RESUMEN
The realization that evolutionary feedbacks need to be considered to fully grasp ecological dynamics has sparked interest in the effect of evolution on community properties like coexistence and productivity. However, little is known about the evolution of community robustness and productivity along diversification processes in species-rich systems. We leverage the recent structural approach to coexistence together with adaptive dynamics to study such properties and their relationships in a general trait-based model of competition on a niche axis. We show that the effects of coevolution on coexistence are two-fold and contrasting depending on the time scale considered. In the short term, evolution of niche differentiation strengthens coexistence, while long-term diversification leads to niche packing and decreased robustness. Moreover, we find that coevolved communities tend to be on average more robust and more productive than non-evolutionary assemblages. We illustrate how our theoretical predictions echo in observed empirical patterns and the implications of our results for empiricists and applied ecologists. We suggest that some of our results such as the improved robustness of Evolutionarily Stable Communities could be tested experimentally in suitable model systems.
Asunto(s)
Evolución Biológica , FenotipoRESUMEN
Automatic real-time warning networks are essential for the almost immediate detection of anomalous levels of radioactivity in the environment. In the case of Extremadura region (SW Spain), a radiological network (RARE) has been operational in the vicinity of the Almaraz nuclear power plant and in other areas farther away since 1992. There are ten air monitoring stations equipped with Geiger-Müller counters in order to evaluate the external ambient gamma dose rate. Four of these stations have a commercial system that provides estimates of the total artificial alpha and beta activity concentrations in aerosols, and of the 131I activity (gaseous fraction). Despite experience having demonstrated the benefits and robustness of these commercial systems, important improvements have been made to one of these air monitoring systems. In this paper, the analytical and maintenance shortcomings of the original commercial air monitoring system are described first; the new custom-designed advanced air monitoring system is then presented. This system is based mainly on the incorporation of gamma spectrometry using two scintillation detectors, one of NaI:Tl and the other of LaBr3:Ce, and compact multichannel analysers. Next, a comparison made of the results provided by the two systems operating simultaneously at the same location for three months shows the advantages of the new advanced air monitoring system. As a result, the gamma spectrometry analysis allows passing from global alpha and beta activity determinations due to artificial radionuclides in aerosols, and the inaccurate measurement of the gaseous 131I activity concentration, to the possibility of identifying a large number of radionuclides and quantifying each of their activity concentrations. Moreover, the new station's dual capacity is designed to work in early warning monitoring mode and surveillance monitoring mode. This is based on custom developed software that includes an intelligent system to issue the necessary warnings when radiological anomalies or technical problems are identified. Implicitly, for the construction of the advanced station, substantial mechanical and electronic developments have been required. They have essentially consisted of integrating a new replacement device, whose operation has reduced the maintenance tasks.
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Contaminantes Radiactivos del Aire/análisis , Exposición a Riesgos Ambientales/análisis , Monitoreo de Radiación/instrumentación , Liberación de Radiactividad Peligrosa , Aerosoles , Diseño de Equipo , Análisis de Falla de Equipo , Dosis de Radiación , EspañaRESUMEN
In late 2013 (5th-7th of November), the Cáceres Urgent Response International Exercise (CURIEX 2013) took place to test the Nuclear Emergency Plan of Cáceres (PENCA) with the collaboration of both national and international support teams. The theme of the exercise was the simulation of a nuclear accident at the Almaraz Nuclear Power Plant located in Extremadura (Spain) with release of radioactive plume. From the point of view of radioactive contamination, the CURIEX exercise objective was to assess the capability of the different radiological teams to quantify the radioactive impact that would occur in this environment, a goal in which the Radiological Emergency Network of Extremadura (RARE) is directly implicated. The present paper analyses in detail the environmental radiological and dosimetrical results obtained by the Radiological Emergency Network of Extremadura during the CURIEX exercise. The rapid radioactivity measurement techniques on air and soil samples performed by the RARE's mobile lab involves great uncertainties. However, the results show a relative good effectiveness both in dose rate car-borne measurements and gamma soil spectrometry with uncertainties over 40%. It also shows a good correlation between the dose rate values measured by car-borne apparatus and those calculated from gamma spectrometry measurements. The capability of the RARE's facilities are evaluated in both the measurements, showing whether or not there is a radiological problem, and the transmission of that data to the decision centres in the shortest time. Although the results were highly satisfactory, some shortcomings were detected and therefore some improvements are proposed in the paper, in order to achieve a greater capacity in response to an event with the characteristics simulated in the CURIEX exercise.
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Planificación en Desastres , Plantas de Energía Nuclear , Monitoreo de Radiación/métodos , Liberación de Radiactividad Peligrosa , Humanos , Unidades Móviles de Salud , Protección Radiológica/métodos , EspañaRESUMEN
The main objective of automatic environmental radiation warning networks is to quantify a set of radiological parameters corresponding to the medium being monitored (water, air, etc) in the shortest possible time so as to be able to provide rapid and precise information on the medium's radiological status, and on any alterations that may occur and their severity. Specifically, in this paper we present the substantial improvements that have been carried out in an automatic near-real-time radiation monitoring of a water system belonging to Radiation Alert Network of Extremadura (RARE) in southwest Spain. These improvements are based on the incorporation of (i) a gamma spectrometry system with solid scintillation detectors and compact digital electronics, (ii) continuous measurement of the water flow that is being monitored, (iii) improvements in the maintenance tasks required to optimise the operation of this type of equipment and (iv) the controlled and automated collection of water samples so that, in the case of a possible radiological anomaly, it will be possible to perform ulterior specific complementary determinations in a low-background laboratory.
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Monitoreo de Radiación/instrumentación , Protección Radiológica/instrumentación , Liberación de Radiactividad Peligrosa , Residuos Radiactivos/análisis , Reología/instrumentación , Aguas Residuales/análisis , Contaminantes Radiactivos del Agua/análisis , Diseño de Equipo , Análisis de Falla de Equipo , Dosis de Radiación , Monitoreo de Radiación/métodos , Protección Radiológica/métodos , Reología/métodos , Robótica/instrumentación , Robótica/métodos , España , Integración de SistemasRESUMEN
We study the reflectivity spectra of photonic crystal slab cavities using an extension of the scattering matrix method that allows treating finite sizes of the spot of the excitation beam. The details of the implementation of the method are presented and then we show that Fano resonances arise as a consequence of the electromagnetic interference between the discrete contribution of the fundamental cavity mode and the continuum contribution of the light scattered by the photonic crystal pattern. We control the asymmetry lineshape of the Fano resonance through the polarization of the incident field, which determines the relative phase between the two electromagnetic contributions to the interference. We analyse the electric field profile inside and outside of the crystal to help in the understanding of the dependence on polarization of the reflectivity lineshape. We also study with our implementation the dependence of the Fano resonances on the size of the incident radiation spot.
RESUMEN
The microscopic structures of two amorphous molecular solids with extremely nonlinear optical properties have been studied. They consist of organotetrel chalcogenide clusters with the chemical formula [(RSn)4S6]. The basic molecular building blocks are adamantane-like {Sn4S6} cores with organic ligands R attached to the Sn atoms. While the material equipped with R=naphthyl generates frequency doubling upon irradiation with a simple infrared laser diode, the material decorated with R=phenyl responds by emitting brilliant white light. The structural differences were investigated using x-ray scattering and extended x-ray absorption fine structure combined with molecular Reverse Monte Carlo. Transmission electron microscopy and scanning precession electron diffraction were used to examine structural differences from mesoscopic down to microscopic scales. Characteristic differences were found on all scales. While close core-to-core distances between {Sn4S6} cluster cores and molecular distortions are found in the white light emitting material, undistorted molecules and significantly larger core distances characterize the material showing frequency doubling. Here however, results of scanning precession electron diffraction reveal the formation of nanocrystalline structures in the amorphous matrix, which we identify as cause for the suppression of white light emission.
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We optimize a silica-encapsulated silicon L3 photonic crystal cavity for ultra-high quality factor by means of a global optimization strategy, where the closest holes surrounding the cavity are varied to minimize out-of-plane losses. We find an optimal value of [Formula: see text], which is predicted to be in the 2 million regime in presence of structural imperfections compatible with state-of-the-art silicon fabrication tolerances.
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We present a case of accidental electrocution in a 62-years-old male. After the accident he referred a non-specific thoracic pain that disappeared in a week, remaining asymptomatic since then. On the other hand, he shows a permanent electrocardiographic pattern of anterolateral subepicardial ischaemia. Myocardial function revealed by echocardiography and pertechnectate gammagraphy, showed an early primary damage, with a posterior slow tendency to recovery. Exercise treadmill test and Tallium-Dipyridamole test were normal, so an ischaemic background could be rejected in this case. No other diseases were presented, so the changes observed could be exclusively connected with the electrical accident.
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Accidentes de Trabajo , Traumatismos por Electricidad/complicaciones , Disfunción Ventricular Izquierda/etiología , Traumatismos por Electricidad/diagnóstico , Electrocardiografía , Humanos , Masculino , Persona de Mediana Edad , Isquemia Miocárdica/diagnóstico , Isquemia Miocárdica/etiología , Factores de Tiempo , Disfunción Ventricular Izquierda/diagnósticoRESUMEN
The objective of this work is to present the improvements that have been made in quasi-real-time air radioactivity concentration monitors which were initially based on overall activity determinations, by incorporating gamma spectrometry into the current prototype. To this end it was necessary to develop a careful efficiency calibration procedure for both the particulate and the gaseous fractions of the air being sampled. The work also reports the values of the minimum detectable activity calculated for different isotopes and acquisition times.
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Captopril/uso terapéutico , Hidroclorotiazida/uso terapéutico , Hipertensión/tratamiento farmacológico , Metildopa/uso terapéutico , Oxprenolol/uso terapéutico , Adulto , Ensayos Clínicos como Asunto , Quimioterapia Combinada , Femenino , Frecuencia Cardíaca/efectos de los fármacos , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , EspañaRESUMEN
The aim of the study was to analyse the semiology of seizures in children with frontal lobe epilepsy (FLE) and to compare them with other paediatric cohorts described in the literature as well as with adult counterparts. We analysed 174 registered seizures of 18 cases under 12 years with lesional epilepsy whose frontal origin was defined by the concordance of neuroimaging and ictal electrographic findings, and confirmed by surgery in the six cases operated on. Seizures were generally short, with a high daily frequency and usually related to sleep. The most characteristic semiological pattern consisted of complex motor seizures, particularly hypermotor. Often seizures corresponded to a mixture of different semiological patterns (tonic, gelastic, automotor, hypermotor, versive) presenting in the same seizure, often as a unique type in the same patient. With regard to several aspects the semiology of FLE in our cohort looks like that reported in adult series, in particular as to the frequency of complex motor seizures. However, our cohort was also characterised by a more protean array of seizure semiology, stressing the occurrence of seizures typically present in adults (versive and complex motor) and of some seizure patterns more characteristic in children such as epileptic spasms; moreover, the rare occurrence of secondarily generalised tonic clonic seizures (SGTCS) was confirmed.
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Epilepsia del Lóbulo Frontal/fisiopatología , Convulsiones/fisiopatología , Niño , Preescolar , Electroencefalografía , Femenino , Humanos , Lactante , Masculino , Sueño/fisiologíaRESUMEN
In order to determine the effect of antibiotics on the course of cholera, precise observations of clinical symptoms and quantitative examination of vibrios in the stool were carried out on 17 patients with cholera El Tor from the Philippines. Seven patients were treated orally with kanamycin, tetracycline, chloramphenicol or erythromycin, 7 intravenously with chloramphenicol or tetracycline, and 3 were not given any antibiotic.Both the oral and the intravenous routes of administration of the antibiotics were suitable for shortening the period of diarrhoea and reducing the excretion of vibrios in the stool.The number of vibrios in 1 ml of watery stool during the first day of illness was about 10(8) in every case. There was marked reduction in the number within 1 hour, and complete disappearance of vibrios within 10 hours, of the start of treatment in most cases. However, vibrios reappeared later in some cases.Kanamycin, a non-absorbable antibiotic, was found to be less effective than adsorbable antibiotics such as chloramphenicol and tetracycline.