On the Whitham hierarchy: dressing scheme, string equations and additional symmetrie

A new description of the universal Whitham hierarchy in terms of a factorization problem in the Lie group of canonical transformations is provided. This scheme allows us to give a natural description of dressing transformations, string equations and additional symmetries for the Whitham hierarchy. We show how to dress any given solution and prove that any solution of the hierarchy may be undressed, and therefore comes from a factorization of a canonical transformation. A particulary important function, related to the $\tau$-function, appears as a potential of the hierarchy. We introduce a class of string equations which extends and contains previous classes of string equations considered by Krichever and by Takasaki and Takebe. The scheme is also applied for an convenient derivation of additional symmetries. Moreover, new functional symmetries of the Zakharov extension of the Benney gas equations are given and the action of additional symmetries over the potential in terms of linear PDEs is characterized

On the Whitham hierarchy: dressing scheme, string equations and additional symmetrie

A new description of the universal Whitham hierarchy in terms of a factorization problem in the Lie group of canonical transformations is provided. This scheme allows us to give a natural description of dressing transformations, string equations and additional symmetries for the Whitham hierarchy. We show how to dress any given solution and prove that any solution of the hierarchy may be undressed, and therefore comes from a factorization of a canonical transformation. A particulary important function, related to the $\tau$-function, appears as a potential of the hierarchy. We introduce a class of string equations which extends and contains previous classes of string equations considered by Krichever and by Takasaki and Takebe. The scheme is also applied for an convenient derivation of additional symmetries. Moreover, new functional symmetries of the Zakharov extension of the Benney gas equations are given and the action of additional symmetries over the potential in terms of linear PDEs is characterized

Instalacion de un sistema de bitacoras para la pesca atunera de superficie en Venezuela y analisis de los primeros resultados

Dans le cadre des recommandations faites par le SCRS de la C.I.C.T.A. un nouveau système de livres de bord a été mis en place au Vénézuela en avril 1986. L'analyse des premiers résultats montre que les déclarations faites par les canneurs et les senneurs divergent pour les espèces de thon peu abondantes dans les eaux vénézueliennes comme le patudo (#Thunnus obesus) ou le thon noir (#Thunnus atlanticus). La comparaison des déclarations réalisées par un senneur et un canneur sur un même banc confirme l'existence de biais qui affecte également les deux principales espèces qui sont l'albacore (#Thunnus albacares) et le listao (#Katsuwonus pelamis) et en particulier les estimations du poids moyen des individus de ces deux espèces ... L'observation d'oiseaux, accompagnée (95,5 % des cas), ou non (50 %), par d'autres indices est la principale source de détection des bancs de thon

Influence of food system conditions on N-acyl-L-homoserine lactones production by <i>Aeromonas</i> spp.

Eleven of 13 Aeromonas strains were shown to produce AHLs. Results of TLC showed that N-butanoyl-L-homoserine lactone (C4-HSL) was the main AHL produced in LB medium at 30 degrees C. The influence of different carbon sources, temperature, pH values and salt concentrations on AHL production was determined in eight A. hydrophila and one A. caviae strain. Additionally a quantitative study of C4-HSL production by A. hydrophila strain 519 under different conditions was performed. Positive results were found in the AHL induction assay for some Aeromonas strains in cultures in LB agar incubated at 12 degrees C after 72-96 h. The induction of the sensor strains by Aeromonas spp. occurred in LB medium supplemented with all carbon sources in a concentration of 0.5%. The production of C4-HSL by A. hydrophila 519 was found until 3.5% (w/v) of NaCl. For pHs close to the neutrality the C4-HSL production by A. hydrophila was evident after 24-48 h of incubation. A. hydrophila 519 produced C4-HSL under anaerobic conditions. Also, the AHL production by Aeromonas strains was studied in simulate agar of shrimp, fish and some vegetables. The production of AHLs was evident by almost all the test strains in shrimp simulated agar. In fish agar only for one of three fish species tested, positive results were found. Induction assay in vegetables simulated agar showed principally negative results, probably because of the presence of inhibitory compounds in these vegetables

BINCOR: An r package for estimating the correlation between two unevenly spaced time series

This paper presents a computational program named BINCOR (BINned CORrelation) for estimating the correlation between two unevenly spaced time series. This program is also applicable to the situation of two evenly spaced time series not on the same time grid. BINCOR is based on a novel estimation approach proposed by Mudelsee (2010) for estimating the correlation between two climate time series with different timescales. The idea is that autocorrelation (e.g. an AR1 process) means that memory enables values obtained on different time points to be correlated. Binned correlation is performed by resampling the time series under study into time bins on a regular grid, assigning the mean values of the variable under scrutiny within those bins. We present two examples of our BINCOR package with real data: instrumental and paleoclimatic time series. In both applications BINCOR works properly in detecting well-established relationships between the climate records compared. © Technische Universitaet Wien

Endothelium-dependent relaxation of human saphenous veins in response to vasopressin and desmopressin

Purpose:The goal of this study was to determine the effects of vasopressin and the selective V2-receptor agonist desmopressin on human saphenous veins, with special emphasis on endothelium-mediated responses.Methods:Human saphenous vein segments were obtained from 35 patients undergoing coronary bypass surgery. Paired segments, one normal and the other deendothelized by gentle rubbing, were mounted for isometric recording of tension in organ baths. Concentration-response curves to vasopressin and desmopressin were determined in the presence and in the absence of either the V,-receptor antagonist d(CH2)5Tyr(Me)AVP (10−6 mol/L), the V1-V2 receptor antagonist desGly-d(CH2)5D-Tyr(Et)ValAVP (10−6 mol/L), indomethacin (10−6 mol/L), or NG-nitro-L-arginine methyl ester hydrochloride (L-NAME, 10−4 mol/L).Results:In vein rings under resting tension, vasopressin produced concentration-dependent, endothelium-independent contractions with a concentration of vasopressin producing-half-maximal contractions (EC50) of 3.44 × 10−8 mol/L. The vasopressin V1-receptor antagonist (10−6 mol/L) displaced the control curve to vasopressin 9.86-fold to the right in a parallel manner. In precontracted vein rings previously treated with the V1-antagonist (10−6 mol/L), vasopressin caused endothelium-dependent relaxations. This relaxation was reduced significantly by indomethacin (10−6 mol/L) and unaffected by the V1-V2-receptor antagonist (10−6 mol/L) or by L-NAME (10−4 mol/L). Desmopressin caused endothelium-dependent relaxations in precontracted vein rings that were inhibited by the mixed V1-V2-receptor antagonist and by indomethacin, but not by the V1-antagonist or by pretreatment with L-NAME.Conclusions:These observations indicate that vasopressin exerts contractile effects on human saphenous vein by V1-receptor stimulation. Vasopressin causes dilatation of human saphenous vein only if V1-receptor blockade is present. This relaxation appears to be mediated by the release of relaxant Prostaglandins, probably derived from endothelial cells, and is independent of V2-receptor stimulation or release of nitric oxide. Desmopressin elicits relaxation that is largely dependent on V2-receptor stimulation, which may bring about the release of dilating Prostaglandins from the endothelial cells

TRALI: Party of One; Real-Time Hemovigilance Demonstrates Multiple Event-Free Transfusions

Mechele Adrian pictured.https://openworks.mdanderson.org/aprn-week-23/1019/thumbnail.jp

A simple device for multiplex ELISA made from melt-extruded plastic microcapillary film

We present a simple device for multiplex quantitative enzyme-linked immunosorbant assays (ELISA) made from a novel melt-extruded microcapillary film (MCF) containing a parallel array of 200µm capillaries along its length. To make ELISA devices different protein antigens or antibodies were immobilised inside individual microcapillaries within long reels of MCF extruded from fluorinated ethylene propylene (FEP). Short pieces of coated film were cut and interfaced with a pipette, allowing sequential uptake of samples and detection solutions into all capillaries from a reagent well. As well as being simple to produce, these FEP MCF devices have excellent light transmittance allowing direct optical interrogation of the capillaries for simple signal quantification. Proof of concept experiments demonstrate both quantitative and multiplex assays in FEP MCF devices using a standard direct ELISA procedure and read using a flatbed scanner. This new multiplex immunoassay platform should find applications ranging from lab detection to point-of-care and field diagnostics