Opposing and following responses in sensorimotor speech control : why responses go both ways

When talking, speakers continuously monitor and use the auditory feedback of their own voice to control and inform speech production processes. When speakers are provided with auditory feedback that is perturbed in real time, most of them compensate for this by opposing the feedback perturbation. But some speakers follow the perturbation. In the current study, we investigated whether the state of the speech production system at perturbation onset may determine what type of response (opposing or following) is given. The results suggest that whether a perturbation-related response is opposing or following depends on ongoing fluctuations of the production system: It initially responds by doing the opposite of what it was doing. This effect and the non-trivial proportion of following responses suggest that current production models are inadequate: They need to account for why responses to unexpected sensory feedback depend on the production-system’s state at the time of perturbation

Liquid drop splashing on smooth, rough and textured surfaces

Splashing occurs when a liquid drop hits a dry solid surface at high velocity. This paper reports experimental studies of how the splash depends on the roughness and the texture of the surfaces as well as the viscosity of the liquid. For smooth surfaces, there is a "corona" splash caused by the presence of air surrounding the drop. There are several regimes that occur as the velocity and liquid viscosity are varied. There is also a "prompt" splash that depends on the roughness and texture of the surfaces. A measurement of the size distribution of the ejected droplets is sensitive to the surface roughness. For a textured surface in which pillars are arranged in a square lattice, experiment shows that the splashing has a four-fold symmetry. The splash occurs predominantly along the diagonal directions. In this geometry, two factors affect splashing the most: the pillar height and spacing between pillars.Comment: 9 pages, 11 figure

A common neural substrate for language production and verbal working memory

Verbal working memory (VWM), the ability to maintain and manipulate representations of speech sounds over short periods, is held by some influential models to be independent from the systems responsible for language production and comprehension [e.g., Baddeley, A. D. Working memory, thought, and action. New York, NY: Oxford University Press, 2007]. We explore the alternative hypothesis that maintenance in VWM is subserved by temporary activation of the language production system [Acheson, D. J., & MacDonald, M. C. Verbal working memory and language production: Common approaches to the serial ordering of verbal information. Psychological Bulletin, 135, 50–68, 2009b]. Specifically, we hypothesized that for stimuli lacking a semantic representation (e.g., nonwords such as mun), maintenance in VWM can be achieved by cycling information back and forth between the stages of phonological encoding and articulatory planning. First, fMRI was used to identify regions associated with two different stages of language production planning: the posterior superior temporal gyrus (pSTG) for phonological encoding (critical for VWM of nonwords) and the middle temporal gyrus (MTG) for lexical–semantic retrieval (not critical for VWM of nonwords). Next, in the same subjects, these regions were targeted with repetitive transcranial magnetic stimulation (rTMS) during language production and VWM task performance. Results showed that rTMS to the pSTG, but not the MTG, increased error rates on paced reading (a language production task) and on delayed serial recall of nonwords (a test of VWM). Performance on a lexical–semantic retrieval task (picture naming), in contrast, was significantly sensitive to rTMS of the MTG. Because rTMS was guided by language production-related activity, these results provide the first causal evidence that maintenance in VWM directly depends on the long-term representations and processes used in speech production

Water entry of a flat elastic plate at high horizontal speed

The two-dimensional problem of an elastic-plate impact onto an undisturbed surface of water of infinite depth is analysed. The plate is forced to move with a constant horizontal velocity component which is much larger than the vertical velocity component of penetration. The small angle of attack of the plate and its vertical velocity vary in time, and are determined as part of the solution, together with the elastic deflection of the plate and the hydrodynamic loads within the potential flow theory. The boundary conditions on the free surface and on the wetted part of the plate are linearized and imposed on the initial equilibrium position of the liquid surface. The wetted part of the plate depends on the plate motion and its elastic deflection. To determine the length of the wetted part we assume that the spray jet in front of the advancing plate is negligible. A smooth separation of the free-surface flow from the trailing edge is imposed. The wake behind the moving body is included in the model. The plate deflection is governed by Euler’s beam equation, subject to free–free boundary conditions. Four different regimes of plate motion are distinguished depending on the impact conditions: (a) the plate becomes fully wetted; (b) the leading edge of the plate touches the water surface and traps an air cavity; (c) the free surface at the forward contact point starts to separate from the plate; (d) the plate exits the water. We could not detect any impact conditions which lead to steady planing of the free plate after the impact. It is shown that a large part of the total energy in the fluid–plate interaction leaves the main bulk of the liquid with the spray jet. It is demonstrated that the flexibility of the plate may increase the hydrodynamic loads acting on it. The impact loads can cause large bending stresses, which may exceed the yield stress of the plate material. The elastic vibrations of the plate are shown to have a significant effect on the fluid flow in the wake

Effects of auditory feedback consistency on vowel production

In investigations of feedback control during speech production, researchers have focused on two different kinds of responses to erroneous or unexpected auditory feedback. Compensation refers to online, feedback-based corrections of articulations. In contrast, adaptation refers to long-term changes in the speech production system after exposure to erroneous/unexpected feedback, which may last even after feedback is normal again. In the current study, we aimed to compare both types of feedback responses by investigating the conditions under which the system starts adapting in addition to merely compensating. Participants vocalized long vowels while they were exposed to either consistently altered auditory feedback, or to feedback that was unpredictably either altered or normal. Participants were not aware of the manipulation of auditory feedback. We predicted that both conditions would elicit compensation, whereas adaptation would be stronger when the altered feedback was consistent across trials. The results show that although there seems to be somewhat more adaptation for the consistently altered feedback condition, a substantial amount of individual variability led to statistically unreliable effects at the group level. The results stress the importance of taking into account individual differences and show that people vary widely in how they respond to altered auditory feedback

Capillary-gravity waves: The effect of viscosity on the wave resistance

The effect of viscosity on the wave resistance experienced by a 2d perturbation moving at uniform velocity over the free surface of a fluid is investigated. The analysis is based on Rayleigh's linearized theory of capillary-gravity waves. It is shown in particular that the wave resistance remains bounded as the velocity of the perturbation approches the minimun phase speed, unlike what is predicted by the inviscid theory.Comment: Europhysics Letters, in pres

Active surveillance of choroidal neovascularisation in children: incidence, aetiology and management findings from a national study in the UK

BACKGROUND/AIMS: To determine the UK incidence, demographics, aetiology, management and visual outcome for children developing choroidal neovascularisation (CNV). METHODS: A prospective population-based observational study of routine practice via the British Ophthalmological Surveillance Unit between January 2012 and December 2013 with subsequent 1-year follow-up in children under 16 years old with newly diagnosed CNV. RESULTS: Twenty-seven children with CNV were reported. The UK estimated annual incidence for those aged 16 and under was 0.21 per 100 000 (95% CI 0.133 to 0.299). The mean age was 11.1 years (SD 3.9, range 4-16). Fourteen were female. Seventy-seven per cent (22 patients) were Caucasian British. Twenty-three children (85%) had unilateral disease. The most common aetiology included inflammatory retinochoroidopathy (n=9), optic disc abnormalities (n=9) and idiopathic (n=5). Optical coherence tomography was performed in all cases and fundus fluorescein angiography in 61%. Management included observation only (n=10), anti-vascular endothelial growth factor (anti-VEGF) injection of bevacizumab (n=14) or ranibizumab (n=2), or both (n=1), and additional use of oral (n=1) and local (periocular n=2 and intravitreal n=2) steroids in five children with inflammatory retinochoroidopathy. The mean number of anti-VEGF injections was 2±1, with eight patients receiving only one injection. The mean (SD) best corrected visual acuity in LogMAR was 0.91 (0.53) at presentation and 0.74 (0.53) at 1-year follow-up (p=0.09). CONCLUSION: This is the first population-based prospective study of CNV in children. This is a rare disorder with a poor visual prognosis irrespective of CNV location and the use of anti-VEGF therapy

Severe underreporting of energy intake in normal weight subjects: use of an appropriate standard and relation to restrained eating

Abstract Objective: To assess the influence of different standards and restrained eating on underreporting in healthy, non-obese, weight-stable young subjects. Design and subjects: Eighty-three young adults (20-38 years, 55 women, 28 men) were assessed under weight-stable conditions with a 7-day dietary record and the three-factor eating questionnaire by Stunkard and Messick. Resting energy expenditure (REE; indirect calorimetry) plus data derived from physical activity records (PA) (Standard 1) or REE times an activity factor (AF) (Standard 2) was used as standard for total energy expenditure (TEE). For comparison, doubly labelled water (DLW) was used to measure TEE in a subgroup of subjects. Results: There was an association between self-reported energy intake and Standard 2 (r = 0.72) but not with Standard 1. When compared with DLW both calculated standards were inaccurate, but Standard 2 avoided high levels of overreporting. Using Standard 2 to identify ‘severe' underreporting (SU; as defined by a deviation of energy intake (EI) and TEE of >20%), SU was seen in 37% of all subjects. It was more frequently found in women than in men (49% of women, 14.3% of men, P < 0.05). Underreporting subjects had a reduced EI (P < 0.01) but there were no significant differences in nutritional status (body weight and height, body mass index, fat mass and fat-free mass), energy expenditure and the proportion of energy from macronutrients between normal and underreporting subjects. However, high restraint was associated with a higher degree of underreporting in the total group, whereas disinhibition had an influence only in men. Conclusions: A high prevalence of SU is seen in non-obese subjects. Characteristics of eating behaviour (restraint and disinhibition) were associated with underreporting but seemed to have a different influence in men and wome