Cambios en la actividad neuronal inducidos por el cadmio y el 17β-estradiol en la zona compacta de la substantia nigra de ratas

It has been reported that cadmium (Cd2+) has similar effects to those produced by estradiol (E2) on the uterus and mammary glands. Given the importance of Cd2+ as an environmental pollutant, and its effects on the central nervous system, we decided to explore whether cadmium applied iontophoretically has similar effects to those produced by 17β-estradiol in the brain. Twelve neurons in zona compacta of the Substantia Nigra were recorded, in these neurons both Cd2+ and E2 were tested on the same neuron (both applied with 40 nA). In these Cd2+ and/or E2 produced significant changes on their firing rate these being predominantly excitatory. These changes becoming apparent towards the end of the application, and usually lasting for several minutes. When the metal was applied ten neurons responded by increasing its firing rate, while one was inhibited and the other one did not respond. In general, the effect was over within 30 minutes. When E2, was applied eight neurons were excited and 4 were inhibited. These responses were initiated faster than those caused by cadmium. In summary in 75% of the neurons tested both cadmium and estradiol produced the same effect, but with different time courses. In addition, in two cells it was found that Cd2+ enhanced the excitatory effect of E2. These results suggest that Cd2+ has effects, on the firing frequency, similar to those of estradiol on the Substantia Nigra.Ha sido reportado que el cadmio (Cd2+) tiene efectos similares a los producidos por el estradiol (E2 ) sobre el útero y las glándulas mamarias. En vista de la importancia del Cd2+ como contaminante ambiental, y dado que han sido demostrados efectos del E2 en varias zonas del sistema nervioso central, se decidió estudiar si a este nivel el Cd2+ aplicado iontoforéticamente, tenía efectos similares a los producidos por el 17β-estradiol. Se registraron 12 neuronas en la zona compacta de la Substantia nigra, en las cuales se pudo aplicar tanto el Cd2+ como el E2 a la misma neurona (ambos con una corriente de 40 nA). En éstas el Cd2+ y/o el E2 produjeron cambios significativos y predominantemente excitatorios sobre su actividad. Estos cambios comienzan a observarse hacia el final de la aplicación y su duración es variable, siendo frecuente que se prolongue varios minutos. Ante la aplicación del metal, diez neuronas respondieron incrementando su frecuencia, mientras que una se inhibió y la otra no respondió. La frecuencia control se recuperó en un período que no sobrepasó los 35 minutos. Al aplicar E2 , ocho neuronas se excitaron y 4 se inhibieron. Estas respuestas se inician más rápidamente que las que produce el Cd2+. Se evidenció una alta coincidencia en los efectos del Cd2+ y del E2 (75%) pero con cursos temporales diferentes. Además, en dos células se pudo comprobar que el Cd2+ potenciaba el efecto excitatorio del E2 . Estos resultados sugieren que el Cd2+ tiene efectos similares a los del estradiol en la Substantia nigra del sistema nervioso central

Assembling the Dead, Gathering the Living: Radiocarbon Dating and Bayesian Modelling for Copper Age Valencina de la Concepción (Seville, Spain)

The great site of Valencina de la Concepción, near Seville in the lower Guadalquivir valley of southwest Spain, is presented in the context of debate about the nature of Copper Age society in southern Iberia as a whole. Many aspects of the layout, use, character and development of Valencina remain unclear, just as there are major unresolved questions about the kind of society represented there and in southern Iberia, from the late fourth to the late third millennium cal BC. This paper discusses 178 radiocarbon dates, from 17 excavated sectors within the c. 450 ha site, making it the best dated in later Iberian prehistory as a whole. Dates are modelled in a Bayesian statistical framework. The resulting formal date estimates provide the basis for both a new epistemological approach to the site and a much more detailed narrative of its development than previously available. Beginning in the 32nd century cal BC, a long-lasting tradition of simple, mainly collective and often successive burial was established at the site. Mud-vaulted tholoi appear to belong to the 29th or 28th centuries cal BC; large stone-vaulted tholoi such as La Pastora appear to date later in the sequence. There is plenty of evidence for a wide range of other activity, but no clear sign of permanent, large-scale residence or public buildings or spaces. Results in general support a model of increasingly competitive but ultimately unstable social relations, through various phases of emergence, social competition, display and hierarchisation, and eventual decline, over a period of c. 900 years

Direct measurement of the muonic content of extensive air showers between 2× 1017 and 2×1018 eV at the Pierre Auger Observatory

The hybrid design of the Pierre Auger Observatory allows for the measurement of the properties of extensive air showers initiated by ultra-high energy cosmic rays with unprecedented precision. By using an array of prototype underground muon detectors, we have performed the first direct measurement, by the Auger Collaboration, of the muon content of air showers between 2 × 10 17 and 2 × 10 18 eV. We have studied the energy evolution of the attenuation-corrected muon density, and compared it to predictions from air shower simulations. The observed densities are found to be larger than those predicted by models. We quantify this discrepancy by combining the measurements from the muon detector with those from the Auger fluorescence detector at 1017.5eV and 1018eV. We find that, for the models to explain the data, an increase in the muon density of 38 % ± 4 % (12 %) ±18%21% for EPOS-LHC, and of 50 % (53 %) ± 4 % (13 %) ±20%23% for QGSJetII-04, is respectively needed. © 2020, The Author(s)