1,244 research outputs found

    Development of Knife-Edge Ridges on Ion-Bombarded Surfaces

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    We demonstrate in both laboratory and numerical experiments that ion bombardment of a modestly sloped surface can create knife-edge like ridges with extremely high slopes. Small pre-fabricated pits expand under ion bombardment, and the collision of two such pits creates knife-edge ridges. Both laboratory and numerical experiments show that the pit propagation speed and the precise shape of the knife edge ridges are universal, independent of initial conditions, as has been predicted theoretically. These observations suggest a novel method of fabrication in which a surface is pre-patterned so that it dynamically evolves to a desired target pattern made of knife-edge ridges.Comment: 5 pages, 4 figure

    Molecular Mechanisms Underlying Cell Death in Spinal Networks in Relation to Locomotor Activity After Acute Injury in vitro

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    Understanding the pathophysiological changes triggered by an acute spinal cord injury is a primary goal to prevent and treat chronic disability with a mechanism-based approach. After the primary phase of rapid cell death at the injury site, secondary damage occurs via autodestruction of unscathed tissue through complex cell-death mechanisms that comprise caspase-dependent and caspase-independent pathways. To devise novel neuroprotective strategies to restore locomotion, it is, therefore, necessary to focus on the death mechanisms of neurons and glia within spinal locomotor networks. To this end, the availability of in vitro preparations of the rodent spinal cord capable of expressing locomotor-like oscillatory patterns recorded electrophysiologically from motoneuron pools offers the novel opportunity to correlate locomotor network function with molecular and histological changes long after an acute experimental lesion. Distinct forms of damage to the in vitro spinal cord, namely excitotoxic stimulation or severe metabolic perturbation (with oxidative stress, hypoxia/aglycemia), can be applied with differential outcome in terms of cell types and functional loss. In either case, cell death is a delayed phenomenon developing over several hours. Neurons are more vulnerable to excitotoxicity and more resistant to metabolic perturbation, while the opposite holds true for glia. Neurons mainly die because of hyperactivation of poly(ADP-ribose) polymerase-1 (PARP-1) with subsequent DNA damage and mitochondrial energy collapse. Conversely, glial cells die predominantly by apoptosis. It is likely that early neuroprotection against acute spinal injury may require tailor-made drugs targeted to specific cell-death processes of certain cell types within the locomotor circuitry. Furthermore, comparison of network size and function before and after graded injury provides an estimate of the minimal network membership to express the locomotor program

    Aggregation effects on pigment coatings: Pigment red 179 as a case study

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    Here, we have studied, with a combined experimental and computational approach, the effect of the crystal environment and aggregation on the electronic properties of Pigment Red 179, which affect both its color and optical energy gap. Spectra acquired in the near-infrared and visible range of energies suggest that this molecule is indeed a "cool" dye, which can be employed as a red pigment that provides effective color coverage to different substrates without contributing to their heating during light irradiation. Spectra acquired on different polymer mixtures at different pigment concentrations (i.e., 2.5-10 wt %) suggest that absorption features depend on chromophoric arrangements promoted by the strong intermolecular I -\u3c0interactions. Calculations, performed at the time-dependent density functional theory level, allowed to both attribute the nature of the electronic transitions causing the observed spectra involved and understand the effect of the environment. Indeed, the visible spectra of the pigment is dominated by two localized transitions, with negligible charge transfer for both a dye monomer and dimer either in vacuum or acetonitrile solution. Instead, models including the crystal environment of the pigment show the presence of a high-wavelength S1 \ue2 S0 charge transfer transition between two adjacent molecules, in quantitative agreement with the experimental absorption energy of the crystal pigment

    Pulmonary Imaging Phenotypes of Chronic Obstructive Pulmonary Disease Using Multiparametric Response Maps

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    Background Pulmonary imaging of chronic obstructive pulmonary disease (COPD) has focused on CT or MRI measurements, but these have not been evaluated in combination. Purpose To generate multiparametric response map (mPRM) measurements in ex-smokers with or without COPD by using volume-matched CT and hyperpolarized helium 3

    Let\u27s talk about antibiotics: A randomised trial of two interventions to reduce antibiotic misuse

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    BACKGROUND: Children with acute respiratory tract infections (ARTIs) receive ≈11.4 million unnecessary antibiotic prescriptions annually. A noted contributor is inadequate parent-clinician communication, however, efforts to reduce overprescribing have only indirectly targeted communication or been impractical. OBJECTIVES: Compare two feasible (higher vs lower intensity) interventions for enhancing parent-clinician communication on the rate of inappropriate antibiotic prescribing. DESIGN: Multisite, parallel group, cluster randomised comparative effectiveness trial. Data collected between March 2017 and March 2019. SETTING: Academic and private practice outpatient clinics. PARTICIPANTS: Clinicians (n=41, 85% of eligible approached) and 1599 parent-child dyads (ages 1-5 years with ARTI symptoms, 71% of eligible approached). INTERVENTIONS: All clinicians received 20 min ARTI diagnosis and treatment education. Higher intensity clinicians received an additional 50 min communication skills training. All parents viewed a 90 second antibiotic education video. MAIN OUTCOMES AND MEASURES: Inappropriate antibiotic treatment was assessed via blinded medical record review by study clinicians and a priori defined as prescriptions for the wrong diagnosis or use of the wrong agent. Secondary outcomes were revisits, adverse drug reactions (both assessed 2 weeks after the visit) and parent ratings of provider communication, shared decision-making and visit satisfaction (assessed at end of the visit on Likert-type scales). RESULTS: Most clinicians completed the study (n=38, 93%), were doctors (n=25, 66%), female (n=30, 78%) and averaged 8 years in practice. All parent-child dyad provided data for the main outcome (n=855 (54%) male, n=1043 (53%) CONCLUSIONS AND RELEVANCE: Rate of inappropriate prescribing was low in both arms. Clinician education coupled with parent education may be sufficient to yield low inappropriate antibiotic prescribing rates. The absence of a significant difference between groups indicates that communication principles previously thought to drive inappropriate prescribing may need to be re-examined or may not have as much of an impact in practices where prescribing has improved in recent years. TRIAL REGISTRATION NUMBER: NCT03037112

    A new CY elliptic fibration and tadpole cancellation

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    Tadpole cancellation in Sen limits in F-theory was recently studied by Aluffi and Esole. We extend their results, generalizing the elliptic fibrations they used and obtaining a new case of universal tadpole cancellation, at least numerically. We could not find an actual Sen limit having the correct brane content, and we argue that such a limit may not exist. We also give a uniform description of the fibration used by Aluffi and Esole as well as a new, simple, fibration which has non-Kodaira type fibers.Comment: 18 pages; added references and minor change

    Inclusion of non-inferiority analysis in superiority-based clinical trials with single-arm, two-stage Simon's design

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    Non-inferiority (NI) analysis is not usually considered in the early phases of clinical development. In some negative phase II trials, a post-hoc NI analysis justified additional phase III trials that were successful. However, the risk of false positive achievements was not controlled in these early phase analyses. We propose to preplan NI analyses in superiority-based Simon's two-stage designs to control type I and II error rates. Simulations have been proposed to assess the control of type I and II errors rates with this method. A total of 12,768 two-stage Simon's design trials were constructed based on different assumptions of rejection response probability, desired response probability, type I and II errors, and NI margins. P-value and type II error were calculated with stochastic ordering using Uniformly Minimum Variance Unbiased Estimator. Type I and II errors were simulated using the Monte Carlo method. The agreement between calculated and simulated values was analyzed with Bland-Altman plots. We observed the same level of agreement between calculated and simulated type I and II errors from both two-stage Simon's superiority designs and designs in which NI analysis was allowed. Different examples has been proposed to explain the utility of this method. Inclusion of NI analysis in superiority-based single-arm clinical trials may be useful for weighing additional factors such as safety, pharmacokinetics, pharmacodynamic, and biomarker data while assessing early efficacy. Implementation of this strategy can be achieved through simple adaptations to existing designs for one-arm phase II clinical trials

    REFORTICCA: Recursos para el Empoderamiento de FORmadores en TIC, Ciencias y Ambiente

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    La línea de investigación y desarrollo que aquí se presenta tiene por objetivo brindar a docentes de educación primaria y secundaria, y a la comunidad educativa en general, recursos educativos y herramientas digitales para ser usadas como soporte del proceso de enseñanza y aprendizaje de ciencias físicas, matemáticas, medio ambiente, y aportar al desarrollo del pensamiento computacional. En particular, se estudian, desarrollan y evalúan aplicaciones de realidad virtual, realidad aumentada, simulaciones, juegos e interacción tangible, con el objeto de resolver procesos de enseñanza y aprendizaje. Además, se propone crear una comunidad virtual de docentes para la construcción colaborativa de propuestas de enseñanza.Eje: Tecnología Informática Aplicada en Educación

    REFORTICCA: Recursos para el Empoderamiento de FORmadores en TIC, Ciencias y Ambiente

    Get PDF
    La línea de investigación y desarrollo que aquí se presenta tiene por objetivo brindar a docentes de educación primaria y secundaria, y a la comunidad educativa en general, recursos educativos y herramientas digitales para ser usadas como soporte del proceso de enseñanza y aprendizaje de ciencias físicas, matemáticas, medio ambiente, y aportar al desarrollo del pensamiento computacional. En particular, se estudian, desarrollan y evalúan aplicaciones de realidad virtual, realidad aumentada, simulaciones, juegos e interacción tangible, con el objeto de resolver procesos de enseñanza y aprendizaje. Además, se propone crear una comunidad virtual de docentes para la construcción colaborativa de propuestas de enseñanza.Eje: Tecnología Informática Aplicada en Educación.Red de Universidades con Carreras en Informátic
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