Definitions and examples in elementary calculus: the case of monotonicity of functions

This paper is devoted to the investigation of students’ understanding and handling of examples in the framework of an example-based introductory mathematics undergraduate course. The plan of the course included a wide use of graphs in standard lectures, tutoring sessions as well as in examinations. This study deals with the notion of increasing function, which has been introduced by means of both the standard definition and a range of examples and non-examples, most often conveyed through graphs. We have analysed students’ interpretations of the notion of increasing function as they applied them in a set of written examination tests. The data gathered have been completed by a number of interviews of students whose answers were difficult to interpret. The outcomes underline the importance of linguistic and semiotic competence and suggest that the design of innovative teaching paths should take care of the linguistic and semiotic skills needed to handle the representations involved.     

Preparation of a new chiral non-racemic sulfur-containing diselenide and applications in asymmetric synthesis

The synthesis of the new chiral non-racemic sulfur-containing diselenide, di-2-methoxy-6-[(1S)-1-(methylthio)ethyl]phenyl diselenide, is described. When treated with ammonium persulfate this diselenide is transformed into the corresponding selenenyl sulfate, which acts as a strong electrophilic reagent and adds to alkenes, in the presence of methanol or water, to afford the products of selenomethoxylation or selenohydroxylation, respectively, with excellent diastereoselectivities. Starting from alkenes containing internal nucleophiles, asymmetric cyclofunctionalization reactions also resulted in good chemical yields, complete regioselectivities, and high diastereoselectivities. This sulfur-containing diselenide can also be used in catalytic amounts to promote one-pot selenenylation-deselenenylation processes, from which several types of products can be obtained in high yield and with good enantiomeric excess.     

Rapid quantitation of globotriaosylceramide in human plasma and urine: a potential application for monitoring enzyme replacement therapy in Anderson-Fabry disease

A method for measuring globotriaosylceramide (Gb3, or GL3) levels in plasma and urine of humans affected by Anderson-Fabry disease has been developed. The analyses are performed using flow injection analysis-electrospray ionization-tandem mass spectrometry (FIA-ESI-MS/MS). The method is rapid, sensitive and hence suitable for high-throughput analyses, requiring only a simple 50-fold dilution for the preparation of plasma and urine samples. The detection of the analytes of interest was achieved using a triple quadrupole instrument operating in the multiple reaction monitoring mode. The linearity of the calibration standard responses, the intra- and inter-assay precision, the accuracy and the detection limit of the method were evaluated. The proposed method allows a rapid and accurate assessment of globotriaosylceramide in biological samples. Data obtained from healthy volunteers and Anderson-Fabry affected subjects suggest a potential role for this technique in monitoring the effectiveness of Anderson-Fabry disease therapy. The results obtained in two actual cases treated with enzyme replacement therapy are reported and discussed.     

Interaction induced localization in a gas of pyramidal molecules

We propose a model to describe a gas of pyramidal molecules interacting via dipole-dipole interactions. The interaction modifies the tunneling properties between the classical equilibrium configurations of the single molecule and, for sufficiently high pressure, the molecules become localized in these classical configurations. We explain quantitatively, without free parameters, the shift to zero frequency of the inversion line observed upon increase of the pressure in a gas of ammonia or deuterated ammonia. For sufficiently high pressures, our model suggests the existence of a super-selection rule for states of different chirality in substituted derivatives.     

ISOLATION AND CHARACTERIZATION OF THE PRESUMED PHOTORECEPTOR PROTEIN OF Blepharisma japonicum

Abstract— Photosensory responses in the ciliated protozoan Blepharisma japonicum are mediated by a hypericin-like chromophore, blepharismin, localized in granules distributed under the cell membrane. A blepharismin-binding protein, with an apparcnt molecular weight ranging between 35 and 38 kDa, has been isolated by means of column separations and preparative isoelectric focusing and characterized by means of gel electrophoresis, analytic isoelectric focusing as well as absorption and fluorescence spectroscopy.     

Alcune classi di epimorfismi d’anelli

Riassunto Si indicano una costruzione e alcune proprietà del morfismo terminale nella categoria degli epimorfismi iniettivi di dato dominioA, conA anello commutativo unitario ridotto. Si considerano poi certi epimorfismi di dominioA, detti ?S-spezzamenti irriducibili? (S⊂A). GliS-spezzamenti irriducibili a codominio ridotto risultano parametrizzati (a meno di isomorfismi) dai chiusi di una opportuna topologia su SpecA.

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Summary LetA be any reduced commutative ring with 1. Consider the category of injective ring-epimorphisms with domainA. In the first part of this paper, a construction and some properties of a final morphism in the above category are shown. In the second part, some special epimorphisms with domainA are considered, which are called irreducible ?S-spezzamenti?. A parametrization of the collection of irreducible ?S-spezzamenti? (up to isomorphisms) is given, by the collection of closed sets of a suitable topology on SpecA.

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Lavoro eseguito nell’ambito del Gruppo Nazionale Strutture Algebriche e Geometriche e Applicazioni del C.N.R.