Topological Shocks in Burgers Turbulence

The dynamics of the multi-dimensional randomly forced Burgers equation is studied in the limit of vanishing viscosity. It is shown both theoretically and numerically that the shocks have a universal global structure which is determined by the topology of the configuration space. This structure is shown to be particularly rigid for the case of periodic boundary conditions.Comment: 4 pages, 4 figures, RevTex4, published versio

Meloxicam decreases the migration and invasion of CF41.Mg canine mammary carcinoma cells

Indexación: Web of Science; Scopus.Cyclooxygenase (COX)-2 expression is positively correlated with malignant features in canine mammary carcinomas. Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit COX activity and may therefore possess anticancer effects. Meloxicam is an NSAID that is widely used in human and veterinary medicine. High concentrations of meloxicam have been reported to be antitumorigenic in vitro; however, the effect of meloxicam at concentrations that are equivalent to those that can be obtained in vivo remains unknown. In the current study, the in vitro effects of low-dose meloxicam (0.25 μg/ml) on CF41.Mg canine mammary carcinoma cells were evaluated. The effects on cell proliferation, apoptosis, cell migration and invasion, in addition to the expression of different molecules associated with tumor invasiveness were analyzed. No effect on cell viability and apoptosis were observed. However, cell migration and invasion were significantly reduced following treatment with meloxicam. MMP-2 expression and activity were similarly reduced, explaining the impaired cell invasion. In addition, β-catenin expression was downregulated, while its phosphorylation increased. These results indicate that 0.25 μg/ml meloxicam reduces cell migration and invasion, in part through modulating MMP-2 and β-catenin expression. Additional studies are required to elucidate the mechanism associated with the anti-invasive effect of meloxicam on CF41.Mg cells. The results of the present study suggest that meloxicam has a potential adjunctive therapeutic application, which could be useful in controlling the invasion and metastasis of canine mammary carcinomas.https://www.spandidos-publications.com/10.3892/ol.2017.640

Aubry-Mather measures in the non convex setting

The adjoint method, introduced in [L. C. Evans, Arch. Ration. Mech. Anal., 197 (2010), pp. 1053–1088] and [H. V. Tran, Calc. Var. Partial Differential Equations, 41 (2011), pp. 301–319], is used to construct analogues to the Aubry–Mather measures for nonconvex Hamiltonians. More precisely, a general construction of probability measures, which in the convex setting agree with Mather measures, is provided. These measures may fail to be invariant under the Hamiltonian flow and a dissipation arises, which is described by a positive semidefinite matrix of Borel measures. However, in the case of uniformly quasiconvex Hamiltonians the dissipation vanishes, and as a consequence the invariance is guaranteed. Copyright © 2011 Society for Industrial and Applied Mathematic

Fronts in randomly advected and heterogeneous media and nonuniversality of Burgers turbulence: Theory and numerics

A recently established mathematical equivalence--between weakly perturbed Huygens fronts (e.g., flames in weak turbulence or geometrical-optics wave fronts in slightly nonuniform media) and the inviscid limit of white-noise-driven Burgers turbulence--motivates theoretical and numerical estimates of Burgers-turbulence properties for specific types of white-in-time forcing. Existing mathematical relations between Burgers turbulence and the statistical mechanics of directed polymers, allowing use of the replica method, are exploited to obtain systematic upper bounds on the Burgers energy density, corresponding to the ground-state binding energy of the directed polymer and the speedup of the Huygens front. The results are complementary to previous studies of both Burgers turbulence and directed polymers, which have focused on universal scaling properties instead of forcing-dependent parameters. The upper-bound formula can be heuristically understood in terms of renormalization of a different kind from that previously used in combustion models, and also shows that the burning velocity of an idealized turbulent flame does not diverge with increasing Reynolds number at fixed turbulence intensity, a conclusion that applies even to strong turbulence. Numerical simulations of the one-dimensional inviscid Burgers equation using a Lagrangian finite-element method confirm that the theoretical upper bounds are sharp within about 15% for various forcing spectra (corresponding to various two-dimensional random media). These computations provide a new quantitative test of the replica method. The inferred nonuniversality (spectrum dependence) of the front speedup is of direct importance for combustion modeling.Comment: 20 pages, 2 figures, REVTeX 4. Moved some details to appendices, added figure on numerical metho

A simple method for counting bacteria with active electron transport system in water and sediment samples [Translation from: Kiel. Meeresforsch. 31(2) 83-86, 1975]

Description of a simple method for counting bacteria with active electron transport systems in water and sediment samples. Sodium succinate, NADH and NADPH served as electron donors. It is possible to see several sites of electron transport in the larger cells. Especially impressive are the plankton-algae, protozoa, and small metazoa. This is a partial translation of the ”method” section only

Thioploca : methylotroph and significance in the food chain

Thioploca constitutes a great portion of the benthic biomass off the Chile-Peru coast. This organism is eaten by the higher organisms and constitutes a major input of organic carbon in the food chain in this region. Thioploca has been an enigma ever since its discovery in 1907 and the prefix "thio" in the genus name has led investigators to believe that hydrogen sulfide is the energy source necessary to synthesize Thioploca biomass. The results of this investigation indicate that methane is the energy and carbon source for the organism. The organism does not use radioactive labeled acetate, glucose, mixture of amino acids, thymine or bicarbonate as demontrated by autoradiography. Since the energy and carbon source is methane, it indicates that Thioploca is a methylotroph. Methane in this area is generated by microbial activity in reduced sediments and from seepage from coal seams that run under the seafloor. Methane, through Thioploca, represents a major new mechanism, other than photosynthesis, to add cellular carbon to the ecosystem oft the Chile-Peru area. Because methane is the energy and carbon source, Thioploca's taxonomic position as weil as its evolutionary position should be re-assessed

In situ primary production of Fucus vesiculosus and Cladophora glomerata

The primary production of two of the most commonly distributed benthic algae in the Baltic proper was measured using different in situ methods (bottles, plastic bags, 14C and O2) during summer. Results on exudation and heterotrophic activity of these exudates have been worked out for Fucus. Low primary production and exudation values are found, while the total bacterial activity seems to be high compared to the net primary production

Scaling of Huygens-front speedup in weakly random media

Front propagation described by Huygens' principle is a fundamental mechanism of spatial spreading of a property or an effect, occurring in optics, acoustics, ecology and combustion. If the local front speed varies randomly due to inhomogeneity or motion of the medium (as in turbulent premixed combustion), then the front wrinkles and its overall passage rate (turbulent burning velocity) increases. The calculation of this speedup is subtle because it involves the minimum-time propagation trajectory. Here we show mathematically that for a medium with weak isotropic random fluctuations, under mild conditions on its spatial structure, the speedup scales with the 4/3 power of the fluctuation amplitude. This result, which verifies a previous conjecture while clarifying its scope, is obtained by reducing the propagation problem to the inviscid Burgers equation with white-in-time forcing. Consequently, field-theoretic analyses of the Burgers equation have significant implications for fronts in random media, even beyond the weak-fluctuation limit.Comment: 7 pages, 3 figures, elsart5p. v2: additional discussion of Hamiltonian formalism; v3: clarification of transient behavio