Time domain Green functions for the homogeneous Timoshenko beam

In this paper, wave splitting technique is applied to a homogeneous Timoshenko beam. The purpose is to obtain a diagonal equation in terms of the split fields. These fields are calculated in the time domain from an appropriate set of boundary conditions. The fields along the beam are represented as a time convolution of Green functions with the excitation. The Green functions do not depend on the wave fields but only on the parameters of the beam. Green functions for a Timoshenko beam are derived, and the exponential behaviour of these functions as well as the split modes are discussed. A transformation that extracts the exponential part is performed. Some numerical examples for various loads are presented and compared with results appearing in the literature

Phylogeography and phenotypic wing shape variation in a damselfly across populations in Europe

Background Describing geographical variation in morphology of organisms in combination with data on genetic differentiation and biogeography can provide important information on how natural selection shapes such variation. Here we study genetic structure using ddRAD seq and wing shape variation using geometric morphometrics in 14 populations of the damselfly Lestes sponsa along its latitudinal range in Europe. Results The genetic analysis showed a significant, yet relatively weak population structure with high genetic heterozygosity and low inbreeding coefficients, indicating that neutral processes contributed very little to the observed wing shape differences. The genetic analysis also showed that some regions of the genome (about 10%) are putatively shaped by selection. The phylogenetic analysis showed that the Spanish and French populations were the ancestral ones with northern Swedish and Finnish populations being the most derived ones. We found that wing shape differed significantly among populations and showed a significant quadratic (but weak) relationship with latitude. This latitudinal relationship was largely attributed to allometric effects of wing size, but non-allometric variation also explained a portion of this relationship. However, wing shape showed no phylogenetic signal suggesting that lineage-specific variation did not contribute to the variation along the latitudinal gradient. In contrast, wing size, which is correlated with body size in L. sponsa, had a strong negative correlation with latitude. Conclusion Our results suggest a relatively weak population structure among the sampled populations across Europe, but a clear differentiation between south and north populations. The observed geographic phenotypic variation in wing shape may have been affected by different local selection pressures or environmental effects

VelociWatch: Designing and evaluating a virtual keyboard for the input of challenging text

© 2019 Association for Computing Machinery. Virtual keyboard typing is typically aided by an auto-correct method that decodes a user’s noisy taps into their intended text. This decoding process can reduce error rates and possibly increase entry rates by allowing users to type faster but less precisely. However, virtual keyboard decoders sometimes make mistakes that change a user’s desired word into another. This is particularly problematic for challenging text such as proper names. We investigate whether users can guess words that are likely to cause auto-correct problems and whether users can adjust their behavior to assist the decoder. We conduct computational experiments to decide what predictions to ofer in a virtual keyboard and design a smartwatch keyboard named VelociWatch. Novice users were able to use the features of VelociWatch to enter challenging text at 17 words-per-minute with a corrected error rate of 3%. Interestingly, they wrote slightly faster and just as accurately on a simpler keyboard with limited correction options. Our fnding suggest users may be able to type dif-fcult words on a smartwatch simply by tapping precisely without the use of auto-correct

Dexmo: An inexpensive and lightweight mechanical exoskeleton for motion capture and force feedback in VR

We present Dexmo: an inexpensive and lightweight mechanical exoskeleton system for motion capturing and force feedback in virtual reality applications. Dexmo combines multiple types of sensors, actuation units and link rod structures to provide users with a pleasant virtual reality experience. The device tracks the user’s motion and uniquely provides passive force feedback. In combination with a 3D graphics rendered environment, Dexmo provides the user with a realistic sensation of interaction when a user is for example grasping an object. An initial evaluation with 20 participants demonstrate that the device is working reliably and that the addition of force feedback resulted in a significant reduction in error rate. Informal comments by the participants were overwhelmingly positive.This is the accepted manuscript. The final version is available at http://dl.acm.org/citation.cfm?doid=2858036.2858487

Breaking the Screen: Interaction Across Touchscreen Boundaries in Virtual Reality for Mobile Knowledge Workers.

Virtual Reality (VR) has the potential to transform knowledge work. One advantage of VR knowledge work is that it allows extending 2D displays into the third dimension, enabling new operations, such as selecting overlapping objects or displaying additional layers of information. On the other hand, mobile knowledge workers often work on established mobile devices, such as tablets, limiting interaction with those devices to a small input space. This challenge of a constrained input space is intensified in situations when VR knowledge work is situated in cramped environments, such as airplanes and touchdown spaces. In this paper, we investigate the feasibility of interacting jointly between an immersive VR head-mounted display and a tablet within the context of knowledge work. Specifically, we 1) design, implement and study how to interact with information that reaches beyond a single physical touchscreen in VR; 2) design and evaluate a set of interaction concepts; and 3) build example applications and gather user feedback on those applications.Comment: 10 pages, 8 figures, ISMAR 202

Parental help-seeking behaviour for, and care of, a sick or injured child during the COVID-19 pandemic: a European online survey

BACKGROUND: Globally, the COVID-19 pandemic had a huge impact on patients and healthcare systems. A decline in paediatric visits to healthcare settings was observed, which might have been due to lower incidence of injury and infectious illness, changes in healthcare services and parental concern. The aim of our study was to examine parental experiences of help-seeking for, and care of, a sick or injured child during COVID-19 lockdown periods in five European countries with different healthcare systems in place. METHODS: An online survey for parents with a child with any kind or illness of injury during COVID-19 lockdowns was circulated through social media in five European countries: Italy, Spain, Sweden, the Netherlands, and the United Kingdom. Parents living in one of these countries with self-identification of a sick or injured child during COVID-19 lockdown periods were eligible to fill in the survey. Descriptive statistics were used for the level of restrictions per country, children's characteristics, family characteristics and reported help-seeking behaviour of parents prior to the lockdown and their real experience during the lockdown. The free text data was subjected to thematic analysis. RESULTS: The survey was fully completed by 598 parents, ranging from 50 to 198 parents per country, during varying lockdown periods from March 2020 until May 2022. Parents who completed the survey were not deterred from seeking medical help for their sick or injured child during the COVID-19 pandemic. This finding was comparable in five European countries with different healthcare systems in place. Thematic analysis identified three main areas: parental experiences of access to healthcare, changes in parents' help-seeking behaviours for a sick or injured child during lockdowns, and the impact of caring for a sick or injured child during the lockdowns. Parents reported limited access to non-urgent care services and were anxious about either their child or themselves catching COVID-19. CONCLUSION: This insight into parental perspectives of help-seeking behaviour and care for a sick or injured child during COVID-19 lockdowns could inform future strategies to improve access to healthcare, and to provide parents with adequate information concerning when and where to seek help and support during pandemics

ReconViguRation: Reconfiguring Physical Keyboards in Virtual Reality.

Physical keyboards are common peripherals for personal computers and are efficient standard text entry devices. Recent research has investigated how physical keyboards can be used in immersive head-mounted display-based Virtual Reality (VR). So far, the physical layout of keyboards has typically been transplanted into VR for replicating typing experiences in a standard desktop environment. In this paper, we explore how to fully leverage the immersiveness of VR to change the input and output characteristics of physical keyboard interaction within a VR environment. This allows individual physical keys to be reconfigured to the same or different actions and visual output to be distributed in various ways across the VR representation of the keyboard. We explore a set of input and output mappings for reconfiguring the virtual presentation of physical keyboards and probe the resulting design space by specifically designing, implementing and evaluating nine VR-relevant applications: emojis, languages and special characters, application shortcuts, virtual text processing macros, a window manager, a photo browser, a whack-a-mole game, secure password entry and a virtual touch bar. We investigate the feasibility of the applications in a user study with 20 participants and find that, among other things, they are usable in VR. We discuss the limitations and possibilities of remapping the input and output characteristics of physical keyboards in VR based on empirical findings and analysis and suggest future research directions in this area

Home Is Where the Smart Is: Development and Validation of the Cybersecurity Self-Efficacy in Smart Homes (CySESH) Scale

The ubiquity of devices connected to the internet raises concerns about the security and privacy of smart homes. The effectiveness of interventions to support secure user behaviors is limited by a lack of validated instruments to measure relevant psychological constructs, such as self-efficacy - the belief that one is able to perform certain behaviors. We developed and validated the Cybersecurity Self-Efficacy in Smart Homes (CySESH) scale, a 12-item unidimensional measure of domain-specific self-efficacy beliefs, across five studies (N = 1247). Three pilot studies generated and refined an item pool. We report evidence from one initial and one major, preregistered validation study for (1) excellent reliability (α = 0.90), (2) convergent validity with self-efficacy in information security (rSEIS = 0.64, p < .001), and (3) discriminant validity with outcome expectations (rOE = 0.26, p < .001), self-esteem (rRSE = 0.17, p < .001), and optimism (rLOT-R = 0.18, p < .001). We discuss CySESH's potential to advance future HCI research on cybersecurity, practitioner user assessments, and implications for consumer protection policy