340 research outputs found

    A Methodology to Assess the Acceptability of Human-Robot Collaboration Using Virtual Reality

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    International audienceRobots are becoming more and more present in our everyday life: they are already used for domestic tasks, for companionship activities, and soon they will be used to assist humans and collaborate with them in their work. Human-robot collaboration has already been studied in the industry, for ergonomics and efficiency purposes, but more from a safety than from an acceptability point of view. In this work, we focused on how people perceive robots in a collaboration task and we proposed to use virtual reality as a simulation environment to test different parameters, by making users collaborate with virtual robots. A simple use case was implemented to compare different robot appearances and different robot movements. Questionnaires and physiological measures were used to assess the acceptability level of each condition with a user study. The results showed that the perception of robot movements depended on robot appearance and that a more anthropomorphic robot, both in its appearance and movements, was not necessarily better accepted by the users in a collaboration task. Finally, this preliminary use case was also the opportunity to guarantee the relevance of using such a methodology -- based on virtual reality, questionnaires and physiological measures --for future studies

    Smoking-induced long-lasting modifications of human platelet serotonin catabolism through a MAO epigenetic regulation

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    Postulating that serotonin, secreted from smoking-activated platelets, could be involved in smoking-induced vascular modifications, we studied 115 men distributed in smokers (S), former smokers (FS) and never smokers (NS). The platelet serotonin content was similar in S and NS but lower in FS. This was unexpected because the monoamine oxidase (MAO) activity, which catabolizes serotonin, was inhibited during smoking. However, the amount of platelet MAO was higher in S and FS than in NS. The persistent elevated MAO amount in FS prompted us to study the methylation of its gene promoter in an additional series of patients: it was markedly lower for S and FS vs. NS due to cigarette smoke-induced increase of nucleic acid demethylase activity. This smoking-induced demethylation of the MAO gene promoter, resulting in high MAO amount persisting long after quitting smoking, has cardiovascular consequences and could impact fields such as behavior, mental health, and cancer

    Monoaminergic modulation of photoreception in ascidian:evidence for a proto-hypothalamo-retinal territory

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    Background : The retina of craniates/vertebrates has been proposed to derive from a photoreceptor prosencephalic territory in ancestral chordates, but the evolutionary origin of the different cell types making the retina is disputed. Except for photoreceptors, the existence of homologs of retinal cells remains uncertain outside vertebrates. Methods : The expression of genes expressed in the sensory vesicle of the ascidian Ciona intestinalis including those encoding components of the monoaminergic neurotransmission systems, was analyzed by in situ hybridization or in vivo transfection of the corresponding regulatory elements driving fluorescent reporters. Modulation of photic responses by monoamines was studied by electrophysiology combined with pharmacological treatments. Results : We show that many molecular characteristics of dopamine-synthesizing cells located in the vicinity of photoreceptors in the sensory vesicle of the ascidian Ciona intestinalis are similar to those of amacrine dopamine cells of the vertebrate retina. The ascidian dopamine cells share with vertebrate amacrine cells the expression of the key-transcription factor Ptf1a, as well as that of dopamine-synthesizing enzymes. Surprisingly, the ascidian dopamine cells accumulate serotonin via a functional serotonin transporter, as some amacrine cells also do. Moreover, dopamine cells located in the vicinity of the photoreceptors modulate the light-off induced swimming behavior of ascidian larvae by acting on alpha2-like receptors, instead of dopamine receptors, supporting a role in the modulation of the photic response. These cells are located in a territory of the ascidian sensory vesicle expressing genes found both in the retina and the hypothalamus of vertebrates (six3/6, Rx, meis, pax6, visual cycle proteins). Conclusion : We propose that the dopamine cells of the ascidian larva derive from an ancestral multifunctional cell population located in the periventricular, photoreceptive field of the anterior neural tube of chordates, which also gives rise to both anterior hypothalamus and the retina in craniates/vertebrates. It also shows that the existence of multiple cell types associated with photic responses predates the formation of the vertebrate retina

    Brassinosteroid control of shoot gravitropism interacts with ethylene and depends on auxin signaling components

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    Premise of the study: To reach favorable conditions for photosynthesis, seedlings grow upward when deprived of light upon underground germination. To direct their growth, they use their negative gravitropic capacity. Negative gravitropism is under tight control of multiple hormones. Methods: By counting the number of standing plants in a population or by real time monitoring of the reorientation of gravistimulated seedlings of Arabidopsis thaliana, we evaluated the negative gravitropism of ethylene or brassinosteroid (BR) treated plants. Meta-analysis of transcriptomic data on AUX/IAA genes was gathered, and subsequent mutant analysis was performed. Key results: Ethylene and BR have opposite effects in regulating shoot gravitropism. Lack of BR enhances gravitropic reorientation in 2-d-old seedlings, whereas ethylene does not. Lack of ethylene signaling results in enhanced BR sensitivity. Ethylene and BRs regulate overlapping sets of AUX/IAA genes. BRs regulate a wider range of auxin signaling components than ethylene. Conclusions: Upward growth in seedlings depends strongly on the internal hormonal balance. Endogenous ethylene stimulates, whereas BRs reduce negative gravitropism in a manner that depends on the function of different, yet overlapping sets of auxin signaling components

    Bilirubin decreases NOS2 expression via inhibition of NAD(P)H oxidase: implications for protection against endotoxic shock in rats.

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    We investigated a possible beneficial role for bilirubin, one of the products of heme degradation by the cytoprotective enzyme heme oxygenase-1 in counteracting Escherichia coli endotoxin-mediated toxicity. Homozygous jaundice Gunn rats, which display high plasma bilirubin levels due to deficiency of glucuronyl transferase activity, and Sprague-Dawley rats subjected to sustained exogenous bilirubin administration were more resistant to endotoxin (LPS)-induced hypotension and death compared with nonhyperbilirubinemic rats. LPS-stimulated production of nitric oxide (NO) was significantly decreased in hyperbilirubinemic rats compared with normal animals; this effect was associated with reduction of inducible NO synthase (NOS2) expression in renal, myocardial, and aortic tissues. Furthermore, NOS2 protein expression and activity were reduced in murine macrophages stimulated with LPS and preincubated with bilirubin at concentrations similar to that found in the serum of hyperbilirubinemic animals. This effect was secondary to inhibition of NAD(P)H oxidase since 1) inhibition of NAD(P)H oxidase attenuated NOS2 induction by LPS, 2) bilirubin decreased NAD(P)H oxidase activity in vivo and in vitro, and 3) down-regulation of NOS2 by bilirubin was reversed by addition of NAD(P)H. These findings indicate that bilirubin can act as an effective agent to reduce mortality and counteract hypotension elicited by endotoxin through mechanisms involving a decreased NOS2 induction secondary to inhibition of NAD(P)H oxidase

    Cities and the origins of capitalism in Natal : the role of cities and towns in the incorporation of Natal in the capitalist world-system, 1837-1899.

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    Thesis (M.A.)-University of KwaZulu-Natal, Durban, 2006.This dissertation looks at the role cities and towns played in the incorporation of Natal into the capitalist world-system. It looks at which urban network came into existence and how this interacted with the development of the economy. It also looks at the cities themselves and how these were the locus of important class and racial struggles. The period that was researched is the second half of the nineteenth century, more concretely from 1837, the year that the voortrekkers crossed the Drakensberg into Natal, to 1899, the year that the Boer War started. The main economic activity in Natal for most of this period was the transit trade. This was also at least partly by default, as commercial settler agriculture was not very successful. This resulted in a pattern of settlement that was characterised by two primate cities, Durban and Pietermaritzburg, and very little urban development in most of the countryside. The pattern of settlement also followed the main trade route. The nature of railway development entrenched this pattern by not fostering agricultural development as the railways were mainly built to serve the trade. The dominance of the commercial elites led to policies that were rather beneficial for the merchants than for the settler farmers, the labour and 'native' policy and the railway development illustrate this. By the end of this period things however started to change, the settler elite became more influential and the pattern of settlement started changing. The urban history of colonial Natal also shows that things do not just turn out as they are planned by governments, elites or 'capital'. The ideal of the white city turned out to be impossible to achieve and also providing a large docile, dependent and cheap black labour force was not a straightforward task. The cities offered Africans and Indians plenty of opportunities to eke out an independent existence in or on the fringes of town, which put them in a strong bargaining position. This led the administration to use a wide range of techniques of social engineering, which in the twentieth century evolved into almost complete urban segregation

    Evidence for Widespread Remagnetizations in South America, Case Study of the Itararé Group Rocks From the State of São Paulo, Brazil

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    Paleomagnetism of South American Jurassic/Cretaceous rocks has been troubled by elongated distributions of poles which has led to contrasting interpretations. Moreover, many discordant paleomagnetic poles from the Carboniferous to the Triassic have also been recognized and systematically explained by a variety of processes, but this portion of the South American apparent polar wonder path (APWP) still remains problematic. To this end, we have conducted a paleomagnetic study of the sedimentary Permo-Carboniferous Itararé Group rocks and three intruding mafic sills of likely Cretaceous age within the state of São Paulo, Brazil. The site-mean VGP distributions obtained from the sedimentary rocks define elongations that include the VGPs of the mafic intrusions. We interpret these distributions as remagnetization paths toward the directions characteristic of the sills. Furthermore, we show that the remanence directions of the sills are partially overprinted by the present time-averaged and current Earth's magnetic field. Our interpretations are supported by extensive rock-magnetic data that provides a viable mechanism for the secondary magnetizations. The current study focuses on the paleomagnetism and rock-magnetism of the mafic intrusions and how they affected the paleomagnetic recording of the sedimentary rocks, however, careful analysis of the paleomagnetic data of the Itararé sedimentary rocks enables isolation of a primary VGP distribution that is consistent with the reference Carboniferous pole position. Extending our study to other Carboniferous to Triassic South American paleomagnetic records reveals that the majority of these data are elongated, similarly to the Itararé Group rocks. Regardless of the age of the rocks, the elongations systematically intersect at the location of the Late Cretaceous reference pole, and at a long- recognized “problematic” location observed in some Jurassic and Cretaceous rock formations. Based on multiple lines of evidence, we interpret the elongations to reflect remagnetizations from the primary VGP positions toward Jurassic-Cretaceous pole locations that occurred as a result of the widespread magmatic events associated with the opening of the South Atlantic. We suggest that the extent of the remagnetizations is formation-specific, and that other rock-formations should be carefully re-evaluated

    A Socially-Aware Conversational Recommender System for Personalized Recipe Recommendations

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    One potential solution to help people change their eating behavior is to develop conversational systems able to recommend healthy recipes. Beyond the intrinsic quality of the recommendations themselves, various factors might also influence users? perception of a recommendation. Two of these factors are the conversational skills of the system and users' interaction modality. In this paper, we present Cora, a conversational system that recommends recipes aligned with its users? eating habits and current preferences. Users can interact with Cora in two different ways. They can select predefined answers by clicking on buttons to talk to Cora or write text in natural language. On the other hand, Cora can engage users through a social dialogue, or go straight to the point. We conduct an experiment to evaluate the impact of Cora's conversational skills and users' interaction mode on users' perception and intention to cook the recommended recipes. Our results show that a conversational recommendation system that engages its users through a rapport-building dialogue improves users' perception of the interaction as well as their perception of the system

    Genome-wide association of multiple complex traits in outbred mice by ultra-low-coverage sequencing

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    Two bottlenecks impeding the genetic analysis of complex traits in rodents are access to mapping populations able to deliver gene-level mapping resolution and the need for population-specific genotyping arrays and haplotype reference panels. Here we combine low-coverage (0.15×) sequencing with a new method to impute the ancestral haplotype space in 1,887 commercially available outbred mice. We mapped 156 unique quantitative trait loci for 92 phenotypes at a 5% false discovery rate. Gene-level mapping resolution was achieved at about one-fifth of the loci, implicating Unc13c and Pgc1a at loci for the quality of sleep, Adarb2 for home cage activity, Rtkn2 for intensity of reaction to startle, Bmp2 for wound healing, Il15 and Id2 for several T cell measures and Prkca for bone mineral content. These findings have implications for diverse areas of mammalian biology and demonstrate how genome-wide association studies can be extended via low-coverage sequencing to species with highly recombinant outbred populations
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