556 research outputs found
Development and Use of a Tool for Automated Alignments of Genes in the Rice BAC\u27s GenBank Card Against Other Species
In many cases, the analysis of the genetic bases of any trait requires molecular markers and if possible co-dominant PCR-based ones. In perennial fodder species, the number of publicly available markers (microsatellites and Sequence Tagged Site (STS)) is limited. Our goal is to use sequences from model grass species, i.e. rice, wheat, maize, barley, in L. perenne in order to develop STS markers in interesting regions such as under a QTL (Quantitative Trait Loci) or around a candidate gene,. As the genome sequence of rice is now available, the objective was to use the sequences of genes included in the BACās GenBank card from rice. As there are almost no available sequences in L. perenne, we are designing consensus primers from an alignment of at least two different species. The problem is that for all the genes included in a BAC, just a few have their sequences known in at least two species. It is very laborious to check āby handā if each gene has an homologous sequence known in another species
Estimation of the Coefficient of Double-Reduction in Autotetraploid Lucerne
Polyploidy plays an important role in the evolution of species and many cultivated species, particularly in angiosperms, are polyploids (Bever and Felber, 1992; Gallais, 2003). Autopolyploid species that show a tetrasomic inheritance have complex genetics. However, some theoretical models were built for: (1) genetic mapping (Hackett et al., 1998), (2) quantitative genetics (Gallais, 2003) and (3) population genetics (Ronfort et al., 1998). But in practice, most data analyses ignore one essential feature of tetrasomic inheritance that is double-reduction. Indeed, in an autotetraploid species, homologous chromosomes can form tetravalents at meiosis. In this case, a double-reduction is observed if crossing-over occurs between a locus and its centromere, and if the sister chromatids migrate to the same pole at anaphase I. The gametes may, thus, carry a pair of sister alleles. Double-reduction frequency is represented by the index of separation (Ī±) (Demarly, 1963; Mather, 1935; Mather, 1936). The parameter Ī± is considered as a product of four probabilities: Ī± = q e a s (Gallais, 2003) in which ā q ā is the probability of multivalent formation, ā e ā the probability of first equational division, related to the frequency of crossing-over, ā a ā is the probability of non-disjunction at first anaphase and āsā is the probability of having two sister chromatids in the same gamete. If separation during anaphase II is random, s = Ā½. Consequently, Ī± will be low for a gene located in the vicinity of the centromere and will increase with distance between the gene and the centromere. It was demonstrated that double-reduction events alter the rate of progression towards equilibrium under inbreeding or under random mating, modify the recombination rate between loci and also alter the rate of decay of linkage disequilibrium under random mating (Bever and Felber, 1992). Current theoretical models allow drawing genetic maps taking into account double-reduction (Luo et al., 2004). Thus, it is possible to estimate Ī± for codominant loci in tetraploid species. To date, we have few estimates of the double-reduction frequency. Haynes and Douches (1993) on potato and Julier et al. (2003) on lucerne found that double-reduction occurs sporadically. In both studies, the low number of progenies hampered a precise estimation of Ī±. The aim of our study was to estimate the frequency of double-reduction in a mapping population of lucerne that includes a large number of individuals
Guidance and surroundings awareness in outdoor handheld augmented reality
Handheld and wearable devices are becoming ubiquitous in our lives and augmented reality technology is stepping out of the laboratory environment and becoming ready to be used by anyone with portable devices. The success of augmented reality applications for pedestrians depends on different factors including a reliable guidance system and preventing risks. We show that different guidance systems can be supplementary to provide directions to a point of interest and offer clues that help the user find the augmented data when they get close to the location they have to visit. We tested the helpfulness of a map with the points of interest, an image preview of the next point of interest to visit, and an arrow showing the direction to it. The results show that the effectiveness of these guidance systems depend on the distance to the point of interest and the accuracy of the data obtained from the Global Positioning System. We also measured the total time that participants spent looking at the screen, as well as the perceived elapsed time as a measurement of real world dissociation. Finally, we discuss preliminary results to minimize the risk of accidents when using augmented reality applications in an outdoor urban environment
Genetic Diversity Among Alfalfa Cultivars Using SSR Markers
Alfalfa (Medicago sativa) is an autotetraploid, allogamous and heterozygous species. Cultivated varieties are synthetic cultivars, usually obtained through 3 or 4 generations of panmictic reproduction of a set of various numbers of parents. The parents can be clones, half-sib or full-sib families. The breeders apply selection pressure for some agronomic traits, to induce changes in the genetic background. The objective of this study was to investigate the differentiation level among seven cultivars originating from one breeding program, and between these cultivars and the breeding pool, with eight SSR markers
QTLs for Morphogenetic Traits in Medicago Truncatula
Plant morphogenesis that includes growth, development and flowering date, drives a large number of agronomical important traits in both grain and forage crops. Quantitative trait locus (QTL) mapping is a way to locate zones of the genome that are involved in the variations observed in a segregating population. Co-location of QTLs and candidate genes is an indication of the involvement of the genes in the variation. The objective of this study was to analyse segregation of aerial morphogenetic traits in a mapping population of recombinant inbred lines of the model legume species M. truncatula , to locate QTLs and candidate genes
VisAge: Augmented reality for heritage
In this paper we describe the VisAge project, which explored how a community-based Augmented Reality (AR) system could be used to tell stories and cultural histories about urban environments. Our work focussed on two main themes - user engagement and immersiveness of the experience. To address the first theme, we developed an online portal where anybody could upload digital content and create their own stories using routes through a physical environment. To address the second theme, we developed a flexible, reconfigurable mobile platform to investigate different types and kinds of displays. The performance of the system was assessed in a series of workshops, which have provided insights to inform the development of future systems
A bank of unscented Kalman filters for multimodal human perception with mobile service robots
A new generation of mobile service robots could be ready soon to operate in human environments if they can robustly estimate position and identity of surrounding people. Researchers in this field face a number of challenging problems, among which sensor uncertainties and real-time constraints.
In this paper, we propose a novel and efficient solution for simultaneous tracking and recognition of people within the observation range of a mobile robot. Multisensor techniques for legs and face detection are fused in a robust probabilistic framework to height, clothes and face recognition algorithms. The system is based on an efficient bank of Unscented Kalman Filters that keeps a multi-hypothesis estimate of the person being tracked, including the case where the latter is unknown to the robot.
Several experiments with real mobile robots are presented to validate the proposed approach. They show that our solutions can improve the robot's perception and recognition of humans, providing a useful contribution for the future application of service robotics
The modern pollen-vegetation relationship of a tropical forest-savannah mosaic landscape, Ghana, West Africa
Transitions between forest and savannah vegetation types in fossil pollen records are often poorly understood due to over-production by taxa such as Poaceae and a lack of modern pollen-vegetation studies. Here, modern pollen assemblages from within a forest-savannah transition in West Africa are presented and compared, their characteristic taxa discussed, and implications for the fossil record considered. Fifteen artificial pollen traps were deployed for 1 year, to collect pollen rain from three vegetation plots within the forest-savannah transition in Ghana. High percentages of Poaceae and Melastomataceae/Combretaceae were recorded in all three plots. Erythrophleum suaveolens characterised the forest plot, Manilkara obovata the transition plot and Terminalia the savannah plot. The results indicate that Poaceae pollen influx rates provide the best representation of the forest-savannah gradient, and that a Poaceae abundance of >40% should be considered as indicative of savannah-type vegetation in the fossil record
Mediated Spatial Narratives: Experiencing Archival Material and Shared Memories in Urban Space
In this paper we report on studies we conducted focusing on the use of Augmented Reality to annotate real sites with relevant archival content. This is an interdisciplinary study of novel interactive technologies and supportive platforms such as geolocation-navigation and contextual digital augmentation of archival material in public spaces. We involved community volunteers, experts and public in a participatory heritage initiative. We designed an experience that supported a multi-platform participation, via an online geo-tagging portal and a mixed reality navigational experience. In an iterative design process we explored the use and preference of mobile devices, the controlled design of digital content anchored to real sites and the use of AR to support urban narratives. We did this by conducting a series of user walkthroughs with recruited participants and workshops with local experts related to the case studies. In this paper we argue on the importance of situating urban experience of digital archives and stories in the actual locations of the events they represent as to better support immersion, enhance place experience and reinforce situated learning. Our work contributes to the design of hybrid spatialities and experiences in urban space that relate to local memory and culture
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