WAVE DRAG IN FRONT CRAWL SWIMMING

When swimming at the surface, swimmers will experience wave drag. It is observed that above a certain speed, wave height grows rapidly with further speed increase, suggesting that wave drag cannot be neglected at high speed. Therefore, the magnitude of this component of total drag was estimated. Total drag was decomposed in 2 parts; wave and pressure drag. Assuming wave drag to be negligible below 1.6 m/s, the velocity dependence of pressure drag was assessed by drag determinations at speeds below 1.6 m/s. By subtracting the estimated pressure drag from total drag values measured at higher speeds, wave drag was estimated. At a mean speed of 1.89 m/s, mean wave drag was 11.5 N, amounting to 12.1 % of total drag. These results underline the importance of reducing wave drag by diving under the surface after start and turns

Asymptotically Optimal Belief Space Planning in Discrete Partially-Observable Domains

Robots often have to operate in discrete partially observable worlds, where the states of world are only observable at runtime. To react to different world states, robots need contingencies. However, computing contingencies is costly and often non-optimal. To address this problem, we develop the improved path tree optimization (PTO) method. PTO computes motion contingencies by constructing a tree of motion paths in belief space. This is achieved by constructing a graph of configurations, then adding observation edges to extend the graph to belief space. Afterwards, we use a dynamic programming step to extract the path tree. PTO extends prior work by adding a camera-based state sampler to improve the search for observation points. We also add support to non-euclidean state spaces, provide an implementation in the open motion planning library (OMPL), and evaluate PTO on four realistic scenarios with a virtual camera in up to 10-dimensional state spaces. We compare PTO with a default and with the new camera-based state sampler. The results indicate that the camera-based state sampler improves success rates in 3 out of 4 scenarios while having a significant lower memory footprint. This makes PTO an important contribution to advance the state-of-the-art for discrete belief space planning.Comment: 6 pages, 7 figures, submitted to ICRA 202

High temperature QCD with three flavors of improved staggered quarks

We present an update of our study of high temperature QCD with three flavors of quarks, using a Symanzik improved gauge action and the Asqtad staggered quark action. Simulations are being carried out on lattices with Nt=4, 6 and 8 for the case of three degenerate quarks with masses less than or equal to the strange quark mass, $m_s$, and on lattices with Nt=6 and 8 for degenerate up and down quarks with masses in the range 0.2 m_s \leq m_{u,d} \leq 0.6 m_s, and the strange quark fixed near its physical value. We also report on first computations of quark number susceptibilities with the Asqtad action. These susceptibilities are of interest because they can be related to event-by-event fluctuations in heavy ion collision experiments. Use of the improved quark action leads to a substantial reduction in lattice artifacts. This can be seen already for free fermions and carries over into our results for QCD.Comment: Lattice2002(Non-zero temperature and density

Volatile and semi-volatile organic compounds in smoke exposure of firefighters during prescribed burning in the Mediterranean region

International audienc

Innovations et gouvernance territoriale : une analyse par les dispositifs

Cette communication vise à présenter les outils méthodologiques d'analyse/évaluation de la gouvernance territoriale élaborés dans le cadre du projet de recherche PSDR Gouv.Innov sur les innovations organisationnelles relatives à la gouvernance territoriale. Il s'agit d'étudier les transformations introduites par les politiques de développement durable au niveau des dispositifs de gouvernance territoriale visant à favoriser une gestion intégrée des espaces ruraux. Dans un contexte de recomposition de l'action publique où les procédures d'aménagement sont plutôt normées par des représentations urbaines, l'accent est mis sur la question des modalités de représentation des activités rurales, pour lesquelles nous faisons l'hypothèse qu'elles sont sous représentées. Les premiers résultats méthodologiques permettent, dans une première partie, de proposer une définition générique et pragmatique de la gouvernance territoriale et de préciser la notion de dispositifs de gouvernance comme objet d'observation. A partir de cette définition une grille d'analyse permettant d'appréhender l'ensemble des dimensions en jeu dans les processus de gouvernance territoriale est élaboré. Dans la deuxième partie nous explorons l'intérêt de la notion de dispositif pour observer les processus de gouvernance et proposons une grille de collecte et de structuration des informations pour constituer des chroniques des dispositifs étudiés.(Résumé d'auteur

Time-resolved single-cell RNA-seq using metabolic RNA labelling

Single-cell RNA sequencing offers snapshots of whole transcriptomes but obscures the temporal RNA dynamics. Here we present single-cell metabolically labeled new RNA tagging sequencing (scNT-seq), a method for massively parallel analysis of newly transcribed and pre-existing mRNAs from the same cell. This droplet microfluidics-based method enables high-throughput chemical conversion on barcoded beads, efficiently marking newly transcribed mRNAs with T-to-C substitutions. Using scNT-seq, we jointly profiled new and old transcriptomes in ~55,000 single cells. These data revealed time-resolved transcription factor activities and cell-state trajectories at the single-cell level in response to neuronal activation. We further determined rates of RNA biogenesis and decay to uncover RNA regulatory strategies during stepwise conversion between pluripotent and rare totipotent two-cell embryo (2C)-like stem cell states. Finally, integrating scNT-seq with genetic perturbation identifies DNA methylcytosine dioxygenase as an epigenetic barrier into the 2C-like cell state. Time-resolved single-cell transcriptomic analysis thus opens new lines of inquiry regarding cell-type-specific RNA regulatory mechanisms

Topological susceptibility with the improved Asqtad action

As a test of the chiral properties of the improved Asqtad (staggered fermion) action, we have been measuring the topological susceptibility as a function of quark masses for 2 + 1 dynamical flavors. We report preliminary results, which show reasonable agreement with leading order chiral perturbation theory for lattice spacing less than 0.1 fm. The total topological charge, however, shows strong persistence over Monte Carlo time.Comment: Lattice2002(algor