979 research outputs found

    Ultrarelativistic polarized positron jets via collision of electron and ultraintense laser beams

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    Relativistic spin-polarized positron beams are indispensable for future electron-positron colliders to test modern high-energy physics theory with high precision. However, present techniques require very large scale facilities for those experiments. We put forward a novel efficient way for generating ultrarelativistic polarized positron beams employing currently available laser fields. For this purpose the generation of polarized positrons via multiphoton Breit-Wheeler pair production and the associated spin dynamics in single-shot interaction of an ultraintense laser pulse with an ultrarelativistic electron beam is investigated in the quantum radiation-dominated regime. A specifically tailored small ellipticity of the laser field is shown to promote splitting of the polarized particles along the minor axis of laser polarization into two oppositely polarized beams. In spite of radiative de-polarization, a dense positron beam with up to about 90\% polarization can be generated in tens of femtoseconds. The method may eventually usher high-energy physics studies into smaller-scale laser laboratories

    Regulation of NF-κB by PML and PML-RARα

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    Promyelocytic Leukemia (PML) is a nuclear protein that forms sub-nuclear structures termed nuclear bodies associated with transcriptionally active genomic regions. PML is a tumour suppressor and regulator of cell differentiation. We demonstrate that PML promotes TNFα-induced transcriptional responses by promoting NF-κB activity. TNFα-treated PML−/− cells show normal IκBα degradation and NF-κB nuclear translocation but significantly reduced NF-κB DNA binding and phosphorylation of NF-κB p65. We also demonstrate that the PML retinoic acid receptor-α (PML-RARα) oncofusion protein, which causes acute promyelocytic leukemia, inhibits TNFα induced gene expression and phosphorylation of NF-κB. This study establishes PML as an important regulator of NF-κB and demonstrates that PML-RARα dysregulates NF-κB

    Análisis de los límites de las tasas de interés en una institución financiera, Lima 2021

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    La presente investigación tiene como propósito hacer un análisis descriptivo de los límites a las tasas de interés, para tal fin el estudio se desarrolló en el área de crédito de una entidad financiera de la ciudad de Lima. El tipo de investigación por su nivel fue descriptivo con enfoque cuantitativo, donde la población estuvo conformada por 28 funcionarios del área de crédito de la entidad financiera, siendo la muestra igual a la población por lo que se llevó adelante un censo; el instrumento aplicado fue un cuestionario compuesto por 28 preguntas que miden las tres dimensiones de la variable, posición de dominio, protección al cliente y disponibilidad de crédito. El instrumento fue validado por tres expertos con grado académico de doctor y la confiabilidad alcanzó el nivel de aceptable determinado por el Alpha de Cronbach. Los resultados fueron trabajados mediante análisis descriptivo y con el uso del software SPSS, los que permitieron establecer que el 100% de los funcionarios encuestados considera que existe límites a las tasas de interés; el 96.4% coinciden en que existe posición de dominio en la entidad financiera en niveles medio y alto; asimismo, el 100% considera que el estado protege al cliente en niveles medio y alto; y que la disponibilidad de crédito tiene percepción media y alta en 96.4%

    Imprint of the stochastic nature of photon emission by electrons on the proton energy spectra in the laser-plasma interaction

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    The impact of stochasticity effects (SEs) in photon emissions on the proton energy spectra during laser-plasma interaction is theoretically investigated in the quantum radiation-dominated regime, which may facilitate SEs experimental observation. We calculate the photon emissions quantum mechanically and the plasma dynamics semiclassically via two-dimensional particle-in-cell simulations. An ultrarelativistic plasma generated and driven by an ultraintense laser pulse head-on collides with another strong laser pulse, which decelerates the electrons due to radiation-reaction effect and results in a significant compression of the proton energy spectra because of the charge separation force. In the considered regime the SEs are demonstrated in the shift of the mean energy of the protons up to hundreds of MeV. This effect is robust with respect to the laser and target parameters and measurable in soon available strong laser facilities

    Advisory panel review on the feasibility of three intervention programmes for children with autism spectrum disorder

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    Introduction: The prevalence of children with autism spectrum disorder is increasing each year. Intervention programmes towards improving the occupational needs such as daily activities of these children are limited. This study aimed to collect opinions from advisory panel for the content validation of the three developed intervention programmes to be implemented among children with autism spectrum disorder aged between 6 to 12 years. The intervention programmes are; i) self-regulated learning, ii) sensory integration intervention and iii) activity-based intervention. Methods: A cross-sectional study was conducted. Twenty occupational therapists with more than three years’ experience working with children with autism spectrum disorders were recruited as advisory panel members. Re-searchers-developed questionnaire was used. The questionnaire consists of nine to eleven items. Each item consists of a five-point Likert scale for quantitative responses and open-ended questions for qualitative responses. Results: Advisory panel ratings of ‘Good’ to ‘Excellent’ was reported across most items in all three intervention programmes. Overall results suggested that the intervention programmes content was rated to be suitable for children with autism spectrum disorder. Constructive comments were adopted to clarify the activities and structure of the intervention programmes. Final development of the intervention programmes is presented. Conclusion: This study provides confidence for the interventions to be incorporated into the future randomised controlled trial

    Methods and measures for investigating microscale motility

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    Motility is an essential factor for an organism's survival and diversification. With the advent of novel single-cell technologies, analytical frameworks and theoretical methods, we can begin to probe the complex lives of microscopic motile organisms and answer the intertwining biological and physical questions of how these diverse lifeforms navigate their surroundings. Herein, we give an overview of different experimental, analytical, and mathematical methods used to study a suite of microscale motility mechanisms across different scales encompassing molecular-, individual- to population-level. We identify transferable techniques, pressing challenges, and future directions in the field. This review can serve as a starting point for researchers who are interested in exploring and quantifying the movements of organisms in the microscale world.Comment: 24 pages, 2 figure
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