Boundaries Control Collective Dynamics of Inertial Self-Propelled Robots

Simple ingredients, such as well-defined interactions and couplings for the velocity and orientation of self-propelled objects, are sufficient to produce complex collective behavior in assemblies of such entities. Here, we use assemblies of rodlike robots made motile through self-vibration. When confined in circular arenas, dilute assemblies of these rods act as a gas. Increasing the surface fraction leads to a collective behavior near the boundaries: polar clusters emerge while, in the bulk, gaslike behavior is retained. The coexistence between a gas and surface clusters is a direct consequence of inertial effects as shown by our simulations. A theoretical model, based on surface mediated transport accounts for this coexistence and illustrates the exact role of the boundaries. Our study paves the way towards the control of collective behavior: By using deformable but free to move arenas, we demonstrate that the surface induced clusters can lead to directed motion, while the topology of the surface states can be controlled by biasing the motility of the particles.

Preservation of force output through progressive reduction of stimulation frequency in human quadriceps femoris muscle

The purpose of this study was to determine the effects of a reduction in the pulse frequency on the fatigue rate of human quadriceps femoris muscle during intermittent (8-second) contractions. Twelve healthy subjects each participated in two experimental sessions. Thirty cycles (cycle time: 8 seconds "on"/12 seconds "off") were applied during each session. During one session, a frequency of 60 pulses per second (pps) was used for all trains. During the other session, the subjects were stimulated with 60 pps for the first train. The stimulating frequency of each train was then progressively reduced, in 5-pps steps, for contractions 2, 3, 5, 8, 12, and 20. By the fifth contraction, the differences in average force produced by the 60-pps trains and the reduced-frequency trains were significant. The difference between the two conditions increased, with the variable-frequency protocol producing 46% more force than the constant-frequency protocol during the last contraction. These results showed that, compared with a constant pulse frequency, reducing the pulse frequency during a fatiguing contraction can markedly decrease the rate of force fatigue of skeletal muscle. This finding suggests that a variable-frequency protocol, similar to the one used in this may prove to be a more effective pattern of stimulation for activation of skeletal muscle than the traditionally used constant-frequency protocol.

Correlation of rat hepatic phenylalanine hydroxylase, with tetrahydrobiopterin and GTP concentrations

Hepatic phenylalanine hydroxylase is reported to be more abundant in experimentally-diabetic rats; whereas livers of animals fed a high protein diet, where gluconeogenesis also prevails, have normal amounts of this enzyme. In this study, in addition to seeking an explanation for this effect of experimental diabetes, we also examined the effects of providing alternative dietary gluconeogenic substrates. In rats fed a diet composed of 40% (w/w) glycerol, the specific activities of hepatic phenylalanine hydroxylase are decreased to about 60% of control values. There is no effect on the apparent state of phosphorylation of the enzyme. However, studies on the incorporation of radiolabelled leucine into liver phenylalanine hydroxylase suggested that there was a decreased rate of synthesis. Similarly, animals fed a diet containing 85% (w/w) fructose also have diminished phenylalanine hydroxylase activities. Under all of the above circumstances and also in streptozotocin-induced diabetic animals, alterations in the concentrations of the hydroxylase cofactor, tetrahydrobiopterin and of GTP closely correlate with the effects on the enzyme activities. They are elevated in livers of diabetic animals and significantly diminished in livers of rats fed diets rich in glycerol or fructose. These observations suggest that in adult rat both liver tetrahydrobiopterin concentrations and the expression of hepatic phenylalanine hydroxylase are regulated by GTP [210].

[Possibility to screen COPD in emergency department]

INTRODUCTION

The COPD is a stake of public health because of its prevalence in the world, its morbi-mortality and its considerable cost (2,2 billion euros/year in France). An early screening allows for a fast and effective intervention.

MATERIAL AND METHOD

The prospective study with in the emergency department of Roanne included smokers and ex-smokers, more than 10PY for the 40 years old and older, more than 20PY for the others, and/or symptomatic of COPD. Screening rested on a questionnaire filled out by the patient. Are excluded patients already diagnosed with COPD. This screening is carried out with the FEV1/FEV6. The criterion of principal judgment rests on the time taken for screening and acceptability by the patients.

RESULTS

One hundred and twenty-two patients were included, 6.5% refused screening. The average time of screening was 4.8 minutes. There were 27 positive patients with the FEV1/FEV6, 14 came to make the classic spirometry. Only 10.53% have a FEV1/FEV6<0.73. On the whole, 15.86% do not have a COPD, 75,25% are at the risk of COPD, 5,94% have a COPD stage 1, 1,98% are stage 2, 0.99% stage 3 and none stage 4.

DISCUSSION

The study thus showed that a screening of the COPD in the emergency rooms is possible because of the simple and reproductible process. Its shows, however its limits since the number of inclusion decrease during days of strong attendance in emergency rooms.

CONCLUSION

The screening of the COPD as foreseen in the study is possible.

Innovative analytical methodologies for characterizing chemical exposure with a view to next-generation risk assessment

The chemical burden on the environment and human population is increasing. Consequently, regulatory risk assessment must keep pace to manage, reduce, and prevent adverse impacts on human and environmental health associated with hazardous chemicals. Surveillance of chemicals of known, emerging, or potential future concern, entering the environment-food-human continuum is needed to document the reality of risks posed by chemicals on ecosystem and human health from a one health perspective, feed into early warning systems and support public policies for exposure mitigation provisions and safe and sustainable by design strategies. The use of less-conventional sampling strategies and integration of full-scan, high-resolution mass spectrometry and effect-directed analysis in environmental and human monitoring programmes have the potential to enhance the screening and identification of a wider range of chemicals of known, emerging or potential future concern. Here, we outline the key needs and recommendations identified within the European Partnership for Assessment of Risks from Chemicals (PARC) project for leveraging these innovative methodologies to support the development of next-generation chemical risk assessment.

Fate of chlordecone in soil food webs in a banana agroecosystem in Martinique

Large quantities of chlordecone-based insecticides were produced and used throughout the world. One of its most important uses was to control the damage caused by Cosmopolites sordidus in banana-growing regions. In the islands of Martinique and Guadeloupe, 18,000 ha of farmland are potentially contaminated. Despite the key role played by soil macrofauna in agroecosystems, there are currently no data on their contamination. The aim of this study was to explore the fate of chlordecone (CLD) and its transfer to different organisms of the soil food web. Seven species of invertebrates representing different taxonomic groups and trophic levels of the soil communities of Martinique were targeted and collected in six experimental banana fields, with a level of contamination within a range of values classically observed. Soil samples and macrofauna from the study sites were analysed for CLD and chlordecol (CLDOH) its main transformation product. The contamination of the soil fauna were related to δ15N (trophic level), proportion of soil ingestion (diet) and types of epidermis (mucus or exoskeleton) in order to study the different mechanisms of macrofauna contamination. Presence of CLD and CLDOH could be quantified in all the soil organisms from contaminated fields. Results showed a significant relationship between the CLD contamination of detritivorous and the ash content of their faeces, suggesting that soil ingestion was the main contamination pathway. In contrast, the exoskeleton-bearing diplopod Trigoniulus coralinus and the soft-bodied earthworm Eudrilus eugeniae, both detritivores with a comparable diet, had similar contamination levels, suggesting that the type of tegument has little influence on bioaccumulation. At the scale of the entire trophic network, a significant relationship was uncovered between δ15N values and CLD contamination of the fauna, therefore providing some in situ evidence for a bioamplification process along the soil food chain.