Algebraically decaying modes and wave packet pseudo-modes in swept Hiemenz flow

The modal structure of the swept Hiemenz flow, a model for the flow near the attachment line of a swept wing, consists of eigenfunctions which exhibit (super-)exponential or algebraic decay as the wall-normal coordinate tends to infinity. The subset of algebraically decaying modes corresponds to parts of the spectrum which are characterized by a significant sensitivity to numerical discretization. Numerical evidence further suggests that a continuous spectrum covering a two-dimensional range of the complex plane exists. We investigate the family of uniform swept Hiemenz modes using eigenvalue computations, numerical simulations and the concept of wave packet pseudo-modes. Three distinct branches of the family of algebraically decaying eigenmodes are identified. They can be superimposed to produce wavefronts propagating towards or away from the boundary layer and standing or travelling wave packets in the free stream. Their role in the exchange of information between the free stream and the attachment-line boundary layer for the swept Hiemenz flow is discussed. The concept of wave packet pseudo-modes has been critical in the analysis of this problem and is expected to lead to further insights into other shear flows in semi- or bi-infinite domain

Algebraically diverging modes upstream of a swept bluff body

Classical stability theory for swept leading-edge boundary layers predicts eigenmodes in the free stream with algebraic decay far from the leading edge. In this article, we extend the classical base flow solution by Hiemenz to a uniformly valid solution for the flow upstream of a bluff body, which includes a three-dimensional boundary layer, an inviscid stagnation-point flow and an outer parallel flow. This extended, uniformly valid base flow additionally supports modes which diverge algebraically outside the boundary layer. The theory of wave packet pseudomodes is employed to derive analytical results for the growth rates and for the eigenvalue spectra of this type of mode. The complete spectral analysis of the flow, including the algebraically diverging modes, will give a more appropriate basis for receptivity studies and will more accurately describe the interaction of perturbations in the free stream with disturbances in the boundary laye

The Scent of Collaboration: Exploring the Efect of Smell on Social Interactions

Social interactions are multisensory experiences. However, it is not well understood how technology-mediated smell can support social interactions, especially in collaborative tasks. To explore its effect on collaboration, we asked eleven pairs of users to work together on a writing task while wearing an interactive jewellery designed to emit scent in a controlled fashion. In a within-subjects experiment, participants were asked to collaboratively write a story about a standardized visual stimulus while exposed to with scent and without scent conditions. We analyzed video recordings and written stories using a combination of methods from HCI, psychology, sociology, and human communication research. We observed differences in both participants' communication and creation of insightful stories in the with scent condition. Furthermore, scent helped participants recover from communication breakdown even though they were unaware of it. We discuss the possible implications of our findings and the potential of technology-mediated scent for collaborative activities

Improving immersive experiences for visitors with sensory impairments to the aquarium of the pacific

This case study describes the development of a mid-air haptic solution to enhance the immersive experience of visitors who are deaf, blind or wheelchair users to the Aquarium of the Pacific's movie theatre. During the project we found that adding a sense of touch, using an innovative ultrasound technology, to an immersive experience can improve the sense of engagement users have with the content, and can help to improve agreement with the topics presented. We present guidelines on the design of haptic sensations. By describing how this project took place within the tight timelines of a commercial deployment, we hope to encourage more organisations to do similar work

Timing of Deformation along the Iron Springs Thrust, Southern Sevier Fold-and-Thrust Belt, Utah: Evidence for an Extensive Thrusting Event in the mid-Cretaceous

The temporal and spatial distribution of strain associated with the Sevier orogeny in western North America is significantly different in the southern end of the belt, at the latitude of Las Vegas, Nevada, than farther to the north at the latitude of Salt Lake City, Utah. Reasons for these differences have been speculative as a lack of temporal constraints on thrusting in the intervening region hindered along-strike correlation across the belt. We determined a crystallization age of 100.18 ± 0.04 Ma for zircons extracted from a recently recognized dacite lapilli ash-fall tuff near the base of the synorogenic Iron Springs Formation. We propose the name “Three Peaks Tuff Member” for this unit, and identify a type stratigraphic section on the western flank of the “Three Peaks,” a topographic landmark in Iron County, Utah. Field relationships and this age constrain movement on the Iron Springs thrust and the end of the sub-Cretaceous unconformity in the critical intervening area to latest Albian/earliest Cenomanian. Movement on the Iron Springs thrust was synchronous with movement on multiple Sevier thrusts at ~100 Ma, indicating that the mid-Cretaceous was a period of extensive thrust-fault movement. This mid-Cretaceous thrusting event coincided with a period of global plate reorganization and increased convergence, and hence an increased subduction rate for the Farallon Plate beneath North America. The accelerated subduction contributed to a Cordilleran arc flare-up event and steepening of the orogenic wedge, which triggered widespread thrusting across the retroarc Sevier deformation belts. Additionally, based on temporal constraints and the strong spatial connection of mid-Cretaceous thrusts to lineaments interpreted as pre-orogenic transform faults, we suggest that temporal and spatial variations along the strike of the orogenic belt reflect tectonic inheritance of basement structures associated with the edge of the rifted Precambrian craton

Communicating cosmology with multisensory metaphorical experiences

We present a novel approach to communicating abstract concepts in cosmology and astrophysics in a more accessible and inclusive manner. We describe an exhibit aiming at creating an immersive, multisensory metaphorical experience of an otherwise imperceptible physical phenomenon-dark matter. Human-Computer Interaction experts and physicists co-created a multisensory journey through dark matter by exploiting the latest advances in haptic and olfactory technology. We present the concept design of a pilot and a second, improved event, both held at the London Science Museum, including the practical setup of the multisensory dark matter experience, the delivery of sensory stimulation and preliminary insights from users' feedback

Smell, Taste, and Temperature Interfaces

Everyday life hinges on smell, taste, and temperature-based experiences, from eating to detecting potential hazards (e.g., smell of rotten food, microbial threats, and non-microbial threats such as from hazardous gases) to responding to thermal behavioral changes. These experiences are formative as visceral, vital signals of information, and contribute directly to our safety, well-being, and enjoyment. Despite this, contemporary technology mostly stimulates vision, audition, and - more recently - touch, unfortunately leaving out the senses of smell taste and temperature. In the last decade, smell, taste, and temperature interfaces have gained a renewed attention in the field of Human Computer Interaction, fueled by the growth of virtual reality and wearable devices. As these modalities are further explored, it is imperative to discuss underlying cultural contexts of these experiences, how researchers can robustly stimulate and sense these modalities, and in what contexts such multisensory technologies are meaningful. This workshop addresses these topics and seeks to provoke critical discussions around chemo- and thermo-sensory HCI

Mapping FoodHCI Futures

Recognizing the significant potential impact that HCI has on food practices and experiences, researchers and practitioners are undertaking a growing number of explorations of novel computing technology and food combinations. These explorations have so far primarily emphasized technology-driven systems and taken a human-centric perspective. We propose a Special Interest Group (SIG) in "foodHCI futures"that creates a space for researchers to discuss the boundaries of food incorporating HCI, and with the simultaneous aims of reconciling food with technology and extending our visions for human-food interactions towards anthropocentrism. Specifically, the SIG will be a beginning of developing a structured conceptual map of the possibilities for future technology interventions in food systems. In developing this map, we hope to encourage democratized debate, provoke new and divergent thoughts on the opportunities for foodHCI, and ultimately gain unique insights that contribute to preferable food futures

Informed consent procedure in a double blind randomized anthelminthic trial on Pemba Island, Tanzania: do pamphlet and information session increase caregivers knowledge?

Background In clinical research, obtaining informed consent from participants is an ethical and legal requirement. Conveying the information concerning the study can be done using multiple methods yet this step commonly relies exclusively on the informed consent form alone. While this is legal, it does not ensure the participant’s true comprehension. New effective methods of conveying consent information should be tested. In this study we compared the effect of different methods on the knowledge of caregivers of participants of a clinical trial on Pemba Island, Tanzania. Methods A total of 254 caregivers were assigned to receive (i) a pamphlet (n = 63), (ii) an oral information session (n = 62) or (iii) a pamphlet and an oral information session (n = 64) about the clinical trial procedures, their rights, benefits and potential risks. Their post-intervention knowledge was assessed using a questionnaire. One group of caregivers had not received any information when they were interviewed (n = 65). Results In contrast to the pamphlet, attending an information session significantly increased caregivers’ knowledge for some of the questions. Most of these questions were either related to the parasite (hookworm) or to the trial design (study procedures). Conclusions In conclusion, within our trial on Pemba Island, a pamphlet was found to not be a good form of conveying clinical trial information while an oral information session improved knowledge. Not all caregivers attending an information session responded correctly to all questions; therefore, better forms of communicating information need to be found to achieve a truly informed consent