Measuring mental workload: ocular astigmatism aberration as a novel objective index

This study assessed the effect of two perceptually matched mental tasks with different levels of mental demand on ocular aberrations in a group of young adults. We measured ocular aberration with a wavefront sensor, and total, internal and corneal RMS (root mean square) aberrations were calculated from Zernike coefficients, considering natural and scaled pupils (5, 4.5, and 4 mm). We found that total, internal and corneal astigmatism RMS showed significant differences between mental tasks with natural pupils (p < .05), and this effect was maintained with 5 mm scaled pupils (total RMS astigmatism, p < .05). Consistently, pupil size, intraocular pressure, perceived mental load and cognitive performance were influenced by the level of mental complexity (p < .05 for all). The findings suggest that ocular astigmatism aberration, mediated by intraocular pressure, could be an objective, valid reliable index to evaluate the impact of cognitive processing in conjunction with others physiological markers in real world contexts.

Practitioner Summary: The search continues for a valid, reliable, convenient method of measuring mental workload. In this study we found ocular astigmatism aberration is sensitive to the cumulative effect of mental effort. It shows promise of being a novel ocular index which may help to assess mental workload in real situations.     

Advances in GML for Geospatial Applications

This paper presents a study of Geography Markup Language (GML), the issues that arise from using GML for spatial applications, including storage, parsing, querying and visualization, as well as the use of GML for mobile devices and web services. GML is a modeling language developed by the Open Geospatial Consortium (OGC) as a medium of uniform geographic data storage and exchange among diverse applications. Many new XML-based languages are being developed as open standards in various areas of application. It would be beneficial to integrate such languages with GML during the developmental stages, taking full advantage of a non-proprietary universal standard. As GML is a relatively new language still in development, data processing techniques need to be refined further in order for GML to become a more efficient medium for geospatial applications.

Multifunctional Role of Lipids in Modulating the Tumorigenic Properties of 4T1 Breast Cancer Cells

Tumor growth and progression are linked to an altered lipid metabolism in the tumor microenvironment (TME), including tumor cells and tumor-associated macrophages (TAMs). A growing number of lipid metabolism targeting drugs have shown efficacy in anti-tumor therapy. In addition, exogenously applied lipids and lipid analogues have demonstrated anti-tumor activities in several cancers, including breast cancer. In this study, we investigated the anti-tumor efficacies of the natural lipids palmitic acid (PA), sphingomyelin (SM), ceramide (Cer) and docosahexaenoic acid (DHA) on breast cancer cells. All tested lipids reduced the malignancy of breast cancer cells in vitro by impairing cell proliferation, migration and invasiveness. PA showed superior anti-tumor properties, as it additionally impaired cancer cell viability by inducing apoptosis, without affecting healthy cells. Co-culture experiments further demonstrated that Cer and PA reduced the immunosuppressive phenotype of M2 macrophages and the M2 macrophage-promoted the epithelial–mesenchymal transition (EMT) and migration of breast cancer cells. At the molecular level, this coincided with the up-regulation of E-cadherin. Our results highlight a powerful role for exogenously applied PA and Cer in reducing breast cancer tumorigenicity by simultaneously targeting cancer cells and M2 macrophages. Our findings support the notion that lipids represent alternative biocompatible therapeutic agents for breast cancer.     

Role of Silicon and Salicylic Acid in the Mitigation of Nitrogen Deficiency Stress in Rice Plants

Application of silicon (Si) and salicylic acid (SA) mitigates plant stress; however, this effect is not known under nitrogen (N) deficiency conditions in rice plants. The objective of the present study was to determine whether foliar application with a soluble form of Si and SA, individually or in combination, could mitigate N deficiency stress in rice plants. The treatments consisted of application of 3.45 g L⁻¹ Si only (sprayed on the leaves), 4.5 mM SA only, a combination of both, and no application as control. Net CO₂ assimilation rate, transpiration, lignin and carbon contents, C:N:P:Si stoichiometric ratio and grain yield were evaluated. Foliar application of Si combined with SA or isolated application of SA did not mitigate N deficiency stress in rice plants. However, silicon application increased rice yield by 18.6% in N-deficient conditions. Our results show that the beneficial effects of Si under nitrogen deficient conditions are related to the stoichiometry change in C with Si and increases of lignin synthesis.

     

Calibration and experimental validation of a dynamic model of the train-track system at a culvert transition zone

This article describes the calibration and experimental validation of the dynamic model of the train-track system at a culvert transition zone. The dynamic analyses were performed explicitly using a 3D model in LS-DYNA software and implicitly using a 2D model on ANSYS software. In both programmes, contact algorithms were employed to take the wheel-rail interaction into account. The parameters for the 3D model were calibrated based on the track receptance test. The 3D model was used for the static and dynamic calibration of the 2D model. The damping adopted in the 2D model was significantly amplified to compensate for the radiation damping in the transverse direction of the track, which cannot be incorporated in a plane model. An excellent agreement was obtained between the vertical displacements of the rail, the vertical accelerations of the sleepers and the wheel-rail interaction forces computed by the two models. The computation time of the 2D model is about 25 times lower than the computation time of the 3D model. The 2D model was used to simulate the passage of the Alfa Pendular train at 220 km/h at the transition zone and a very good match between measured and computed responses has been obtained.     

Ultrathin Supported Lipid Monolayer with Unprecedented Mechanical and Dielectric Properties

The development of ultrathin dielectrics for low power electronics operations, flexible and printed electronics, and field‐effect‐transistor‐based sensors is still a challenge. Here, monolayers of engineered lipids supported on silicon are reported presenting exceptional mechanical and dielectric properties. The lipid monolayers are stabilized using a simple procedure based on a two‐stage reticulation process in both their aliphatic chains and their head‐group. With a thickness lower than 3 nm, such layers are demonstrated to offer exceptional mechanical and dielectric stability with unprecedented low leakage current and dielectric strength. Surprisingly, the mechanical and dielectric pressures required to rupture/breakdown the monolayers are shown to be similar. These results suggest the presence of a strong correlation between mechanical and dielectric properties, as well as between the mechanisms of rupture and breakdown.     

Backside contact effect on the morphological and optical features of porous silicon photonic crystals

The present work reports on the effect of the type of backside contact used in the electrochemical process and their relation with the structural features and optical responses of the one-dimensional photonic crystal (PC) anodized in simple and double electrochemical cell. The PC, obtained in the single cell, showed to have thicker layers than of the PC obtained in double electrochemical cell. Additionally, the PC obtained in double cell showed highest reflectance in the band gap region than of the PCs obtained in single cell. These results suggest that the interface roughness between adjacent layers in the PC devices obtained in double electrochemical cell is minimized.     

GABAergic Regulation of Astroglial Gliotransmission through Cx43 Hemichannels

Gamma-Aminobutyric acid (GABA) is the primary inhibitory neurotransmitter in the brain. It is produced by interneurons and recycled by astrocytes. In neurons, GABA activates the influx of Cl^- via the GABA_A receptor or efflux or K⁺ via the GABA_B receptor, inducing hyperpolarization and synaptic inhibition. In astrocytes, the activation of both GABA_A and GABA_B receptors induces an increase in intracellular Ca²⁺ and the release of glutamate and ATP. Connexin 43 (Cx43) hemichannels are among the main Ca²⁺-dependent cellular mechanisms for the astroglial release of glutamate and ATP. However, no study has evaluated the effect of GABA on astroglial Cx43 hemichannel activity and Cx43 hemichannel-mediated gliotransmission. Here we assessed the effects of GABA on Cx43 hemichannel activity in DI NCT1 rat astrocytes and hippocampal brain slices. We found that GABA induces a Ca²⁺-dependent increase in Cx43 hemichannel activity in astrocytes mediated by the GABA_A receptor, as it was blunted by the GABA_A receptor antagonist bicuculline but unaffected by GABA_B receptor antagonist {"type":"entrez-protein","attrs":{"text":"CGP55845","term_id":"875097176","term_text":"CGP55845"}}CGP55845. Moreover, GABA induced the Cx43 hemichannel-dependent release of glutamate and ATP, which was also prevented by bicuculline, but unaffected by CGP. Gliotransmission in response to GABA was also unaffected by pannexin 1 channel blockade. These results are discussed in terms of the possible role of astroglial Cx43 hemichannel-mediated glutamate and ATP release in regulating the excitatory/inhibitory balance in the brain and their possible contribution to psychiatric disorders.     

Calculation of view factors for complex geometries using Stokes’ theorem

This paper presents an algorithm that calculates the radiative view factors based on Stokes’ theorem. The authors propose a formulation where the original surfaces are divided into a grid of elementary areas and Stokes’ theorem is applied for the determination of the view factors between these elementary areas. With this approach, the account of the shading effect of obstructions is significantly improved. The capabilities of the proposed formulation were tested with the calculation of radiative view factors between flat and curved surfaces. The results obtained showed a good agreement with the corresponding analytical solutions, with relative errors (REs) lower than 2%. The proposed methodology was also compared with the application of the double integral area formulation and a better agreement was found, between RE and the CPU, using the present formulation.