Browse Articles

Age-related differences in the effect of mental fatigue on obstacle crossing in virtual reality

Time Persistence of the FMRI Resting-State Functional Brain Networks

Time persistence is a fundamental property of many complex physical and biological systems; thus understanding the phenomenon in the brain is of high importance. Time persistence has been explored at the level of stand-alone neural time-series, but since the brain functions as an interconnected network, it is essential to examine time persistence at the network level. Changes in resting-state networks have been previously investigated using both dynamic (i.e., examining connectivity states) and static functional connectivity (i.e., test–retest reliability), but no systematic investigation of the time persistence as a network was conducted, particularly across different timescales (i.e., seconds, minutes, dozens of seconds, days) and different brain subnetworks. Additionally, individual differences in network time persistence have not been explored. Here, we devised a new framework to estimate network time persistence at both the link (i.e., connection) and node levels. In a comprehensive series analysis of three functional MRI resting-state datasets including both sexes, we established that (1) the resting-state functional brain network becomes gradually less similar to itself for the gaps up to 23 min within the run and even less similar for the gap between the days; (2) network time persistence varies across functional networks, while the sensory networks are more persistent than nonsensory networks; (3) participants show stable individual characteristic persistence, which has a genetic component; and (4) individual characteristic persistence could be linked to behavioral performance. Overall, our detailed characterization of network time persistence sheds light on the potential role of time persistence in brain functioning and cognition.

A neuroadaptive interface shows intentional control alters the experience of time

Adaptive image encryption approach using an enhanced swarm intelligence algorithm

Abstract Chaos-based encryption methods have gained popularity due to the unique properties of chaos. The performance of chaos-based encryption methods is highly impacted by the values of initial and control parameters. Therefore, this work proposes Iterative Cosine operator-based Hippopotamus Optimization (ICO-HO) to select optimal parameters for chaotic maps, which is further used to design an adaptive image encryption approach. ICO-HO algorithm improves the Hippopotamus Optimization (HO) by integrating a new phase (Phase 4) to update the position of the hippopotamus. ICO-HO updates the position of hippopotamuses using ICO and opposition-based learning, which enhances the exploration and exploitation capabilities of the HO algorithm. ICO-HO algorithm’s better performance is signified by the Friedman mean rank test applied to mean values obtained on the CEC-2017 benchmark functions. The ICO-HO algorithm is utilized to optimize the parameters of PWLCM and PWCM chaotic maps to generate a secret key in the confusion and diffusion phases of image encryption. The performance of the proposed encryption approach is evaluated on grayscale, RGB, and hyperspectral medical images of different modalities, bit depth, and sizes. Different analyses, such as visual analysis, statistical attack analysis, differential attack analysis, and quantitative analysis, have been utilized to assess the effectiveness of the proposed encryption approach. The higher NPCR and UACI values, i.e., 99.60% and 33.40%, respectively, ensure security against differential attacks. Furthermore, the proposed encryption approach is compared with five state-of-the-art encryption techniques available in the literature and six similar metaheuristic techniques using NPCR, UACI, entropy, and correlation coefficient. The proposed methods exhibit 7.9995 and 15.8124 entropy values on 8-bit and 16-bit images, respectively, which is better than all other stated methods, resulting in improved image encryption with high randomness.

The Representation of Stimulus Features during Stable Fixation and Active Vision

Predictive updating of an object's spatial coordinates from presaccade to postsaccade contributes to stable visual perception. Whether object features are predictively remapped remains contested. We set out to characterize the spatiotemporal dynamics of feature processing during stable fixation and active vision. To do so, we applied multivariate decoding methods to EEG data collected while human participants (male and female) viewed brief visual stimuli. Stimuli appeared at different locations across the visual field at either high or low spatial frequency (SF). During fixation, classifiers were trained to decode SF presented at one parafoveal location and cross-tested on SF from either the same, adjacent, or more peripheral locations. When training and testing on the same location, SF was classified shortly after stimulus onset (∼79 ms). Decoding of SF at locations farther from the trained location emerged later (∼144–295 ms), with decoding latency modulated by eccentricity. This analysis provides a detailed time course for the spread of feature information across the visual field. Next, we investigated how active vision impacts the emergence of SF information. In the presence of a saccade, the decoding time of peripheral SF at parafoveal locations was earlier, indicating predictive anticipation of SF due to the saccade. Crucially, however, this predictive effect was not limited to the specific remapped location. Rather, peripheral SF was correctly classified, at an accelerated time course, at all parafoveal positions. This indicates spatially coarse, predictive anticipation of stimulus features during active vision, likely enabling a smooth transition on saccade landing.

Development of machine learning-based differential diagnosis model and risk prediction model of organ damage for severe Mycoplasma pneumoniae pneumonia in children

A study on the effects of different isokinetic testing modes of knee flexion-extension muscle strength ratios on lower extremity stiffness during jumping

Individual gaze predicts individual scene descriptions

Abstract Do different people looking at the same scene perceive individual versions of what’s in front of them? If perception is individual, which mechanisms mediate our particular view of the world? Recent findings have shown systematic observer differences in gaze, but it is unclear whether individual fixation biases translate to divergent impressions of the same scene. Here, we find systematic differences in the scene descriptions individual observers provide for identical complex scenes. Crucially, observer differences in fixation patterns predicted pairwise differences in scene descriptions, particularly the use of nouns, even for out-of-sample images. Part of this could be explained by the individual tendency to fixate text and people predicting corresponding description references. Our results strongly suggest that subjective scene perception is shaped by individual gaze.

Optimization of durability characteristics of engineered cementitious composites combined with titanium dioxide as a nanomaterial applying RSM modelling

Abstract Currently, chemical attacks, including acid attacks and sulphate attacks, pose a significant problem for the long-term durability of concrete infrastructures that encounter many types of water, including swamp water, marine water, sewage water, drinkable water, and groundwater. Therefore, the intention of this work is to enhance the durability and resistance of concrete against chemical attack by blending titanium dioxide (TiO2) as nanoparticles into designed cementitious composites. The purpose of current study is to obtain an appropriate TiO2 based on the cement’s weight and polyvinyl alcohol (PVA) fiber in composites using multi-objective optimisation. Thirteen mixtures comprising diverse combinations of variables (TiO2: 1–2%, PVA: 1–2%) were formulated utilising RSM modelling. Seven responses were assessed for these mixtures, including weight loss, compressive strength, expansion, a rapid chloride permeability test (RCPT) and a pH test. Analysis of variance, on the other hand, was utilised to construct and assess eight response models (one linear and six quadratics in nature). The R2 values for models spanning from 88 to 99%. The multi-objective optimisation generated optimal response values and ideal variable values (1% PVA and 1.5% TiO2). Experimental verification revealed that the predicted values correlated exceedingly well with the experimental data, with an error rate of less than 5%. The outcomes indicate that a 30% rise in compressive strength was noted when 1.5% TiO2 nanomaterial was incorporated into ECC. Furthermore, the expansion caused by sulphate attack decreases when TiO2 used as a nanomaterial increases in composites. Besides, when the concentration of TiO2 in ECC increased, the pH value, and weight loss caused by acid attack reduced. In addition, the RCPT is recorded reducing when the content of TiO2 increases but it increases with addition of PVA fiber. It has been shown that including 1.5% TiO2 and 1% PVA fiber yields the optimal results for the building sector.

K _V 1 Channels Enable Myelinated Axons to Transmit Spikes Reliably without Spiking Ectopically

Action potentials (spikes) are regenerated at each node of Ranvier during saltatory transmission along a myelinated axon. The high density of voltage-gated sodium channels required by nodes to reliably transmit spikes increases the risk of ectopic spike generation in the axon. Here we show that ectopic spiking is avoided because K V 1 channels prevent nodes from responding to slow depolarization; instead, axons respond selectively to rapid depolarization because K V 1 channels implement a high-pass filter. To characterize this filter, we compared spike initiation properties in the soma and axon of CA1 pyramidal neurons from mice of both sexes, using spatially restricted photoactivation of channelrhodopsin-2 (ChR2) to evoke spikes in either region while simultaneously recording at the soma. Somatic photostimulation evoked repetitive spiking whereas axonal photostimulation evoked transient spiking. Blocking K V 1 channels converted the axon photostimulation response to repetitive spiking and encouraged spontaneous ectopic spike initiation in the axon. According to computational modeling, the high-pass filter implemented by K V 1 channels matches the axial current waveform associated with saltatory conduction, enabling axons to faithfully transmit digital signals by maximizing their signal-to-noise ratio for this task. Specifically, a node generates a single spike only when rapidly depolarized, which is precisely what occurs during saltatory conduction when a pulse of axial current (triggered by a spike occurring at the upstream node) reaches the next node. The soma and axon use distinct spike initiation mechanisms (filters) appropriate for the task required of each region, namely, analog-to-digital transduction in the soma versus digital signal transmission in the axon.

Automated evaluation of accessibility issues of webpage content: tool and evaluation

Abstract In recent years, there has been a growing field of research focused on comprehending complexity in relation to web platform accessibility. It has shown that it is quite difficult to accurately assess and identify web accessibility concerns while taking multifaceted factors into account. It is imperative to prioritize multi-dimensional characteristics as they facilitate the integration of many aspects into the assessment process, which is a critical component in enhancing the accessibility evaluation process. Although many existing solutions with varying degrees of computational success have been proposed by scholars, they are confined to (1) following a certain set of rules of a specific guideline; (2) limited evaluation properties; (3) disregard for user criteria; and (4) complex functional properties or architectural design. To address these problems, we present in this work a straightforward yet precise model that assesses webpage accessibility by taking into account common features of the structural and visual elements of webpages that are part of the HTML Document Object Model (DOM) structure. In order to predict a webpage’s accessibility status, we implemented three distinct algorithms to analyze web features/objects considering both semantic and non-semantic aspects. We performed experimental work to validate 20 university webpages in Hungary through our developed tool. The computed result of the developed tool was assessed by comparing the result with a user study where we performed user testing that included 40 users’ 80 reviews on the same 20 university webpages in Hungary. Additionally, we compared our developed tool with other scientific models (that already exist) and existing ten open-source commercial automated testing tools considering several functional characteristics or properties. This two-phase assessment result shows that the developed tool has several advanced properties and the potential to predict the accessibility issues of the tested webpages.

Experimental study of a fixed OWC-type wave energy converter in irregular wave conditions

Inertial motion of a circular cylinder approaching obliquely an ice cover

Abstract Two-dimensional unsteady problem of an inertial motion of a circular cylinder approaching obliquely an ice cover and the response of ice to this motion are investigated. The liquid under the ice is inviscid, incompressible and of infinite depth. The ice sheet floating on water surface is modelled as a thin elastic plate of constant thickness and of infinite extent. The movement of the cylinder is governed by its inertia, gravity, hydrodynamic force, deflection of the ice cover and the initial conditions. The general coupled problem is approximately decoupled for relatively small speeds of the body. Within the decoupled approach, the cylinder motion, the generated flow, and the hydrodynamic pressure in the fluid are determined by conformal mapping method without account for the ice deflection. The obtained hydrodynamic loads are applied to the equation of elastic ice sheet, and the ice deflection, speed of deflection and strains in the ice are evaluated by Fourier transform method. The oblique inertial motion of a circular cylinder under the rigid plate is described analytically. A critical Froude number for a heavy cylinder, which is only dependent on the initial submergence depth, is introduced and used in classification of the body motions. The present study is focused on the motions of circular cylinders without their impacts with the plate. It is shown that the ice can be damaged even before the cylinder arrives at the position closest to the plate. For a given radius of the cylinder and its initial kinetic energy, the conditions of the motion including the angle of attack and the dimensionless submergence depth which lead to ice breaking are predicted.

Scaling of Ventral Hippocampal Activity during Anxiety

The hippocampus supports a multiplicity of functions, with the dorsal region contributing to spatial representations and memory and the ventral hippocampus (vH) being primarily involved in emotional processing. While spatial encoding has been extensively investigated, how the vH activity is tuned to emotional states, e.g., to different anxiety levels, is not well understood. We developed an adjustable linear track maze for male mice with which we could induce a scaling of behavioral anxiety levels within the same spatial environment. Using in vivo single-unit recordings, optogenetic manipulations, and population-level analysis, we examined the changes and causal effects of vH activity at different anxiety levels. We found that anxiogenic experiences activated the vH and that this activity scaled with increasing anxiety levels. We identified two processes that contributed to this scaling of anxiety-related activity: increased tuning and successive remapping of neurons to the anxiogenic compartment. Moreover, optogenetic inhibition of the vH reduced anxiety across different levels, while anxiety-related activity scaling could be decoded using a linear classifier. Collectively, our findings position the vH as a critical limbic region that functions as an “anxiometer” by scaling its activity based on perceived anxiety levels. Our discoveries go beyond the traditional theory of cognitive maps in the hippocampus underlying spatial navigation and memory, by identifying hippocampal mechanisms selectively regulating anxiety.

Structural insights into fungal and human topoisomerase II with implications for in silico antifungal drug design

Abstract Topoisomerases are essential enzymes regulating DNA supercoiling and disentanglement, critical for genomic integrity. While topoisomerase inhibitors are well-established in anticancer and antibacterial chemotherapy, their potential as antifungal agents remains underexplored or even not proofed. This study investigates structural distinctions between Saccharomyces cerevisiae topoisomerase II (ScTopoII) and human topoisomerase IIα (hTopoIIα), aiming to identify if ScTopoII can be a selective target for antifungal drug development. A comprehensive sequence analysis, extending to various fungal strains and evolutionary ancient organisms, reveals dissimilarities in the transducer and transducer linker domains of these proteins, as well as in the lysine-rich K-loop region. Molecular dynamics simulations emphasize structural differences in the K-loop, α-helix (or helix-like region), and helix supporting loop region, as well as show unique patterns in hydrophilic and hydrophobic intramolecular interactions in ScTopoII. Moreover, phylogenetic comparisons support the importance of specific regions studied. The study includes topos from different organisms, highlighting discrepancies in helix stability near the K-loop and the role of helix supporting loop region. This broad analysis provides insights into the structural basis of human and fungal enzymes presenting potential pharmacophore “hot spots” in ScTopoII which may give hope for developing selective antifungal agents.

From Circuits to Lifespan: Translating Mouse and Human Timelines with Neuroimaging-Based Tractography

Animal models are commonly used to investigate developmental processes and disease risk, but humans and model systems (e.g., mice) differ substantially in the pace of development and aging. The timeline of human developmental circuits is well known, but it is unclear how such timelines compare with those in mice. We lack age alignments across the lifespan of mice and humans. Here, we build upon our Translating Time resource, which is a tool that equates corresponding ages during development. We collected 1,125 observations from age-related changes in body, bone, dental, and brain processes to equate corresponding ages across humans, mice, and rats to boost power for comparison across humans and mice. We acquired high-resolution diffusion MR scans of mouse brains ( n  = 16) of either sex at sequential stages of postnatal development [postnatal day (P)3, 4, 12, 21, 60] to track brain circuit maturation (e.g., olfactory association, transcallosal pathways). We found heterogeneity in white matter pathway growth. Corpus callosum growth largely ceases days after birth, while the olfactory association pathway grows through P60. We found that a P3–4, mouse equates to a human at roughly GW24 and a P60 mouse equates to a human in teenage years. Therefore, white matter pathway maturation is extended in mice as it is in humans, but there are species-specific adaptations. For example, olfactory-related wiring is protracted in mice, which is linked to their reliance on olfaction. Our findings underscore the importance of translational tools to map common and species-specific biological processes from model systems to humans.

Human health risk assessment of toxic metals in Nass smokeless tobacco in Iran

Explainable TabNet ensemble model for identification of obfuscated URLs with features selection to ensure secure web browsing

Alien spiders in a palm house with the first report of parthenogenetic Triaeris stenaspis (Araneae: Oonopidae) infected by Wolbachia from new supergroup X

Abstract Palm houses in Europe serve as urban biodiversity hot spots for alien spiders. As a result of several years of research in the Poznań Palm House, we documented the occurrence of 14 spider species, 9 of which were alien to Europe: Coleosoma floridanum, Hasarius adansoni, Howaia mogera, Ostearius melanopygius, Parasteatoda tabulata, Parasteatoda tepidariorum, Scytodes fusca, Spermophora kerinci and Triaeris stenaspis. The most abundant species was C. floridanum (39.9%). Three spider species were recorded for the first time in Poland: C. floridanum, S. fusca and S. kerinci. We studied the occurrence of endosymbiotic Wolbachia and Cardinium in parthenogenetic T. stenaspis and recorded for the first time the occurrence of Wolbachia in this spider. The endosymbiont was characterized based on the sequences of six bacterial housekeeping genes: 16S rRNA, coxA, fbpA, ftsZ, gatB and hcpA. Our phylogenetic reconstruction of Wolbachia supergroups revealed that the bacteria recovered from the spider formed distinct lineages in relation to all known supergroups. We assigned it to a novel supergroup X with unique sequences within the 16S rRNA and ftsZ genes. We discussed faunistic results in terms of long-term survival rates and the risk of invasion of alien species of spiders.

Involvement of aSPOC in the Online Updating of Reach-to-Grasp to Mechanical Perturbations of Hand Transport

Humans adjust their movement to changing environments effortlessly via multisensory integration of the effector’s state, motor commands, and sensory feedback. It is postulated that frontoparietal (FP) networks are involved in the control of prehension, with dorsomedial (DM) and dorsolateral (DL) regions processing the reach and the grasp, respectively. This study tested (five female and five male participants) the differential involvement of FP nodes [ventral premotor cortex (PMv), dorsal premotor cortex (PMd), anterior intraparietal sulcus (aIPS), and anterior superior parieto-occipital cortex (aSPOC)] in online adjustments of reach-to-grasp coordination to mechanical perturbations (MP) that disrupted arm transport. We used event-related transcranial magnetic stimulation (TMS) to test whether the nodes of these pathways causally contribute to the processing of proprioceptive information when reaching for a virtual visual target at two different perturbation latencies. TMS over aSPOC selectively altered the correction magnitude of arm transport during late perturbations, demonstrating that aSPOC processes proprioceptive inputs related to mechanical perturbations in a movement phase-dependent manner.