Insights into the Assembly of Arctic Alaska: Provenance and Geochemical Data from the Doonerak Fenster and Endicott Mountains Allochthon

The Doonerak fenster of the central Brooks Range contains the Apoon assemblage, a suite of Early Paleozoic mafic-to-intermediate volcanic and siliciclastic rocks. The fenster exposes deep structural levels of the Brooks Range between regions of Laurentian and non-Laurentian origin in Arctic Alaska. During the Mesozoic to Cenozoic formation of the Brooks Range, Upper Devonian to Triassic siliciclastic and carbonate rocks of the Endicott Mountains allochthon were thrusted northward and juxtaposed over the top of this volcanic suite.;New geochemical data indicates that the Apoon assemblage formed as part of an island arc complex. The assemblage contains basaltic-to-andesitic rocks with diverse textures, including pillow basalts and cross-cutting dikes and sills. Enrichment in large ion lithophile elements (e.g. Cs, Rb, Ba, Th), depletion in high field strength elements (e.g. Nb, P, Zr, Ti), and chondrite-normalized rare-earth element (REE) trends within the Apoon volcanics are consistent with formation in an island arc setting and corroborate previous work.;Detrital zircon spectra from volcaniclastic portions of the Apoon assemblage show a prominent unimodal 440--530 Ma population centered on 504 Ma with only minor populations potentially derived from Laurentia. The siliciclastic units unconformably overlying the Apoon assemblage (Ellesmerian sequence) and those of the Endicott Mountains allochthon mostly lack detritus from this 504 Ma population and are instead dominated by 400--440 Ma populations centered on ~420 Ma. While this is dissimilar from the Apoon assemblage, detritus of this age is common in rocks of the Canadian Arctic, Svalbard, and eastern Greenland and is associated with the Caledonian orogeny.;The coexistence of Caledonian detritus alongside 800--550 Ma populations within samples from the northern margin of the fenster also indicates a connection to the Timanian orogen of northern Baltica. The youngest portions of the Apoon assemblage also show significant Laurentian and Caledonian age detritus. This shift in provenance could be explained by the closure of an oceanic basin, providing newly integrated sediment pathways. Collectively, evidence presented here indicates that the Apoon assemblage formed as part of an island arc, which initially formed in a relatively isolated geographic position and received detritus from mostly proximal sources (single unimodal 504 Ma population). This arc progressively approached and eventually docked onto the margin of northwest Laurentian during closure of the northernmost Iapetus Ocean, eventually amalgamating regions of Laurentian and non-Laurentian origin. Thus, the Doonerak fenster preserves an island arc complex and marks the location of a Paleozoic suture between Laurentian and non-Laurentian portions of Arctic Alaska

I see where this is going: a psychophysical study of directional mid-air haptics and apparent tactile motion

Mid-air haptic technology can render a plethora of tactile sensations including points, lines, shapes, and textures. To do so, one requires increasingly complex haptic displays. Meanwhile, tactile illusions have had widespread success in the development of contact and wearable haptic displays. In this paper, we exploit the apparent tactile motion illusion to display mid-air haptic directional lines; a prerequisite for the rendering of shapes and icons. We present two pilot studies and a psychophysical study that contrasts a dynamic tactile pointer (DTP) to an apparent tactile pointer (ATP) in terms of direction recognition. To that end, we identify optimal duration and direction parameters for both DTP and ATP mid-air haptic lines and discuss the implications of our findings with respect to haptic feedback design, and device complexity

Quantifying spatial acuity of frequency resolved midair ultrasound vibrotactile stimuli

Spatial acuity is a fundamental property of any sensory system. In the case of the somatosensory system, the two-point discrimination (2PD) test has long been used to investigate tactile spatial resolution. However, the somatosensory system comprises three main mechanoreceptive channels: the slowly adapting channel (SA) responds to steady pressure, the rapidly adapting channel (RA) responds to low-frequency vibration, and the Pacinian channel (PC) responds to high-frequency vibration. The use of mechanical stimuli in the classical 2PD test means that previous studies on tactile acuity have primarily focussed on the pressure-sensitive channel alone, while neglecting other submodalities. Here, we used a novel ultrasound stimulation to systematically investigate the spatial resolution of the two main vibrotactile channels. Contrary to the textbook view of poor spatial resolution for PC-like stimuli, across four experiments we found that high-frequency vibration produced surprisingly good spatial acuity. This effect remained after controlling for interchannel differences in stimulus detectability and perceived intensity. Laser doppler vibrometry experiments confirmed that the acuity of the PC channel was not simply an artifact of the skin's resonance to high-frequency mechanical stimulation. Thus, PC receptors may transmit substantial spatial information, despite their sparse distribution, deep location, and large receptive fields

Sampling strategy for ultrasonic mid-air haptics

Mid-air tactile stimulation using ultrasonics has been used in a variety of human computer interfaces in the form of prototypes as well as products. When generating these tactile patterns with mid-air tactile ultrasonic displays, the common approach has been to sample the patterns using the hardware update rate capabilities to their full extent. In the current study we show that the hardware update rate can impact perception, but unexpectedly we find that higher update rates do not improve pattern perception. In a first user study, we highlight the effect of update rate on the perceived strength of a pattern, especially for patterns rendered at slow rate of less than 10 Hz. In a second user study, we identify the evolution of the optimal update rate according to variations in pattern size. Our main results show that update rate should be designated as additional parameter for tactile patterns. We also discuss how the relationships we defined in the current study can be implemented into designer tools so that designers remain oblivious to this additional complexity

It Sounds Cool: Exploring Sonification of Mid-Air Haptic Textures Exploration on Texture Judgments, Body Perception, and Motor Behaviour

Ultrasonic mid-air haptic technology allows for the perceptual rendering of textured surfaces onto the user's hand. Unlike real textured surfaces, however, mid-air haptic feedback lacks implicit multisensory cues needed to reliably infer a texture's attributes (e.g., its roughness). In this paper, we combined mid-air haptic textures with congruent sound feedback to investigate how sonification could influence people's (1) explicit judgment of the texture attributes, (2) explicit sensations of their own hand, and (3) implicit motor behavior during haptic exploration. Our results showed that audio cues (presented solely or combined with haptics) influenced participants' judgment of the texture attributes (roughness, hardness, moisture and viscosity), produced some hand sensations (the feeling of having a hand smoother, softer, looser, more flexible, colder, wetter and more natural), and changed participants' speed (moving faster or slower) while exploring the texture. We then conducted a principal component analysis to better understand and visualize the found results and conclude with a short discussion on how audio-haptic associations can be used to create embodied experiences in emerging application scenarios in the metaverse

Responsible Innovation of Touchless Haptics: A Prospective Design Exploration in Social Interaction

The rapid development of touchless systems has introduced many innovations in social interaction scenarios in recent years. People now can interact with touchless systems in social applications that are aimed to be used in everyday situations in the future. This accelerated development makes us ask, what will the next generation of touchless systems be like? How can we responsibly develop new touchless technologies in the future? To answer the first question, we brought together 20 experts to ideate, speculate, and evaluate possible touchless applications for social interactions. A total of 48 ideas were generated from two consecutive workshops. Then, to answer the second question, we critically analyzed those ideas through a thematic analysis using a responsible innovation (RI) framework, and identified key ethical considerations to guide developers, practitioners when designing future touchless systems. We argue that the social scenarios described, and the RI framework proposed in this paper are a useful starting point for responsibly designing the next generation of touchless systems