538 research outputs found

    Phylogenetic signal in amphibian sensitivity to copper sulfate relative to experimental temperature

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    The release of large quantities of chemicals into the environment represents a major source of environmental disturbance. In recent years, the focus of ecotoxicology has shifted from describing the effects of chemical contaminants on individual species to developing more integrated approaches for predicting and evaluating long term effects of chemicals across species and ecosystems. Traditional ecotoxicology is typically based on data of sensitivity of a few surrogate species to a contaminant and often considers little variability in chemical sensitivity within and among taxonomic groups. This approach assumes that evolutionary history and phylogenetic relatedness among species have little or no impact on species’ sensitivity to chemical compounds. Few studies have tested this assumption. Using phylogenetic comparative methods and published data for amphibians, we show that sensitivity to copper sulfate, a commonly used pesticide, exhibits a strong phylogenetic signal when controlling for experimental temperature. Our results indicate that evolutionary history needs to be accounted for to make accurate predictions of amphibian sensitivity to this contaminant under different temperature scenarios. Since physiological and metabolic traits showing high phylogenetic signal likely underlie variation in species sensitivity to chemical stressors, future studies should evaluate and predict species vulnerability to pollutants using evolutionarily informed approaches

    Light effective hole mass in undoped Ge/SiGe quantum wells

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    We report density-dependent effective hole mass measurements in undoped germanium quantum wells. We are able to span a large range of densities (2.011×10112.0-11\times10^{11} cm2^{-2}) in top-gated field effect transistors by positioning the strained buried Ge channel at different depths of 12 and 44 nm from the surface. From the thermal damping of the amplitude of Shubnikov-de Haas oscillations, we measure a light mass of 0.061me0.061m_e at a density of 2.2×10112.2\times10^{11} cm2^{-2}. We confirm the theoretically predicted dependence of increasing mass with density and by extrapolation we find an effective mass of 0.05me\sim0.05m_e at zero density, the lightest effective mass for a planar platform that demonstrated spin qubits in quantum dots

    Inclusive University didactics and technological devices: a case study

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    This paper provides a review of projects related to new technologies used to favour the teaching-learning processes and the inclusive practices in the University context for students with disabilities and with Specific Learning Disorders. Authors present a review of strategies, trajectories and perspectives activated in the national and international scene, aiming to guarantee a significant pedagogical framework of reference. Furthermore, the paper focuses on a meaningful path activated at the University of Macerata, the project Inclusion 3.0, a relevant example of new technologies in support of teaching- learning processes and inclusion practices among all students

    Low disordered, stable, and shallow germanium quantum wells: a playground for spin and hybrid quantum technology

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    Buried-channel semiconductor heterostructures are an archetype material platform to fabricate gated semiconductor quantum devices. Sharp confinement potential is obtained by positioning the channel near the surface, however nearby surface states degrade the electrical properties of the starting material. In this paper we demonstrate a two-dimensional hole gas of high mobility (5×1055\times 10^{5} cm2^2/Vs) in a very shallow strained germanium channel, which is located only 22 nm below the surface. This high mobility leads to mean free paths 6μm\approx6 \mu m, setting new benchmarks for holes in shallow FET devices. Carriers are confined in an undoped Ge/SiGe heterostructure with reduced background contamination, sharp interfaces, and high uniformity. The top-gate of a dopant-less field effect transistor controls the carrier density in the channel. The high mobility, along with a percolation density of 1.2×1011 cm21.2\times 10^{11}\text{ cm}^{-2}, light effective mass (0.09 me_e), and high g-factor (up to 77) highlight the potential of undoped Ge/SiGe as a low-disorder material platform for hybrid quantum technologies

    The Notch-mediated circuitry in the evolution and generation of new cell lineages: the tooth model

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    The Notch pathway is an ancient, evolutionary conserved intercellular signaling mechanism that is involved in cell fate specification and proper embryonic development. The Jagged2 gene, which encodes a ligand for the Notch family of receptors, is expressed from the earliest stages of odontogenesis in epithelial cells that will later generate the enamel-producing ameloblasts. Homozygous Jagged2 mutant mice exhibit abnormal tooth morphology and impaired enamel deposition. Enamel composition and structure in mammals are tightly linked to the enamel organ that represents an evolutionary unit formed by distinct dental epithelial cell types. The physical cooperativity between Notch ligands and receptors suggests that Jagged2 deletion could alter the expression profile of Notch receptors, thus modifying the whole Notch signaling cascade in cells within the enamel organ. Indeed, both Notch1 and Notch2 expression are severely disturbed in the enamel organ of Jagged2 mutant teeth. It appears that the deregulation of the Notch signaling cascade reverts the evolutionary path generating dental structures more reminiscent of the enameloid of fishes rather than of mammalian enamel. Loss of interactions between Notch and Jagged proteins may initiate the suppression of complementary dental epithelial cell fates acquired during evolution. We propose that the increased number of Notch homologues in metazoa enabled incipient sister cell types to form and maintain distinctive cell fates within organs and tissues along evolution

    Effects of Uncertainty of Outlet Boundary Conditions in a Patient-Specific Case of Aortic Coarctation

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    Computational Fluid Dynamics (CFD) simulations of blood flow are widely used to compute a variety of hemodynamic indicators such as velocity, time-varying wall shear stress, pressure drop, and energy losses. One of the major advances of this approach is that it is non-invasive. The accuracy of the cardiovascular simulations depends directly on the level of certainty on input parameters due to the modelling assumptions or computational settings. Physiologically suitable boundary conditions at the inlet and outlet of the computational domain are needed to perform a patient-specific CFD analysis. These conditions are often affected by uncertainties, whose impact can be quantified through a stochastic approach. A methodology based on a full propagation of the uncertainty from clinical data to model results is proposed here. It was possible to estimate the confidence associated with model predictions, differently than by deterministic simulations. We evaluated the effect of using three-element Windkessel models as the outflow boundary conditions of a patient-specific aortic coarctation model. A parameter was introduced to calibrate the resistances of the Windkessel model at the outlets. The generalized Polynomial Chaos method was adopted to perform the stochastic analysis, starting from a few deterministic simulations. Our results show that the uncertainty of the input parameter gave a remarkable variability on the volume flow rate waveform at the systolic peak simulating the conditions before the treatment. The same uncertain parameter had a slighter effect on other quantities of interest, such as the pressure gradient. Furthermore, the results highlight that the fine-tuning of Windkessel resistances is not necessary to simulate the post-stenting scenario

    Characterization of gaze in handwriting of High and Low Frequency Word of Schoolchildren with Dyslexia

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    Writing is extremely important for our academic and professional life and can affect our performance in productive educational activities, favouring us or not. Schoolchildren with dyslexia bring difficulties and reduced school performance due to their condition of deprivation in written production. This is because schoolchildren with dyslexia have difficulty acquiring spelling knowledge and show poor phonological skills. This study aimed to characterize the performance of schoolchildren with dyslexia in “gaze” for the handwriting of High and Low-frequency words. A total of 24 schoolchildren participated in the study. They were between 8 to 11 years and 11 months of age, of both sexes, and they were attending the 3rd to the 5th year of Elementary School in the city of Marília-SP. The schoolchildren were divided into groups: GI, composed of 12schoolchildren with an interdisciplinary diagnosis of developmental dyslexia, and GII, composed of 12 schoolchildren with good academic performance, paired with GI according to the school grade level. These schoolchildren were submitted to computerized handwriting evaluation using a Brazilian adaptation of the Software Ductus. All schoolchildren were submitted to a copy of words already selected according to Brazilian Portuguese criteria of frequency and codification rule. A measure of “gaze” was used, that is, when the schoolchildren stopped their handwriting to search/look up at the screen to confirm the information about the words. The results indicated a significant difference between GI and GII, with GI schoolchildren performing more gaze when compared with GII, i.e., taking longer motor breaks to perform the gaze. Therefore, there was a rupture in the central processing with the peripheral when the child performed the gauze more times since he had to confirm the characteristics of this word during the writing process (difficulty in accessing the orthographic lexicon) and with that, there was a break in the movement of handwriting (since there was not enough information in the central plane to complete that motor memory and finish the word). It was concluded that there were gaps between the central (orthographic) and peripheral (motor pauses processes, suggesting deficits in the formation of motor programs for GI and the lack of automation of motor processes

    Speed and pressure of handwriting as critical issues of the contemporary age: A research in Italian students in early literacy

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    Among the present critical issues that pedagogy and special teaching have to deal with it is possible to notice the contrast between writing and technology, up to the pertinent field of prevention and observation of dysgraphies. The authors present in the following article a study conducted in Italy aimed at evaluating writing, specifically in the speed and pressure parameters in early literacy using NeuroScript Movalyzer Software. The aim is to implement suitable research paths to support the dissemination of observation procedures and inclusive teaching practices, capable of enhancing the fluidity of writing by all students
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