146 research outputs found
Kinetics of the invasion and egress processes of Babesia divergens, observed by time-lapse video microscopy
Based on confocal fluorescence and bright field video microscopy, we present detailed observations on the processes of invasion and egress of erythrocytes by the apicomplexan parasite Babesia divergens. Time-lapse images reveal numerous unexpected findings associated with the dynamics of B. divergens and its ability to manipulate the erythrocyte during both processes in its asexual cycle under in vitro conditions. Despite the speed at which these processes occur and the small size of the parasite, we capture infective merozoites moving vigorously and causing striking deformations in the erythrocyte's plasma membrane during an active invasion. We also observed intraerythrocytic dynamic stages as paired pyriforms, double paired pyriforms, tetrads, unattached pyriform sister cells and multiple parasite stages resulting in the release of large numbers of merozoites over a short period. Of considerable interest is that time-lapse images reveal a novel mechanism of egress used by B. divergens to exit the human erythrocyte. The release occurs when B. divergens parasites establish contacts with the plasma membrane of the erythrocyte from within, before exiting the cell. Visualization and analysis of the images enabled us to obtain useful information and broaden our knowledge of complex and crucial events involved with parasitisation of human erythrocytes by B. divergens.This work was funded by grants from Ministerio de Economía y Competitividad from Spain (AGL2010-21774, AGL2014-56193 R to EM and LMG). E. Sevilla was awarded a research fellowship from Plan Estatal de Investigación Científica y Técnica y de Innovación, Ministerio de Economía y Competitividad, Spain.S
Factors selection in landslide susceptibility modelling on large scale following the gis matrix method: application to the river Beiro basin (Spain)
A procedure to select the controlling factors connected to the slope instability has been defined. It allowed us to assess the landslide susceptibility in the Rio Beiro basin (about 10 km2) over the northeastern area of the city of Granada (Spain). Field and remote (Google EarthTM) recognition techniques allowed us to generate a landslide inventory consisting in 127 phenomena. To discriminate between stable and unstable conditions, a diagnostic area had been chosen as the one limited to the crown and the toe of the scarp of the landslide. 15 controlling or determining factors have been defined considering topographic, geologic, geomorphologic and pedologic available data. Univariate tests, using both association coefficients and validation results of single-variable susceptibility models, allowed us to select the best predictors, which were combined for the unique conditions analysis. For each of the five recognised landslide typologies, susceptibility maps for the best models were prepared. In order to verify both the goodness of fit and the prediction skill of the susceptibility models, two different validation procedures were applied and compared. Both procedures are based on a random partition of the landslide archive for producing a test and a training subset. The first method is based on the analysis of the shape of the success and prediction rate curves, which are quantitatively analysed exploiting two morphometric indexes. The second method is based on the analysis of the degree of fit, by considering the relative error between the intersected target landslides by each of the different susceptibility classes in which the study area was partitioned. Both the validation procedures confirmed a very good predictive performance of the susceptibility models and of the actual procedure followed to select the controlling factors.This research was supported by project CGL2008-04854 funded by the Ministry of Science and Education of Spain and was developed in the RNM121 Research
Group funded by the Andalusian Research Plan
Un pequeño análisis comparativo de los estudios superiores de Informática entre el noroeste de México y España: el caso de la UAS y la UPM
La Informática es una ciencia de carácter fundamental en las sociedades del siglo XXI. En particular hay que señalar el carácter ubicuo de la Informática, pues está presente en el trabajo, en el coche, en el hogar, etc. Sin embargo, dado que México es un país del tercer mundo y un pobre productor de tecnología, la Informática es, en este país, sólo reutilizada. En este artículo hacemos una comparación de los planes de estudios de Informática de la Universidad Autónoma de Sinaloa (UAS) y de la Universidad Politécnica de Madrid (UPM). El objetivo es determinar qué tan lejos se encuentra la Universidad Autónoma de Sinaloa de universidades europeas que ya han adaptado sus planes al Espacio Europeo de Educación Superior, así como determinar si existe un mínimo común denominador que defina a las titulaciones superiores de Informática en universidades de prestigio y, si este denominador puede ser considerado como un agente que promueva la producción de nuevas tecnologías
Babesia and Theileria Identification in Adult Ixodid Ticks from Tapada Nature Reserve, Portugal
This study, conducted in a nature reserve in southern Portugal, investigated the frequency and diversity of tick-borne piroplasms in six species of adult ixodid ticks removed from 71 fallow deer (Dama dama) and 12 red deer (Cervus elaphus), collected over the period 2012-2019. The majority of 520 ticks were Ixodes ricinus (78.5%), followed by Rhipicephalus sanguineus sensu lato, Hyalomma lusitanicum, Haemaphysalis punctata, Dermacentor marginatus, and Ixodes hexagonus. The R. sanguineus ticks collected from the deer were clearly exophilic, in contrast to the endophilic species usually associated with dogs. Four tick-borne piroplasms, including Theileria spp., and the zoonotic species, Babesia divergens and Babesia microti, were detected. B. divergens 18S rDNA, identical to that of the bovine reference strain U16370 and to certain strains from red deer, was detected in I. ricinus ticks removed from fallow deer. The sporadic detection of infections in ticks removed from the same individual hosts suggests that the piroplasms were present in the ticks rather than the hosts. Theileria sp. OT3 was found in I. ricinus and, along with T. capreoli, was also detected in some of the other tick species. The natural vector and pathogenic significance of this piroplasm are unknown.Funding was provided by a grant from the Health Institute Carlos III (PI20CIII/00037 to E.M. and L.G.M.), Spain and a grant from Alfonso X el Sabio Foundation (1.010.911 to N.F.), Spain.S
Improvements on the carrier-based control method for a three-level T-type, quasi-impedance-source inverter
The boost feature that characterizes Z-source and quasi-Z-source converters is usually achieved by means of a proper insertion of short-circuit states in the full DC-link. In this work, a novel pulse width modulation carrier-based strategy for a three-phase, three-level T-type, quasi-Z-source inverter is introduced, based on the addition of alternate short-circuits in the two halves of the DC-link bus. This technique achieves better performance, less electromagnetic interference, and lower harmonic distortion of the output line-to-line voltage compared to the traditional methods based on the full DC-link shoot-through. At the same time, generating the switching states is to easy implement.
The proposed strategy permits the use of electronic devices with lower blocking voltage capability, thus improving converter reliability, size, and cost. The new method may be implemented in another multilevel inverter with an impedance-source network as well. A comprehensive simulation study is performed in order to validate the adopted method, with different inverter input voltages, which
is taken as representative of a photovoltaic array. Comparisons are conducted with conventional strategy insertions using the same topology in order to show the improvements achieved.• Junta de Extremadura (Regional Government), Spain. Programa de Becas de Movilidad para Personal Docente e Investigador de la Comunidad Autónoma de Extremadura 2018, por el fondo para el grupo de investigación (GR18087) y el proyecto regional (IB18067).
• Agencia Estatal de Investigación (AEI) y Fondo Europeo de Desarrollo Regional (FEDER) españoles, bajo el Proyecto TEC2016-77632-C3-1-R (AEI / FEDER, UE), y a través de FCT bajo los contratos UID / CEC / 50021/2019 , Pest-E / EEI / LA0021 / 2014 y UID / Multi / 00308/2019.peerReviewe
Secondary Control for Storage Power Converters in Isolated Nanogrids to Allow Peer-to-Peer Power Sharing
It is usual in literature that power sharing among grid-forming sources of an isolated microgrid obeys their energy rating, instead of economic agreements between stakeholders, and circulating energy among them is usually avoided. However, these energy interchanges make strong sense and classical power sharing methods must be reformulated in the context of prosumer-based microgrids. This paper proposes a secondary control method for a prosumer-based low-voltage nanogrid that allows for energy interchange between prosumers, where storage systems, together with PV generators, are the controllable grid-forming sources. A power flow technique adapted to islanded microgrids is used for secondary control algorithm and the whole hierarchical control strategy for the prosumer converter is simulated and validated. This hierarchical control consists of three stages: tertiary control plans the energy interchange among prosumers, secondary obtains different voltage and power setpoints for each of the grid-forming sources, and, finally, primary control guarantees stable voltage and frequency values within the nanogrid with droop rules. Inner control loops for the power converter are also defined to track setpoints and assure stable performance. Simulation tests are carried out, which prove the stability of the proposed methods and the accuracy of the setpoint tracking
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