Static flow on complete noncompact manifolds I: short-time existence and asymptotic expansions at conformal infinity

In this paper, we study short-time existence of static flow on complete noncompact asymptotically static manifolds from the point of view that the stationary points of the evolution equations can be interpreted as static solutions of the Einstein vacuum equations with negative cosmological constant. For a static vacuum $(M^n,g,V),$ we also compute the asymptotic expansions of $g$ and $V$ at conformal infinity.Comment: 25 page

Gene Expression Profiling of Soft and Firm Atlantic Salmon Fillet

Texture of salmon fillets is an important quality trait for consumer acceptance as well as for the suitability for processing. In the present work we measured fillet firmness in a population of farmed Atlantic salmon with known pedigree and investigated the relationship between this trait and gene expression. Transcriptomic analyses performed with a 21 K oligonucleotide microarray revealed strong correlations between firmness and a large number of genes. Highly similar expression profiles were observed in several functional groups. Positive regression was found between firmness and genes encoding proteasome components (41 genes) and mitochondrial proteins (129 genes), proteins involved in stress responses (12 genes), and lipid metabolism (30 genes). Coefficients of determination (R2) were in the range of 0.64–0.74. A weaker though highly significant negative regression was seen in sugar metabolism (26 genes, R2 = 0.66) and myofiber proteins (42 genes, R2 = 0.54). Among individual genes that showed a strong association with firmness, there were extracellular matrix proteins (negative correlation), immune genes, and intracellular proteases (positive correlation). Several genes can be regarded as candidate markers of flesh quality (coiled-coil transcriptional coactivator b, AMP deaminase 3, and oligopeptide transporter 15) though their functional roles are unclear. To conclude, fillet firmness of Atlantic salmon depends largely on metabolic properties of the skeletal muscle; where aerobic metabolism using lipids as fuel, and the rapid removal of damaged proteins, appear to play a major role

Seaweed polysaccharide-based hydrogels used for the regeneration of articular cartilage

This manuscript provides an overview of the in vitro and in vivo studies reported in the literature focusing on seaweed polysaccharides based hydrogels that have been proposed for applications in regenerative medicine, particularly, in the field of cartilage tissue engineering. For a better understanding of the main requisites for these specific applications, the main aspects of the native cartilage structure, as well as recognized diseases that affect this tissue are briefly described. Current available treatments are also presented to emphasize the need for alternative techniques. The following part of this review is centered on the description of the general characteristics of algae polysaccharides, as well as relevant properties required for designing hydrogels for cartilage tissue engineering purposes. An in-depth overview of the most well known seaweed polysaccharide, namely agarose, alginate, carrageenan and ulvan biopolymeric gels, that have been proposed for engineering cartilage is also provided. Finally, this review describes and summarizes the translational aspect for the clinical application of alternative systems emphasizing the importance of cryopreservation and the commercial products currently available for cartilage treatment.Authors report no declarations of interest. Authors thank the Portuguese Foundation for Science and Technology (FCT) for the PhD fellowship of Elena G. Popa (SFRH/BD/64070/2009) and research project (MIT/ECE/0047/2009). The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement no REGPOT-CT2012-316331-POLARIS

Ricci solitons, Ricci flow, and strongly coupled CFT in the Schwarzschild Unruh or Boulware vacua

The elliptic Einstein-DeTurck equation may be used to numerically find Einstein metrics on Riemannian manifolds. Static Lorentzian Einstein metrics are considered by analytically continuing to Euclidean time. Ricci-DeTurck flow is a constructive algorithm to solve this equation, and is simple to implement when the solution is a stable fixed point, the only complication being that Ricci solitons may exist which are not Einstein. Here we extend previous work to consider the Einstein-DeTurck equation for Riemannian manifolds with boundaries, and those that continue to static Lorentzian spacetimes which are asymptotically flat, Kaluza-Klein, locally AdS or have extremal horizons. Using a maximum principle we prove that Ricci solitons do not exist in these cases and so any solution is Einstein. We also argue that Ricci-DeTurck flow preserves these classes of manifolds. As an example we simulate Ricci-DeTurck flow for a manifold with asymptotics relevant for AdS_5/CFT_4. Our maximum principle dictates there are no soliton solutions, and we give strong numerical evidence that there exists a stable fixed point of the flow which continues to a smooth static Lorentzian Einstein metric. Our asymptotics are such that this describes the classical gravity dual relevant for the CFT on a Schwarzschild background in either the Unruh or Boulware vacua. It determines the leading O(N^2) part of the CFT stress tensor, which interestingly is regular on both the future and past Schwarzschild horizons.Comment: 48 pages, 7 figures; Version 2 - section 2.2.1 on manifolds with boundaries substantially modified, corrected and extended. Discussion in section 3.1 amended. References added and minor change

Effects of four tanniferous plant extracts on the in vitro exsheathment of third-stage larvae of parasitic nematodes

The anthelmintic properties of tanniferous plants and of their secondary metabolites represent one possible alternative to chemotherapy that is currently being explored as a means of achieving sustainable control of gastrointestinal nematodes in ruminants. Previous in vivo and in vitro results suggest that tanniferous plants can have direct anti-parasitic effect against different stages of nematodes. However, the mode of action of the bioactive plant compounds remains obscure. The objectives of the current study were (1) to examine the hypothesis that extracts of tanniferous plants might interfere with the exsheathment of third-stage infective larvae (L3); (2) to assess the role of tannins in the process by examining the consequence of adding an inhibitor of tannins (polyethylene glycol: PEG) to extracts. The effects of 4 tanniferous plant extracts on exsheathment have been examined on L3 of Haemonchus contortus and Trichostrongylus colubriformis. Artificial exsheathment was induced in vitro by adding hypochlorite solution to larval suspension. The evolution of exsheathment with time was measured by repeated observations at 10-min interval for 60 min. The selected plants were: genista (Sarothamnus scoparius), heather (Erica erigena), pine tree (Pinus sylvestris), and chestnut tree (Castanea sativa), with tannin contents ranging from 1.5 to 24.7% of DM. Extracts of a non-tanniferous plant (rye grass, tannin content: 0.3% of DM) were included in the assay as negative controls. The extracts were tested at the concentration of 600 mg/ml and the effects were compared to the rate of exsheathment of control larvae in PBS. No statistical differences in the pattern of exsheathment was observed after addition of rye grass or genista extracts for both nematode species and with heather extracts for T. colubriformis. In contrast, pine tree extracts on larvae of both species and heather extracts with H. contortus induced a significant delay in exsheathment. Last, contact with chest nut extracts led to a total inhibition of the process for both nematodes. These results suggest that extracts of tanniferous plants might affect a key process in the very early stages of larval invasion of the host. In most cases, the addition of PEG led to a total or partial restoration towards control values. This suggests that tannins are largely involved in the inhibitory process. However, other secondary metabolites may also interfere with the process that would help to explain some of the differences in response observed between the two nematode species

Are surface water characteristics efficient to locate hyporheic biodiversity hotspots ?

International audienceLocation of river-groundwater exchange zones and biodiversity hotspot is essential for a river management plan,especially for Mediterranean karstic rivers. This location is often difficult and time-consuming when long riversectors are considered. We studied a 13 km-long sector of the Cèze River (Southern France) located in a karsticcanyon.We compared five indicators of river-groundwater exchanges: longitudinal profiles of temperature, electricalconductivity and 222Rn concentrations in the surface water of the river, chemical characteristics of thehyporheic water and hyporheic biodiversity. Upwelling zones occurred downstream of geomorphological heterogeneities(here at the tail of gravel bars). Surface water chemistry, especially electrical conductivity and222Rn concentrations, clearly traces large scale gaining sections, which were not associated to valley narrowingbut with lateral springs, suggesting a crucial role of the geological structuration of the karstic plateau ofMéjanne-le-Clap. Hyporheic water chemistry fits with the large-scale hydrological pattern, but with a high variabilitycorresponding to local heterogeneities. The stygobite fauna (obligate groundwater organisms) and benthicEPTC (Ephemeroptera, Plecoptera, Trichoptera and Coleoptera) occurred preferentially in the gainingsections fed by groundwater, likely because of oligotrophicwater and cooler temperature. The spatial distributionof river-groundwater exchange zone and hyporheic biodiversity may be thus predicted using changes in surfacewater chemistry, especially for electrical conductivity and 222Rn concentrations

Multidisciplinary diagnostic to characterize river/karst exchanges

International audienc