The Effects Of Sleep Apnea on Heart Rate Variability in a Simulator

Heart rate variability has been used as a measure of mental workload, stress, and fatigue in drivers. The main goal of this study was to evaluate whether drivers with obstructive sleep apnea syndrome (OSAS) may have significantly different heart rate variability from those who do not have OSAS. Such a condition may indicate lower stress levels and an increase in crash risk due to sleepiness. This study also evaluates whether significant deviations in HRV may occur as drivers become drowsier over time. Eleven drivers with OSAS were compared to twelve other drivers with no known sleep disorder. All were tested in a driving simulator over a 60-minute period that consisted of three uneventful drive segments on two-lane rural roads. Heart rates were collected using electrocardiogram (ECG). The variability of heart rate was computed for each subsequent five-minute interval by calculating the standard deviations of the R-R intervals (i.e., the time duration between two consecutive R waves of the ECG) within that time. Results showed that there were no significant differences in HRV over time for the comparison group. However, HRV for drivers with OSAS increased by each subsequent time interval. Drivers with OSAS also had significantly higher mean heart rate variability over the course of the drive. Specifically, based on the second regression model, the difference in heart rate variability between drivers with OSAS and the comparison group significantly increased after about 25 minutes of driving. This likely reflects the physiological effects of increased fatigue, which would lead to inattention to the driving environment and increased crash risk

Layered Model for Radiation-Induced Chemical Evolution of Icy Surface Composition on Kuiper Belt and Oort Cloud Bodies

The diversity of albedos and surface colors on observed Kuiper Belt and Inner Oort Cloud objects remains to be explained in terms of competition between primordial intrinsic versus exogenic drivers of surface and near-surface evolution. Earlier models have attempted without success to attribute this diversity to the relations between surface radiolysis from cosmic ray irradiation and gardening by meteoritic impacts. A more flexible approach considers the different depth-dependent radiation profiles produced by low-energy plasma, suprathermal, and maximally penetrating charged particles of the heliospheric and local interstellar radiation environments. Generally red objects of the dynamically cold (low inclination, circular orbit) Classical Kuiper Belt might be accounted for from erosive effects of plasma ions and reddening effects of high energy cosmic ray ions, while suprathermal keV-MeV ions could alternatively produce more color neutral surfaces. The deepest layer of more pristine ice can be brought to the surface from meter to kilometer depths by larger impact events and potentially by cryovolcanic activity. The bright surfaces of some larger objects, e.g. Eris, suggest ongoing resurfacing activity. Interactions of surface irradiation, resultant chemical oxidation, and near-surface cryogenic fluid reservoirs have been proposed to account for Enceladus cryovolcanism and may have further applications to other icy irradiated bodies. The diversity of causative processes must be understood to account for observationally apparent diversities of the object surfaces

High Speed Gear Sized and Configured to Reduce Windage Loss

A gear and drive system utilizing the gear include teeth. Each of the teeth has a first side and a second side opposite the first side that extends from a body of the gear. For each tooth of the gear, a first extended portion is attached to the first side of the tooth to divert flow of fluid adjacent to the body of the gear to reduce windage losses that occur when the gear rotates. The gear may be utilized in drive systems that may have high rotational speeds, such as speeds where the tip velocities are greater than or equal to about 68 m/s. Some embodiments of the gear may also utilize teeth that also have second extended portions attached to the second sides of the teeth to divert flow of fluid adjacent to the body of the gear to reduce windage losses that occur when the gear rotates

Heliosheath Space Environment Interactions with Icy Bodies in the Outermost Solar System

The Voyager 1 and 2 spacecraft are exploring the space environment of the outermost solar system at the same time that earth-based astronomy continues to discover new icy bodies, one larger than Pluto, in the transitional region outward from the Classical Kuiper Belt to the Inner Oort Cloud. Some of the Scattered Disk Objects in this region periodically pass through the heliosheath, entered by Voyager 1 in Dec. 2004 and later expected to be reached by Voyager 2, and out even beyond the heliopause into the Very Local Interstellar Medium. The less energetic heliosheath ions, important for implantation and sputtering processes, are abundant near and beyond the termination shock inner boundary, but the source region of the more penetrating anomalous cosmic ray component has not yet been found. Advantageous for modeling of icy body interactions, the measured heliosheath flux spectra are relatively more stable within this new regime of isotropic compressional magnetic turbulence than in the upstream heliospheric environment. The deepest interactions and resultant radiation-induced chemistry arise from the inwardly diffusing component of the galactic cosmic ray ions with significant intensity modulation also arising in the heliosheath beyond Voyager 1. Surface gardening by high-velocity impacts of smaller bodies (e.g., fragments of previous KBO collisions) and dust is a further space weathering process setting the time scales for long term exposure of different regolith layers to the ion irradiation. Sputtering and ionization of impact ejecta grains may provide a substantial feedback of pickup ions for multiple cycles of heliosheath acceleration and icy body interaction. Thus the space weathering interactions are potentially of interest not only for effects on sensible surface composition of the icy bodies but also for evolution of the heliosheath plasma energetic ion, and neutral emission environment

Dual positive and negative regulation of GPCR signaling by GTP hydrolysis

G protein-coupled receptors (GPCRs) regulate a variety of intracellular pathways through their ability to promote the binding of GTP to heterotrimeric G proteins. Regulator of G protein signaling (RGS) proteins increase the intrinsic GTPase activity of G-subunits and are widely regarded as negative regulators of G protein signaling. Using yeast we demonstrate that GTP hydrolysis is not only required for desensitization, but is essential for achieving a high maximal (saturated level) response. Thus RGS-mediated GTP hydrolysis acts as both a negative (low stimulation) and positive (high stimulation) regulator of signaling. To account for this we generated a new kinetic model of the G protein cycle where GGTP enters an inactive GTP-bound state following effector activation. Furthermore, in vivo and in silico experimentation demonstrates that maximum signaling output first increases and then decreases with RGS concentration. This unimodal, non-monotone dependence on RGS concentration is novel. Analysis of the kinetic model has revealed a dynamic network motif that shows precisely how inclusion of the inactive GTP-bound state for the G produces this unimodal relationship

Comparing student’s fluency in using multiple representations (graphs, words and equations) with their university physics expertise

It is suggested physics expertise comes with an increasing literacy of using the disciplinary discourse (Airey and Linder 2009). One facet of the physics disciplinary discourse is the different representations that are reproduced on written material such as graphs, equations and words and it would appear that being fluent in these representations is a necessary skill for success in physics. According to Redish (2004), alternative representations, or epistemic resources, are important in scientific knowledge formation, so the ability to use multiple representations would appear to also improve students’ ability to learn physics. We have created a survey with seven general physics problems which involve particularly the representations of graphs and words in both question and answer. This has been given to over 450 physics students at the University of Sydney from first year, to the honours level. The results will be presented through investigation into both how different level students answer particular questions in relation to the representational format but also their preference of representation across the survey. This aims to provide a means to track where representational literacy develops through tertiary physics education. REFERENCES Airey, J. and C. Linder. (2009). A Disciplinary Discourse Perspective on University Science Learning: Achieving Fluency in a Critical Constellation of Modes. Journal of Research in Science Teaching, 46, 27-49. Redish, E. F. (2004). A theoretical framework for physics education research: Modeling student thinking. Research on Physics Education, 156, 1-63

Knockdown of the schizophrenia susceptibility gene TCF4 alters gene expression and proliferation of progenitor cells from the developing human neocortex

BACKGROUND: Common variants in the TCF4 gene are among the most robustly supported genetic risk factors for schizophrenia. Rare TCF4 deletions and loss-of-function point mutations cause Pitt-Hopkins syndrome, a developmental disorder associated with severe intellectual disability. METHODS: To explore molecular and cellular mechanisms by which TCF4 perturbation could interfere with human cortical development, we experimentally reduced the endogenous expression of TCF4 in a neural progenitor cell line derived from the developing human cerebral cortex using RNA interference. Effects on genome-wide gene expression were assessed by microarray, followed by Gene Ontology and pathway analysis of differentially expressed genes. We tested for genetic association between the set of differentially expressed genes and schizophrenia using genome-wide association study data from the Psychiatric Genomics Consortium and competitive gene set analysis (MAGMA). Effects on cell proliferation were assessed using high content imaging. RESULTS: Genes that were differentially expressed following TCF4 knockdown were highly enriched for involvement in the cell cycle. There was a nonsignificant trend for genetic association between the differentially expressed gene set and schizophrenia. Consistent with the gene expression data, TCF4 knockdown was associated with reduced proliferation of cortical progenitor cells in vitro. LIMITATIONS: A detailed mechanistic explanation of how TCF4 knockdown alters human neural progenitor cell proliferation is not provided by this study. CONCLUSION: Our data indicate effects of TCF4 perturbation on human cortical progenitor cell proliferation, a process that could contribute to cognitive deficits in individuals with Pitt-Hopkins Syndrome and risk for schizophrenia

Systematic investigation of imprinted gene expression and 1 enrichment in the mouse brain explored at single-cell resolution

BACKGROUND: Although a number of imprinted genes are known to be highly expressed in the brain, and in certain brain regions in particular, whether they are truly over-represented in the brain has never been formally tested. Using thirteen single-cell RNA sequencing datasets we systematically investigated imprinted gene over-representation at the organ, brain region, and cell-specific levels. RESULTS: We established that imprinted genes are indeed over-represented in the adult brain, and in neurons particularly compared to other brain cell-types. We then examined brain-wide datasets to test enrichment within distinct brain regions and neuron subpopulations and demonstrated over-representation of imprinted genes in the hypothalamus, ventral midbrain, pons and medulla. Finally, using datasets focusing on these regions of enrichment, we identified hypothalamic neuroendocrine populations and the monoaminergic hindbrain neurons as specific hotspots of imprinted gene expression. CONCLUSIONS: These analyses provide the first robust assessment of the neural systems on which imprinted genes converge. Moreover, the unbiased approach, with each analysis informed by the findings of the previous level, permits highly informed inferences about the functions on which imprinted gene expression converges. Our findings indicate the neuronal regulation of motivated behaviours such as feeding and sleep, alongside the regulation of pituitary function, as functional hotspots for imprinting. This adds statistical rigour to prior assumptions and provides testable predictions for novel neural and behavioural phenotypes associated with specific genes and imprinted gene networks. In turn, this work sheds further light on the potential evolutionary drivers of genomic imprinting in the brain. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12864-022-08986-8