The band spectrum of the periodic airy-schrodinger operator on the real line

We introduce the periodic Airy-Schr\"odinger operator and we study its band spectrum. This is an example of an explicitly solvable model with a periodic potential which is not differentiable at its minima and maxima. We define a semiclassical regime in which the results are stated for a fixed value of the semiclassical parameter and are thus estimates instead of asymptotic results. We prove that there exists a sequence of explicit constants, which are zeroes of classical functions, giving upper bounds of the semiclassical parameter for which the spectral bands are in the semiclassical regime. We completely determine the behaviour of the edges of the first spectral band with respect to the semiclassical parameter. Then, we investigate the spectral bands and gaps situated in the range of the potential. We prove precise estimates on the widths of these spectral bands and these spectral gaps and we determine an upper bound on the integrated spectral density in this range. Finally, in the semiclassical regime, we get estimates of the edges of every spectral bands and thus of the widths of every spectral bands and spectral gaps

Localization Properties of the Chalker-Coddington Model

The Chalker Coddington quantum network percolation model is numerically pertinent to the understanding of the delocalization transition of the quantum Hall effect. We study the model restricted to a cylinder of perimeter 2M. We prove firstly that the Lyapunov exponents are simple and in particular that the localization length is finite; secondly that this implies spectral localization. Thirdly we prove a Thouless formula and compute the mean Lyapunov exponent which is independent of M.Comment: 29 pages, 1 figure. New section added in which simplicity of the Lyapunov spectrum and finiteness of the localization length are proven. To appear in Annales Henri Poincar

Nitrogen deficiency increases basal branching and modifies visual quality of the rose bushes

Rosebush architecture resulting from the spatial organisation of the plant axes induces plant shape and consequently within ornamental horticulture context, its visual quality and commercial value. This architecture can be modulated by environmental conditions, particularly in the horticulture context in which the possibilities to control growing conditions are numerous. The objectives of the study were to determine, in young rose bushes, (1) whether short periods of nitrogen deficiency affect branching and (2) whether this effect is sufficient to modify the visual quality of the plant in a sustainable manner. Between vegetative bud burst and the petal colour visible stage of the generated primary branch, young rooted cuttings of bush rose (cv Radrazz) were subjected to one of three nitrogen regimes: (1) no nitrogen deficiency, (2) continuous nitrogen deficiency, i.e. 35 days of N deficiency, and (3) nitrogen deficiency restricted to the flowering stages, i.e. 18 days of N deficiency. After the petal colour visible stage, all three groups of plants were supplied continuously with nitrogen. We observed the morphology of the axes and the kinetics of axillary bud burst. Twelve weeks after the petal colour visible stage, the visual quality of the rose bushes was evaluated by an expert jury. We found that nitrogen deficiencies (1) increased bud burst ratios in the medial and basal zones of the primary branch, (2) delayed the bud burst in the apical zone of the primary branch and (3) had long-term effects on plant visual quality. The continuous nitrogen deficiency regime produced flatter, more asymmetric and less vigorous rose bushes than the no nitrogen deficiency regime. By contrast, nitrogen deficiency during the flowering stages only resulted in more symmetric, taller and more vigorous rose bushes than the no nitrogen deficiency regime. Based on these results, the role of nitrogen on bud burst was discussed and candidate processes at the origin of the visual quality modification were suggested. This new approach combining ecophysiology and sensory assessment of ornamental plants enabled the identification of some early architecture components to be correlated with later visual quality characteristics and then to better target the physiological processes of interest

Antioxidant activity and chemical constituents of Warionia saharae Benth. & Coss. (Compositae) from Algeria.

Phytochemical investigations of chloroform and ethyl acetate extracts from the aerial parts of Warionia saharae Benth. & Coss. from Algeria resulted in the isolation of ten known compounds: β-sitosterol, stigmasterol, scopoletin, cirsimaritin, chrysoeriol, hispidulin, luteolin, esculetin, (2R,3R) taxifolin, quercetin. Their structures were elucidated on the basis of extensive spectroscopic analysis and comparison with the related known compounds. The EtOAc extract which was evaluated for DPPH radical scavenging activity and of lipid peroxide inhibition showed potent antioxidant ability compared to the quercetin and ascorbic acid used as positive control

The Antidiabetic Effect of MSCs Is Not Impaired by Insulin Prophylaxis and Is Not Improved by a Second Dose of Cells

Type 1 diabetes mellitus (T1D) is due to autoimmune destruction of pancreatic beta-cells. Previously, we have shown that intravenously administered bone marrow-derived multipotent mesenchymal stromal cells (MSCs) allows pancreatic islet recovery, improves insulin secretion and reverts hyperglycemia in low doses streptozotocin (STZ)-induced diabetic mice. Here we evaluate whether insulin prophylaxis and the administration of a second dose of cells affect the antidiabetic therapeutic effect of MSC transplantation. Insulitis and subsequent elimination of pancreatic beta-cells was promoted in C57BL/6 mice by the injection of 40 mg/kg/day STZ for five days. Twenty-four days later, diabetic mice were distributed into experimental groups according to if they received or not insulin and/or one or two doses of healthy donor-derived MSCs. Three and half months later: glycemia, pancreatic islets number, insulinemia, glycated hemoglobin level and glucose tolerance were determined in animals that did not received exogenous insulin for the last 1.5 months. Also, we characterized MSCs isolated from mice healthy or diabetic. The therapeutic effect of MSC transplantation was observed in diabetic mice that received or not insulin prophylaxis. Improvements were similar irrespective if they received one or two doses of cells. Compared to MSCs from healthy mice, MSCs from diabetic mice had the same proliferation and adipogenic potentials, but were less abundant, with altered immunophenotype and no osteogenic potential

Multiple wells Airy-Schrödinger operator and integrated density of states of the periodic Airy-Schrödinger operator

We compute an explicit formula for the integrated density of states of the periodic Airy-Schrödinger operator on the real line. For this purpose, we study precisely the spectrum of the restriction of the periodic Airy-Schrödinger operator to a finite number of periods. We prove that all the eigenvalues of this restriction are in the spectral bands of the periodic Airy-Schrödinger operator and none of them are in its spectral gaps. We count exactly the number of eigenvalues in each of the spectral bands, this number being equal to the number of periods to which the periodic operator is restricted, plus one. Note that our results depends on a semiclassical parameter but are not stated in the semiclassical limit. They are valid for values of the semiclassical larger than explicit constants

Hydrogen production on iron-magnesium oxide in the high-temperature water-gas shift reaction

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Acaricidal activity of flavonoids extract of Borago officinalis L. (Boraginaceae) against brown dog tick, Rhipicephalus sanguineus (Latreille, 1806)

International audienceBorago officinalis L. (Boraginaceae) is a plant of the Boraginaceae family, used in Algeria for food and medicinal purposes. This study reports the effect of flavonoids extracted from the aerial part of Borago officinalis L. (Boraginaceae) on the larvae and engorged adult females of the brown dog tick Rhipicephalus sanguineus (Latreille, 1806) using adults immersion test (AIT) and larval immersion test (LIT). For this purpose, the larvae and engorged female of Rhipicephalus sanguineus (Latreille, 1806) were exposed to serial dilutions of flavonoids extract (50 mg/ml, 25 mg/ml, 12.5 mg/ml and 6.25 mg/ml) using ``dipping method'' in vitro. The plant extract was obtained by fractionation using appropriate solvents. The extraction yield is 22% with a flavonoids concentration equal to 129.12 mu g equivalent of quercetin/ml of the extract. The chromatographic analysis by high performance thin layer chromatography (HPTLC) reveals the presence of gallic acid, vanillic acid, kaempferol, dihydroxybenzoic and quercetin. The results obtained show that the flavonoids extract of Borago officunalis L. (Boraginaceae) considerably reduces the oviposition and the hatching rate of the eggs of Rhipicephalus sanguineus (Latreille, 1806) and was shown to be toxic against newly hatched larvae of Rhipicephalus sanguineus (Latreille, 1806) (P < 0.05)

Acaricidal activity of flavonoids extract of Borago officinalis L. (Boraginaceae) against brown dog tick, Rhipicephalus sanguineus (Latreille, 1806)

International audienceBorago officinalis L. (Boraginaceae) is a plant of the Boraginaceae family, used in Algeria for food and medicinal purposes. This study reports the effect of flavonoids extracted from the aerial part of Borago officinalis L. (Boraginaceae) on the larvae and engorged adult females of the brown dog tick Rhipicephalus sanguineus (Latreille, 1806) using adults immersion test (AIT) and larval immersion test (LIT). For this purpose, the larvae and engorged female of Rhipicephalus sanguineus (Latreille, 1806) were exposed to serial dilutions of flavonoids extract (50 mg/ml, 25 mg/ml, 12.5 mg/ml and 6.25 mg/ml) using ``dipping method'' in vitro. The plant extract was obtained by fractionation using appropriate solvents. The extraction yield is 22% with a flavonoids concentration equal to 129.12 mu g equivalent of quercetin/ml of the extract. The chromatographic analysis by high performance thin layer chromatography (HPTLC) reveals the presence of gallic acid, vanillic acid, kaempferol, dihydroxybenzoic and quercetin. The results obtained show that the flavonoids extract of Borago officunalis L. (Boraginaceae) considerably reduces the oviposition and the hatching rate of the eggs of Rhipicephalus sanguineus (Latreille, 1806) and was shown to be toxic against newly hatched larvae of Rhipicephalus sanguineus (Latreille, 1806) (P < 0.05)