2,102 research outputs found

    Measurement of uncertainty costs with dynamic traffic simulations

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    Non-recurrent congestion in transportation networks occurs as a consequence of stochastic factors affecting demand and supply. Intelligent Transportation Systems such as Advanced Traveler Information Systems (ATIS) and Advanced Traffic Management Systems (ATMS) are designed in order to reduce the impacts of non-recurrent congestion by providing information to a fraction of users or by controlling the variability of traffic flows. For these reasons, the design of ATIS and ATMS requires reliable forecast of non-recurrent congestion. This paper proposes a new method to measure the impacts of non-recurrent congestion on travel costs by taking risk aversion into account. The traffic model is based on the dynamic traffic simulations model METROPOLIS. Incidents are generated randomly by reducing the capacity of the network. Users can instantaneously adapt to the unexpected travel conditions or can also change their behavior via a day-to-day adjustment process. Comparisons with incident-free simulations provide a benchmark for potential travel time savings that can be brought in by a state-of-the-art information system. We measure the impact of variable travel conditions by describing the willingness to pay to avoid risky or unreliable journeys. Indeed, for risk averse drivers, any uncertainty corresponds to a utility loss. This utility loss is computed for several levels of network disruption. The main results of the paper is that the utility loss due to uncertainty is of the same order of magnitude as the total travel costs.

    Qualitative Supervision of Naval Diesel Engine Turbocharger Systems

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    FAC Intelligent Components and Instruments for Control Applications, Malaga, Spain, 1992This paper presents a qualitative model the diesel engine turbocharger system of a ship. The paper also shows how qualitative models can be use for an intelligent monitoring of the process concerned

    Nouveaux Orthoptères (Ensifera, Insecta) du Trias des Vosges (France)

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    Trois nouveaux Orthoptera, Ensifera (Hagloidea et Gryllavoidea) du Grès à Voltzia (Buntsandstein supérieur, Trias inférieur/moyen) des Vosges (France) représentés par des ailes antérieures, sont décrits. Galliagryllavus vogesiacus n. gen., n.sp. (Gryllavidae) montre des affinités avec Gryllavus madyge nicus SHAROV 1968 du Trias de Madygen (Kirghizistan). Triassoparacyrtophyllites bifurcatus n. gen., n.sp. (Tuphellidae) présente des analogies avec Pa racyrtophillites undulatus SHAROV 1968 du Jurassique supérieur de Karatau (Kazakhstan). Voltziahagla pseudoveinosa n. gen., n.sp. (Haglidae) semble proche du genre Archaboilus MARTYNOV 1937 du Jurassique inférieur de Shurab (Tadjikistan). Ces trois Ensifera qui appartiennent à des familles distinctes mettent en évidence la diversité de ce groupe à la limite du Trias inférieur/moyen. Une révision cladistique des Hagloidea et des Gryllavoidea serait nécessaire pour pouvoir déterminer les relations phylogénétiques entre ces différentes familles.Three new Orthoptera, Ensifera (Hagloidea and Gryllavoidea) from the Grés à Voltzia (Upper Buntsandstein, transition Lower / Middle Triassic) of the Vosges (France) are described based on forewings. Galliagryllavus vogesiacus n.gen., n.sp. (Gryllavidae) shows affinities with Gryllavus madygenicus SHAROV 1968 from the Triassic of Madygen (Kirghizistan). Triassoparacyrtophyllites bifurcatus n.gen., n.sp. (Tuphellidae) displays some similarities with Paracyrtophillites undulatus SHAROV 1968 from the Upper Jurassic of Karatau (Kazakhstan). Voltziahagla pseudoveinosa n.gen., n.sp. (Haglidae) seems close to the genus Archaboilus MARTYNOV 1937 from the Lower Jurassic of Shurab (Tadjikistan). These three Ensifera which belong to distinct families underscore the diversity of the Hagloidea and the Gryllavoidea at the boundary between the Lower and Middle Triassic. A cladistic study would be necessary to determine the phylogenetical relationships between the different families

    Nouveaux Orthoptères (Ensifera, Insecta) du Trias des Vosges (France)

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    Three new Orthoptera, Ensifera (Hagloidea and Gryllavoidea) from the Grés à Voltzia (Upper Buntsandstein, transition Lower / Middle Triassic) of the Vosges (France) are described based on forewings. Galliagryllavus vogesiacus n.gen., n.sp. (Gryllavidae) shows affinities with Gryllavus madygenicus SHAROV 1968 from the Triassic of Madygen (Kirghizistan). Triassoparacyrtophyllites bifurcatus n.gen., n.sp. (Tuphellidae) displays some similarities with Paracyrtophillites undulatus SHAROV 1968 from the Upper Jurassic of Karatau (Kazakhstan). Voltziahagla pseudoveinosa n.gen., n.sp. (Haglidae) seems close to the genus Archaboilus MARTYNOV 1937 from the Lower Jurassic of Shurab (Tadjikistan). These three Ensifera which belong to distinct families underscore the diversity of the Hagloidea and the Gryllavoidea at the boundary between the Lower and Middle Triassic. A cladistic study would be necessary to determine the phylogenetical relationships between the different families

    Action minimizing orbits in the n-body problem with simple choreography constraint

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    In 1999 Chenciner and Montgomery found a remarkably simple choreographic motion for the planar 3-body problem (see \cite{CM}). In this solution 3 equal masses travel on a eight shaped planar curve; this orbit is obtained minimizing the action integral on the set of simple planar choreographies with some special symmetry constraints. In this work our aim is to study the problem of nn masses moving in \RR^d under an attractive force generated by a potential of the kind 1/rα1/r^\alpha, α>0\alpha >0, with the only constraint to be a simple choreography: if q1(t),...,qn(t)q_1(t),...,q_n(t) are the nn orbits then we impose the existence of x \in H^1_{2 \pi}(\RR,\RR^d) such that q_i(t)=x(t+(i-1) \tau), i=1,...,n, t \in \RR, where τ=2π/n\tau = 2\pi / n. In this setting, we first prove that for every d,n \in \NN and α>0\alpha>0, the lagrangian action attains its absolute minimum on the planar circle. Next we deal with the problem in a rotating frame and we show a reacher phenomenology: indeed while for some values of the angular velocity minimizers are still circles, for others the minima of the action are not anymore rigid motions.Comment: 24 pages; 4 figures; submitted to Nonlinearit

    Distinct expression and methylation patterns for genes with different fates following a single whole-genome duplication in flowering plants

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    For most sequenced flowering plants, multiple whole-genome duplications (WGDs) are found. Duplicated genes following WGD often have different fates that can quickly disappear again, be retained for long(er) periods, or subsequently undergo small-scale duplications. However, how different expression, epigenetic regulation, and functional constraints are associated with these different gene fates following a WGD still requires further investigation due to successive WGDs in angiosperms complicating the gene trajectories. In this study, we investigate lotus (Nelumbo nucifera), an angiosperm with a single WGD during the K–pg boundary. Based on improved intraspecific-synteny identification by a chromosome-level assembly, transcriptome, and bisulfite sequencing, we explore not only the fundamental distinctions in genomic features, expression, and methylation patterns of genes with different fates after a WGD but also the factors that shape post-WGD expression divergence and expression bias between duplicates. We found that after a WGD genes that returned to single copies show the highest levels and breadth of expression, gene body methylation, and intron numbers, whereas the long-retained duplicates exhibit the highest degrees of protein–protein interactions and protein lengths and the lowest methylation in gene flanking regions. For those long-retained duplicate pairs, the degree of expression divergence correlates with their sequence divergence, degree in protein–protein interactions, and expression level, whereas their biases in expression level reflecting subgenome dominance are associated with the bias of subgenome fractionation. Overall, our study on the paleopolyploid nature of lotus highlights the impact of different functional constraints on gene fate and duplicate divergence following a single WGD in plant

    Cell-Associated HIV-1 RNA in Blood as Indicator of Virus Load in Lymph Nodes

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    We have developed sensitive assays for viremia and cell-associated human immunodeficiency virus type 1 (HIV-1) RNA and DNA to assess the predictive value of virological parameters determined in blood for virus load in lymph nodes (LNs). Eighteen patients were included; 13 received stavudine/didanosine/hydroxyurea and 5 stavudine/didanosine, and all had viremia 3 months. At the time of LN biopsy (median, 10 months), the median viremia was 2.09 log copies/mL (range, <0.70-3.34). Cell-associated HIV-1 RNA and DNA were detectable in blood and LNs of all patients. The median cell-associated RNA and DNA were 2.16 log copies/106 cells and 2.60 log copies/106 cells in blood versus 4.31 log RNA copies/106 cells and 3.26 log DNA copies/106 cells in LNs. Regression analysis shows that, in treated patients with sustained low viremia, cell-associated RNA and DNA in blood are better predictors of virus load in LNs than viremi

    Distribution and origin of natural gas leakage in the Colorado Basin, offshore Argentina Margin, South America : seismic interpretation and 3D basin modelling

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    The detailed analysis of a dense 2D seismic reflection dataset and data from 8 exploration wells, allowed us to identify, map out and characterize possible indications of past and present-day hydrocarbon leakage (i.e. gas chimneys, gas pockets, and seafloor mounds and pockmarks) on the continental shelf and slope of the Colorado Basin, offshore Argentina, where Permian, Jurassic and Early Cretaceous source rocks are potentially present and may be currently mature. Identified gas leakage features, developed both in the syn-rift and post-rift successions, were also analysed in relation to the structural the stratigraphic elements of the basin. A family of seabed pockmarks, located close to an array of submarine channels, was identified on the distal slope of the basin. These pockmarks are overlying a series of sub-vertical to vertical seismic chimneys in the subsurface. A calibrated basin-wide 3D petroleum system model comprising generation and migration of hydrocarbons was carried out and compared with the observations from the seismic analysis. Preliminary results from this model indicate that although synrift and early Cretaceous source rock (SR) intervals may be depleted in the central areas of the basin, an active kitchen from the Aptian SR may be present below the slope areas. Hydrocarbon migration pathways predicted by the 3D model (Hybrid method) coincide with the interpreted seismic chimneys underlying the observed seabed slope pockmarks. Hence, our results indicate that thermogenic gas may be currently generated in the distal slope of the basin from mature early post-rift source rocks within the Early Cretaceous (Aptian) sequences and migrates vertically, due to seal failure, through the stratigraphic column. This migrating thermogenic gas is feeding the seafloor pockmarks identified in the distal slope of the basin, although up-dip lateral migration along stratigraphic layers to the more proximal slope areas cannot be ruled out. The present work represents the first published study integrating detailed seismic analysis and 3D basin modelling linking observed gas-leakage indicators and associated seepage pathways, to their relative abundance, distribution and feeding systems offshore Argentina's continental margin
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