Time domains of the hypoxic ventilatory response in ectothermic vertebrates

Over a decade has passed since Powell et al. (Respir Physiol 112:123–134, 1998) described and defined the time domains of the hypoxic ventilatory response (HVR) in adult mammals. These time domains, however, have yet to receive much attention in other vertebrate groups. The initial, acute HVR of fish, amphibians and reptiles serves to minimize the imbalance between oxygen supply and demand. If the hypoxia is sustained, a suite of secondary adjustments occur giving rise to a more long-term balance (acclimatization) that allows the behaviors of normal life. These secondary responses can change over time as a function of the nature of the stimulus (the pattern and intensity of the hypoxic exposure). To add to the complexity of this process, hypoxia can also lead to metabolic suppression (the hypoxic metabolic response) and the magnitude of this is also time dependent. Unlike the original review of Powell et al. (Respir Physiol 112:123–134, 1998) that only considered the HVR in adult animals, we also consider relevant developmental time points where information is available. Finally, in amphibians and reptiles with incompletely divided hearts the magnitude of the ventilatory response will be modulated by hypoxia-induced changes in intra-cardiac shunting that also improve the match between O2 supply and demand, and these too change in a time-dependent fashion. While the current literature on this topic is reviewed here, it is noted that this area has received little attention. We attempt to redefine time domains in a more ‘holistic’ fashion that better accommodates research on ectotherms. If we are to distinguish between the genetic, developmental and environmental influences underlying the various ventilatory responses to hypoxia, however, we must design future experiments with time domains in mind

Physics Performance of the ATLAS GNN4ITk Track Reconstruction Chain

Graph-based techniques and graph neural networks (GNNs) in particular are a promising solution for particle track reconstruction at the HL-LHC. Simulations of the HL-LHC environment produce noisy, heterogeneous and ambiguous data. We present an upgrade to the ATLAS GNN4ITk pipeline that allows detector regions to be handled heterogeneously. We perform direct comparisons of our results with those of existing tracking algorithms on a range of physics metrics, including reconstruction efficiency, track reconstruction performance in dense environments, and track parameter resolutions. By integrating this solution within the offline ATLAS Athena framework, we also explore different reconstruction chain configurations, for example using the GNN4ITk pipeline together with traditional techniques for track cleaning and fitting

delphes/delphes: Delphes-3.5.1pre10

<ul> <li>added vertexing with neutrals (thanks to @fbedesch)</li> <li>added Scenario II FCC-hh card (nominal)</li> <li>added CLD card</li> </ul&gt