986 research outputs found

    Comparación de la dosis estimada en recto y vejiga con planificación de Braquiterapia 3D vs 2D: Estimated dose comparison in the rectum and bladder with 3D vs. 2D brachytherapy planning

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    Cervical cancer is one of the main female neoplasia the treatment requires multidisciplinary management.Intracavity brachytherapy occupies a fundamental role. Brachytherapy represented an important improvement in the last years with the growth of the three-dimensional planning. But in many countries, two dimensional planning is still the only option of treatment. We seek to establish the benefit that is obtained with brachytherapy in three dimensions, in the protection to organs of risk. This is an observational, longitudinal cohort study; we extrapolated treatment schemes in three dimensions, to planning in two dimensions. Then turned to move this planning, to the tridimensional system again and we got doses- olume histograms of rectum and bladder. Finally, we determined the average of doses received in 2cc of rectum and bladder in three-dimensional planning and compared with those obtained in the two dimensional planning, using Student’s T test. The dose average in 2cc bladder in two-dimensional plan was 5.5 Gy. And in three-dimensional plan was 5.1 Gy (p=0.01). The dose average in 2cc rectum in two-dimensional plan was 2.8 Gy, and in three-dimensional plan was 3.0 Gy (p=0.06). This study gives an approximation to the dosimetry improvement obtained through the using of the three- dimensional planning, for the reduction of doses in the bladder.El cáncer de cuello uterino se ubica entre las principales neoplasia femeninas, su tratamiento requiere del manejo multidisciplinario, donde la braquiterapia ocupa un sitial fundamental. Está ha presentado una importante evolución en los últimos años con el surgimiento de la planificación en tres dimensiones. En muchas partes del mundo, la modalidad en dos dimensiones sigue siendo la única opción de tratamiento. Como objetivo buscamos establecer el beneficio que se obtiene con braquiterapia en tres dimensiones sobre la técnica convencional de braquiterapia, en la protección a los órganos de riesgo. Planteamos un estudio observacional de cohorte longitudinal, extrapolando planificaciones de tratamiento en tres dimensiones, a planificación en dos dimensiones. Posteriormente se volvió a trasladar esta planificación, al sistema en tres dimensiones y se obtuvo histogramas dosis volumen de recto y vejiga. Determinamos el promedio de dosis recibidas en 2 cc de recto y vejiga en la planificación tridimensional y comparamos con las obtenidos en la planificación en dos dimensiones, mediante la T de Student. El promedio de la planificación de las dosis en vejiga con dos dimensiones fue 5.5 Gy, y con tres dimensiones fue 5.1 Gy, p= 0.01. El promedio de la planificación de las dosis en recto con dos dimensiones fue 2.8 Gy; y con tres dimensiones fue 3.0 Gy p= 0.06. Este estudio nos da una aproximación al beneficio dosimétrico que se obtiene mediante el uso de la planificación tridimensional, para la reducción de dosis que llega a vejiga

    Reflexiones desde la enseñanza y el aprendizaje de la arquitectura 2

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    La segunda entrega del libro Doceo “Reflexiones desde la enseñanza y el aprendizaje de la arquitectura”, es fruto de metodologías de enseñanza- aprendizaje diseñadas para cada caso, y que representan la impronta personal de cada autor. Es importante resaltar, que todos los argumentos presentados en esta obra corresponden a experiencias en el aula, conclusiones de docentes y/o estudiantes en el marco de una asignatura desarrollada en la Universidad de la Costa con sede en Barranquilla, Colombia. El Volumen dos de esta entrega se ha editado progresivamente, en una primera parte la compilación estuvo a cargo de la profesora Stephania Mouthon, quien centralizó todos los manuscritos, luego de esto, hemos construido de manera conjunta el diseño editorial, estructura del cuerpo y demás aspectos de perfeccionamiento del documento.Departamento de Arquitectura, Universidad de la Cost

    Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

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    A measurement of the cosmic-ray spectrum for energies exceeding 4×10184{\times}10^{18} eV is presented, which is based on the analysis of showers with zenith angles greater than 6060^{\circ} detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above 5.3×10185.3{\times}10^{18} eV, the "ankle", the flux can be described by a power law EγE^{-\gamma} with index γ=2.70±0.02(stat)±0.1(sys)\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)} followed by a smooth suppression region. For the energy (EsE_\text{s}) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find Es=(5.12±0.25(stat)1.2+1.0(sys))×1019E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19} eV.Comment: Replaced with published version. Added journal reference and DO

    Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory

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    The Auger Engineering Radio Array (AERA) is part of the Pierre Auger Observatory and is used to detect the radio emission of cosmic-ray air showers. These observations are compared to the data of the surface detector stations of the Observatory, which provide well-calibrated information on the cosmic-ray energies and arrival directions. The response of the radio stations in the 30 to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of the incoming electric field. For the latter, the energy deposit per area is determined from the radio pulses at each observer position and is interpolated using a two-dimensional function that takes into account signal asymmetries due to interference between the geomagnetic and charge-excess emission components. The spatial integral over the signal distribution gives a direct measurement of the energy transferred from the primary cosmic ray into radio emission in the AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air shower arriving perpendicularly to the geomagnetic field. This radiation energy -- corrected for geometrical effects -- is used as a cosmic-ray energy estimator. Performing an absolute energy calibration against the surface-detector information, we observe that this radio-energy estimator scales quadratically with the cosmic-ray energy as expected for coherent emission. We find an energy resolution of the radio reconstruction of 22% for the data set and 17% for a high-quality subset containing only events with at least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO

    Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy

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    We measure the energy emitted by extensive air showers in the form of radio emission in the frequency range from 30 to 80 MHz. Exploiting the accurate energy scale of the Pierre Auger Observatory, we obtain a radiation energy of 15.8 \pm 0.7 (stat) \pm 6.7 (sys) MeV for cosmic rays with an energy of 1 EeV arriving perpendicularly to a geomagnetic field of 0.24 G, scaling quadratically with the cosmic-ray energy. A comparison with predictions from state-of-the-art first-principle calculations shows agreement with our measurement. The radiation energy provides direct access to the calorimetric energy in the electromagnetic cascade of extensive air showers. Comparison with our result thus allows the direct calibration of any cosmic-ray radio detector against the well-established energy scale of the Pierre Auger Observatory.Comment: Replaced with published version. Added journal reference and DOI. Supplemental material in the ancillary file

    Combined searches for the production of supersymmetric top quark partners in proton-proton collisions at root s=13 TeV

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    A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV

    Measurement of t(t)over-bar normalised multi-differential cross sections in pp collisions at root s=13 TeV, and simultaneous determination of the strong coupling strength, top quark pole mass, and parton distribution functions

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    An embedding technique to determine ττ backgrounds in proton-proton collision data

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    An embedding technique is presented to estimate standard model tau tau backgrounds from data with minimal simulation input. In the data, the muons are removed from reconstructed mu mu events and replaced with simulated tau leptons with the same kinematic properties. In this way, a set of hybrid events is obtained that does not rely on simulation except for the decay of the tau leptons. The challenges in describing the underlying event or the production of associated jets in the simulation are avoided. The technique described in this paper was developed for CMS. Its validation and the inherent uncertainties are also discussed. The demonstration of the performance of the technique is based on a sample of proton-proton collisions collected by CMS in 2017 at root s = 13 TeV corresponding to an integrated luminosity of 41.5 fb(-1).Peer reviewe

    Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

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    A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe
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