1,340 research outputs found

    Ocular-based automatic summarization of documents: is re-reading informative about the importance of a sentence?

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    Automatic document summarization (ADS) has been introduced as a viable solution for reducing the time and the effort needed to read the ever-increasing textual content that is disseminated. However, a successful universal ADS algorithm has not yet been developed. Also, despite progress in the field, many ADS techniques do not take into account the needs of different readers, providing a summary without internal consistency and the consequent need to re-read the original document. The present study was aimed at investigating the usefulness of using eye tracking for increasing the quality of ADS. The general idea was of that of finding ocular behavioural indicators that could be easily implemented in ADS algorithms. For instance, the time spent in re-reading a sentence might reflect the relative importance of that sentence, thus providing a hint for the selection of text contributing to the summary. We have tested this hypothesis by comparing metrics based on the analysis of eye movements of 30 readers with the highlights they made afterward. Results showed that the time spent reading a sentence was not significantly related to its subjective value, thus frustrating our attempt. Results also showed that the length of a sentence is an unavoidable confounding because longer sentences have both the highest probability of containing units of text judged as important, and receive more fixations and re-fixations

    Getting old through the blood. Circulating molecules in aging and senescence of cardiovascular regenerative cells

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    Global aging is a hallmark of our century. The natural multifactorial process resulting in aging involves structural and functional changes, affecting molecules, cells, and tissues. As the western population is getting older, we are witnessing an increase in the burden of cardiovascular events, some of which are known to be directly linked to cellular senescence and dysfunction. In this review, we will focus on the description of a few circulating molecules, which have been correlated to life span, aging, and cardiovascular homeostasis. We will review the current literature concerning the circulating levels and related signaling pathways of selected proteins (insulin-like growth factor 1, growth and differentiation factor-11, and PAI-1) and microRNAs of interest (miR-34a, miR-146a, miR-21), whose bloodstream levels have been associated to aging in different organisms. In particular, we will also discuss their potential role in the biology and senescence of cardiovascular regenerative cell types, such as endothelial progenitor cells, mesenchymal stromal cells, and cardiac progenitor cells

    A Multiscale Thermo-Fluid Computational Model for a Two-Phase Cooling System

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    In this paper, we describe a mathematical model and a numerical simulation method for the condenser component of a novel two-phase thermosyphon cooling system for power electronics applications. The condenser consists of a set of roll-bonded vertically mounted fins among which air flows by either natural or forced convection. In order to deepen the understanding of the mechanisms that determine the performance of the condenser and to facilitate the further optimization of its industrial design, a multiscale approach is developed to reduce as much as possible the complexity of the simulation code while maintaining reasonable predictive accuracy. To this end, heat diffusion in the fins and its convective transport in air are modeled as 2D processes while the flow of the two-phase coolant within the fins is modeled as a 1D network of pipes. For the numerical solution of the resulting equations, a Dual Mixed-Finite Volume scheme with Exponential Fitting stabilization is used for 2D heat diffusion and convection while a Primal Mixed Finite Element discretization method with upwind stabilization is used for the 1D coolant flow. The mathematical model and the numerical method are validated through extensive simulations of realistic device structures which prove to be in excellent agreement with available experimental data

    Groups with normality conditions for subgroups of infinite rank

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    A well-known theorem of B. H. Neumann states that a group has finite conjugacy classes of subgroups if and only if it is central-by-finite. It is proved here that if G is a generalized radical group of infinite rank in which the conjugacy classes of subgroups of infinite rank are finite, then every subgroup of G has finitely many conjugates, and so G=Z(G) is finite. Corresponding results are proved for groups in which every subgroup of infinite rank has fiznite index in its normal closure, and for those in which every subgroup of infinite rank is finite over its core

    Simultaneous Extraction of Density of States Width, Carrier Mobility and Injection Barriers in Organic Semiconductors

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    The predictive accuracy of state–of–the–art continuum models for charge transport in organic semiconductors is highly dependent on the accurate tuning of a set of parameters whose values cannot be effectively estimated either by direct measurements or by first principles. Fitting the complete set of model parameters at once to experimental data requires to set up extremely complex multi–objective optimization problems whose solution is, on the one hand, overwhelmingly computationally expensive and, on the other, it provides no guarantee of the physical soundness of the value obtained for each individual parameter. In the present study we present a step–by–step procedure that enables to determine the most relevant model parameters, namely the density of states width, the carrier mobility and the injection barrier height, by fitting experimental data from a sequence of relatively simple and inexpensive measurements to suitably devised numerical simulations. At each step of the proposed procedure only one parameter value is sought for, thus highly simplifying the numerical fitting and enhancing its robustness, reliability and accuracy. As a case study we consider a prototypical n-type organic polymer. A very satisfactory fitting of experimental measurements is obtained, and physically meaningful values for the aforementioned parameters are extracted

    Soot inception: A DFT study of σ and π dimerization of resonantly stabilized aromatic radicals

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    Recent advances in the soot studies have shown experimental evidences of π-radicals and cross-linked structures among the molecular constituents of just-nucleated soot particles. π-radicals could have an important role in particle nucleation by increasing the binding energy between polycyclic aromatic hydrocarbons with respect to pure van der Waals interactions. In this work we use density functional theory by Grimme D3 dispersion correction (DFT-D3) with hybrid functional and localized Gaussian basis set (B3LYP/6-31G**) to analyze and classify the clustering behaviors of two aromatic radicals visualized experimentally by atomic force microscopy (Commodo et al. Combust. Flame 205: 154–164, 2019). These aromatic radicals have different topological structures and delocalization of the unpaired electron. The binding energy and energy bandgap characteristics of the clusters are calculated. The theoretical results show a different clustering behavior for the two aromatic radicals. The one with a partial localization of the unpaired electron tends to form a σ-dimer; conversely, the radical with a greater delocalization of the unpaired electron leads to π-stacking formation with a slight overbinding of few kcal mol−1 with respect to pure van der Waals interactions and a marked lowering of the energy bandgap. The formation of π-stacking induced by delocalized π-radicals could in part explain some spectroscopic evidences observed during soot nucleation. © 2020 Elsevier Lt

    Î’-blockers treatment of cardiac surgery patients enhances isolation and improves phenotype of cardiosphere-derived cells

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    Β-blockers (BB) are a primary treatment for chronic heart disease (CHD), resulting in prognostic and symptomatic benefits. Cardiac cell therapy represents a promising regenerative treatment and, for autologous cell therapy, the patients clinical history may correlate with the biology of resident progenitors and the quality of the final cell product. This study aimed at uncovering correlations between clinical records of biopsy-donor CHD patients undergoing cardiac surgery and the corresponding yield and phenotype of cardiospheres (CSs) and CS-derived cells (CDCs), which are a clinically relevant population for cell therapy, containing progenitors. We describe a statistically significant association between BB therapy and improved CSs yield and CDCs phenotype. We show that BB-CDCs have a reduced fibrotic-like CD90 + subpopulation, with reduced expression of collagen-I and increased expression of cardiac genes, compared to CDCs from non-BB donors. Moreover BB-CDCs had a distinctive microRNA expression profile, consistent with reduced fibrotic features (miR-21, miR-29a/b/c downregulation), and enhanced regenerative potential (miR-1, miR-133, miR-101 upregulation) compared to non-BB. In vitro adrenergic pharmacological treatments confirmed cytoprotective and anti-fibrotic effects of β1-blocker on CDCs. This study shows anti-fibrotic and pro-commitment effects of BB treatment on endogenous cardiac reparative cells, and suggests adjuvant roles of β-blockers in cell therapy applications

    CHM/REP1 Transcript Expression and Loss of Visual Function in Patients Affected by Choroideremia

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    PURPOSE. To evaluate the disease progression in patients with clinical and genetic diagnoses of choroideremia during a long-term follow-up and to investigate the relationship between pathogenic variants in the CHM/REP1 gene and disease phenotypes. METHODS. We performed a retrospective longitudinal study on 51 affected men by reviewing medical charts at baseline and follow-up visits to extract the following ocular findings: best-corrected visual acuity, Goldmann visual field, optical coherence tomography, microperimetry. Data obtained from the analysis of DNA and mRNA were reevaluated for genetic classification of patients. RESULTS. The longitudinal analysis showed a significant (P < 0.001) worsening of best-corrected visual acuity with a mean rate of 0.011 logMar per year before 50 years and 0.025 logMar per year after 50 years. Similarly, V4e Goldmann visual field area significantly (P ≤ 0.01) decreased at a mean rate of 2.7% per year before 40 years and 5.7% after 40 years. Moreover, we observed a significant (P < 0.05) decrease of macular sensitivity with a mean rate of 5.0% per year and a decrease of mean macular thickness with a mean rate of 0.8% per year. We classified our patients into two groups according to the expression of the CHM/ REP1 gene transcript and observed that mutations leading to mRNA absence are associated with an earlier best-corrected visual acuity and Goldmann visual field loss. CONCLUSIONS. Our analysis of morphological and functional parameters in choroideremia patients showed a slow disease progression, particularly in the first decades of life. Overall, reevaluation of clinical and molecular data suggests exploring the genotype–phenotype relationship based on CHM/REP1 transcript expression. PURPOSE. To evaluate the disease progression in patients with clinical and genetic diagnoses of choroideremia during a long-term follow-up and to investigate the relationship between pathogenic variants in the CHM/REP1 gene and disease phenotypes. METHODS. We performed a retrospective longitudinal study on 51 affected men by reviewing medical charts at baseline and follow-up visits to extract the following ocular findings: best-corrected visual acuity, Goldmann visual field, optical coherence tomography, microperimetry. Data obtained from the analysis of DNA and mRNA were reevaluated for genetic classification of patients. RESULTS. The longitudinal analysis showed a significant (P < 0.001) worsening of best-corrected visual acuity with a mean rate of 0.011 logMar per year before 50 years and 0.025 logMar per year after 50 years. Similarly, V4e Goldmann visual field area significantly (P ≤ 0.01) decreased at a mean rate of 2.7% per year before 40 years and 5.7% after 40 years. Moreover, we observed a significant (P < 0.05) decrease of macular sensitivity with a mean rate of 5.0% per year and a decrease of mean macular thickness with a mean rate of 0.8% per year. We classified our patients into two groups according to the expression of the CHM/ REP1 gene transcript and observed that mutations leading to mRNA absence are associated with an earlier best-corrected visual acuity and Goldmann visual field loss. CONCLUSIONS. Our analysis of morphological and functional parameters in choroideremia patients showed a slow disease progression, particularly in the first decades of life. Overall, reevaluation of clinical and molecular data suggests exploring the genotype–phenotype relationship based on CHM/REP1 transcript expression

    Multiphysics simulation of corona discharge induced ionic wind

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    Ionic wind devices or electrostatic fluid accelerators are becoming of increasing interest as tools for thermal management, in particular for semiconductor devices. In this work, we present a numerical model for predicting the performance of such devices, whose main benefit is the ability to accurately predict the amount of charge injected at the corona electrode. Our multiphysics numerical model consists of a highly nonlinear strongly coupled set of PDEs including the Navier-Stokes equations for fluid flow, Poisson's equation for electrostatic potential, charge continuity and heat transfer equations. To solve this system we employ a staggered solution algorithm that generalizes Gummel's algorithm for charge transport in semiconductors. Predictions of our simulations are validated by comparison with experimental measurements and are shown to closely match. Finally, our simulation tool is used to estimate the effectiveness of the design of an electrohydrodynamic cooling apparatus for power electronics applications.Comment: 24 pages, 17 figure
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