the masking function reached a plateau would correspond to the temporal integration period. As expected, fast-moving dots caused greater masking of parallel gratings than orthogonal gratings, and slow motion produced only modest masking of either grating orientation. Masking strength in the fast, parallel condition increased with time and reached a plateau after 77 ms, providing an estimate of the temporal integration period for mechanisms encoding motion streaks. Interestingly, the greater masking by fast motion of parallel compared with orthogonal gratings first reached significance at 48 ms before motion onset, indicating an effect of backward masking by motion streaks