Blocking and unblocking in a navigation task

Rodrigo, Chamizo, McLaren, & Mackintosh (1997) demonstrated the blocking effect in a navigational task using a swimming pool: rats initially trained to use three landmarks (ABC) to find an invisible platform learned less about a fourth landmark (X) added later than did rats trained from the outset with these four landmarks (ABCX). The aim of the experiment reported here was to demonstrate unblocking using a similar procedure as in the previous work. Three groups of rats were initially trained to find an invisible platfom in the presence of three landmarks: ABC for the Blocking and Unblocking groups and LMN for the Control group. Then, all animals were trained to find the platform in the presence of four landmarks, ABCX. In this second training, unlike animals in the Blocking group to which only a new landmark (X) was added in comparison to the first training, the animals in the Unblocking group also had a change in the platform position. In the Control group, both the four landmarks and the platform position were totally new at the beginning of this second training. As in Rodrigo et al. (1997) a blocking effect was found: rats in the Blocking group learned less with respect to the added landmark (X) than did animals in the Control group. However, rats in the Unblocking group learned about the added landmark (X) as well as did animals in the Control group. The results are interpreted as an unblocking effect due to a change in the platform position between the two phases of training, similarly to what is normal in classical conditioning experiments, in which a change in the conditions of reinforcement between the two training phases of a blocking design produce an attenuation or elimination of this effect. These results are explained within an error-correcting connectionist account of spatial navigation (McLaren, 2002)

The LHC Dipole Geometry as Built in Industry

The LHC dipoles magnets are produced in 5 industrial production sites in Europe. The production is well underway and more than half of the total quantity has been delivered to CERN. One of the important characteristics of the dipole magnets is their geometry. To achieve the requested mechanical tolerances on the magnets, which are 15 m long and have a 28 t mass, the final assembly operations includes precise optical measurements. To ensure the good quality and high production rate, the final assembly procedure has been automated as much as possible. The authors report here about the assembly procedure, the features of the software that guides the optical measurements (and consequently the assembly operations) and the results obtained on the geometry in the different sites

Rabdomiólisis tras la práctica de spinning: una asociación peculiar

ResumenLa rabdomiólisis de esfuerzo es una entidad clínica con unas características especiales. Se describe un cuadro de rabdomiólisis en un varón joven y sano, tras la práctica de una única sesión de spinning y se compara con otros descritos en la literatura. El objetivo es exponer las peculiaridades de la asociación del spinning con la rabdomiólisis por esfuerzo y conocer el riesgo de esta patología, aun en personas sanas, en relación con esta práctica deportiva. La contracción muscular que se produce en este ejercicio y la percepción disminuida del esfuerzo, al ser una actividad realizada en grupo, estimulada ambientalmente y alentada por un monitor, pueden contribuir a esta asociación.AbstractExertional rhabdomyolysis is a distinct entity with special characteristics. We present a case report, and literature review, of rhabdomyolysis in a young healthy male adult after practicing a single spinning session. The objective is to explain the peculiarities of the association spinning and exertional rhabdomyolysis and determine the risk of this disease, even in healthy people, concerning this sport. Muscular contraction during this exercise and the diminished perception of effort, due to being a group activity encouraged by a monitor, may contribute to its association

Measurement of Pu and U isotopes on the 1 MV AMS system at the Centro Nacional de Aceleradores

In the last decade, compact AMS systems have demonstrated their potential to measure actinides (236U, 239,240,244Pu, 237Np). With an appropriate detection system, kinematic filters with enough mass resolution, and a simple chemical procedure, the determination of plutonium isotopes and 237Np at environmental levels is currently possible with this new generation of facilities with even better performance than with conventional AMS systems. However, the measurement of 236U (T1/2=23.4 My), produced by neutron capture on 235U, is still a challenge, due to the interference caused by 235U and 238U. In this work, we will explore the possibilities that the 1 MV AMS system at the CNA offers for the measurement of uranium isotopes at environmental levels, in terms of detection limit, efficiency, and precision. Considering the very promising 239Pu/238U mass suppression factor achieved with our system, of about 10-9, a limiting 236U/238U atomic ratio of about 10-11 was expected, approaching the levels expected in natural uranium. However, to date, only the 10-9 level has been obtained, possibly due to the lack of an appropriate uranium material. Currently, different natural uranium materials are being studied, in order to elucidate the origin of the interference. On the other hand, we will discuss the status of the plutonium measurements at our facility, based on the experience we have accumulated in recent years from the analysis of different matrixes over a wide range of plutonium concentrations

Estrategias cognitivas para afrontar situaciones de acoso/ciberacoso: diferencias entre chicos y chicas

Peer violence has a negative impact on involved adolescents’ health. One of the factors that has shown evidence to predict the performance and suffering of aggressive behaviours are cognitive emotional coping strategies. Nevertheless, in bullying and cyberbullying contexts, there are few studies that have analysed the role of these strategies and, even less, separately for boys and girls. Therefore, this study had two objectives: to analyse sex differences on aggression and victimisation in bullying and cyberbullying situations as well on the use of cognitive coping strategies, and to explore which coping strategies best predict victimisation and aggression in both situations separately for boys and girls. A sample of 1,904 adolescents participated by filling out three questionnaires assessing bullying, cyberbullying, and cognitive coping strategies. The results showed significant sex differences in aggression, victimisation, cyberaggression, and in five strategies. Moreover, the outcomes of regression analysis reported that, for instance, other-blame strategy was one of those that best predicted aggression and victimisation in bullying and cyberbullying in boys and girls. Finally, limitations and implications derived of this study are discussed.La violencia entre iguales provoca un impacto negativo sobre la salud de los adolescentes implicados. Entre los factores que han mostrado evidencias para predecir la realización y el sufrimiento de conductas agresivas, se encuentran las estrategias de afrontamiento cognitivo-emocional. Sin embargo, en contextos de acoso y ciberacoso pocos estudios han analizado el papel de estas estrategias y, aún menos, de manera separada para chicos y chicas. Por ello, este estudio planteó dos objetivos: analizar las diferencias por sexo en agresión y victimización en acoso y ciberacoso, así como en el uso de las estrategias de afrontamiento; y explorar cuáles son las estrategias que mejor predicen la victimización y agresión en ambas situaciones de manera separada para chicos y chicas. Una muestra de 1904 adolescentes completó tres cuestionarios que evaluaban el acoso, el ciberacoso y las estrategias de afrontamiento cognitivo. Los resultados mostraron diferencias significativas por sexo en agresión, victimización, ciberagresión y en cinco estrategias. Además, los resultados de las regresiones indicaron que, por ejemplo, la estrategia de culpar a otros fue una de las que mejor predijo la agresión y victimización en acoso y ciberacoso en chicos y chicas. Por último, se discuten las limitaciones e implicaciones derivadas de este estudio

From the Eukaryotic Molybdenum Cofactor Biosynthesis to the Moonlighting Enzyme mARC

All eukaryotic molybdenum (Mo) enzymes contain in their active site a Mo Cofactor (Moco), which is formed by a tricyclic pyranopterin with a dithiolene chelating the Mo atom. Here, the eukaryotic Moco biosynthetic pathway and the eukaryotic Moco enzymes are overviewed, including nitrate reductase (NR), sulfite oxidase, xanthine oxidoreductase, aldehyde oxidase, and the last one discovered, the moonlighting enzyme mitochondrial Amidoxime Reducing Component (mARC). The mARC enzymes catalyze the reduction of hydroxylated compounds, mostly N-hydroxylated (NHC), but as well of nitrite to nitric oxide, a second messenger. mARC shows a broad spectrum of NHC as substrates, some are prodrugs containing an amidoxime structure, some are mutagens, such as 6-hydroxylaminepurine and some others, which most probably will be discovered soon. Interestingly, all known mARC need the reducing power supplied by different partners. For the NHC reduction, mARC uses cytochrome b5 and cytochrome b5 reductase, however for the nitrite reduction, plant mARC uses NR. Despite the functional importance of mARC enzymatic reactions, the structural mechanism of its Moco-mediated catalysis is starting to be revealed. We propose and compare the mARC catalytic mechanism of nitrite versus NHC reduction. By using the recently resolved structure of a prokaryotic MOSC enzyme, from the mARC protein family, we have modeled an in silico three-dimensional structure of a eukaryotic homologue