Non-overlapping neural networks in Hydra vulgaris

To understand the emergent properties of neural circuits it would be ideal to record the activity of every neuron in a behaving animal and decode how it relates to behavior. We have achieved this with the cnidarian Hydra vulgaris, using calcium imaging of genetically engineered animals to measure the activity of essentially all of its neurons. While the nervous system of Hydra is traditionally described as a simple nerve net, we surprisingly find instead a series of functional networks that are anatomically non-overlapping and are associated with specific behaviors. Three major functional networks extend through the entire animal and are activated selectively during longitudinal contractions, elongations in response to light and radial contractions, while an additional network is located near the hypostome and is active during nodding. Additionally, we show that the behavior of Hydra is made of regularly occurring radial contractions, which expel the content of the gastric cavity about every 45 minutes. These results demonstrate the functional sophistication of apparently simple nerve nets, and the potential of Hydra and other basal metazoans as a model system for neural circuit studies

The regulator-regulatee interaction : insights taken from a risk-laden business firm

The viewpoint taken in this paper is to give a description of the interaction between regulators and regulated organisations, built on an empirical case-study in the French chemical industry

Comprehensive machine learning analysis of Hydra behavior reveals a stable basal behavioral repertoire

Animal behavior has been studied for centuries, but few efficient methods are available to automatically identify and classify it. Quantitative behavioral studies have been hindered by the subjective and imprecise nature of human observation, and the slow speed of annotating behavioral data. Here, we developed an automatic behavior analysis pipeline for the cnidarian Hydra vulgaris using machine learning. We imaged freely behaving Hydra, extracted motion and shape features from the videos, and constructed a dictionary of visual features to classify pre-defined behaviors. We also identified unannotated behaviors with unsupervised methods. Using this analysis pipeline, we quantified 6 basic behaviors and found surprisingly similar behavior statistics across animals within the same species, regardless of experimental conditions. Our analysis indicates that the fundamental behavioral repertoire of Hydra is stable. This robustness could reflect a homeostatic neural control of "housekeeping" behaviors which could have been already present in the earliest nervous systems

A threefold perspective on the role of a pockmark in benthic faunal communities and biodiversity patterns

Pockmarks are circular-shaped depressions that increase seabed heterogeneity and are characterized by discontinuous fluid emissions. To understand how environmental conditions of pockmarks affect the structure of macroand meiofauna, we investigated two sites in a pockmark field in the northwestern Madagascar margin. In a comparative approach, we explored the community structure of the dominant taxa (Polychaeta, Nematoda and hyaline foraminifera) in each component (macro-, metazoan meiofauna and foraminifera, respectively). The investigated active pockmark showed approximately two times higher meiofauna abundance compared to in a site away from another pockmark field, but macrofauna showed the opposite trend, with almost half density at the pockmark site. However, at both sites, macroand meiofauna showed higher richness and abundance values in the top well-oxygenated layers of the sediment than in the underlaying ones. Polychaeta and Nematoda showed lower richness in the pockmark, opposed to hyaline foraminiferans, but lower evenness in the pockmark was found for the three groups. The detection of gas flares in the water column attests of the recent activity within the pockmark. High amount of sulfur-bearing minerals (mainly pyrite) evidences a production of dissolved free sulfides (not detected at the time of sampling) by sulfate reduction process driven by organic matter degradation and anaerobic oxidation of methane. Furthermore, recent increase in sedimentation rates in the past 70 years and organic matter inputs could have led to higher organic matter degradation rates resulting in reduced conditions and a high oxygen consumption. All this together seem to act as key factors in the determination of variation in richness, abundance and community composition of macrofauna and meiofauna. Additionally, some taxa seem to be more tolerant to these extreme conditions, such as species belonging to the Nematoda genus Desmodora and the phylum Kinorhyncha, which are highly abundant in the pockmark, and hence, may be considered as potential bioindicators of pockmark activity in this area. Further studies are required for a better assessment

The past, present, and future of the Brain Imaging Data Structure (BIDS)

The Brain Imaging Data Structure (BIDS) is a community-driven standard for the organization of data and metadata from a growing range of neuroscience modalities. This paper is meant as a history of how the standard has developed and grown over time. We outline the principles behind the project, the mechanisms by which it has been extended, and some of the challenges being addressed as it evolves. We also discuss the lessons learned through the project, with the aim of enabling researchers in other domains to learn from the success of BIDS

Is it time, in the process industry, to question the limits of safety audits ?

International audienceMany major accidents in the past ten years in the process industry have been challenging industry, regulators but also public's confidence about our ability to prevent them (e.g. Toulouse, 2001, Billy Berclau, 2003, Ghislenghien, 2004, Texas City, 2005, Buncefield, 2005, Macondo,2010, Pembroke, 2011). This abstract intends therefore to provide a critical perspective to the question addressed in the call 'How do I know that I am not going to have a major accident tomorrow?' This question has, in the literature, almost a thirty years old history. It was indeed Perrow's contention that 'normal accidents' could occur from time to time, despite all preventive measures, due the levels of complexity and coupling of certain kind of high risk systems (Perrow, 1984).His approach was very much technological, or structural, leaving not much space in his interpretation to understand the part played by actors, organisations and institutions in the genesis of technological catastrophes. Thus, a sociologist like Vaughan (1996) has been able to extend Perrow's argument, using Turner's incubation framework (Turner, 1978) in order to show that complex socio technical systems could fruitfully be analysed from a historical, dynamic and systemic point of view. Her study of NASA Challenger's accident has become a landmark in the fields of both social and safety sciences

Approche experimentale des collisions electron-atome a trois electrons actifs. Ionisation et excitation simultanees; double ionisation

SIGLEINIST T 75108 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Traitement et analyse d'images pour la mesure de grandeurs cinematiques, deplacements et deformations a partir de la granularite laser et de reseaux croises, et pour l'etude de couplages thermomecaniques

SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : TD 82246 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc