Air radon concentration decrease in a waste water treatment plant

Rn-222 is a naturally occurring gas created from the decay of Ra-226. The long-term health risk of breathing radon is lung cancer. One particular place where indoor radon concentrations can exceed national guidelines is in wastewater treatment plants (WWTPs) where treatment processes may contribute to ambient airborne concentrations. The aim of this paper was to study the radon concentration decrease after the application of corrective measures in a Spanish WWTP. According to first measures, air radon concentration exceeded International Commission Radiologica1 Protection (ICRP) normative (recommends intervention between 400 and 1000 Bq m(-3)). Therefore, the WWTP improved mechanical forced ventilation to lower occupational exposure. This measure allowed to increase the administrative controls, since the limitation of workers access to the plant changed from 2 h d(-1) (considering a maximum permissible dose of 20 mSv y(-1) averaged over 5 y) to 7 h d(-1).Juste Vidal, BJ.; Ortiz Moragón, J.; Verdú Martín, GJ.; Martorell Alsina, SS. (2015). Air radon concentration decrease in a waste water treatment plant. Oxford University Press. doi:10.1093/RPD/NCV329

Uncertainty and sensitivity analysis of the effect of the mean energy and FWHM of the initial electron fluence on the Bremsstrahlung photon spectra of linear accelerators

A calculation of the correct dose in radiation therapy requires an accurate description of the radiation source because uncertainties in characterization of the linac photon spectrum are propagated through the dose calculations. Unfortunately, detailed knowledge of the initial electron beam parameters is not readily available, and many researchers adjust the initial electron fluence values by trial-and-error methods. The main goal of this work was to develop a methodology to characterize the fluence of initial electrons before they hit the tungsten target of an Elekta Precise medical linear accelerator. To this end, we used a Monte Carlo technique to analyze the influence of the characteristics of the initial electron beam on the distribution of absorbed dose from a 6 MV linac photon beam in a water phantom. The technique is based on calculations with Software for Uncertainty and Sensitivity Analysis (SUSA) and Monte Carlo simulations with the MCNP5 transport code. The free parameters used in the SUSA calculations were the mean energy and full-width-at-half-maximum (FWHM) of the initial electron distribution. A total of 93 combinations of these parameters gave initial electron fluence configurations. The electron spectra thus obtained were used in a simulation of the electron transport through the target of the linear accelerator, which produced different photon (Bremsstrahlung) spectra. The simulated photon spectra were compared with the 6-MV photon spectrum provided by the linac manufacturer (Elekta). This comparison revealed how the mean energy and FWHM of the initial electron fluence affect the spectrum of the generated photons. This study has made it possible to fine-tune the examined electron beam parameters to obtain the resulted absorbed doses with acceptable accuracy (error < 1%). (C) 2012 Elsevier Ltd. All rights reserved.Juste Vidal, BJ.; Miró Herrero, R.; Verdú Martín, GJ.; Macian, R. (2012). Uncertainty and sensitivity analysis of the effect of the mean energy and FWHM of the initial electron fluence on the Bremsstrahlung photon spectra of linear accelerators. Applied Radiation and Isotopes. 70(7):1267-1271. doi:10.1016/j.apradiso.2012.03.040S1267127170

Probing Electroweak Top Quark Couplings at Hadron Colliders

We consider QCD t\bar{t}\gamma and t\bar{t}Z production at hadron colliders as a tool to measure the tt\gamma and ttZ couplings. At the Tevatron it may be possible to perform a first, albeit not very precise, test of the tt\gamma vector and axial vector couplings in t\bar{t}\gamma production, provided that more than 5 fb^{-1} of integrated luminosity are accumulated. The t\bar{t}Z cross section at the Tevatron is too small to be observable. At the CERN Large Hadron Collider (LHC) it will be possible to probe the tt\gamma couplings at the few percent level, which approaches the precision which one hopes to achieve with a next-generation e^+e^- linear collider. The LHC's capability of associated QCD t\bar{t}V (V=\gamma, Z) production has the added advantage that the tt\gamma and ttZ couplings are not entangled. For an integrated luminosity of 300 fb^{-1}, the ttZ vector (axial vector) coupling can be determined with an uncertainty of 45-85% (15-20%), whereas the dimension-five dipole form factors can be measured with a precision of 50-55%. The achievable limits improve typically by a factor of 2-3 for the luminosity-upgraded (3 ab^{-1}) LHC.Comment: Revtex3, 30 pages, 9 Figures, 6 Table

Kinematic assessment of subject personification of human body models (THUMS)

The goal of this study was to quantify the effect of improving the geometry of a human body model on the accuracy of the predicted kinematics for 4 post-mortem human subject sled tests. Three modifications to the computational human body model THUMS were carried out to evaluate if subject personification can increase the agreement between predicted and measured kinematics of post-mortem human subjects in full frontal and nearside oblique impacts. The modifications consisted of: adjusting the human body model mass to the actual subject mass, morphing it to the actual anthropometry of each subject and finally adjustment of the model initial position to the measured position in selected post-mortem human subject tests. A quantitative assessment of the agreement between predicted and measured response was carried out by means of CORA analysis by comparing the displacement of selected anatomical landmarks (head CoG, T1 and T8 vertebre and H-Point). For all three scenarios, the more similar the human body model was to the anthropometry and posture of the sled tested post-mortem human subject, the more similar the predictions were to the measured responses of the post-mortem human subject, resulting in higher CORA score

Experiencias en el Uso de Códigos Neutrónicos en la Docencia en Ingeniería Nuclear

[ES] El equipo de innovación docente SEERISN (Simulación en la Enseñanza de Radiaciones Ionizantes y Seguridad Nuclear) de la UPV ha retomado sus actividades con el objetivo de abordar desde un punto de vista global la necesidad de formar a los estudiantes en el uso de códigos neutrónicos para el cálculo de reactores nucleares tal como se demanda desde las empresas del sector nuclear. El análisis de las diferentes actividades que ya se estaban realizando ha puesto de manifiesto la necesidad de revisar estas actividades para una introducción gradual y específica del uso de códigos neutrónicos en varias asignaturas de una manera sistemática y consciente, estableciendo grados de dificultad crecientes adecuados a cada titulación incluyendo medidas de evaluación del grado de consecución de las mismas. Este proceso se ha planteado en diferentes etapas y acciones. En este trabajo se presenta la primera fase de implantación en una asignatura de grado y los resultados obtenidos.[ES] The teaching innovation team SEERISN (Simulation in the Teaching of Ionizing Radiation and Nuclear Safety) of the UPV has resumed its activities with the aim of addressing, from a global point of view, the need to train students in the use of neutron codes to the calculation of nuclear reactors as demanded by companies in the nuclear sector. The analysis of the different activities that were already being carried out has revealed the need to review these activities for a gradual and specific introduction of the use of neutronic codes in various subjects in a systematic and conscious manner, establishing increasing degrees of difficulty appropriate to each qualification including evaluation measures of the degree of achievement of the same. This process has been proposed in different stages and actions. This paper presents the first phase of implementation in one subject for a degree and the results obtained.Barrachina, T.; Juste, B.; Miró, R.; Verdú, G. (2023). Experiencias en el Uso de Códigos Neutrónicos en la Docencia en Ingeniería Nuclear. Editorial Universitat Politècnica de València. 679-687. https://doi.org/10.4995/INRED2023.2023.1656867968

VARIAN CLINAC 6 MeV Photon Spectra Unfolding using a Monte Carlo Meshed Model

[EN] Energy spectrum is the best descriptive function to determine photon beam quality of a Medical Linear Accelerator (LinAc). The use of realistic photon spectra in Monte Carlo simulations has a great importance to obtain precise dose calculations in Radiotherapy Treatment Planning (RTP). Reconstruction of photon spectra emitted by medical accelerators from measured depth dose distributions in a water cube is an important tool for commissioning a Monte Carlo treatment planning system. Regarding this, the reconstruction problem is an inverse radiation transport function which is ill conditioned and its solution may become unstable due to small perturbations in the input data. This paper presents a more stable spectral reconstruction method which can be used to provide an independent confirmation of source models for a given machine without any prior knowledge of the spectral distribution. Monte Carlo models used in this work are built with unstructured meshes to simulate with realism the linear accelerator head geometry.Ha recibido financiación de DESARROLLO E IMPLEMENTACION DE UN SISTEMA DE PLANIFICACION RADIOTERAPÉUTICA (TELETERAPIA Y BRAQUITERAPIA) BASADO EN EL MÉTODO MONTECARLO PARA EL HUPLAFE (UNIVERSIDAD POLITECNICA DE VALENCIA), DESARROLLO Y VALIDACION EXPERIMENTAL DE UN SISTEMA DE PLANIFICACION DE TRATAMIENTOS RADIOTERAPEUTICOS UTILIZANDO TECNICAS DE MONTE CARLO (UNIVERSIDAD POLITECNICA DE VALENCIA), Dosimetría in vivo en radioterapia sin filtro aplanador (FFF) (UNIVERSIDAD POLITECNICA DE VALENCIA), MONTE CARLO TREATMENT PLANNING SYSTEM: SOFTWARE PARA EL CALCULO DOSIMETRICO DE ALTA PRECISION EN RADIOTERAPIA. (UNIVERSIDAD POLITECNICA DE VALENCIA) y SISTEMA DE PLANIFICACION DE TRATAMIENTOS EN RADIOTERAPIA BASADO EN EL METODO DE MOTE CARLO Y EL PROCESADO 3D DE IMAGENES MEDICAS (GENERALITAT VALENCIANA)Morató-Rafet, S.; Juste Vidal, BJ.; Miró Herrero, R.; Verdú Martín, GJ. (2017). VARIAN CLINAC 6 MeV Photon Spectra Unfolding using a Monte Carlo Meshed Model. EPJ Web of Conferences. 153(04012):1-7. https://doi.org/10.1051/epjconf/201715304012S171530401

MCNP6 unstructured mesh application to estimate the photoneutron distribution and induced activity inside a linac bunker

[EN] Unwanted neutrons in radiation therapy treatments are typically generated by photonuclear reactions. High-energy beams emitted by medical Linear Accelerators (LinAcs) interact with high atomic number materials situated in the accelerator head and release neutrons. Since neutrons have a high relative biological effectiveness, even low neutron doses may imply significant exposure of patients. It is also important to study radioactivity induced by these photoneutrons when interacting with the different materials and components of the treatment head facility and the shielding room walls, since persons not present during irradiation (e.g. medical staff) may be exposed to them even when the accelerator is not operating.These problems are studied in this work in order to contribute to challenge the radiation protection in these treatment locations. The work has been performed by simulation using the latest state of the art of Monte-Carlo computer code MCNP6. To that, a detailed model of particles transport inside the bunker and treatment head has been carried out using a meshed geometry model. The LinAc studied is an Elekta Precise accelerator with a treatment photon energy of 15. MeV used at the Hospital Clinic Universitari de Valencia, Spain.We would like to thank the "Hospital Clinic Universitari de Valencia" for the given help. This work has received support via "Programa para la innovacion e incentivacion" from Universitat Politecnica de Valencia "INNOVA 2012".Juste Vidal, BJ.; Morató Rafet, S.; Miró Herrero, R.; Verdú Martín, GJ.; Diez Domingo, S. (2015). MCNP6 unstructured mesh application to estimate the photoneutron distribution and induced activity inside a linac bunker. Radiation Physics and Chemistry. 1-5. doi:10.1016/j.radphyschem.2016.03.016S1

Structure and vacancy distribution in copper telluride nanoparticles influence plasmonic activity in the near-infrared

Copper chalcogenides find applications in different domains including photonics, photothermal therapy and photovoltaics. CuTe nanocrystals have been proposed as an alternative to noble metal particles for plasmonics. Although it is known that deviations from stoichiometry are a prerequisite for plasmonic activity in the near-infrared, an accurate description of the material and its (optical) properties is hindered by an insufficient understanding of the atomic structure and the influence of defects, especially for materials in their nanocrystalline form. We demonstrate that the structure of Cu1.5±xTe nanocrystals can be determined using electron diffraction tomography. Real-space high-resolution electron tomography directly reveals the three-dimensional distribution of vacancies in the structure. Through first-principles density functional theory, we furthermore demonstrate that the influence of these vacancies on the optical properties of the nanocrystals is determined. Since our methodology is applicable to a variety of crystalline nanostructured materials, it is expected to provide unique insights concerning structure–property correlations

Considering adaptive genetic variation in climate change vulnerability assessment reduces species range loss projections

Local adaptations can determine the potential of populations to respond to environmental changes, yet adaptive genetic variation is commonly ignored in models forecasting species vulnerability and biogeographical shifts under future climate change. Here we integrate genomic and ecological modeling approaches to identify genetic adaptations associated with climate in two cryptic forest bats. We then incorporate this information directly into forecasts of range changes under future climate change and assessment of population persistence through the spread of climate-adaptive genetic variation (evolutionary rescue potential). Considering climate-adaptive potential reduced range loss projections, suggesting that failure to account for intraspecific variability can result in overestimation of future losses. On the other hand, range overlap between species was projected to increase, indicating that interspecific competition is likely to play an important role in limiting species’ future ranges. We show that although evolutionary rescue is possible, it depends on a population’s adaptive capacity and connectivity. Hence, we stress the importance of incorporating genomic data and landscape connectivity in climate change vulnerability assessments and conservation management