Aborto epidémico y endémico asociado a la infección por Neospora caninum en el ganado bovino: relación entre la respuesta inmune y las consecuencias de la infección a lo largo de la gestación

Neospora caninum es un protozoo intracelular obligado perteneciente al Phylum Apicomplexa. La neosporosis bovina se considera una de las principales causas de fallo reproductivo en el ganado bovino. La transmisión transplacentaria del parásito puede originar aborto ó el nacimiento de terneros congénitamente infectados. La transmisión transplacentaria endógena ocurre tras la recrudescencia de una infección crónica en la hembra durante la gestación, mientras que la exógena se da tras una primoinfección adquirida de forma postnatal. Un mayor conocimiento de la epidemiología, integrado con el empleo de adecuadas técnicas de diagnóstico serológico son la base del control. El objetivo del presente estudio fue determinar mediante diferentes pruebas diagnósticas la relación existente entre la respuesta serológica desarrollada por reproductoras bovinas infectadas a lo largo de una gestación, el origen de la infección y sus repercusiones reproductivas.Neospora caninum is an apicomplexan protozoan parasite. At present bovine neosporosis is one of the main causes of reproductive failure in cattle worldwide. Transplacental transmission of the parasite can lead to abortion or birth of congenitally infected calves. Endogenous transplacental transmission occurs as a consequence of the recrudescence of a previous chronic infection in the cow during gestation. On the other hand, exogenous transplacental transmission occurs after an acquired postnatal primo infection. Control programmes are based on updated knowledge about the epidemiology together with the employment of appropriate diagnostic serological tests. The aim of the present study was to determine the relationship between the serologic response developed by infected breeding cattle along gestation, the mode of transmission and the future consequences in reproduction

Synchronization of Kuramoto Oscillators in Scale-Free Networks

In this work, we study the synchronization of coupled phase oscillators on the underlying topology of scale-free networks. In particular, we assume that each network's component is an oscillator and that each interacts with the others following the Kuramoto model. We then study the onset of global phase synchronization and fully characterize the system's dynamics. We also found that the resynchronization time of a perturbed node decays as a power law of its connectivity, providing a simple analytical explanation to this interesting behavior.Comment: 7 pages and 4 eps figures, the text has been slightly modified and new references have been included. Final version to appear in Europhysics Letter

Local versus Global Knowledge in the Barabasi-Albert scale-free network model

The scale-free model of Barabasi and Albert gave rise to a burst of activity in the field of complex networks. In this paper, we revisit one of the main assumptions of the model, the preferential attachment rule. We study a model in which the PA rule is applied to a neighborhood of newly created nodes and thus no global knowledge of the network is assumed. We numerically show that global properties of the BA model such as the connectivity distribution and the average shortest path length are quite robust when there is some degree of local knowledge. In contrast, other properties such as the clustering coefficient and degree-degree correlations differ and approach the values measured for real-world networks.Comment: Revtex format. Final version appeared in PR

Critical load and congestion instabilities in scale-free networks

We study the tolerance to congestion failures in communication networks with scale-free topology. The traffic load carried by each damaged element in the network must be partly or totally redistributed among the remaining elements. Overloaded elements might fail on their turn, triggering the occurrence of failure cascades able to isolate large parts of the network. We find a critical traffic load above which the probability of massive traffic congestions destroying the network communication capabilities is finite.Comment: 4 pages, 3 figure

Time dependence of breakdown in a global fiber-bundle model with continuous damage

A time-dependent global fiber-bundle model of fracture with continuous damage is formulated in terms of a set of coupled non-linear differential equations. A first integral of this set is analytically obtained. The time evolution of the system is studied by applying a discrete probabilistic method. Several results are discussed emphasizing their differences with the standard time-dependent model. The results obtained show that with this simple model a variety of experimental observations can be qualitatively reproduced.Comment: APS style, two columns, 4 figures. To appear in Phys. Rev.

Changes of the Neutron Flux of the Nuclear Reactor Triga Mark III Since the Conversion from High to Low 235U Enrichment

The neutron flux of the Triga Mark III research reactor was studied using nuclear track detectors. The facility of the National Institute for Nuclear Research (ININ), operates with a new core load of 85 LEU 30/20 (Low Enriched Uranium) fuel elements. The reactor provides a neutron flux around 2 × 1012 n cm-2s-1 at the irradiation channel. In this channel, CR-39 (allyl diglycol policarbonate) Landauer® detectors were exposed to neutrons; the detectors were covered with a 3 mm acrylic sheet for (n, p) reaction. Results show a linear response between the reactor power in the range 0.1 - 7 kW, and the average nuclear track density with data reproducibility and relatively low uncertainty (±5%). The method is a simple technique, fast and reliable procedure to monitor the research reactor operating power levels

Direct visualization of the native structure of viroid RNAs at single-molecule resolution by atomic force microscopy

[EN] Viroids are small infectious, non-protein-coding circular RNAs that replicate independently and, in some cases, incite diseases in plants. They are classified into two families: Pospiviroidae, composed of species that have a central conserved region (CCR) and replicate in the cell nucleus, and Avsunviroidae, containing species that lack a CCR and whose multimeric replicative intermediates of either polarity generated in plastids self-cleave through hammerhead ribozymes. The compact, rod-like or branched, secondary structures of viroid RNAs have been predicted by RNA folding algorithms and further examined using different in vitro and in vivo experimental techniques. However, direct data about their native tertiary structure remain scarce. Here we have applied atomic force microscopy (AFM) to image at single-molecule resolution different variant RNAs of three representative viroids: potato spindle tuber viroid (PSTVd, family Pospiviroidae), peach latent mosaic viroid and eggplant latent viroid (PLMVd and ELVd, family Avsunviroidae). Our results provide a direct visualization of their native, three-dimensional conformations at 0 and 4 mM Mg2+ and highlight the role that some elements of tertiary structure play in their stabilization. The AFM images show that addition of 4 mM Mg2+ to the folding buffer results in a size contraction in PSTVd and ELVd, as well as in PLMVd when the kissing-loop interaction that stabilizes its 3D structure is preserved.This work was supported by the Spanish Ministerio de Economia y Competitividad (MINECO) grants BIO2016-79618-R (funded by EU under the FEDER programme) to C.B. and BFU2104-56812-P to R.F., as well as by the Comunidad de Madrid grant S2018/NMT-4349 to L.V. CIBERehd is funded by the Instituto de Salud Carlos III (ISCIII).Moreno, M.; Vázquez, L.; López Carrasco, A.; Martín-Gago, JA.; Flores Pedauye, R.; Briones, C. (2019). Direct visualization of the native structure of viroid RNAs at single-molecule resolution by atomic force microscopy. RNA Biology. 16(3):295-308. https://doi.org/10.1080/15476286.2019.1572436S295308163Diener, T. O. (2003). Discovering viroids — a personal perspective. Nature Reviews Microbiology, 1(1), 75-80. doi:10.1038/nrmicro736Flores, R., Hernández, C., Alba, A. E. M. de, Daròs, J.-A., & Serio, F. D. (2005). Viroids and Viroid-Host Interactions. Annual Review of Phytopathology, 43(1), 117-139. doi:10.1146/annurev.phyto.43.040204.140243Ding, B. (2009). The Biology of Viroid-Host Interactions. Annual Review of Phytopathology, 47(1), 105-131. doi:10.1146/annurev-phyto-080508-081927Zhang, Z., Qi, S., Tang, N., Zhang, X., Chen, S., Zhu, P., … Wu, Q. (2014). 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Time evolution of damage under variable ranges of load transfer

We study the time evolution of damage in a fiber bundle model in which the range of interaction of fibers varies through an adjustable stress transfer function recently introduced. We find that the lifetime of the material exhibits a crossover from mean field to short range behavior as in the static case. Numerical calculations showed that the value at which the transition takes place depends on the system's disorder. Finally, we have performed a microscopic analysis of the failure process. Our results confirm that the growth dynamics of the largest crack is radically different in the two limiting regimes of load transfer during the first stages of breaking.Comment: 8 pages, 7 figures, revtex4 styl