The motion of a drop in a rigid surface

The assumptions of a region of slip near a moving contact line (to remove the force singularity) and a constant contact angle are used to obtain the equation for the shape of a thin drop of liquid resting on a rigid plane. Three asymptotic expansions are matched together to obtain an expression for the rate at which the drop spreads. Some cases of sliding motion are also examined. Although the technique is presented here for thin drops only, it can also be applied to drops of arbitrary size

Exploring modality switching effects in negated sentences: further evidence for grounded representations

Theories of embodied cognition (e.g., Perceptual Symbol Systems Theory; Barsalou, 1999, 2009) suggest that modality specific simulations underlie the representation of concepts. Supporting evidence comes from modality switch costs: participants are slower to verify a property in one modality (e.g., auditory, BLENDER-loud) after verifying a property in a different modality (e.g., gustatory, CRANBERRIES-tart) compared to the same modality (e.g., LEAVES-rustling, Pecher et al., 2003). Similarly, modality switching costs lead to a modulation of the N400 effect in event-related potentials (ERPs; Collins et al., 2011; Hald et al., 2011). This effect of modality switching has also been shown to interact with the veracity of the sentence (Hald et al., 2011). The current ERP study further explores the role of modality match/mismatch on the processing of veracity as well as negation (sentences containing “not”). Our results indicate a modulation in the ERP based on modality and veracity, plus an interaction. The evidence supports the idea that modality specific simulations occur during language processing, and furthermore suggest that these simulations alter the processing of negation

Free surface flows with large slopes: beyond lubrication theory

The description of free surface flows can often be simplified to thin film (or lubrication) equations, when the slopes of the liquid-gas interface are small. Here we present a long wavelength theory that remains fully quantitative for steep interface slopes, by expanding about Stokes flow in a wedge. For small capillary numbers, the variations of the interface slope are slow and can be treated perturbatively. This geometry occurs naturally for flows with contact lines: we quantify the difference with ordinary lubrication theory through a numerical example and analytically recover the full Cox-Voinov asymptotic solution.Comment: 4 pages, 3 figure

From continua to R-trees

We show how to associate an R-tree to the set of cut points of a continuum. If X is a continuum without cut points we show how to associate an R-tree to the set of cut pairs of X.Comment: This is the version published by Algebraic & Geometric Topology on 1 November 200

A phenomenological study of occupational engagement in recovery from mental illness

This study aimed to uncover the meaning of occupation for 13 people who self identified as being in recovery from mental illness. Recovery narratives were collected from the participants in a series of open ended conversational interviews that were recorded and transcribed. The interview transcripts were analysed using phenomenological and hermeneutic approaches, with a focus on participants’ descriptions of engagement in everyday occupations. A range of experiences were evident, from complete disengagement to complete absorption in occupations. Participants described significant shifts in their experience of time, space, body and other people while in different modes of occupation and these were captured under the themes of ‘non-doing’, ‘half-doing’, ‘engaged doing’ and ‘absorbed doing’. Each mode had the potential to support recovery by creating opportunities for participants to reconnect with aspects of their being-in-the-world. The findings highlight the dynamics at play in different modes of occupation and suggest that all forms of engagement, including disengagement, can be significant in the recovery process. A greater understanding of the dynamics of occupation for people experiencing mental illness will enable carers and mental health services to more effectively support people in their recovery

Hydrodynamic theory of de-wetting

A prototypical problem in the study of wetting phenomena is that of a solid plunging into or being withdrawn from a liquid bath. In the latter, de-wetting case, a critical speed exists above which a stationary contact line is no longer sustainable and a liquid film is being deposited on the solid. Demonstrating this behavior to be a hydrodynamic instability close to the contact line, we provide the first theoretical explanation of a classical prediction due to Derjaguin and Levi: instability occurs when the outer, static meniscus approaches the shape corresponding to a perfectly wetting fluid

Modality switching and negation: ERP evidence for modality-specific simulations during negation processing

The Perceptual Symbol System Theory of cognition (Barsalou, 1999) suggests that modality-specific simulations underlie representation of concepts. This is evidenced by processing costs for switching modalities. That is, participants are slower to verify a property in the auditory modality (e.g., BLENDER-loud) after verifying a property in a different modality (e.g., CRANBERRIES-tart) and faster when verifying a property in the same modality (e.g., LEAVES-rustling). The modality switch cost has also been shown to lead to a modulation of the N400 event-related potential (ERP) (Collins, Pecher, Zeelenberg & Coulson, 2011 using a property verification task; Hald, Marshall, Janssen & Garnham, 2011 using a sentence verification task). In a separate line of research, ERP studies have indicated that without a discourse context, negated sentences are more difficult to process than affirmative sentences, leading to a different N400 pattern for negative sentences than for affirmative sentences (e.g., Fischler, Bloom, Childers, Roucos, & Perry, 1983.) Unlike affirmative sentences, sentences containing negation show a larger N400 for correct, semantically coherent single sentences (i.e., factually true sentences) than for semantically incorrect sentences (i.e., false sentences). However, Nieuwland and Kuperberg (2008,) found that the pragmatics of the sentence can change this N400 pattern to one closer to affirmative sentences. The goal of the current study was to explore whether the processing of negation could be aided by modality matching information. Other evidence suggests that comprehenders create a simulation of negative sentences (Kaup, Yaxley, Madden, Zwaan, & Lüdtke, 2007), but it is unclear whether modality matching information could modulate the processing cost of negation. Essentially, can modality matching information as reported by Collins et al., (2011) and Hald et al., (2011) lead to a modulation of the N400 for true negated sentences similar to that seen when discourse pragmatics supports negation? Furthermore, we were interested in whether the modality switch effect would lead to a similar pattern in the ERPs as that found with affirmative sentences (Collins et al., 2011 & Hald et al., 2011). Using a within-subjects design we used 160 pairs of experimental pairs which were either of the same or of a different modality. All experimental items were either visual or tactile modality and were drawn from existing sets of materials (Pecher, et al., 2003; Van Dantzig, et al., 2008). For example, a different modality pair was “A light bulb is very hot” followed by “Rice isn’t black” versus a same visual modality pair “A giraffe is spotted” followed by “Rice isn’t black”. We predicted that the underlined word is where a modulation in the N400 may be seen. Additionally, we explored veracity by making half of the experimental target sentences false (“Rice isn’t white”). Participants were asked to judge whether each sentence was typically true or false. Our initial results indicate a modulation in the ERP based on both modality and veracity. For true (“Rice isn’t black”) and false target statements (“Rice isn’t white”) different modality pairs elicit a larger frontal-central N400 like effect compared to same modality pairs (Figure 1), replicating Hald et al., (2011). When comparing true versus false, the different modality pairs elicit a large posterior N400 for true compared to false sentences (replicating the effect for negated sentences, i.e., Fischler et al., 1983). However for same modality pairs there is a reduction in the N400 to true statements; no difference is seen between true and false statements in the ERP (Figure 2). These results replicate and extend previous ERP findings using the modality switch paradigm. The evidence suggests that not only do modality-specific simulations occur but they can even aid the processing of negation

Bridging the Gap: Applying Assurance Arguments to MIL-HDBK-516C Certification of a Neural Network Control System with ASIF Run Time Assurance Architecture

Recent advances in artificial intelligence and machine learning may soon yield paradigm-shifting benefits for aerospace systems. However, complexity and possible continued on-line learning makes neural network control systems (NNCS) difficult or impossible to certify under the United States Military Airworthiness Certification Criteria defined in MIL-HDBK-516C. Run time assurance (RTA) is a control system architecture designed to maintain safety properties regardless of whether a primary control system is fully verifiable. This work examines how to satisfy compliance with MIL-HDBK-516C while using active set invariance filtering (ASIF), an advanced form of RTA not envisaged by the 516c committee. ASIF filters the commands from a primary controller, passing on safe commands while optimally modifying unsafe commands to ensure safety with minimal deviation from the desired control action. This work examines leveraging the core theory behind ASIF as assurance argument explaining novel satisfaction of 516C compliance criteria. The result demonstrates how to support compliance of novel technologies with 516C as well as elaborate how such standards might be updated for emerging technologies

Innovating for improved healthcare: Sociotechnical and innovation systems perspectives and lessons from the NHS

Healthcare systems with limited resources face rising demand pressures. Healthcare decision-makers increasingly recognise the potential of innovation to help respond to this challenge and to support high-quality care. However, comprehensive and actionable evidence on how to realise this potential is lacking. We adopt sociotechnical systems and innovation systems theoretical perspectives to examine conditions that can support and sustain innovating healthcare systems. We use primary data focussing on England (with 670 contributions over time) and triangulate findings against globally-relevant literature. We discuss the complexity of factors influencing an innovating healthcare system’s ability to support the development and uptake of innovations and share practical learning about changes in policy, culture, and behaviour that could support system improvement. Three themes are examined in detail: skills, capabilities, and leadership; motivations and accountabilities; and collaboration and coordination. We also contribute to advancing applications of sociotechnical systems thinking to major societal transformation challenges