Influencia del campo de temperaturas en la dinámica ambiental de la cueva de Altamira

RESUMEN: El estudio de las condiciones climáticas de una cueva como la de Altamira es fundamental para determinar los factores que conducen al deterioro de su arte rupestre. La evolución temporal de la temperatura de la cavidad viene determinada principalmente por la propagación de la onda térmica del exterior a través de la masa rocosa que la encierra e influye sobre los demás parámetros ambientales. A partir de la variación periódica tanto de la temperatura del exterior como del interior, se ha desarrollado un modelo predictivo con el fin de estimar la temperatura de la cueva y así poder planificar la entrada de visitantes teniendo en cuenta los límites de accesibilidad establecidos. El intercambio gaseoso de la cavidad con el exterior se ha estudiado a partir de la evolución del dióxido de carbono y el radón. La influencia antrópica sobre el ambiente de la cueva se ha analizado en base a las visitas públicas estandarizadas que se realizan en la actualidad.ABSTRACT: The study of the climatic conditions of a cave such as Altamira is essential to determine the factors that lead to the deterioration of its rock art. The temporal evolution of the temperature of the cavity is determined mainly by the thermal wave propagation through the rocky mass that encloses it and it influences the other environmental parameters. A predictive model has been developed from the periodic variation of the outside and interior temperatures in order to estimate the temperature of the cave and thus be able to plan the entrance of visitors taking into account the established accessibility limits. The air exchange of the cavity with the outside has been studied from the evolution of carbon dioxide and radon. The anthropic influence on the cave environment has been analyzed based on standardized public visits that are currently carried out

A new methodology for defining radon priority areas in spain

One of the requirements of EU-BSS (European Basic Safety Standards) is the design and implementation of a National Radon Action Plan in the member states. This should define, as accurately as possible, areas of risk for the presence of radon gas (222Rn) in homes and workplaces. The concept used by the Spanish Nuclear Safety Council (CSN), the body responsible for nuclear safety and radiation protection in Spain, to identify "radon priority areas" is that of radon potential. This paper establishes a different methodology from that used by the CSN, using the same study variables (indoor radon measurements, gamma radiation exposure data, and geological information) to prepare a radon potential map that improves the definition of the areas potentially exposed to radon in Spain. The main advantage of this methodology is that by using simple data processing the definition of these areas is improved. In addition, the application of this methodology can improve the delimitation of radon priority areas and can be applied within the cartographic system used by the European Commission-Joint Research Center (EC-JRC) in the representation of different environmental parameters

Mechanical behavior and microstructural changes in polyurethane exposed to high doses of X rays, gamma rays or neutron irradiation

Polymeric materials are widely used in applications where the environmental conditions entail their exposure to different sources of irradiation (in most cases ultraviolet or low dose of electromagnetic irradiation for sterilization). In contrast, in this study we have assessed the modifications undergone by a series of polyurethane joints exposed to high radioactive doses of either X-rays or gamma rays (with doses of 20.5, 100, 300 and 900?kGy) or neutron irradiation (with a fluence of 7.23·1010 n/cm2) which are typical of the environment of nuclear reactors. Tensile tests were carried out to assess the change in mechanical properties derived from the radioactive exposure. Three mechanical parameters were used to monitor the evolution of strength, ductility and toughness: the tensile strength (?max), the strain corresponding to ?max (??max) and the density of energy absorbed prior to maximum load (U?max). With regards to X and gamma rays, a negative impact of radiation on strength, ductility and toughness was observed. The detailed statistical analysis of the results has shown that a threshold dose of 300?kGy must be overcome to trigger the damage process. For the fluence employed in this study, neutron irradiation produced very little change in the mechanical properties. The SEM fractographic study has allowed the influence of irradiation on the material failure mechanisms to be identified. Thus, the fracture surface of unirradiated samples shows evidence of plastic deformation and ductile tearing. In contrast, the fracture surface of those samples exposed to a dose of 900?kGy corresponds to brittle fracture. In a consistent way, samples exposed to neutron irradiation have a fracture surface similar to that of the non-irradiated material. In summary, electromagnetic radiation for doses above the threshold leads to the embrittlement of polyurethane. Raman spectroscopy was employed to identify the microstructural changes induced by the different sources of radiation at the molecular level. The band corresponding to the vibration of the C-H bending bonds present in the polyurethane was measured as a function of the dose, finding a strong correlation between its vibration frequency and the dose of exposure to electromagnetic radiation. This shift is more sensitive than the mechanical material response since the frequency is affected at doses of 100?kGy, below the threshold previously identified for any of the mechanical properties. This correlation opens the door for the use of Raman spectroscopy as a novel non-destructive tool to characterize the microstructural effect of irradiation on polyurethane

Methodological Approaches to Radon in Water Measurements: Comparative Experiences between Romania and Spain

The EC Directive 2013/51/EURATOM of 22 October 2013 represents the first time that a radon limit for drinking water has been proposed. Transposition of this Directive into Spanish legislation was by means of the recent RD 314/2016 which sets a limit value of 500 Bq l?1 for radon (222Rn) in water for human consumption while that in Romanian legislation the Law 301/2015 provides a limit value of 100 Bq l-1 for 222Rn concentration in water for human consumption as well as a total effective dose of 0.1 mSv y-1 from all radionuclides present in water (same dose value established by Spanish law). For several years, both in Romania and in Spain, there have been campaigns to measure the concentration of 222Rn in waters of different origins in order to determine the possible exposure of the population through this irradiation path, and also to use the presence of radon dissolved in water as a source of indoor radon in thermal spa facilities, and also as a tracer of dynamic processes (C. Sainy et al., Sci. Tot. Envir. 543, 460 (2016); 1). In this article, an assessment of the results from measurement campaigns in both countries will be presented and compared. In addition, the different measurement techniques used will be described, and the description of an intercomparison exercise on radon measurement in water organized by the Environmental Radioactivity Laboratory of the University of Cantabria (LaRUC) will be presented, in order to evaluate the quality of the performance of the techniques used.This work was partially supported by the project ID P_37_229, Contract No. 22/01.09.2016, with the title Smart Systems for Public Safety through Control and Mitigation of Residential Radon linked with Energy Efficiency Optimization of Buildings in Romanian Major Urban Agglomerations SMART-RAD-EN of the POC Programme

Intercomparison of Indoor Radon Measurements Under Field Conditions In the Framework of MetroRADON European Project

Interlaboratory comparisons are a basic part of the regular quality controls of laboratories to warranty the adequate performance of test and measurements. The exercise presented in this article is the comparison of indoor radon gas measurements under field conditions performed with passive detectors and active monitors carried out in the Laboratory of Natural Radiation (LNR). The aim is to provide a direct comparison between different methodologies and to identify physical reasons for possible inconsistencies, particularly related to sampling and measurement techniques. The variation of radon concentration during the comparison showed a big range of values, with levels from approximately 0.5 to 30 kBq/m3. The reference values for the two exposure periods have been derived from a weighted average of participants' results applying an iterative algorithm. The indexes used to analyze the participants' results were the relative percentage difference D(%), the Zeta score ( ? ), and the z-score ( z ). Over 80% of the results for radon in air exposure are within the interval defined by the reference value and 20% and 10% for the first and the second exposure, respectively. Most deviations were detected with the overestimating of the exposure using passive detectors due to the related degassing time of detector holder materials.This research was funded by the European Metrology Programme for Innovation and Research (EMPIR), JRP‐Contract 16ENV10 MetroRADON (http://www.euramet.org). The EMPIR initiative is co‐funded by the European Union’s Horizon 2020 research and innovation programme and the EMPIR Participating States

Variations in radon dosimetry under different assessment approaches in the Altamira Cave

The atmosphere of caves is a special environment where it is necessary to take into account some particular characteristics when assessing the radon dose. The equilibrium factor (F) between radon and its progeny, and especially its unattached fraction ( fp), is a key parameter in radon dose evaluation. In order to consider the specific features of the atmosphere in the Altamira Cave, the radon and particle concentrations have been measured. The mean annual radon concentration inside the cave over the period 2013?2019 is around 3500 Bq m?3 with a standard deviation of 1833 Bq m?3 and this exhibits seasonal variations. This value surpasses all international (WHO, IAEA, ICRP) upper action and reference levels (occupational and non-occupational). Dose rate levels expressed in ?Sv h?1 were estimated for four different equilibrium scenarios between radon and its progeny 218Po, 214Pb, 214Bi and 214Po. The most recent dose conversion factors have been used and the contribution made to the dose by the unattached fraction of radon progeny fp has been also assessed from the particle concentration. The results suggest that the mean annual dose levels show variations of up to 500% due to the range of F and the fp considered in this study. Given the high radon concentrations usually found in show caves, the best way to reduce this variability and its associated uncertainty in dose assessment is to conduct specific studies aimed at determining both F and fp.This work was supported by the Ministry of Education, Culture and Sport of Spain (MECD) (grant number J180052) under the Project ‘Servicio de control y seguimiento de las condiciones ambientales y del biodeterioro de la Cueva de Altamira’, and The Cantabrian International Institute for Prehistoric Research (IIIPC)

The Metrological Traceability, Performance and Precision of European Radon Calibration Facilities

An interlaboratory comparison for European radon calibration facilities was conducted to evaluate the establishment of a harmonized quality level for the activity concentration of radon in air and to demonstrate the performance of the facilities when calibrating measurement instruments for radon. Fifteen calibration facilities from 13 different European countries participated. They represented different levels in the metrological hierarchy: national metrology institutes and designated institutes, national authorities for radiation protection and participants from universities. The interlaboratory comparison was conducted by the German Federal Office for Radiation Protection (BfS) and took place from 2018 to 2020. Participants were requested to measure radon in atmospheres of their own facilities according to their own procedures and requirements for metrological traceability. A measurement device with suitable properties was used to determine the comparison values. The results of the comparison showed that the radon activity concentrations that were determined by European calibration facilities complying with metrological traceability requirements were consistent with each other and had common mean values. The deviations from these values were normally distributed. The range of variation of the common mean value was a measure of the degree of agreement between the participants. For exposures above 1000 Bq/m3, the variation was about 4% for a level of confidence of approximately 95% (k=2). For lower exposure levels, the variation increased to about 6%

Differences in clinical features and mortality in very old unvaccinated patients (≥ 80 years) hospitalized with COVID-19 during the first and successive waves from the multicenter SEMI-COVID-19 Registry (Spain)

Background: Old age is one of the most important risk factors for severe COVID-19. Few studies have analyzed changes in the clinical characteristics and prognosis of COVID-19 among older adults before the availability of vaccines. This work analyzes differences in clinical features and mortality in unvaccinated very old adults during the first and successive COVID-19 waves in Spain. Methods This nationwide, multicenter, retrospective cohort study analyzes unvaccinated patients >= 80 years hospitalized for COVID-19 in 150 Spanish hospitals (SEMI-COVID-19 Registry). Patients were classified according to whether they were admitted in the first wave (March 1-June 30, 2020) or successive waves (July 1-December 31, 2020). The endpoint was all-cause in-hospital mortality, expressed as the case fatality rate (CFR). Results Of the 21,461 patients hospitalized with COVID-19, 5,953 (27.7%) were >= 80 years (mean age [IQR]: 85.6 [82.3-89.2] years). Of them, 4,545 (76.3%) were admitted during the first wave and 1,408 (23.7%) during successive waves. Patients hospitalized in successive waves were older, had a greater Charlson Comorbidity Index and dependency, less cough and fever, and met fewer severity criteria at admission (qSOFA index, PO2/FiO2 ratio, inflammatory parameters). Significant differences were observed in treatments used in the first (greater use of antimalarials, lopinavir, and macrolides) and successive waves (greater use of corticosteroids, tocilizumab and remdesivir). In-hospital complications, especially acute respiratory distress syndrome and pneumonia, were less frequent in patients hospitalized in successive waves, except for heart failure. The CFR was significantly higher in the first wave (44.1% vs. 33.3%; -10.8%; p = 95 years (54.4% vs. 38.5%; -15.9%; p < 0.001). After adjustments to the model, the probability of death was 33% lower in successive waves (OR: 0.67; 95% CI: 0.57-0.79). Conclusions Mortality declined significantly between the first and successive waves in very old unvaccinated patients hospitalized with COVID-19 in Spain. This decline could be explained by a greater availability of hospital resources and more effective treatments as the pandemic progressed, although other factors such as changes in SARS-CoV-2 virulence cannot be ruled out

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio