Three-dimensional wave breaking.

Although a ubiquitous natural phenomenon, the onset and subsequent process of surface wave breaking are not fully understood. Breaking affects how steep waves become and drives air-sea exchanges1. Most seminal and state-of-the-art research on breaking is underpinned by the assumption of two-dimensionality, although ocean waves are three dimensional. We present experimental results that assess how three-dimensionality affects breaking, without putting limits on the direction of travel of the waves. We show that the breaking-onset steepness of the most directionally spread case is double that of its unidirectional counterpart. We identify three breaking regimes. As directional spreading increases, horizontally overturning 'travelling-wave breaking' (I), which forms the basis of two-dimensional breaking, is replaced by vertically jetting 'standing-wave breaking' (II). In between, 'travelling-standing-wave breaking' (III) is characterized by the formation of vertical jets along a fast-moving crest. The mechanisms in each regime determine how breaking limits steepness and affects subsequent air-sea exchanges. Unlike in two dimensions, three-dimensional wave-breaking onset does not limit how steep waves may become, and we produce directionally spread waves 80% steeper than at breaking onset and four times steeper than equivalent two-dimensional waves at their breaking onset. Our observations challenge the validity of state-of-the-art methods used to calculate energy dissipation and to design offshore structures in highly directionally spread seas.

The responsiveness of novel, dynamic, contrast-enhanced magnetic resonance measures of total knee synovitis after intra-articular corticosteroid for painful osteoarthritis.

OBJECTIVE: Sensitive biomarkers are needed to understand synovial response to therapy in osteoarthritis (OA). Dynamic, contrast-enhanced magnetic resonance imaging (DCE MRI) provides quantitative, novel measures of synovial inflammation. This exploratory study examined DCE-assessed synovial response to intra-articular corticosteroid (IACS). METHODS: People with ACR clinical criteria OA knee underwent 3 T MRI pre- and 2 weeks post-IACS. Five MRI variables were assessed blindly: total synovial volume (semi-automated computer program), early enhancement rate (EER) and late enhancement ratio of the entire knee, synovial volume × late enhancement and a semi-quantitative (SQ) score (six sites scored 0-3). Clinical symptoms were assessed using pain visual analogue score (VAS) and WOMAC. RESULTS: 13 participants (5 male, mean age 63, mean pain VAS 66 mm mean body mass index (BMI) 31.3 kg/m(2)) were included. The majority of MRIs demonstrated no change in SQ score although the DCE variables changed to some extent in all. There was generally a reduction in synovial volume ((Wilcoxon test) median (interquartile range (IQR)) reduction 14 cm(3) (-1, 29)), EER (0.2% (-0.3, 0.6)) and late enhancement ratio (8% (-0.5, 41)). Synovial volume × late enhancement ratio demonstrated a substantive reduction (2250 (-930, 5630)) as well as the largest effect size, r = 0.45. There was a median 26% reduction in EER in participants with good symptomatic response to IACS, contrasting with a 23% increase in those who responded poorly. CONCLUSIONS: DCE MRI may be more sensitive than a SQ score at detecting post-therapy synovial changes. The association between EER and symptomatic response to IACS may reflect a closer relation of this biomarker to synovial inflammation than with volumetric assessment.

A novel contactless technique to measure water waves using a single photon avalanche diode detector array.

Commonly deployed measurement systems for water waves are intrusive and measure a limited number of parameters. This results in difficulties in inferring detailed sea state information while additionally subjecting the system to environmental loading. Optical techniques offer a non-intrusive alternative, yet documented systems suffer a range of problems related to usability and performance. Here, we present experimental data obtained from a 256 × 256 Single Photon Avalanche Diode (SPAD) detector array used to measure water waves in a laboratory facility. 12 regular wave conditions are used to assess performance. Picosecond resolution time-of-flight measurements are obtained, without the use of dye, over an area of the water surface and processed to provide surface elevation data. The SPAD detector array is installed 0.487 m above the water surface and synchronized with a pulsed laser source with a wavelength of 532 nm and mean power <1 mW. Through analysis of the experimental results, and with the aid of an optical model, we demonstrate good performance up to a limiting steepness value, ka, of 0.11. Through this preliminary proof-of-concept study, we highlight the capability for SPAD-based systems to measure water waves within a given field-of-view simultaneously, while raising potential solutions for improving performance.

Environmental & load data: 1:15 Scale tidal turbine subject to a variety of regular wave conditions.

Experimental data was obtained in order to investigate the effect of waves on the loads and performance of tidal turbines. An instrumented 1:15 scale tidal turbine was installed in the FloWave Ocean Energy Research Facility, and a wide range of regular wave conditions were generated; systematically varying both wave frequency and height. Waves were generated both following and opposing a fixed mean current velocity of 0.81 m/s. Data are made available of the measured turbine loads and environmental conditions obtained for five repeats of 24 wave conditions via https://doi.org/10.7488/ds/2472. A description of the data collection process, data processing, file structure and naming conventions are provided in this article. The analysis and presentation of the described dataset can be found in Ref. [1].

Cognitive dissonance. 1: An overview of the literature and its integration into theory and practice in clinical psychology.

PURPOSE: Clinical psychology may not be making full use of the experimental psychological research available to it. The purpose of this article is to review the literature on cognitive dissonance in order to assess its usefulness in developing and deconstructing clinical psychological therapies and practice. METHODS: Experimental, theoretical and review articles were examined in relation to their possible clinical implications, and included in this review if they related to the arousal, maintenance and reduction of the state termed cognitive dissonance. Well replicated findings based on experimentally sound paradigms were integrated to produce an overall view of the evidence in favour of the existence of these processes, and of the principles behind them. RESULTS: It is concluded that there is an effect on attitudes and behaviour of creating inconsistency in individuals, and that this is not explained away by alternative theories, which in many cases refer to special conditions which maximally arouse dissonance. The dissonant state lasts for a few minutes, but its effects can last for up to two weeks, and might be reinstated by reintroducing the original inconsistency. Individuals can react to dissonance through a variety of cognitive alterations which reinstate consistency. The choice of response is a function of its salience and the difficulty in its execution. CONCLUSIONS: The literature supports the existence of the phenomenon termed cognitive dissonance, and one can distil the principles underlying its production, maintenance and reduction. This body of literature may provide insights into the conduct of therapy generally, as well as into the mechanisms of specific therapies which may guide modifications or development of alternative interventions.

Cognitive dissonance. 2: A theoretical grounding of motivational interviewing.

PURPOSE: The aim of this article is to demonstrate the utility of the concept of cognitive dissonance in clinical psychology by showing how it may underlie an existing intervention. The technique of motivational interviewing (MI) is taken as an example of an area where the literature on cognitive dissonance can find such an application. The further aim of this exercise is to utilize insights from cognitive dissonance to suggest possible modifications to the intervention as it currently stands. METHODS: A mapping is undertaken of principles of cognitive dissonance as found in Draycott & Dabbs (1998) onto the description of nature, principles and techniques of MI as set out by Miller & Rollnick (1991). Following this, areas where insights from cognitive dissonance are ignored or underutilized are drawn out and used to suggest modifications to MI. RESULTS: The nature, principles and techniques of MI are, without exception, found to relate to one or more of the principles of cognitive dissonance. Criticisms and amendments to the technique of MI can be offered with the aim of making this mapping of cognitive dissonance more exact. Several practical suggestions can be made and a more structured approach offered. CONCLUSIONS: The concept of cognitive dissonance can clearly be seen to be of use in understanding the mechanism of action of MI. It can further be of use in guiding modifications to this existing intervention. This concept, and others available through the experimental psychological literature, can be of use in all branches of clinical psychology.