A counterexample for H ∞ approximable functions

Let D be the unit disk. We show that for some relatively closed set F ⊂ D there is a function f that can be uniformly approximated on F by functions of H∞, but such that f cannot be written as f = h + g, with h ∈ H∞ and g uniformly continuous on F. This answers a question of Stray.Fil: Suarez, Fernando Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; Argentin

Approximation and the n-Berezin transform of operators on the Bergman space

To any bounded operator S on the Bergman space La2 we associate a sequence of linear transforms Bn(S ) ∈ L∞(D), where n ≧ 0, and prove that the Toeplitz operators article image tend to S for some especial classes of operators S. In particular, this holds for every radial operator in the Toeplitz algebra. Finally, we show that the inclusion of the Toeplitz algebra into the essential commutant of the Bergman shift is proper.Fil: Suarez, Fernando Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; Argentina. Universitat Autònoma de Barcelona; Españ

Localisation techniques for division in Douglas algebras

In this paper we use uniform algebra techniques and recent results on separation properties to prove several division theorems for closed subalgebras of L∞ containing H∞. We also study ideals having the local approximation property and we show that not every ideal in such algebras is local.Fil: Suarez, Fernando Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; Argentin

The Toeplitz algebra on the Bergman space coincides with its commutator ideal

Let L^2-a be the Bergman space of the unit disk and T(L^2_a) be the Banach algebra generated by Toeplitz operators T_f , with f ∈ L∞. We prove that the closed bilateral ideal of T(L2a) generated by operators of the form T_fT_g − T_gT_f coincides with T(L^2_a).Fil: Suarez, Fernando Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; Argentin

Approximation by invertible functions of H∞

We provide an analytic proof that if H∞ is the algebra of bounded analytic functions on the unit disk, A is a Banach algebra and f : H∞→A is a Banach algebras morphism with dense image, then f((H∞) −1 ) is dense in A−1.Fil: Nicolau, Artur. Universitat Autònoma de Barcelona; EspañaFil: Suarez, Fernando Daniel. Universitat Autònoma de Barcelona; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderon; Argentin

Norm closed invariant subspaces in H∞ and L∞

We characterize norm closed subspaces B of L∞(∂D) such that C(∂D)B ⊂ B, and maximal ones in the family of proper closed subspaces B of L∞(∂D) such that A(D)B ⊂ B, where A(D) is the disk algebra. Analogously, we characterize closed subspaces of H∞ that are simultaneously invariant under S and S∗, the forward and the backward shift operators, and maximal invariant subspaces of H∞.Fil: Suarez, Fernando Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; ArgentinaFil: IzuchiI, Keiji. Niigata University; Japó

Identifying yeats belonging to the Brettanomyces/Dekkera genera through the use of selective-differential media

The purpose of this work was to compare and optimise different selective and differential media to aid in isolating spoilage yeasts belonging to the Brettanomyces/Dekkera genera. Growth media containing selective and differential factors were employed. These were inoculated with strains of yeast representing Spanish oenological microbiota. Lastly, some of these isolation media were successfully applied in 24 types of wine with a high ethylphenol content, all of which were from the Haro Oenological Station (La Rioja, Spain). p-coumaric acid was determined using High performance liquid chromatography-photodiode-array detection-electrospray ionization mass spectrometry (HPLC-DAD-ESI/MS); 4-ethylphenol by using Solid phase micro extraction-gas chromatography-mass spectrometry (SPME-GC-MS); and the rest of the analysis was carried out using official OIV methodology. Actidione is the most effective selective factor for isolating Brettanomyces/Dekkera yeast genera. Other secondary selective factors (selective carbon sources, sorbic acid and ethanol as a microbicide agent) may be used successfully to eliminate potential false positivities; however, they slow growth and delay the time to obtain results

Physiological features of Schizosaccharomyces pombe of interest in the making of white wines

This work studies the physiology of Schizosaccharomyces pombe strain 938 in the production of white wine with high malic acid levels as the sole fermentative yeast, as well as in mixed and sequential fermentations with Saccharomyces cerevisiae Cru Blanc. The induction of controlled maloalcoholic fermentation through the use of Schizosaccharomyces spp. is now being viewed with much interest. The acetic, malic and pyruvic acid concentrations, relative density and pH of the musts were measured over the entire fermentation period. In all fermentations in which Schizo. pombe 938 was involved, nearly all the malic acid was consumed and moderate acetic concentrations produced. The urea content and alcohol level of these wines were notably lower than in those made with Sacch. cerevisiae Cru Blanc alone. The pyruvic acid concentration was significantly higher in Schizo. pombe fermentations. The sensorial properties of the different final wines varied widely

Schizosaccharomyces selective differential media

This study discusses the optimisation of a selectiv e and differential medium which would facilitate the isolation of Schizosaccharomyces (a genus with a low incidence compared to other microorganisms) to select individuals from this genus for industrial purposes, especially in light of the recent approval of the use of yeasts from this genus in the wine industry by the International Organisation of Vine and Wine, or to detect the presence of such yeasts, for those many authors who consider them food spoilers. To this end, we studied various selective differential agents based on the main thephysiological characteristics of this species, such as its high resistance to high concentrations of sugar, sulfur dioxide, sorbic acid, benzoic acid, acetic acid or malo ethanolic fermentation. This selective medium is based on the resistance of the genus to the antibiotic actidione and its high resistance to inhibitory agents such as benzoic acid compared to possible microorganisms which can give rise to false positive results. Malic acid was used as a differential fact or due to the ability of this genus to metabolise it to ethanol, which allows detecting of the degradation of this compound. Lastly, the medium was successfully used to isolate strains of Schizosaccharomyces pombe from honey

Cellulose recycling as a source of raw chirality

Modern organic chemistry requires easily obtainable chiral building blocks that show high chemical versatility for their application in the synthesis of enantiopure compounds. Biomass has been demonstrated to be a widely available raw material that represents the only abundant source of renewable organic carbon. Through the pyrolitic conversion of cellulose or cellulose-containing materials it is possible to produce levoglucosenone, a highly functionalized chiral structure. This compound has been innovatively used as a template for the synthesis of key intermediates of biologically active products and for the preparation of chiral auxiliaries, catalysts, and organocatalysts for their application in asymmetric synthesis.Fil: Biava, Hernan Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Química Rosario; ArgentinaFil: Spanevello, Rolando Angel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Química Rosario; ArgentinaFil: Suarez, Alejandra Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Química Rosario; ArgentinaFil: Mata, Ernesto Gabino. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Química Rosario; ArgentinaFil: Mangione, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Química Rosario; ArgentinaFil: Sarotti, Ariel Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Química Rosario; ArgentinaFil: Corne, Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Química Rosario; ArgentinaFil: Botta, María Celeste. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Química Rosario; ArgentinaFil: Giordano, Enrique David Victor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Química Rosario; ArgentinaFil: Giri, German Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Química Rosario; ArgentinaFil: Llompart, David Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Química Rosario; Argentin