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A hybrid neuro-experimental decision support system to classify overconfidence and performance in a simulated bubble using a passive BCI
No full textSignificant advancements in brain-computer interfaces (BCIs) can lead to the development of enhanced decision-making platforms. Irrational behavior generating potential negative consequences can be better calibrated using experimental approaches. One such example is asset bubbles. Experimental methods using neuroimaging equipment can improve understanding of the phenomenon, while advancements in artificial intelligence can be used to classify and predict behavior based on the cognitive neurodynamics at play. Towards this goal, we ran an EEG-based experiment where subjects traded in a risky environment simulating the boom and bust of a financial bubble. We used blind source separation and empirical mode decomposition on EEG neural data to estimate approximate entropy as a metric of brain activity, which was subsequently used as feature vector input into various machine learning classifiers. We thus develop a decision support system to classify subjects according to overconfidence and trading performance using a hybrid classification methodology. We report average accuracy ratios ranging between 80 and 85%, using classifiers such as linear discriminants, decision trees, support vector machines, Naïve Bayes, multi-layer perceptron, and an artificial neural network. Not only does the hybrid method we employ produce high classification accuracy ratios in a cognitively demanding task of financial decision-making, but it can also be used in the classification of motor imagery tasks that can be coupled with financial decisions in the future. We contribute to the literature in neurofinance from an empirical perspective, while also providing a technical framework that can act as a basis for developing expert BCI systems
White matter microstructure in habit and reward circuits in anorexia nervosa: Insights from a neurite orientation dispersion and density imaging study
No full textBackground: Behavioral features of anorexia nervosa (AN) suggest abnormalities in reward and habit. Neuroimaging evidence suggests morphometric and functional perturbations within these circuits, although fewer studies have assessed white matter characteristics in AN, and no studies to date have assessed white matter microstructure in AN.
Methods: In this brain imaging study, 29 female adolescents with partially or fully weight-restored AN and 27 healthy controls, all between 10 and 19 years, underwent whole-brain multi-shell diffusion tensor imaging. Utilizing neurite orientation dispersion and density imaging methods, we investigated group differences in white matter neurite density, orientation dispersion, and myelin density in tracts between prominent nodes of the reward circuit (ventral tegmental area (VTA) to nucleus accumbens (NAcc)) and the habit circuit (sensory motor area [SMA] to putamen).
Results: Findings revealed reduced neurite (F = 5.20, p = 0.027) and myelin density (F = 5.39, p = 0.025) in the left VTA-NAcc tract, and reduced orientation dispersion in the left (F = 7.00, p = 0.011) and right (F = 6.77, p = 0.012) VTA-NAcc tract. There were no significant group differences in the SMA-putamen tract. Significant relationships, after corrections, were not evident between tract microstructure and reward responsiveness, compulsive behaviors, illness duration, or BMI.
Conclusions: Adolescents with AN exhibit less dense, undermyelinated, and less dispersed white matter tracts connecting prominent reward system nodes, which could potentially signify underutilization of this part of the reward circuit. These results provide a detailed examination of white matter microstructure in tracts underlying instrumental behavioral phenotypes contributing to illness in AN
Fe³⁺/Feᵀ ratios of amphiboles determined by high spatial resolution single-crystal synchrotron Mössbauer spectroscopy
No full textThe Fe³⁺/Feᵀ ratios (Fe³⁺/[Fe²⁺+Fe³⁺]) in minerals can be used to understand their crystallization and post-crystallization conditions. However, as natural minerals are often zoned and contain inclusions, bulk techniques, e.g., wet chemistry, may not provide accurate Fe³⁺/Feᵀ values for a single phase of interest. We determined Fe³⁺/Feᵀ ratios of amphiboles in different crystallographic orientations by single-crystal synchrotron Mössbauer spectroscopy (SMS) in energy and time domain modes from four volcanic localities (Long Valley Caldera, Mount St. Helens, Lassen Volcanic Center, U.S.A., and Mt. Pinatubo, Philippines). The high spatial resolution (as low as 12 × 12 μm spot size) and standard-free nature of SMS allow the detection of intra-grain compositional heterogeneities in Fe³⁺/Feᵀ with relatively low uncertainties.
We combine SMS with major element compositions, water contents, and hydrogen isotope compositions to document the Fe³⁺/Feᵀ ratios as a function of mineral composition and post-crystallization dehydrogenation. Spectra were fitted with up to five distinct sites: ferrous iron on M(1), M(2), M(3), and ferric iron on M(2) and M(3), consistent with X-ray diffraction studies on single crystals of amphibole. The Fe³⁺/Feᵀ ratios range from 0.14 ± 0.03 (Long Valley Caldera), 0.51 to 0.63 ± 0.02 (representing intra-grain heterogeneities, Mount St. Helens) to 0.86 ± 0.03 (Lassen Volcanic Center). The latter grain experienced post-crystallization dehydrogenation, shown by its low water content (0.6 ± 0.05 wt%) and its elevated hydrogen isotope composition (δD = +25 ± 3‰ relative to SMOW). The Fe³⁺/Feᵀ ratios of 0.62 ± 0.01 and 0.20 ± 0.01 of two Mt. Pinatubo grains correlate with high-Al₂O₃ cores and low-Al₂O₃ rims and smaller phenocrysts in the sample, respectively. This study shows that SMS is capable of distinguishing two different domains with dissimilar Fe³⁺/Feᵀ values formed under different crystallization conditions, demonstrating that SMS in combination with major element, water, and hydrogen isotope compositions allows the interpretation of amphibole Fe³⁺/Feᵀ ratios in the context of crystallization and post-crystallization processes
Micropyramid-patterned, oxygen-permeable bottomed dish for high density culture of pancreatic islets
No full textThe need for maintaining cell-spheroid viability and function within high-density cultures is unmet for various clinical and experimental applications, including cell therapies. One immediate application is for transplantation of pancreatic islets, a clinically recognized treatment option to cure type 1 diabetes; islets are isolated from a donor for subsequent culture prior to transplantation. However, high seeding conditions cause unsolicited fusion of multiple spheroids, thereby limiting oxygen diffusion to induce hypoxic cell death. Here we introduce a culture dish incorporating a micropyramid-patterned surface to prevent the unsolicited fusion and oxygen-permeable bottom for optimal oxygen environment. A 400 µm-thick, oxygen-permeable polydimethylsiloxane sheet topped with micropyramid pattern of 400 µm-base and 200 µm-height was fabricated to apply to the 24-well plate format. The micropyramid pattern separated the individual pancreatic islets to prevent the fusion of multiple islets. This platform supported the high oxygen demand of islets at high seeding density at 260 islet equivalents cm⁻², a 2–3-fold higher seeding density compared to the conventional islet culture used in a preparation for the clinical islet transplantations, demonstrating improved islet morphology, metabolism and function in a 4 d-culture. Transplantation of these islets into immunodeficient diabetic mice exhibited significantly improved engraftment to achieve euglycemia compared to islets cultured in the conventional culture wells. Collectively, this simple design modification allows for high-density cultures of three-dimensional cell spheroids to improve the viability and function for an array of investigational and clinical replacement tissues
Assessing the efficacy of dissection gestures in robotic surgery
No full textOur group previously defined a dissection gesture classification system that deconstructs robotic tissue dissection into its most elemental yet meaningful movements. The purpose of this study was to expand upon this framework by adding an assessment of gesture efficacy (ineffective, effective, or erroneous) and analyze dissection patterns between groups of surgeons of varying experience. We defined three possible gesture efficacies as ineffective (no meaningful effect on the tissue), effective (intended effect on the tissue), and erroneous (unintended disruption of the tissue). Novices (0 prior robotic cases), intermediates (1–99 cases), and experts (≥ 100 cases) completed a robotic dissection task in a dry-lab training environment. Video recordings were reviewed to classify each gesture and determine its efficacy, then dissection patterns between groups were analyzed. 23 participants completed the task, with 9 novices, 8 intermediates with median caseload 60 (IQR 41–80), and 6 experts with median caseload 525 (IQR 413–900). For gesture selection, we found increasing experience associated with increasing proportion of overall dissection gestures (p = 0.009) and decreasing proportion of retraction gestures (p = 0.009). For gesture efficacy, novices performed the greatest proportion of ineffective gestures (9.8%, p < 0.001), intermediates commit the greatest proportion of erroneous gestures (26.8%, p < 0.001), and the three groups performed similar proportions of overall effective gestures, though experts performed the greatest proportion of effective retraction gestures (85.6%, p < 0.001). Between groups of experience, we found significant differences in gesture selection and gesture efficacy. These relationships may provide insight into further improving surgical training
Logarithmic Riemann–Hilbert correspondences for rigid varieties
No full textOn any smooth algebraic variety over a p-adic local field, we construct a tensor functor from the category of de Rham p-adic étale local systems to the category of filtered algebraic vector bundles with integrable connections satisfying the Griffiths transversality, which we view as a p-adic analogue of Deligne's classical Riemann--Hilbert correspondence. A crucial step is to construct canonical extensions of the desired connections to suitable compactifications of the algebraic variety with logarithmic poles along the boundary, in a precise sense characterized by the eigenvalues of residues; hence the title of the paper. As an application, we show that this p-adic Riemann--Hilbert functor is compatible with the classical one over all Shimura varieties, for local systems attached to representations of the associated reductive algebraic groups
Advances in optical metalenses
No full textOptical metalenses—two-dimensional arrays of submicrometre scatterers that collectively focus light—have experienced growing research interest in recent years as they can realize conventional optical elements while offering novel functionalities. Their progress is driven by the need for low-cost, high-performance miniaturized optical systems and is supported by advances in nanofabrication and computational tools and techniques. Here we review the main capabilities offered by metalenses, such as their multifunctionality and their ability to efficiently focus light to subwavelength spots. We discuss how these characteristics enable new applications and provide an overview of the current state of the art of optical metasystems. We conclude by discussing the outstanding challenges in the field and highlighting application areas where metalenses could have a substantial impact
Long non-coding RNAs: definitions, functions, challenges and recommendations
No full textGenes specifying long non-coding RNAs (lncRNAs) occupy a large fraction of the genomes of complex organisms. The term ‘lncRNAs’ encompasses RNA polymerase I (Pol I), Pol II and Pol III transcribed RNAs, and RNAs from processed introns. The various functions of lncRNAs and their many isoforms and interleaved relationships with other genes make lncRNA classification and annotation difficult. Most lncRNAs evolve more rapidly than protein-coding sequences, are cell type specific and regulate many aspects of cell differentiation and development and other physiological processes. Many lncRNAs associate with chromatin-modifying complexes, are transcribed from enhancers and nucleate phase separation of nuclear condensates and domains, indicating an intimate link between lncRNA expression and the spatial control of gene expression during development. lncRNAs also have important roles in the cytoplasm and beyond, including in the regulation of translation, metabolism and signalling. lncRNAs often have a modular structure and are rich in repeats, which are increasingly being shown to be relevant to their function. In this Consensus Statement, we address the definition and nomenclature of lncRNAs and their conservation, expression, phenotypic visibility, structure and functions. We also discuss research challenges and provide recommendations to advance the understanding of the roles of lncRNAs in development, cell biology and disease
Leonardo da Vinci’s Visualization of Gravity as a Form of Acceleration
No full textDespite limited tools, Leonardo da Vinci displayed ingenious problemsolving. The authors examine a combination of Leonardo’s thought and physical experiments regarding the acceleration of falling objects. Leonardo recorded that if a water-pouring vase moves transversally (sideways), mimicking the trajectory of a vertically falling object, it generates a right (as in orthogonal) triangle with equal leg length, composed of falling material lining up diagonally (forming the hypotenuse) and the vase trajectory forming one of the legs. On the hypotenuse, Leonardo wrote “Equatione di Moti,” or equalization of motions, noting the equivalence of the two orthogonal motions, one effected by gravity and the other prescribed by the experimenter. The authors present an analytical solution using Newtonian mechanics to confirm Leonardo’s “Equivalence principle.
Io’s Optical Aurorae in Jupiter’s Shadow
No full textDecline and recovery timescales surrounding eclipse are indicative of the controlling physical processes in Io’s atmosphere. Recent studies have established that the majority of Io’s molecular atmosphere, SO₂ and SO, condenses during its passage through Jupiter’s shadow. The eclipse response of Io’s atomic atmosphere is less certain, having been characterized solely by ultraviolet aurorae. Here we explore the response of optical aurorae for the first time. We find oxygen to be indifferent to the changing illumination, with [O i] brightness merely tracking the plasma density at Io’s position in the torus. In shadow, line ratios confirm sparse SO₂ coverage relative to O, since their collisions would otherwise quench the emission. Io’s sodium aurora mostly disappears in eclipse and e-folding timescales, for decline and recovery differ sharply: ∼10 minutes at ingress and nearly 2 hr at egress. Only ion chemistry can produce such a disparity; Io’s molecular ionosphere is weaker at egress due to rapid recombination. Interruption of a NaCl⁺ photochemical pathway best explains Na behavior surrounding eclipse, implying that the role of electron impact ionization is minor relative to photons. Auroral emission is also evident from potassium, confirming K as the major source of far red emissions seen with spacecraft imaging at Jupiter. In all cases, direct electron impact on atomic gas is sufficient to explain the brightness without invoking significant dissociative excitation of molecules. Surprisingly, the nonresponse of O and rapid depletion of Na is opposite the temporal behavior of their SO₂ and NaCl parent molecules during Io’s eclipse phase