The Biology of Malaria Gametocytes

Gametocytes are sexual precursor cells of the malaria parasite that mediate the transmission of the parasite from its mammalian host to the Anopheles mosquito. Unlike the asexual blood stages, which are responsible for the clinical outcome of malaria, gametocytes cause no clinical manifestations. However, they are very crucial for the transmission of the disease thus represent key targets for transmission-blocking interventions. Despite their essential role in malaria transmission, only in the last decade gametocytes became a hot topic of research and their biology is not well understood. This chapter provides a detailed review on the biology of the human malaria gametocytes with emphasis on aspects such as gametocyte commitment, gametocyte maturation (gametocytogenesis), gametocyte metabolism and gametogenesis. Proper understanding of these processes will deepen our knowledge on the gametocyte biology and therefore open up more avenues for the development of malaria transmission-blocking intervention strategies

Taking SPARQL 1.1 extensions into account in the SWIP system

International audienceThe SWIP system aims at hiding the complexity of expressing a query in a graph query language such as SPARQL. We propose a mechanism by which a query expressed in natural language is translated into a SPARQL query. Our system analyses the sentence in order to exhibit concepts, instances and relations. Then it generates a query in an internal format called the pivot language. Finally, it selects pre-written query patterns and instantiates them with regard to the keywords of the initial query. These queries are presented by means of explicative natural language sentences among which the user can select the query he/she is actually interested in. We are currently focusing on new kinds of queries which are handled by the new version of our system, which is now based on the 1.1 version of SPARQL

Examination of stick-slip scenario on lubricated spring-brake systems

Several complex mechanisms can be responsible for undesirable friction-induced vibrations in many mechanical systems. This paper presents a tribological and dynamic analysis of the stick-slip problem, under greased lubrication, taking into account the practical application of a spring-brake system used in electric tubular motors. The main functioning of these brakes is based on the frictional greased contact between a stationary cylinder and a torsional spring, which rotates inside it. The identification of the parameters that most affect the stick-slip appearance in greased contacts requires a complete understanding and appropriate analysis of the entire system, to identify the effects of all physical parameters on the system. Here the global dynamics and the local contact behaviour is analysed, providing an in-depth examination of the stick-slip phenomenon on a greased contact

Modeling Trap-Awareness and Related Phenomena in Capture-Recapture Studies

Trap-awareness and related phenomena whereby successive capture events are not independent is a feature of the majority of capture-recapture studies. This phenomenon was up to now difficult to incorporate in open population models and most authors have chosen to neglect it although this may have damaging consequences. Focusing on the situation where animals exhibit a trap response at the occasion immediately following one where they have been trapped but revert to their original naïve state if they are missed once, we show that trap-dependence is more naturally viewed as a state transition and is amenable to the current models of capture-recapture. This approach has the potential to accommodate lasting or progressively waning trap effects

Ségrégation suivant la forme et la taille des grains pour des écoulements dans un tambour tournant

Afin de prendre en compte l'angularité des particules dans les écoulements granulaires, l'IFP a développé un outil numérique : GRAINS3D. Ce dernier repose sur la méthode des éléments discrets et un algorithme de détection de contact développé pour la réalité virtuelle (algorithme Gilbert-Johnson-Keerthi). A l'aide de ce code, nous proposons, dans cette communication, d'étudier et de quantifier l'influence de l'angularité sur les écoulements granulaires. Nous nous intéressons au phénomène de ségrégation pour des massifs granulaires morphologiquement homogènes qui contiennent des particules de taille différente et des mélanges binaires de formes. Les résultats obtenus sont confrontés à ceux de la littérature. Dans le cas de formes plus complexes, une analyse du comportement des particules en fonction de leur convexité est proposée

Open and laparoscopic living donor nephrectomy in Switzerland: a retrospective assessment of clinical outcomes and the motivation to donate

Background. Laparoscopic living kidney nephrectomy is thought to be associated with reduced morbidity, when compared to open nephrectomy. The purpose of this study was to explore the impact of these techniques on donors' clinical outcomes, satisfaction and motivation to donate. Methods. Clinical outcomes were retrospectively compared in 152 open (n = 71) or laparoscopic (n = 81) donor procedures. Donor satisfaction and motivation were assessed with a self-administered questionnaire. Results. The complication rate was the same with both procedures and the majority of complications were mild. Laparoscopy was significantly less painful and resulted in an insignificantly faster return to active life. More than 80% of the donors volunteered to donate without pressure. Worries about future health status, pain or scars were not important in the decision to donate. Similarly, only 15% considered the surgical procedure as instrumental for their decision. Few donors currently worried about their health with one kidney and more than 95% of the donors in both groups stated that they would give their kidney again. Conclusions. Living donor nephrectomy is safe, regardless of the procedure used. Although the laparoscopic nephrectomy offers clear short-term benefits over the open nephrectomy, donors' satisfaction was excellent with both surgical approaches. Moreover, the type of procedure did not seem to influence their decision to donat

A symmoriiform chondrichthyan braincase and the origin of chimaeroid fishes

Chimaeroid fishes (Holocephali) are one of the four principal divisions of modern gnathostomes (jawed vertebrates). Despite only 47 described living species1, chimaeroids are the focus of resurgent interest as potential archives of genomic data2 and for the unique perspective they provide on chondrichthyan and gnathostome ancestral conditions. Chimaeroids are also noteworthy for their highly derived body plan1,3,4. However, like other living groups with distinctive anatomies5, fossils have been of limited use in unravelling their evolutionary origin, as the earliest recognized examples already exhibit many of the specializations present in modern forms6,7. Here we report the results of a computed tomography analysis of Dwykaselachus, an enigmatic chondrichthyan braincase from the ~280 million year old Karoo sediments of South Africa8. Externally, the braincase is that of a symmoriid shark9,10,11,12,13and is by far the most complete uncrushed example yet discovered. Internally, the morphology exhibits otherwise characteristically chimaeroid specializations, including the otic labyrinth arrangement and the brain space configuration relative to exceptionally large orbits. These results have important implications for our view of modern chondrichthyan origins, add robust structure to the phylogeny of early crown group gnathostomes, reveal preconditions that suggest an initial morpho-functional basis for the derived chimaeroid cranium, and shed new light on the chondrichthyan response to the extinction at the end of the Devonian period

Astrometric accuracy of phase-referenced observations with the VLBA and EVN

Astrometric accuracy of complex modern VLBI arrays cannot be calculated analytically. We study the astrometric accuracy of phase-referenced VLBI observations for the VLBA, EVN and global VLBI array by simulating VLBI data for targets at declinations -25$^\circ$, 0$^\circ$, 25$^\circ$, 50$^\circ$, 75$^\circ$ and 85$^\circ$. The systematic error components considered in this study are calibrator position, station coordinate, Earth orientation and troposphere parameter uncertainties. We provide complete tables of the astrometric accuracies of these arrays for a source separation of 1$^\circ$ either along the right ascension axis or along the declination axis. Astrometric accuracy is 50microas at mid declination and is 300microas at low (-25$^\circ$) and high (85$^\circ$) declinations for the VLBA and EVN. In extending our simulations to source separations of 0.5$^\circ$ and 2$^\circ$, we establish the formula for the astrometric accuracy of the VLBA: Delta = (Delta_1$^\circ$-14)*d+ 14 (microas) where Delta_1$^\circ$ is the astrometric accuracy for a separation d=1$^\circ$ provided in our tables for various declinations and conditions of the wet troposphere. We argue that this formula is also valid for the astrometric accuracy of the EVN and global VLBI array.Comment: 10 pages, 4 figures, accepted for publication in Journal of Astrophysics and Astronom