Equilibrium of stellar dynamical systems in the context of the Vlasov-Poisson model

This short review is devoted to the problem of the equilibrium of stellar dynamical systems in the context of the Vlasov-Poisson model. In a first part we will review some classical problems posed by the application of the Vlasov-Poisson model to the astrophysical systems like globular clusters or galaxies. In a second part we will recall some recent numerical results which may give us some some quantitative hints about the equilibrium state associated to those systems.Comment: 8 pages, no figures, accepted in Communications in Nonlinear Science and Numerical Simulatio

Is there an arms race in the Arctic?

To what extent does the military posturing of Arctic coastal states reflect an ongoing arms race for the control of the Arctic? This idea first emerged after the 2007 planting of a Russian flag at the North Pole, and is regularly quoted by the media and several political analysts as the most likely scenario. However, the fact that most countries are engaged in the restructuring of their navies does not mean they are engaged in an arms race, a behaviour where every country increases its military capacity in reaction to the neighbours’ developments. The overall picture of Arctic military evolution is one of limited modernization, limited increases or change in equipment. There has indeed been some modest military buildup by the Arctic states, and often the new equipment was replacement, not expansion. But that buildup hardly signals aggressive designs. Rather, it seems little more than a prosaic response to expanded jurisdictional space with the melting of the ice, and continued resource development

Ultraviolet Resonant Nanogap Antennas with Rhodium Nanocube Dimers for Enhancing Protein Intrinsic Autofluorescence

Plasmonic optical nanoantennas offer compelling solutions for enhancing light-matter interactions at the nanoscale. However, until now, their focus has been mainly limited to the visible and near-infrared regions, overlooking the immense potential of the ultraviolet (UV) range, where molecules exhibit their strongest absorption. Here, we present the realization of UV resonant nanogap antennas constructed from paired rhodium nanocubes. Rhodium emerges as a robust alternative to aluminum, offering enhanced stability in wet environments and ensuring reliable performance in the UV range. Our results showcase the nanoantenna ability to enhance the UV autofluorescence of label-free streptavidin and hemoglobin proteins. We achieve significant enhancements of the autofluorescence brightness per protein by up to 120-fold, and reach zeptoliter detection volumes enabling UV autofluorescence correlation spectroscopy (UV-FCS) at high concentrations of several tens of micromolar. We investigate the modulation of fluorescence photokinetic rates and report excellent agreement between experimental results and numerical simulations. This work expands the applicability of plasmonic nanoantennas into the deep UV range, unlocking the investigation of label-free proteins at physiological concentrations

Whistle source levels of free-ranging beluga whales in Saguenay-St. Lawrence marine park

International audienceWild beluga whistle source levels (SLs) are estimated from 52 three-dimensional (3D) localized calls using a 4-hydrophone array. The probability distribution functions of the root-mean-square (rms) SL in the time domain, and the peak, the strongest 3-dB, and 10-dB SLs from the spectrogram, were non-Gaussian. The average rms SL was 143.8 +- 6.7 dB re 1microPa at 1m. SL spectral metrics were, respectively, 145.8 +- 8 dB, 143.2 +-7.1 dB, and 138.5 +-6.9 dB re 1 microPa. 1microPa / Hz at 1m

Arrays of high aspect ratio magnetic microstructures for large trapping throughput in lab-on-chip systems

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Joint analysis of quantitative trait loci and major-effect causative mutations affecting meat quality and carcass composition traits in pigs

Background: Detection of quantitative trait loci (QTLs) affecting meat quality traits in pigs is crucial for the design of efficient marker-assisted selection programs and to initiate efforts toward the identification of underlying polymorphisms. The RYR1 and PRKAG3 causative mutations, originally identified from major effects on meat characteristics, can be used both as controls for an overall QTL detection strategy for diversely affected traits and as a scale for detected QTL effects. We report on a microsatellite-based QTL detection scan including all autosomes for pig meat quality and carcass composition traits in an F2 population of 1,000 females and barrows resulting from an intercross between a Pietrain and a Large White-Hampshire-Duroc synthetic sire line. Our QTL detection design allowed side-by-side comparison of the RYR1 and PRKAG3 mutation effects seen as QTLs when segregating at low frequencies (0.03-0.08), with independent QTL effects detected from most of the same population, excluding any carrier of these mutations.[br/] Results: Large QTL effects were detected in the absence of the RYR1 and PRKGA3 mutations, accounting for 12.7% of phenotypic variation in loin colour redness CIE-a* on SSC6 and 15% of phenotypic variation in glycolytic potential on SSC1. We detected 8 significant QTLs with effects on meat quality traits and 20 significant QTLs for carcass composition and growth traits under these conditions. In control analyses including mutation carriers, RYR1 and PRKAG3 mutations were detected as QTLs, from highly significant to suggestive, and explained 53% to 5% of the phenotypic variance according to the trait.[br/] Conclusions: Our results suggest that part of muscle development and backfat thickness effects commonly attributed to the RYR1 mutation may be a consequence of linkage with independent QTLs affecting those traits. The proportion of variation explained by the most significant QTLs detected in this work is close to the influence of major-effect mutations on the least affected traits, but is one order of magnitude lower than effect on variance of traits primarily affected by these causative mutations. This suggests that uncovering physiological traits directly affected by genetic polymorphisms would be an appropriate approach for further characterization of QTLs

Preventing Corrosion of Aluminum Metal with Nanometer-Thick Films of Al2O3 Capped with TiO2 for Ultraviolet Plasmonics

Extending plasmonics into the ultraviolet range imposes the use of aluminum to achieve the best optical performance. However, water corrosion is a major limiting issue for UV aluminum plasmonics, as this phenomenon occurs significantly faster in presence of UV light, even at low laser powers of a few microwatts. Here we assess the performance of nanometer-thick layers of various metal oxides deposited by atomic layer deposition (ALD) and plasma-enhanced chemical vapor deposition (PECVD) on top of aluminum nanoapertures to protect the metal against UV photocorrosion. The combination of a 5 nm Al2O3 layer covered by a 5 nm TiO2 capping provides the best resistance performance, while a single 10 nm layer of SiO2 or HfO2 is a good alternative. We also report the influence of the laser wavelength, the laser operation mode and the pH of the solution. Properly choosing these conditions significantly extends the range of optical powers for which the aluminum nanostructures can be used. As application, we demonstrate the label-free detection of streptavidin proteins with improved signal to noise ratio. Our approach is also beneficial to promote the long-term stability of the aluminum nanostructures. Finding the appropriate nanoscale protection against aluminum corrosion is the key to enable the development of UV plasmonic applications in chemistry and biology

Impedance analysis of film-forming amines for the corrosion protection of a carbon steel

Octadecylamine (ODA) is a well-known organic inhibitor for the corrosion protection of carbon steels. In the present study, electrochemical impedance data analysis was performed to extract physical parameters of the ODA thin film that formed on a P275 carbon steel surface. First, surface observations and contact angle measurements showed the steel surface modification after the ODA treatment linked to the adsorption of an organic hydrophobic thin film. X-ray photoelectron spectroscopy confirmed the presence of a very thin organic layer and revealed the presence of iron oxide/hydroxide underlying the ODA film. The impedance data analysis with a power-law distribution of resistivity in the organic film allowed the permittivity and thickness to be extracted. Finally, from the impedance results with and without ODA, the instantaneous corrosion inhibition efficiency was determined

Polymeric nanocapsules prevent oxidation of core-loaded molecules: evidence based on the effects of docosahexaenoic acid and neuroprostane on breast cancer cells proliferation

International audienceBackground:Nanocapsules, as a delivery system, are able to target drugs and other biologically sensitive moleculesto specific cells or organs. This system has been intensively investigated as a way to protect bioactives drugs frominactivation upon interaction with the body and to ensure the release to the target. However, the mechanism ofimproved activity of the nanoencapsulated molecules is far from being understood at the cellular and subcellularlevels. Epidemiological studies suggest that dietary polyunsaturated fatty acids (PUFA) can reduce the morbidityand mortality from breast cancer. This influence could be modulated by the oxidative status of the diet and it hasbeen suggested that the anti-proliferative properties of docosahexaenoic acid (DHA) are enhanced by pro-oxidantagents Methods:The effect of encapsulation of PUFA on breast cancer cell proliferation in different oxidative mediumwas evaluated in vitro. We compared the proliferation of the human breast cancer cell line MDA-MB-231 and ofthe non-cancer human mammary epithelial cell line MCF-10A in different experimental conditions. Results:DHA possessed anti-proliferative properties that were prevented by alpha-tocopherol (an antioxidant) andenhanced by the pro-oxidant hydrogen peroxide that confirmsthat DHA has to be oxidized to exert its anti-proliferativeproperties. We also evaluated the anti-proliferative effects of the 4(RS)-4-F4t-neuroprostane, a bioactive, non-enzymaticoxygenated metabolite of DHA known to play a major role inthe prevention of cardiovascular diseases. DHA-loadednanocapsules was less potent than non-encapsulated DHA while co-encapsulation of DHA with H2O2maintainedthe inhibition of proliferation. The nanocapsules slightly improves the anti-proliferative effect in the case of4(RS)-4-F4t-neuroprostane that is more hydrophilic than DHA. Conclusion:Overall, our findings suggest that the sensitivity of tumor cell lines to DHA involves oxidized metabolites.They also indicate that neuroprostane is a metabolite participating in the growth reducing effect of DHA, but it is not thesole. These results also suggest that NC seek to enhance the stability against degradation, enhance cellular availability,and control the release of bioactive fatty acids following their lipophilicities