Ice nucleating particles in the Canadian High Arctic during the fall with implications for climate feedback mechanisms in the region

Ice nucleating particles (INPs) are a small subset of atmospheric particles that can initiate the formation of ice in mixed-phase clouds. Here we report concentrations of INPs during October and...

Assessing Ecologically Valid Methods of Auditory Feedback Measurement in Individuals With Typical Speech

Purpose: Auditory feedback is thought to contribute to the online control of speech production. Yet, the standard method of estimating auditory feedback control (i.e., reflexive responses to auditory–motor perturbations), although sound, requires specialized instrumentation, meticulous calibration, unnatural tasks, and specific acoustic environments. The purpose of this study was to explore more ecologically valid features of speech production to determine their relationships with auditory feedback mechanisms. Method: Two previously proposed measures of within-utterance variability (centering and baseline variability) were compared with reflexive response magnitudes in 30 adults with typical speech. These three measures were estimated for both the laryngeal and articulatory subsystems of speech. Results: Regardless of the speech subsystem, neither centering nor baseline variability was shown to be related to reflexive response magnitudes. Likewise, no relationships were found between centering and baseline variability. Conclusions: Despite previous suggestions that centering and baseline variability may be related to auditory feedback mechanisms, this study did not support these assertions. However, the detection of such relationships may have required a larger degree of variability in responses, relative to that found in those with typical speech. Future research on these relationships is warranted in populations with more heterogeneous responses, such as children or clinical populations. Supplemental Material https://doi.org/10.23641/asha.17330546

Developmental Differences in the Prospective Organisation of Goal-Directed Movement Between Children with Autism and Typically Developing Children: A Smart Tablet Serious Game Study

Movement is prospective. It structures self-generated engagement with objects and social partners and is fundamental to children’s learning and development. In autistic children, previous reports of differences in movement kinematics compared to neurotypical peers suggest its prospective organisation might be disrupted. Here, we employed a smart tablet serious game paradigm to assess differences in the feedforward and feedback mechanisms of prospective action organisation, between autistic and neurotypical preschool children. We analysed 3926 goal-directed finger movements made during smart-tablet ecological gameplay, from 28 children with Childhood Autism (ICD-10; ASD) and 43 neurotypical children (TD), aged 3-6 years old. Using linear and generalised linear mixed-effect models, we found the ASD group executed movements with longer Movement Time (MT) and Time to Peak Velocity (TTPV), lower Peak Velocity (PV), with peak velocity less likely to occur in the first movement unit, and with a greater number of Movement Units After Peak Velocity (MU-APV). Interestingly, compared to the TD group, the ASD group showed smaller increases in PV, TTPV and MT with an increase in Age (ASD x Age interaction), together with a smaller reduction in MU-APV and an increase in MU-APV at shorter target distances (ASD x Dist interaction). Our results are the first to highlight different developmental trends in anticipatory feedforward and compensatory feedback mechanisms of control, contributing to differences in movement kinematics observed between autistic and neurotypical children. These findings point to differences in integration of prospective perceptuomotor information, with implications for embodied cognition and learning from self-generated action in autism.

Age-Dependent Honey Bee Appetite Regulation Is Mediated by Trehalose and Octopamine Baseline Levels

There are multiple feedback mechanisms involved in appetite regulation, which is an integral part of maintaining energetic homeostasis. Older forager honey bees, in comparison to newly emerged bees and nurse bees, are known to have highly fluctuating hemolymph trehalose levels, higher appetite changes due to starvation, and higher octopamine levels in the brain. What remains unknown is if the hemolymph trehalose and octopamine levels interact with one another and how this varies as the bee ages. We manipulated trehalose and octopamine levels across age using physiological injections and found that nurse and forager bees increase their appetite levels due to increased octopamine levels in the brain. This is further enhanced by lower trehalose levels in the hemolymph. Moreover, nurse bees with high octopamine levels in the brain and low trehalose levels had the same appetite levels as untreated forager bees. Our findings suggest that the naturally higher levels of octopamine as the bee ages may result in higher sensitivity to fluctuating trehalose levels in the hemolymph that results in a more direct way of assessing the energetic state of the individual. Consequently, forager bees have a mechanism for more precise regulation of appetite in comparison to newly emerged and nurse bees.

Fabrication of micro-mechanical planar cantilever beam-mass structures on quartz substrates using an ECDM process

Electrochemical discharge machining (ECDM) processes have been used to realize miniature structures such as micro-channels and micro-holes on non-conductive materials such as quartz and Pyrex for a variety of applications. However, for realizing mechanical/physical sensors, actuators, energy harvesters, and resonators on glass substrates, free-standing devices with movable components such as beam-mass structures and cantilevers are required. There has been a negligible focus on developing miniature glass-based devices with movable components primarily due to the non-linear material removal rate (MRR) of the ECDM processes, requiring continuous measurement, tracking, and maintaining the working gap in the range of a few micrometers during micromachining. A couple of techniques were proposed to address maintaining a constant working gap, however, using costly equipment with complex feedback mechanisms. We report a two-stage experimental approach – without using feedback mechanisms and additional equipment – to realize micro-mechanical planar cantilever beam-mass structures on thick quartz substrates in the present work. In the first stage, the process parameters such as applied voltage, tool travel rate (TTR), and initial working gap ( Wg) are optimized for fabricating broader and deeper micro-channels using needle-shaped tools. In the second stage, using the optimized parameters, an array of micro-channels is fabricated. The cumulative depth, corresponding depth, and the width of each layer of the channels are measured, and this data is utilized for fabricating planar beam-mass structures on quartz substrates. We envisage that the experimental results of the present study would be beneficial for ECDM researchers to fabricate glass-based miniature devices with movable components without using complex tools and equipment.

Homeostatic model of human thermoregulation with bi-stability

All homoiothermic organisms are capable of maintaining a stable body temperature using various negative feedback mechanisms. However, current models cannot satisfactorily describe the thermal adaptation of homoiothermic living systems in a physiologically meaningful way. Previously, we introduced stress entropic load, a novel variable designed to quantify adaptation costs, i.e. the stress of the organism, using a thermodynamic approach. In this study, we use stress entropic load as a starting point for the construction of a novel dynamical model of human thermoregulation. This model exhibits bi-stable mechanisms, a physiologically plausible features which has thus far not been demonstrated using a mathematical model. This finding allows us to predict critical points at which a living system, in this case a human body, may proceed towards two stabilities, only one of which is compatible with being alive. In the future, this may allow us to quantify not only the direction but rather the extent of therapeutic intervention in critical care patients.